1# SPDX-License-Identifier: GPL-2.0+ 2# 3# (C) Copyright 2000 - 2013 4# Wolfgang Denk, DENX Software Engineering, wd@denx.de. 5 6Summary: 7======== 8 9This directory contains the source code for U-Boot, a boot loader for 10Embedded boards based on PowerPC, ARM, MIPS and several other 11processors, which can be installed in a boot ROM and used to 12initialize and test the hardware or to download and run application 13code. 14 15The development of U-Boot is closely related to Linux: some parts of 16the source code originate in the Linux source tree, we have some 17header files in common, and special provision has been made to 18support booting of Linux images. 19 20Some attention has been paid to make this software easily 21configurable and extendable. For instance, all monitor commands are 22implemented with the same call interface, so that it's very easy to 23add new commands. Also, instead of permanently adding rarely used 24code (for instance hardware test utilities) to the monitor, you can 25load and run it dynamically. 26 27 28Status: 29======= 30 31In general, all boards for which a configuration option exists in the 32Makefile have been tested to some extent and can be considered 33"working". In fact, many of them are used in production systems. 34 35In case of problems see the CHANGELOG file to find out who contributed 36the specific port. In addition, there are various MAINTAINERS files 37scattered throughout the U-Boot source identifying the people or 38companies responsible for various boards and subsystems. 39 40Note: As of August, 2010, there is no longer a CHANGELOG file in the 41actual U-Boot source tree; however, it can be created dynamically 42from the Git log using: 43 44 make CHANGELOG 45 46 47Where to get help: 48================== 49 50In case you have questions about, problems with or contributions for 51U-Boot, you should send a message to the U-Boot mailing list at 52<u-boot@lists.denx.de>. There is also an archive of previous traffic 53on the mailing list - please search the archive before asking FAQ's. 54Please see http://lists.denx.de/pipermail/u-boot and 55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot 56 57 58Where to get source code: 59========================= 60 61The U-Boot source code is maintained in the Git repository at 62git://www.denx.de/git/u-boot.git ; you can browse it online at 63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary 64 65The "snapshot" links on this page allow you to download tarballs of 66any version you might be interested in. Official releases are also 67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/ 68directory. 69 70Pre-built (and tested) images are available from 71ftp://ftp.denx.de/pub/u-boot/images/ 72 73 74Where we come from: 75=================== 76 77- start from 8xxrom sources 78- create PPCBoot project (http://sourceforge.net/projects/ppcboot) 79- clean up code 80- make it easier to add custom boards 81- make it possible to add other [PowerPC] CPUs 82- extend functions, especially: 83 * Provide extended interface to Linux boot loader 84 * S-Record download 85 * network boot 86 * ATA disk / SCSI ... boot 87- create ARMBoot project (http://sourceforge.net/projects/armboot) 88- add other CPU families (starting with ARM) 89- create U-Boot project (http://sourceforge.net/projects/u-boot) 90- current project page: see http://www.denx.de/wiki/U-Boot 91 92 93Names and Spelling: 94=================== 95 96The "official" name of this project is "Das U-Boot". The spelling 97"U-Boot" shall be used in all written text (documentation, comments 98in source files etc.). Example: 99 100 This is the README file for the U-Boot project. 101 102File names etc. shall be based on the string "u-boot". Examples: 103 104 include/asm-ppc/u-boot.h 105 106 #include <asm/u-boot.h> 107 108Variable names, preprocessor constants etc. shall be either based on 109the string "u_boot" or on "U_BOOT". Example: 110 111 U_BOOT_VERSION u_boot_logo 112 IH_OS_U_BOOT u_boot_hush_start 113 114 115Versioning: 116=========== 117 118Starting with the release in October 2008, the names of the releases 119were changed from numerical release numbers without deeper meaning 120into a time stamp based numbering. Regular releases are identified by 121names consisting of the calendar year and month of the release date. 122Additional fields (if present) indicate release candidates or bug fix 123releases in "stable" maintenance trees. 124 125Examples: 126 U-Boot v2009.11 - Release November 2009 127 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree 128 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release 129 130 131Directory Hierarchy: 132==================== 133 134/arch Architecture specific files 135 /arc Files generic to ARC architecture 136 /arm Files generic to ARM architecture 137 /m68k Files generic to m68k architecture 138 /microblaze Files generic to microblaze architecture 139 /mips Files generic to MIPS architecture 140 /nds32 Files generic to NDS32 architecture 141 /nios2 Files generic to Altera NIOS2 architecture 142 /openrisc Files generic to OpenRISC architecture 143 /powerpc Files generic to PowerPC architecture 144 /riscv Files generic to RISC-V architecture 145 /sandbox Files generic to HW-independent "sandbox" 146 /sh Files generic to SH architecture 147 /x86 Files generic to x86 architecture 148/api Machine/arch independent API for external apps 149/board Board dependent files 150/cmd U-Boot commands functions 151/common Misc architecture independent functions 152/configs Board default configuration files 153/disk Code for disk drive partition handling 154/doc Documentation (don't expect too much) 155/drivers Commonly used device drivers 156/dts Contains Makefile for building internal U-Boot fdt. 157/examples Example code for standalone applications, etc. 158/fs Filesystem code (cramfs, ext2, jffs2, etc.) 159/include Header Files 160/lib Library routines generic to all architectures 161/Licenses Various license files 162/net Networking code 163/post Power On Self Test 164/scripts Various build scripts and Makefiles 165/test Various unit test files 166/tools Tools to build S-Record or U-Boot images, etc. 167 168Software Configuration: 169======================= 170 171Configuration is usually done using C preprocessor defines; the 172rationale behind that is to avoid dead code whenever possible. 173 174There are two classes of configuration variables: 175 176* Configuration _OPTIONS_: 177 These are selectable by the user and have names beginning with 178 "CONFIG_". 179 180* Configuration _SETTINGS_: 181 These depend on the hardware etc. and should not be meddled with if 182 you don't know what you're doing; they have names beginning with 183 "CONFIG_SYS_". 184 185Previously, all configuration was done by hand, which involved creating 186symbolic links and editing configuration files manually. More recently, 187U-Boot has added the Kbuild infrastructure used by the Linux kernel, 188allowing you to use the "make menuconfig" command to configure your 189build. 190 191 192Selection of Processor Architecture and Board Type: 193--------------------------------------------------- 194 195For all supported boards there are ready-to-use default 196configurations available; just type "make <board_name>_defconfig". 197 198Example: For a TQM823L module type: 199 200 cd u-boot 201 make TQM823L_defconfig 202 203Note: If you're looking for the default configuration file for a board 204you're sure used to be there but is now missing, check the file 205doc/README.scrapyard for a list of no longer supported boards. 206 207Sandbox Environment: 208-------------------- 209 210U-Boot can be built natively to run on a Linux host using the 'sandbox' 211board. This allows feature development which is not board- or architecture- 212specific to be undertaken on a native platform. The sandbox is also used to 213run some of U-Boot's tests. 214 215See doc/arch/index.rst for more details. 216 217 218Board Initialisation Flow: 219-------------------------- 220 221This is the intended start-up flow for boards. This should apply for both 222SPL and U-Boot proper (i.e. they both follow the same rules). 223 224Note: "SPL" stands for "Secondary Program Loader," which is explained in 225more detail later in this file. 226 227At present, SPL mostly uses a separate code path, but the function names 228and roles of each function are the same. Some boards or architectures 229may not conform to this. At least most ARM boards which use 230CONFIG_SPL_FRAMEWORK conform to this. 231 232Execution typically starts with an architecture-specific (and possibly 233CPU-specific) start.S file, such as: 234 235 - arch/arm/cpu/armv7/start.S 236 - arch/powerpc/cpu/mpc83xx/start.S 237 - arch/mips/cpu/start.S 238 239and so on. From there, three functions are called; the purpose and 240limitations of each of these functions are described below. 241 242lowlevel_init(): 243 - purpose: essential init to permit execution to reach board_init_f() 244 - no global_data or BSS 245 - there is no stack (ARMv7 may have one but it will soon be removed) 246 - must not set up SDRAM or use console 247 - must only do the bare minimum to allow execution to continue to 248 board_init_f() 249 - this is almost never needed 250 - return normally from this function 251 252board_init_f(): 253 - purpose: set up the machine ready for running board_init_r(): 254 i.e. SDRAM and serial UART 255 - global_data is available 256 - stack is in SRAM 257 - BSS is not available, so you cannot use global/static variables, 258 only stack variables and global_data 259 260 Non-SPL-specific notes: 261 - dram_init() is called to set up DRAM. If already done in SPL this 262 can do nothing 263 264 SPL-specific notes: 265 - you can override the entire board_init_f() function with your own 266 version as needed. 267 - preloader_console_init() can be called here in extremis 268 - should set up SDRAM, and anything needed to make the UART work 269 - these is no need to clear BSS, it will be done by crt0.S 270 - for specific scenarios on certain architectures an early BSS *can* 271 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing 272 of BSS prior to entering board_init_f()) but doing so is discouraged. 273 Instead it is strongly recommended to architect any code changes 274 or additions such to not depend on the availability of BSS during 275 board_init_f() as indicated in other sections of this README to 276 maintain compatibility and consistency across the entire code base. 277 - must return normally from this function (don't call board_init_r() 278 directly) 279 280Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at 281this point the stack and global_data are relocated to below 282CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of 283memory. 284 285board_init_r(): 286 - purpose: main execution, common code 287 - global_data is available 288 - SDRAM is available 289 - BSS is available, all static/global variables can be used 290 - execution eventually continues to main_loop() 291 292 Non-SPL-specific notes: 293 - U-Boot is relocated to the top of memory and is now running from 294 there. 295 296 SPL-specific notes: 297 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and 298 CONFIG_SPL_STACK_R_ADDR points into SDRAM 299 - preloader_console_init() can be called here - typically this is 300 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a 301 spl_board_init() function containing this call 302 - loads U-Boot or (in falcon mode) Linux 303 304 305 306Configuration Options: 307---------------------- 308 309Configuration depends on the combination of board and CPU type; all 310such information is kept in a configuration file 311"include/configs/<board_name>.h". 312 313Example: For a TQM823L module, all configuration settings are in 314"include/configs/TQM823L.h". 315 316 317Many of the options are named exactly as the corresponding Linux 318kernel configuration options. The intention is to make it easier to 319build a config tool - later. 320 321- ARM Platform Bus Type(CCI): 322 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which 323 provides full cache coherency between two clusters of multi-core 324 CPUs and I/O coherency for devices and I/O masters 325 326 CONFIG_SYS_FSL_HAS_CCI400 327 328 Defined For SoC that has cache coherent interconnect 329 CCN-400 330 331 CONFIG_SYS_FSL_HAS_CCN504 332 333 Defined for SoC that has cache coherent interconnect CCN-504 334 335The following options need to be configured: 336 337- CPU Type: Define exactly one, e.g. CONFIG_MPC85XX. 338 339- Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS. 340 341- 85xx CPU Options: 342 CONFIG_SYS_PPC64 343 344 Specifies that the core is a 64-bit PowerPC implementation (implements 345 the "64" category of the Power ISA). This is necessary for ePAPR 346 compliance, among other possible reasons. 347 348 CONFIG_SYS_FSL_TBCLK_DIV 349 350 Defines the core time base clock divider ratio compared to the 351 system clock. On most PQ3 devices this is 8, on newer QorIQ 352 devices it can be 16 or 32. The ratio varies from SoC to Soc. 353 354 CONFIG_SYS_FSL_PCIE_COMPAT 355 356 Defines the string to utilize when trying to match PCIe device 357 tree nodes for the given platform. 358 359 CONFIG_SYS_FSL_ERRATUM_A004510 360 361 Enables a workaround for erratum A004510. If set, 362 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and 363 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set. 364 365 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV 366 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional) 367 368 Defines one or two SoC revisions (low 8 bits of SVR) 369 for which the A004510 workaround should be applied. 370 371 The rest of SVR is either not relevant to the decision 372 of whether the erratum is present (e.g. p2040 versus 373 p2041) or is implied by the build target, which controls 374 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set. 375 376 See Freescale App Note 4493 for more information about 377 this erratum. 378 379 CONFIG_A003399_NOR_WORKAROUND 380 Enables a workaround for IFC erratum A003399. It is only 381 required during NOR boot. 382 383 CONFIG_A008044_WORKAROUND 384 Enables a workaround for T1040/T1042 erratum A008044. It is only 385 required during NAND boot and valid for Rev 1.0 SoC revision 386 387 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY 388 389 This is the value to write into CCSR offset 0x18600 390 according to the A004510 workaround. 391 392 CONFIG_SYS_FSL_DSP_DDR_ADDR 393 This value denotes start offset of DDR memory which is 394 connected exclusively to the DSP cores. 395 396 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR 397 This value denotes start offset of M2 memory 398 which is directly connected to the DSP core. 399 400 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR 401 This value denotes start offset of M3 memory which is directly 402 connected to the DSP core. 403 404 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT 405 This value denotes start offset of DSP CCSR space. 406 407 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK 408 Single Source Clock is clocking mode present in some of FSL SoC's. 409 In this mode, a single differential clock is used to supply 410 clocks to the sysclock, ddrclock and usbclock. 411 412 CONFIG_SYS_CPC_REINIT_F 413 This CONFIG is defined when the CPC is configured as SRAM at the 414 time of U-Boot entry and is required to be re-initialized. 415 416 CONFIG_DEEP_SLEEP 417 Indicates this SoC supports deep sleep feature. If deep sleep is 418 supported, core will start to execute uboot when wakes up. 419 420- Generic CPU options: 421 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN 422 423 Defines the endianess of the CPU. Implementation of those 424 values is arch specific. 425 426 CONFIG_SYS_FSL_DDR 427 Freescale DDR driver in use. This type of DDR controller is 428 found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core 429 SoCs. 430 431 CONFIG_SYS_FSL_DDR_ADDR 432 Freescale DDR memory-mapped register base. 433 434 CONFIG_SYS_FSL_DDR_EMU 435 Specify emulator support for DDR. Some DDR features such as 436 deskew training are not available. 437 438 CONFIG_SYS_FSL_DDRC_GEN1 439 Freescale DDR1 controller. 440 441 CONFIG_SYS_FSL_DDRC_GEN2 442 Freescale DDR2 controller. 443 444 CONFIG_SYS_FSL_DDRC_GEN3 445 Freescale DDR3 controller. 446 447 CONFIG_SYS_FSL_DDRC_GEN4 448 Freescale DDR4 controller. 449 450 CONFIG_SYS_FSL_DDRC_ARM_GEN3 451 Freescale DDR3 controller for ARM-based SoCs. 452 453 CONFIG_SYS_FSL_DDR1 454 Board config to use DDR1. It can be enabled for SoCs with 455 Freescale DDR1 or DDR2 controllers, depending on the board 456 implemetation. 457 458 CONFIG_SYS_FSL_DDR2 459 Board config to use DDR2. It can be enabled for SoCs with 460 Freescale DDR2 or DDR3 controllers, depending on the board 461 implementation. 462 463 CONFIG_SYS_FSL_DDR3 464 Board config to use DDR3. It can be enabled for SoCs with 465 Freescale DDR3 or DDR3L controllers. 466 467 CONFIG_SYS_FSL_DDR3L 468 Board config to use DDR3L. It can be enabled for SoCs with 469 DDR3L controllers. 470 471 CONFIG_SYS_FSL_DDR4 472 Board config to use DDR4. It can be enabled for SoCs with 473 DDR4 controllers. 474 475 CONFIG_SYS_FSL_IFC_BE 476 Defines the IFC controller register space as Big Endian 477 478 CONFIG_SYS_FSL_IFC_LE 479 Defines the IFC controller register space as Little Endian 480 481 CONFIG_SYS_FSL_IFC_CLK_DIV 482 Defines divider of platform clock(clock input to IFC controller). 483 484 CONFIG_SYS_FSL_LBC_CLK_DIV 485 Defines divider of platform clock(clock input to eLBC controller). 486 487 CONFIG_SYS_FSL_PBL_PBI 488 It enables addition of RCW (Power on reset configuration) in built image. 489 Please refer doc/README.pblimage for more details 490 491 CONFIG_SYS_FSL_PBL_RCW 492 It adds PBI(pre-boot instructions) commands in u-boot build image. 493 PBI commands can be used to configure SoC before it starts the execution. 494 Please refer doc/README.pblimage for more details 495 496 CONFIG_SYS_FSL_DDR_BE 497 Defines the DDR controller register space as Big Endian 498 499 CONFIG_SYS_FSL_DDR_LE 500 Defines the DDR controller register space as Little Endian 501 502 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY 503 Physical address from the view of DDR controllers. It is the 504 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But 505 it could be different for ARM SoCs. 506 507 CONFIG_SYS_FSL_DDR_INTLV_256B 508 DDR controller interleaving on 256-byte. This is a special 509 interleaving mode, handled by Dickens for Freescale layerscape 510 SoCs with ARM core. 511 512 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS 513 Number of controllers used as main memory. 514 515 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS 516 Number of controllers used for other than main memory. 517 518 CONFIG_SYS_FSL_HAS_DP_DDR 519 Defines the SoC has DP-DDR used for DPAA. 520 521 CONFIG_SYS_FSL_SEC_BE 522 Defines the SEC controller register space as Big Endian 523 524 CONFIG_SYS_FSL_SEC_LE 525 Defines the SEC controller register space as Little Endian 526 527- MIPS CPU options: 528 CONFIG_SYS_INIT_SP_OFFSET 529 530 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack 531 pointer. This is needed for the temporary stack before 532 relocation. 533 534 CONFIG_XWAY_SWAP_BYTES 535 536 Enable compilation of tools/xway-swap-bytes needed for Lantiq 537 XWAY SoCs for booting from NOR flash. The U-Boot image needs to 538 be swapped if a flash programmer is used. 539 540- ARM options: 541 CONFIG_SYS_EXCEPTION_VECTORS_HIGH 542 543 Select high exception vectors of the ARM core, e.g., do not 544 clear the V bit of the c1 register of CP15. 545 546 COUNTER_FREQUENCY 547 Generic timer clock source frequency. 548 549 COUNTER_FREQUENCY_REAL 550 Generic timer clock source frequency if the real clock is 551 different from COUNTER_FREQUENCY, and can only be determined 552 at run time. 553 554- Tegra SoC options: 555 CONFIG_TEGRA_SUPPORT_NON_SECURE 556 557 Support executing U-Boot in non-secure (NS) mode. Certain 558 impossible actions will be skipped if the CPU is in NS mode, 559 such as ARM architectural timer initialization. 560 561- Linux Kernel Interface: 562 CONFIG_CLOCKS_IN_MHZ 563 564 U-Boot stores all clock information in Hz 565 internally. For binary compatibility with older Linux 566 kernels (which expect the clocks passed in the 567 bd_info data to be in MHz) the environment variable 568 "clocks_in_mhz" can be defined so that U-Boot 569 converts clock data to MHZ before passing it to the 570 Linux kernel. 571 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of 572 "clocks_in_mhz=1" is automatically included in the 573 default environment. 574 575 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only] 576 577 When transferring memsize parameter to Linux, some versions 578 expect it to be in bytes, others in MB. 579 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes. 580 581 CONFIG_OF_LIBFDT 582 583 New kernel versions are expecting firmware settings to be 584 passed using flattened device trees (based on open firmware 585 concepts). 586 587 CONFIG_OF_LIBFDT 588 * New libfdt-based support 589 * Adds the "fdt" command 590 * The bootm command automatically updates the fdt 591 592 OF_TBCLK - The timebase frequency. 593 OF_STDOUT_PATH - The path to the console device 594 595 boards with QUICC Engines require OF_QE to set UCC MAC 596 addresses 597 598 CONFIG_OF_BOARD_SETUP 599 600 Board code has addition modification that it wants to make 601 to the flat device tree before handing it off to the kernel 602 603 CONFIG_OF_SYSTEM_SETUP 604 605 Other code has addition modification that it wants to make 606 to the flat device tree before handing it off to the kernel. 607 This causes ft_system_setup() to be called before booting 608 the kernel. 609 610 CONFIG_OF_IDE_FIXUP 611 612 U-Boot can detect if an IDE device is present or not. 613 If not, and this new config option is activated, U-Boot 614 removes the ATA node from the DTS before booting Linux, 615 so the Linux IDE driver does not probe the device and 616 crash. This is needed for buggy hardware (uc101) where 617 no pull down resistor is connected to the signal IDE5V_DD7. 618 619 CONFIG_MACH_TYPE [relevant for ARM only][mandatory] 620 621 This setting is mandatory for all boards that have only one 622 machine type and must be used to specify the machine type 623 number as it appears in the ARM machine registry 624 (see http://www.arm.linux.org.uk/developer/machines/). 625 Only boards that have multiple machine types supported 626 in a single configuration file and the machine type is 627 runtime discoverable, do not have to use this setting. 628 629- vxWorks boot parameters: 630 631 bootvx constructs a valid bootline using the following 632 environments variables: bootdev, bootfile, ipaddr, netmask, 633 serverip, gatewayip, hostname, othbootargs. 634 It loads the vxWorks image pointed bootfile. 635 636 Note: If a "bootargs" environment is defined, it will overwride 637 the defaults discussed just above. 638 639- Cache Configuration: 640 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot 641 642- Cache Configuration for ARM: 643 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache 644 controller 645 CONFIG_SYS_PL310_BASE - Physical base address of PL310 646 controller register space 647 648- Serial Ports: 649 CONFIG_PL010_SERIAL 650 651 Define this if you want support for Amba PrimeCell PL010 UARTs. 652 653 CONFIG_PL011_SERIAL 654 655 Define this if you want support for Amba PrimeCell PL011 UARTs. 656 657 CONFIG_PL011_CLOCK 658 659 If you have Amba PrimeCell PL011 UARTs, set this variable to 660 the clock speed of the UARTs. 661 662 CONFIG_PL01x_PORTS 663 664 If you have Amba PrimeCell PL010 or PL011 UARTs on your board, 665 define this to a list of base addresses for each (supported) 666 port. See e.g. include/configs/versatile.h 667 668 CONFIG_SERIAL_HW_FLOW_CONTROL 669 670 Define this variable to enable hw flow control in serial driver. 671 Current user of this option is drivers/serial/nsl16550.c driver 672 673- Console Baudrate: 674 CONFIG_BAUDRATE - in bps 675 Select one of the baudrates listed in 676 CONFIG_SYS_BAUDRATE_TABLE, see below. 677 678- Autoboot Command: 679 CONFIG_BOOTCOMMAND 680 Only needed when CONFIG_BOOTDELAY is enabled; 681 define a command string that is automatically executed 682 when no character is read on the console interface 683 within "Boot Delay" after reset. 684 685 CONFIG_RAMBOOT and CONFIG_NFSBOOT 686 The value of these goes into the environment as 687 "ramboot" and "nfsboot" respectively, and can be used 688 as a convenience, when switching between booting from 689 RAM and NFS. 690 691- Serial Download Echo Mode: 692 CONFIG_LOADS_ECHO 693 If defined to 1, all characters received during a 694 serial download (using the "loads" command) are 695 echoed back. This might be needed by some terminal 696 emulations (like "cu"), but may as well just take 697 time on others. This setting #define's the initial 698 value of the "loads_echo" environment variable. 699 700- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined) 701 CONFIG_KGDB_BAUDRATE 702 Select one of the baudrates listed in 703 CONFIG_SYS_BAUDRATE_TABLE, see below. 704 705- Removal of commands 706 If no commands are needed to boot, you can disable 707 CONFIG_CMDLINE to remove them. In this case, the command line 708 will not be available, and when U-Boot wants to execute the 709 boot command (on start-up) it will call board_run_command() 710 instead. This can reduce image size significantly for very 711 simple boot procedures. 712 713- Regular expression support: 714 CONFIG_REGEX 715 If this variable is defined, U-Boot is linked against 716 the SLRE (Super Light Regular Expression) library, 717 which adds regex support to some commands, as for 718 example "env grep" and "setexpr". 719 720- Device tree: 721 CONFIG_OF_CONTROL 722 If this variable is defined, U-Boot will use a device tree 723 to configure its devices, instead of relying on statically 724 compiled #defines in the board file. This option is 725 experimental and only available on a few boards. The device 726 tree is available in the global data as gd->fdt_blob. 727 728 U-Boot needs to get its device tree from somewhere. This can 729 be done using one of the three options below: 730 731 CONFIG_OF_EMBED 732 If this variable is defined, U-Boot will embed a device tree 733 binary in its image. This device tree file should be in the 734 board directory and called <soc>-<board>.dts. The binary file 735 is then picked up in board_init_f() and made available through 736 the global data structure as gd->fdt_blob. 737 738 CONFIG_OF_SEPARATE 739 If this variable is defined, U-Boot will build a device tree 740 binary. It will be called u-boot.dtb. Architecture-specific 741 code will locate it at run-time. Generally this works by: 742 743 cat u-boot.bin u-boot.dtb >image.bin 744 745 and in fact, U-Boot does this for you, creating a file called 746 u-boot-dtb.bin which is useful in the common case. You can 747 still use the individual files if you need something more 748 exotic. 749 750 CONFIG_OF_BOARD 751 If this variable is defined, U-Boot will use the device tree 752 provided by the board at runtime instead of embedding one with 753 the image. Only boards defining board_fdt_blob_setup() support 754 this option (see include/fdtdec.h file). 755 756- Watchdog: 757 CONFIG_WATCHDOG 758 If this variable is defined, it enables watchdog 759 support for the SoC. There must be support in the SoC 760 specific code for a watchdog. For the 8xx 761 CPUs, the SIU Watchdog feature is enabled in the SYPCR 762 register. When supported for a specific SoC is 763 available, then no further board specific code should 764 be needed to use it. 765 766 CONFIG_HW_WATCHDOG 767 When using a watchdog circuitry external to the used 768 SoC, then define this variable and provide board 769 specific code for the "hw_watchdog_reset" function. 770 771- Real-Time Clock: 772 773 When CONFIG_CMD_DATE is selected, the type of the RTC 774 has to be selected, too. Define exactly one of the 775 following options: 776 777 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC 778 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC 779 CONFIG_RTC_MC146818 - use MC146818 RTC 780 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC 781 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC 782 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC 783 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC 784 CONFIG_RTC_DS164x - use Dallas DS164x RTC 785 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC 786 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC 787 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337 788 CONFIG_SYS_RV3029_TCR - enable trickle charger on 789 RV3029 RTC. 790 791 Note that if the RTC uses I2C, then the I2C interface 792 must also be configured. See I2C Support, below. 793 794- GPIO Support: 795 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO 796 797 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of 798 chip-ngpio pairs that tell the PCA953X driver the number of 799 pins supported by a particular chip. 800 801 Note that if the GPIO device uses I2C, then the I2C interface 802 must also be configured. See I2C Support, below. 803 804- I/O tracing: 805 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O 806 accesses and can checksum them or write a list of them out 807 to memory. See the 'iotrace' command for details. This is 808 useful for testing device drivers since it can confirm that 809 the driver behaves the same way before and after a code 810 change. Currently this is supported on sandbox and arm. To 811 add support for your architecture, add '#include <iotrace.h>' 812 to the bottom of arch/<arch>/include/asm/io.h and test. 813 814 Example output from the 'iotrace stats' command is below. 815 Note that if the trace buffer is exhausted, the checksum will 816 still continue to operate. 817 818 iotrace is enabled 819 Start: 10000000 (buffer start address) 820 Size: 00010000 (buffer size) 821 Offset: 00000120 (current buffer offset) 822 Output: 10000120 (start + offset) 823 Count: 00000018 (number of trace records) 824 CRC32: 9526fb66 (CRC32 of all trace records) 825 826- Timestamp Support: 827 828 When CONFIG_TIMESTAMP is selected, the timestamp 829 (date and time) of an image is printed by image 830 commands like bootm or iminfo. This option is 831 automatically enabled when you select CONFIG_CMD_DATE . 832 833- Partition Labels (disklabels) Supported: 834 Zero or more of the following: 835 CONFIG_MAC_PARTITION Apple's MacOS partition table. 836 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc. 837 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the 838 bootloader. Note 2TB partition limit; see 839 disk/part_efi.c 840 CONFIG_SCSI) you must configure support for at 841 least one non-MTD partition type as well. 842 843- IDE Reset method: 844 CONFIG_IDE_RESET_ROUTINE - this is defined in several 845 board configurations files but used nowhere! 846 847 CONFIG_IDE_RESET - is this is defined, IDE Reset will 848 be performed by calling the function 849 ide_set_reset(int reset) 850 which has to be defined in a board specific file 851 852- ATAPI Support: 853 CONFIG_ATAPI 854 855 Set this to enable ATAPI support. 856 857- LBA48 Support 858 CONFIG_LBA48 859 860 Set this to enable support for disks larger than 137GB 861 Also look at CONFIG_SYS_64BIT_LBA. 862 Whithout these , LBA48 support uses 32bit variables and will 'only' 863 support disks up to 2.1TB. 864 865 CONFIG_SYS_64BIT_LBA: 866 When enabled, makes the IDE subsystem use 64bit sector addresses. 867 Default is 32bit. 868 869- SCSI Support: 870 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and 871 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID * 872 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the 873 maximum numbers of LUNs, SCSI ID's and target 874 devices. 875 876 The environment variable 'scsidevs' is set to the number of 877 SCSI devices found during the last scan. 878 879- NETWORK Support (PCI): 880 CONFIG_E1000 881 Support for Intel 8254x/8257x gigabit chips. 882 883 CONFIG_E1000_SPI 884 Utility code for direct access to the SPI bus on Intel 8257x. 885 This does not do anything useful unless you set at least one 886 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC. 887 888 CONFIG_E1000_SPI_GENERIC 889 Allow generic access to the SPI bus on the Intel 8257x, for 890 example with the "sspi" command. 891 892 CONFIG_EEPRO100 893 Support for Intel 82557/82559/82559ER chips. 894 Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM 895 write routine for first time initialisation. 896 897 CONFIG_TULIP 898 Support for Digital 2114x chips. 899 Optional CONFIG_TULIP_SELECT_MEDIA for board specific 900 modem chip initialisation (KS8761/QS6611). 901 902 CONFIG_NATSEMI 903 Support for National dp83815 chips. 904 905 CONFIG_NS8382X 906 Support for National dp8382[01] gigabit chips. 907 908- NETWORK Support (other): 909 910 CONFIG_DRIVER_AT91EMAC 911 Support for AT91RM9200 EMAC. 912 913 CONFIG_RMII 914 Define this to use reduced MII inteface 915 916 CONFIG_DRIVER_AT91EMAC_QUIET 917 If this defined, the driver is quiet. 918 The driver doen't show link status messages. 919 920 CONFIG_CALXEDA_XGMAC 921 Support for the Calxeda XGMAC device 922 923 CONFIG_LAN91C96 924 Support for SMSC's LAN91C96 chips. 925 926 CONFIG_LAN91C96_USE_32_BIT 927 Define this to enable 32 bit addressing 928 929 CONFIG_SMC91111 930 Support for SMSC's LAN91C111 chip 931 932 CONFIG_SMC91111_BASE 933 Define this to hold the physical address 934 of the device (I/O space) 935 936 CONFIG_SMC_USE_32_BIT 937 Define this if data bus is 32 bits 938 939 CONFIG_SMC_USE_IOFUNCS 940 Define this to use i/o functions instead of macros 941 (some hardware wont work with macros) 942 943 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT 944 Define this if you have more then 3 PHYs. 945 946 CONFIG_FTGMAC100 947 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet 948 949 CONFIG_FTGMAC100_EGIGA 950 Define this to use GE link update with gigabit PHY. 951 Define this if FTGMAC100 is connected to gigabit PHY. 952 If your system has 10/100 PHY only, it might not occur 953 wrong behavior. Because PHY usually return timeout or 954 useless data when polling gigabit status and gigabit 955 control registers. This behavior won't affect the 956 correctnessof 10/100 link speed update. 957 958 CONFIG_SH_ETHER 959 Support for Renesas on-chip Ethernet controller 960 961 CONFIG_SH_ETHER_USE_PORT 962 Define the number of ports to be used 963 964 CONFIG_SH_ETHER_PHY_ADDR 965 Define the ETH PHY's address 966 967 CONFIG_SH_ETHER_CACHE_WRITEBACK 968 If this option is set, the driver enables cache flush. 969 970- TPM Support: 971 CONFIG_TPM 972 Support TPM devices. 973 974 CONFIG_TPM_TIS_INFINEON 975 Support for Infineon i2c bus TPM devices. Only one device 976 per system is supported at this time. 977 978 CONFIG_TPM_TIS_I2C_BURST_LIMITATION 979 Define the burst count bytes upper limit 980 981 CONFIG_TPM_ST33ZP24 982 Support for STMicroelectronics TPM devices. Requires DM_TPM support. 983 984 CONFIG_TPM_ST33ZP24_I2C 985 Support for STMicroelectronics ST33ZP24 I2C devices. 986 Requires TPM_ST33ZP24 and I2C. 987 988 CONFIG_TPM_ST33ZP24_SPI 989 Support for STMicroelectronics ST33ZP24 SPI devices. 990 Requires TPM_ST33ZP24 and SPI. 991 992 CONFIG_TPM_ATMEL_TWI 993 Support for Atmel TWI TPM device. Requires I2C support. 994 995 CONFIG_TPM_TIS_LPC 996 Support for generic parallel port TPM devices. Only one device 997 per system is supported at this time. 998 999 CONFIG_TPM_TIS_BASE_ADDRESS 1000 Base address where the generic TPM device is mapped 1001 to. Contemporary x86 systems usually map it at 1002 0xfed40000. 1003 1004 CONFIG_TPM 1005 Define this to enable the TPM support library which provides 1006 functional interfaces to some TPM commands. 1007 Requires support for a TPM device. 1008 1009 CONFIG_TPM_AUTH_SESSIONS 1010 Define this to enable authorized functions in the TPM library. 1011 Requires CONFIG_TPM and CONFIG_SHA1. 1012 1013- USB Support: 1014 At the moment only the UHCI host controller is 1015 supported (PIP405, MIP405); define 1016 CONFIG_USB_UHCI to enable it. 1017 define CONFIG_USB_KEYBOARD to enable the USB Keyboard 1018 and define CONFIG_USB_STORAGE to enable the USB 1019 storage devices. 1020 Note: 1021 Supported are USB Keyboards and USB Floppy drives 1022 (TEAC FD-05PUB). 1023 1024 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the 1025 txfilltuning field in the EHCI controller on reset. 1026 1027 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2 1028 HW module registers. 1029 1030- USB Device: 1031 Define the below if you wish to use the USB console. 1032 Once firmware is rebuilt from a serial console issue the 1033 command "setenv stdin usbtty; setenv stdout usbtty" and 1034 attach your USB cable. The Unix command "dmesg" should print 1035 it has found a new device. The environment variable usbtty 1036 can be set to gserial or cdc_acm to enable your device to 1037 appear to a USB host as a Linux gserial device or a 1038 Common Device Class Abstract Control Model serial device. 1039 If you select usbtty = gserial you should be able to enumerate 1040 a Linux host by 1041 # modprobe usbserial vendor=0xVendorID product=0xProductID 1042 else if using cdc_acm, simply setting the environment 1043 variable usbtty to be cdc_acm should suffice. The following 1044 might be defined in YourBoardName.h 1045 1046 CONFIG_USB_DEVICE 1047 Define this to build a UDC device 1048 1049 CONFIG_USB_TTY 1050 Define this to have a tty type of device available to 1051 talk to the UDC device 1052 1053 CONFIG_USBD_HS 1054 Define this to enable the high speed support for usb 1055 device and usbtty. If this feature is enabled, a routine 1056 int is_usbd_high_speed(void) 1057 also needs to be defined by the driver to dynamically poll 1058 whether the enumeration has succeded at high speed or full 1059 speed. 1060 1061 CONFIG_SYS_CONSOLE_IS_IN_ENV 1062 Define this if you want stdin, stdout &/or stderr to 1063 be set to usbtty. 1064 1065 If you have a USB-IF assigned VendorID then you may wish to 1066 define your own vendor specific values either in BoardName.h 1067 or directly in usbd_vendor_info.h. If you don't define 1068 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME, 1069 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot 1070 should pretend to be a Linux device to it's target host. 1071 1072 CONFIG_USBD_MANUFACTURER 1073 Define this string as the name of your company for 1074 - CONFIG_USBD_MANUFACTURER "my company" 1075 1076 CONFIG_USBD_PRODUCT_NAME 1077 Define this string as the name of your product 1078 - CONFIG_USBD_PRODUCT_NAME "acme usb device" 1079 1080 CONFIG_USBD_VENDORID 1081 Define this as your assigned Vendor ID from the USB 1082 Implementors Forum. This *must* be a genuine Vendor ID 1083 to avoid polluting the USB namespace. 1084 - CONFIG_USBD_VENDORID 0xFFFF 1085 1086 CONFIG_USBD_PRODUCTID 1087 Define this as the unique Product ID 1088 for your device 1089 - CONFIG_USBD_PRODUCTID 0xFFFF 1090 1091- ULPI Layer Support: 1092 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via 1093 the generic ULPI layer. The generic layer accesses the ULPI PHY 1094 via the platform viewport, so you need both the genric layer and 1095 the viewport enabled. Currently only Chipidea/ARC based 1096 viewport is supported. 1097 To enable the ULPI layer support, define CONFIG_USB_ULPI and 1098 CONFIG_USB_ULPI_VIEWPORT in your board configuration file. 1099 If your ULPI phy needs a different reference clock than the 1100 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to 1101 the appropriate value in Hz. 1102 1103- MMC Support: 1104 The MMC controller on the Intel PXA is supported. To 1105 enable this define CONFIG_MMC. The MMC can be 1106 accessed from the boot prompt by mapping the device 1107 to physical memory similar to flash. Command line is 1108 enabled with CONFIG_CMD_MMC. The MMC driver also works with 1109 the FAT fs. This is enabled with CONFIG_CMD_FAT. 1110 1111 CONFIG_SH_MMCIF 1112 Support for Renesas on-chip MMCIF controller 1113 1114 CONFIG_SH_MMCIF_ADDR 1115 Define the base address of MMCIF registers 1116 1117 CONFIG_SH_MMCIF_CLK 1118 Define the clock frequency for MMCIF 1119 1120- USB Device Firmware Update (DFU) class support: 1121 CONFIG_DFU_OVER_USB 1122 This enables the USB portion of the DFU USB class 1123 1124 CONFIG_DFU_NAND 1125 This enables support for exposing NAND devices via DFU. 1126 1127 CONFIG_DFU_RAM 1128 This enables support for exposing RAM via DFU. 1129 Note: DFU spec refer to non-volatile memory usage, but 1130 allow usages beyond the scope of spec - here RAM usage, 1131 one that would help mostly the developer. 1132 1133 CONFIG_SYS_DFU_DATA_BUF_SIZE 1134 Dfu transfer uses a buffer before writing data to the 1135 raw storage device. Make the size (in bytes) of this buffer 1136 configurable. The size of this buffer is also configurable 1137 through the "dfu_bufsiz" environment variable. 1138 1139 CONFIG_SYS_DFU_MAX_FILE_SIZE 1140 When updating files rather than the raw storage device, 1141 we use a static buffer to copy the file into and then write 1142 the buffer once we've been given the whole file. Define 1143 this to the maximum filesize (in bytes) for the buffer. 1144 Default is 4 MiB if undefined. 1145 1146 DFU_DEFAULT_POLL_TIMEOUT 1147 Poll timeout [ms], is the timeout a device can send to the 1148 host. The host must wait for this timeout before sending 1149 a subsequent DFU_GET_STATUS request to the device. 1150 1151 DFU_MANIFEST_POLL_TIMEOUT 1152 Poll timeout [ms], which the device sends to the host when 1153 entering dfuMANIFEST state. Host waits this timeout, before 1154 sending again an USB request to the device. 1155 1156- Journaling Flash filesystem support: 1157 CONFIG_JFFS2_NAND 1158 Define these for a default partition on a NAND device 1159 1160 CONFIG_SYS_JFFS2_FIRST_SECTOR, 1161 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS 1162 Define these for a default partition on a NOR device 1163 1164- Keyboard Support: 1165 See Kconfig help for available keyboard drivers. 1166 1167 CONFIG_KEYBOARD 1168 1169 Define this to enable a custom keyboard support. 1170 This simply calls drv_keyboard_init() which must be 1171 defined in your board-specific files. This option is deprecated 1172 and is only used by novena. For new boards, use driver model 1173 instead. 1174 1175- Video support: 1176 CONFIG_FSL_DIU_FB 1177 Enable the Freescale DIU video driver. Reference boards for 1178 SOCs that have a DIU should define this macro to enable DIU 1179 support, and should also define these other macros: 1180 1181 CONFIG_SYS_DIU_ADDR 1182 CONFIG_VIDEO 1183 CONFIG_CFB_CONSOLE 1184 CONFIG_VIDEO_SW_CURSOR 1185 CONFIG_VGA_AS_SINGLE_DEVICE 1186 CONFIG_VIDEO_LOGO 1187 CONFIG_VIDEO_BMP_LOGO 1188 1189 The DIU driver will look for the 'video-mode' environment 1190 variable, and if defined, enable the DIU as a console during 1191 boot. See the documentation file doc/README.video for a 1192 description of this variable. 1193 1194- LCD Support: CONFIG_LCD 1195 1196 Define this to enable LCD support (for output to LCD 1197 display); also select one of the supported displays 1198 by defining one of these: 1199 1200 CONFIG_ATMEL_LCD: 1201 1202 HITACHI TX09D70VM1CCA, 3.5", 240x320. 1203 1204 CONFIG_NEC_NL6448AC33: 1205 1206 NEC NL6448AC33-18. Active, color, single scan. 1207 1208 CONFIG_NEC_NL6448BC20 1209 1210 NEC NL6448BC20-08. 6.5", 640x480. 1211 Active, color, single scan. 1212 1213 CONFIG_NEC_NL6448BC33_54 1214 1215 NEC NL6448BC33-54. 10.4", 640x480. 1216 Active, color, single scan. 1217 1218 CONFIG_SHARP_16x9 1219 1220 Sharp 320x240. Active, color, single scan. 1221 It isn't 16x9, and I am not sure what it is. 1222 1223 CONFIG_SHARP_LQ64D341 1224 1225 Sharp LQ64D341 display, 640x480. 1226 Active, color, single scan. 1227 1228 CONFIG_HLD1045 1229 1230 HLD1045 display, 640x480. 1231 Active, color, single scan. 1232 1233 CONFIG_OPTREX_BW 1234 1235 Optrex CBL50840-2 NF-FW 99 22 M5 1236 or 1237 Hitachi LMG6912RPFC-00T 1238 or 1239 Hitachi SP14Q002 1240 1241 320x240. Black & white. 1242 1243 CONFIG_LCD_ALIGNMENT 1244 1245 Normally the LCD is page-aligned (typically 4KB). If this is 1246 defined then the LCD will be aligned to this value instead. 1247 For ARM it is sometimes useful to use MMU_SECTION_SIZE 1248 here, since it is cheaper to change data cache settings on 1249 a per-section basis. 1250 1251 1252 CONFIG_LCD_ROTATION 1253 1254 Sometimes, for example if the display is mounted in portrait 1255 mode or even if it's mounted landscape but rotated by 180degree, 1256 we need to rotate our content of the display relative to the 1257 framebuffer, so that user can read the messages which are 1258 printed out. 1259 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be 1260 initialized with a given rotation from "vl_rot" out of 1261 "vidinfo_t" which is provided by the board specific code. 1262 The value for vl_rot is coded as following (matching to 1263 fbcon=rotate:<n> linux-kernel commandline): 1264 0 = no rotation respectively 0 degree 1265 1 = 90 degree rotation 1266 2 = 180 degree rotation 1267 3 = 270 degree rotation 1268 1269 If CONFIG_LCD_ROTATION is not defined, the console will be 1270 initialized with 0degree rotation. 1271 1272 CONFIG_LCD_BMP_RLE8 1273 1274 Support drawing of RLE8-compressed bitmaps on the LCD. 1275 1276 CONFIG_I2C_EDID 1277 1278 Enables an 'i2c edid' command which can read EDID 1279 information over I2C from an attached LCD display. 1280 1281- Splash Screen Support: CONFIG_SPLASH_SCREEN 1282 1283 If this option is set, the environment is checked for 1284 a variable "splashimage". If found, the usual display 1285 of logo, copyright and system information on the LCD 1286 is suppressed and the BMP image at the address 1287 specified in "splashimage" is loaded instead. The 1288 console is redirected to the "nulldev", too. This 1289 allows for a "silent" boot where a splash screen is 1290 loaded very quickly after power-on. 1291 1292 CONFIG_SPLASHIMAGE_GUARD 1293 1294 If this option is set, then U-Boot will prevent the environment 1295 variable "splashimage" from being set to a problematic address 1296 (see doc/README.displaying-bmps). 1297 This option is useful for targets where, due to alignment 1298 restrictions, an improperly aligned BMP image will cause a data 1299 abort. If you think you will not have problems with unaligned 1300 accesses (for example because your toolchain prevents them) 1301 there is no need to set this option. 1302 1303 CONFIG_SPLASH_SCREEN_ALIGN 1304 1305 If this option is set the splash image can be freely positioned 1306 on the screen. Environment variable "splashpos" specifies the 1307 position as "x,y". If a positive number is given it is used as 1308 number of pixel from left/top. If a negative number is given it 1309 is used as number of pixel from right/bottom. You can also 1310 specify 'm' for centering the image. 1311 1312 Example: 1313 setenv splashpos m,m 1314 => image at center of screen 1315 1316 setenv splashpos 30,20 1317 => image at x = 30 and y = 20 1318 1319 setenv splashpos -10,m 1320 => vertically centered image 1321 at x = dspWidth - bmpWidth - 9 1322 1323- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP 1324 1325 If this option is set, additionally to standard BMP 1326 images, gzipped BMP images can be displayed via the 1327 splashscreen support or the bmp command. 1328 1329- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8 1330 1331 If this option is set, 8-bit RLE compressed BMP images 1332 can be displayed via the splashscreen support or the 1333 bmp command. 1334 1335- Compression support: 1336 CONFIG_GZIP 1337 1338 Enabled by default to support gzip compressed images. 1339 1340 CONFIG_BZIP2 1341 1342 If this option is set, support for bzip2 compressed 1343 images is included. If not, only uncompressed and gzip 1344 compressed images are supported. 1345 1346 NOTE: the bzip2 algorithm requires a lot of RAM, so 1347 the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should 1348 be at least 4MB. 1349 1350- MII/PHY support: 1351 CONFIG_PHY_CLOCK_FREQ (ppc4xx) 1352 1353 The clock frequency of the MII bus 1354 1355 CONFIG_PHY_RESET_DELAY 1356 1357 Some PHY like Intel LXT971A need extra delay after 1358 reset before any MII register access is possible. 1359 For such PHY, set this option to the usec delay 1360 required. (minimum 300usec for LXT971A) 1361 1362 CONFIG_PHY_CMD_DELAY (ppc4xx) 1363 1364 Some PHY like Intel LXT971A need extra delay after 1365 command issued before MII status register can be read 1366 1367- IP address: 1368 CONFIG_IPADDR 1369 1370 Define a default value for the IP address to use for 1371 the default Ethernet interface, in case this is not 1372 determined through e.g. bootp. 1373 (Environment variable "ipaddr") 1374 1375- Server IP address: 1376 CONFIG_SERVERIP 1377 1378 Defines a default value for the IP address of a TFTP 1379 server to contact when using the "tftboot" command. 1380 (Environment variable "serverip") 1381 1382 CONFIG_KEEP_SERVERADDR 1383 1384 Keeps the server's MAC address, in the env 'serveraddr' 1385 for passing to bootargs (like Linux's netconsole option) 1386 1387- Gateway IP address: 1388 CONFIG_GATEWAYIP 1389 1390 Defines a default value for the IP address of the 1391 default router where packets to other networks are 1392 sent to. 1393 (Environment variable "gatewayip") 1394 1395- Subnet mask: 1396 CONFIG_NETMASK 1397 1398 Defines a default value for the subnet mask (or 1399 routing prefix) which is used to determine if an IP 1400 address belongs to the local subnet or needs to be 1401 forwarded through a router. 1402 (Environment variable "netmask") 1403 1404- BOOTP Recovery Mode: 1405 CONFIG_BOOTP_RANDOM_DELAY 1406 1407 If you have many targets in a network that try to 1408 boot using BOOTP, you may want to avoid that all 1409 systems send out BOOTP requests at precisely the same 1410 moment (which would happen for instance at recovery 1411 from a power failure, when all systems will try to 1412 boot, thus flooding the BOOTP server. Defining 1413 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be 1414 inserted before sending out BOOTP requests. The 1415 following delays are inserted then: 1416 1417 1st BOOTP request: delay 0 ... 1 sec 1418 2nd BOOTP request: delay 0 ... 2 sec 1419 3rd BOOTP request: delay 0 ... 4 sec 1420 4th and following 1421 BOOTP requests: delay 0 ... 8 sec 1422 1423 CONFIG_BOOTP_ID_CACHE_SIZE 1424 1425 BOOTP packets are uniquely identified using a 32-bit ID. The 1426 server will copy the ID from client requests to responses and 1427 U-Boot will use this to determine if it is the destination of 1428 an incoming response. Some servers will check that addresses 1429 aren't in use before handing them out (usually using an ARP 1430 ping) and therefore take up to a few hundred milliseconds to 1431 respond. Network congestion may also influence the time it 1432 takes for a response to make it back to the client. If that 1433 time is too long, U-Boot will retransmit requests. In order 1434 to allow earlier responses to still be accepted after these 1435 retransmissions, U-Boot's BOOTP client keeps a small cache of 1436 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this 1437 cache. The default is to keep IDs for up to four outstanding 1438 requests. Increasing this will allow U-Boot to accept offers 1439 from a BOOTP client in networks with unusually high latency. 1440 1441- DHCP Advanced Options: 1442 You can fine tune the DHCP functionality by defining 1443 CONFIG_BOOTP_* symbols: 1444 1445 CONFIG_BOOTP_NISDOMAIN 1446 CONFIG_BOOTP_BOOTFILESIZE 1447 CONFIG_BOOTP_SEND_HOSTNAME 1448 CONFIG_BOOTP_NTPSERVER 1449 CONFIG_BOOTP_TIMEOFFSET 1450 CONFIG_BOOTP_VENDOREX 1451 CONFIG_BOOTP_MAY_FAIL 1452 1453 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip 1454 environment variable, not the BOOTP server. 1455 1456 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found 1457 after the configured retry count, the call will fail 1458 instead of starting over. This can be used to fail over 1459 to Link-local IP address configuration if the DHCP server 1460 is not available. 1461 1462 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable 1463 to do a dynamic update of a DNS server. To do this, they 1464 need the hostname of the DHCP requester. 1465 If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content 1466 of the "hostname" environment variable is passed as 1467 option 12 to the DHCP server. 1468 1469 CONFIG_BOOTP_DHCP_REQUEST_DELAY 1470 1471 A 32bit value in microseconds for a delay between 1472 receiving a "DHCP Offer" and sending the "DHCP Request". 1473 This fixes a problem with certain DHCP servers that don't 1474 respond 100% of the time to a "DHCP request". E.g. On an 1475 AT91RM9200 processor running at 180MHz, this delay needed 1476 to be *at least* 15,000 usec before a Windows Server 2003 1477 DHCP server would reply 100% of the time. I recommend at 1478 least 50,000 usec to be safe. The alternative is to hope 1479 that one of the retries will be successful but note that 1480 the DHCP timeout and retry process takes a longer than 1481 this delay. 1482 1483 - Link-local IP address negotiation: 1484 Negotiate with other link-local clients on the local network 1485 for an address that doesn't require explicit configuration. 1486 This is especially useful if a DHCP server cannot be guaranteed 1487 to exist in all environments that the device must operate. 1488 1489 See doc/README.link-local for more information. 1490 1491 - MAC address from environment variables 1492 1493 FDT_SEQ_MACADDR_FROM_ENV 1494 1495 Fix-up device tree with MAC addresses fetched sequentially from 1496 environment variables. This config work on assumption that 1497 non-usable ethernet node of device-tree are either not present 1498 or their status has been marked as "disabled". 1499 1500 - CDP Options: 1501 CONFIG_CDP_DEVICE_ID 1502 1503 The device id used in CDP trigger frames. 1504 1505 CONFIG_CDP_DEVICE_ID_PREFIX 1506 1507 A two character string which is prefixed to the MAC address 1508 of the device. 1509 1510 CONFIG_CDP_PORT_ID 1511 1512 A printf format string which contains the ascii name of 1513 the port. Normally is set to "eth%d" which sets 1514 eth0 for the first Ethernet, eth1 for the second etc. 1515 1516 CONFIG_CDP_CAPABILITIES 1517 1518 A 32bit integer which indicates the device capabilities; 1519 0x00000010 for a normal host which does not forwards. 1520 1521 CONFIG_CDP_VERSION 1522 1523 An ascii string containing the version of the software. 1524 1525 CONFIG_CDP_PLATFORM 1526 1527 An ascii string containing the name of the platform. 1528 1529 CONFIG_CDP_TRIGGER 1530 1531 A 32bit integer sent on the trigger. 1532 1533 CONFIG_CDP_POWER_CONSUMPTION 1534 1535 A 16bit integer containing the power consumption of the 1536 device in .1 of milliwatts. 1537 1538 CONFIG_CDP_APPLIANCE_VLAN_TYPE 1539 1540 A byte containing the id of the VLAN. 1541 1542- Status LED: CONFIG_LED_STATUS 1543 1544 Several configurations allow to display the current 1545 status using a LED. For instance, the LED will blink 1546 fast while running U-Boot code, stop blinking as 1547 soon as a reply to a BOOTP request was received, and 1548 start blinking slow once the Linux kernel is running 1549 (supported by a status LED driver in the Linux 1550 kernel). Defining CONFIG_LED_STATUS enables this 1551 feature in U-Boot. 1552 1553 Additional options: 1554 1555 CONFIG_LED_STATUS_GPIO 1556 The status LED can be connected to a GPIO pin. 1557 In such cases, the gpio_led driver can be used as a 1558 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO 1559 to include the gpio_led driver in the U-Boot binary. 1560 1561 CONFIG_GPIO_LED_INVERTED_TABLE 1562 Some GPIO connected LEDs may have inverted polarity in which 1563 case the GPIO high value corresponds to LED off state and 1564 GPIO low value corresponds to LED on state. 1565 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined 1566 with a list of GPIO LEDs that have inverted polarity. 1567 1568- I2C Support: CONFIG_SYS_I2C 1569 1570 This enable the NEW i2c subsystem, and will allow you to use 1571 i2c commands at the u-boot command line (as long as you set 1572 CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c 1573 based realtime clock chips or other i2c devices. See 1574 common/cmd_i2c.c for a description of the command line 1575 interface. 1576 1577 ported i2c driver to the new framework: 1578 - drivers/i2c/soft_i2c.c: 1579 - activate first bus with CONFIG_SYS_I2C_SOFT define 1580 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE 1581 for defining speed and slave address 1582 - activate second bus with I2C_SOFT_DECLARATIONS2 define 1583 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2 1584 for defining speed and slave address 1585 - activate third bus with I2C_SOFT_DECLARATIONS3 define 1586 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3 1587 for defining speed and slave address 1588 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define 1589 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4 1590 for defining speed and slave address 1591 1592 - drivers/i2c/fsl_i2c.c: 1593 - activate i2c driver with CONFIG_SYS_I2C_FSL 1594 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register 1595 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and 1596 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first 1597 bus. 1598 - If your board supports a second fsl i2c bus, define 1599 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset 1600 CONFIG_SYS_FSL_I2C2_SPEED for the speed and 1601 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the 1602 second bus. 1603 1604 - drivers/i2c/tegra_i2c.c: 1605 - activate this driver with CONFIG_SYS_I2C_TEGRA 1606 - This driver adds 4 i2c buses with a fix speed from 1607 100000 and the slave addr 0! 1608 1609 - drivers/i2c/ppc4xx_i2c.c 1610 - activate this driver with CONFIG_SYS_I2C_PPC4XX 1611 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0 1612 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1 1613 1614 - drivers/i2c/i2c_mxc.c 1615 - activate this driver with CONFIG_SYS_I2C_MXC 1616 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1 1617 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2 1618 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3 1619 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4 1620 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED 1621 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE 1622 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED 1623 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE 1624 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED 1625 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE 1626 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED 1627 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE 1628 If those defines are not set, default value is 100000 1629 for speed, and 0 for slave. 1630 1631 - drivers/i2c/rcar_i2c.c: 1632 - activate this driver with CONFIG_SYS_I2C_RCAR 1633 - This driver adds 4 i2c buses 1634 1635 - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0 1636 - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0 1637 - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1 1638 - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1 1639 - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2 1640 - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2 1641 - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3 1642 - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3 1643 - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses 1644 1645 - drivers/i2c/sh_i2c.c: 1646 - activate this driver with CONFIG_SYS_I2C_SH 1647 - This driver adds from 2 to 5 i2c buses 1648 1649 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0 1650 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0 1651 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1 1652 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1 1653 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2 1654 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2 1655 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3 1656 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3 1657 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4 1658 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4 1659 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses 1660 1661 - drivers/i2c/omap24xx_i2c.c 1662 - activate this driver with CONFIG_SYS_I2C_OMAP24XX 1663 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0 1664 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0 1665 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1 1666 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1 1667 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2 1668 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2 1669 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3 1670 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3 1671 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4 1672 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4 1673 1674 - drivers/i2c/s3c24x0_i2c.c: 1675 - activate this driver with CONFIG_SYS_I2C_S3C24X0 1676 - This driver adds i2c buses (11 for Exynos5250, Exynos5420 1677 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung) 1678 with a fix speed from 100000 and the slave addr 0! 1679 1680 - drivers/i2c/ihs_i2c.c 1681 - activate this driver with CONFIG_SYS_I2C_IHS 1682 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0 1683 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0 1684 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0 1685 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1 1686 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1 1687 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1 1688 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2 1689 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2 1690 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2 1691 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3 1692 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3 1693 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3 1694 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL 1695 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1 1696 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1 1697 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1 1698 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1 1699 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1 1700 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1 1701 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1 1702 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1 1703 1704 additional defines: 1705 1706 CONFIG_SYS_NUM_I2C_BUSES 1707 Hold the number of i2c buses you want to use. 1708 1709 CONFIG_SYS_I2C_DIRECT_BUS 1710 define this, if you don't use i2c muxes on your hardware. 1711 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can 1712 omit this define. 1713 1714 CONFIG_SYS_I2C_MAX_HOPS 1715 define how many muxes are maximal consecutively connected 1716 on one i2c bus. If you not use i2c muxes, omit this 1717 define. 1718 1719 CONFIG_SYS_I2C_BUSES 1720 hold a list of buses you want to use, only used if 1721 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example 1722 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and 1723 CONFIG_SYS_NUM_I2C_BUSES = 9: 1724 1725 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \ 1726 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \ 1727 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \ 1728 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \ 1729 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \ 1730 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \ 1731 {1, {I2C_NULL_HOP}}, \ 1732 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \ 1733 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \ 1734 } 1735 1736 which defines 1737 bus 0 on adapter 0 without a mux 1738 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1 1739 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2 1740 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3 1741 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4 1742 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5 1743 bus 6 on adapter 1 without a mux 1744 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1 1745 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2 1746 1747 If you do not have i2c muxes on your board, omit this define. 1748 1749- Legacy I2C Support: 1750 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT) 1751 then the following macros need to be defined (examples are 1752 from include/configs/lwmon.h): 1753 1754 I2C_INIT 1755 1756 (Optional). Any commands necessary to enable the I2C 1757 controller or configure ports. 1758 1759 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL) 1760 1761 I2C_ACTIVE 1762 1763 The code necessary to make the I2C data line active 1764 (driven). If the data line is open collector, this 1765 define can be null. 1766 1767 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA) 1768 1769 I2C_TRISTATE 1770 1771 The code necessary to make the I2C data line tri-stated 1772 (inactive). If the data line is open collector, this 1773 define can be null. 1774 1775 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA) 1776 1777 I2C_READ 1778 1779 Code that returns true if the I2C data line is high, 1780 false if it is low. 1781 1782 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0) 1783 1784 I2C_SDA(bit) 1785 1786 If <bit> is true, sets the I2C data line high. If it 1787 is false, it clears it (low). 1788 1789 eg: #define I2C_SDA(bit) \ 1790 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \ 1791 else immr->im_cpm.cp_pbdat &= ~PB_SDA 1792 1793 I2C_SCL(bit) 1794 1795 If <bit> is true, sets the I2C clock line high. If it 1796 is false, it clears it (low). 1797 1798 eg: #define I2C_SCL(bit) \ 1799 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \ 1800 else immr->im_cpm.cp_pbdat &= ~PB_SCL 1801 1802 I2C_DELAY 1803 1804 This delay is invoked four times per clock cycle so this 1805 controls the rate of data transfer. The data rate thus 1806 is 1 / (I2C_DELAY * 4). Often defined to be something 1807 like: 1808 1809 #define I2C_DELAY udelay(2) 1810 1811 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA 1812 1813 If your arch supports the generic GPIO framework (asm/gpio.h), 1814 then you may alternatively define the two GPIOs that are to be 1815 used as SCL / SDA. Any of the previous I2C_xxx macros will 1816 have GPIO-based defaults assigned to them as appropriate. 1817 1818 You should define these to the GPIO value as given directly to 1819 the generic GPIO functions. 1820 1821 CONFIG_SYS_I2C_INIT_BOARD 1822 1823 When a board is reset during an i2c bus transfer 1824 chips might think that the current transfer is still 1825 in progress. On some boards it is possible to access 1826 the i2c SCLK line directly, either by using the 1827 processor pin as a GPIO or by having a second pin 1828 connected to the bus. If this option is defined a 1829 custom i2c_init_board() routine in boards/xxx/board.c 1830 is run early in the boot sequence. 1831 1832 CONFIG_I2C_MULTI_BUS 1833 1834 This option allows the use of multiple I2C buses, each of which 1835 must have a controller. At any point in time, only one bus is 1836 active. To switch to a different bus, use the 'i2c dev' command. 1837 Note that bus numbering is zero-based. 1838 1839 CONFIG_SYS_I2C_NOPROBES 1840 1841 This option specifies a list of I2C devices that will be skipped 1842 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS 1843 is set, specify a list of bus-device pairs. Otherwise, specify 1844 a 1D array of device addresses 1845 1846 e.g. 1847 #undef CONFIG_I2C_MULTI_BUS 1848 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68} 1849 1850 will skip addresses 0x50 and 0x68 on a board with one I2C bus 1851 1852 #define CONFIG_I2C_MULTI_BUS 1853 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}} 1854 1855 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1 1856 1857 CONFIG_SYS_SPD_BUS_NUM 1858 1859 If defined, then this indicates the I2C bus number for DDR SPD. 1860 If not defined, then U-Boot assumes that SPD is on I2C bus 0. 1861 1862 CONFIG_SYS_RTC_BUS_NUM 1863 1864 If defined, then this indicates the I2C bus number for the RTC. 1865 If not defined, then U-Boot assumes that RTC is on I2C bus 0. 1866 1867 CONFIG_SOFT_I2C_READ_REPEATED_START 1868 1869 defining this will force the i2c_read() function in 1870 the soft_i2c driver to perform an I2C repeated start 1871 between writing the address pointer and reading the 1872 data. If this define is omitted the default behaviour 1873 of doing a stop-start sequence will be used. Most I2C 1874 devices can use either method, but some require one or 1875 the other. 1876 1877- SPI Support: CONFIG_SPI 1878 1879 Enables SPI driver (so far only tested with 1880 SPI EEPROM, also an instance works with Crystal A/D and 1881 D/As on the SACSng board) 1882 1883 CONFIG_SOFT_SPI 1884 1885 Enables a software (bit-bang) SPI driver rather than 1886 using hardware support. This is a general purpose 1887 driver that only requires three general I/O port pins 1888 (two outputs, one input) to function. If this is 1889 defined, the board configuration must define several 1890 SPI configuration items (port pins to use, etc). For 1891 an example, see include/configs/sacsng.h. 1892 1893 CONFIG_SYS_SPI_MXC_WAIT 1894 Timeout for waiting until spi transfer completed. 1895 default: (CONFIG_SYS_HZ/100) /* 10 ms */ 1896 1897- FPGA Support: CONFIG_FPGA 1898 1899 Enables FPGA subsystem. 1900 1901 CONFIG_FPGA_<vendor> 1902 1903 Enables support for specific chip vendors. 1904 (ALTERA, XILINX) 1905 1906 CONFIG_FPGA_<family> 1907 1908 Enables support for FPGA family. 1909 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX) 1910 1911 CONFIG_FPGA_COUNT 1912 1913 Specify the number of FPGA devices to support. 1914 1915 CONFIG_SYS_FPGA_PROG_FEEDBACK 1916 1917 Enable printing of hash marks during FPGA configuration. 1918 1919 CONFIG_SYS_FPGA_CHECK_BUSY 1920 1921 Enable checks on FPGA configuration interface busy 1922 status by the configuration function. This option 1923 will require a board or device specific function to 1924 be written. 1925 1926 CONFIG_FPGA_DELAY 1927 1928 If defined, a function that provides delays in the FPGA 1929 configuration driver. 1930 1931 CONFIG_SYS_FPGA_CHECK_CTRLC 1932 Allow Control-C to interrupt FPGA configuration 1933 1934 CONFIG_SYS_FPGA_CHECK_ERROR 1935 1936 Check for configuration errors during FPGA bitfile 1937 loading. For example, abort during Virtex II 1938 configuration if the INIT_B line goes low (which 1939 indicated a CRC error). 1940 1941 CONFIG_SYS_FPGA_WAIT_INIT 1942 1943 Maximum time to wait for the INIT_B line to de-assert 1944 after PROB_B has been de-asserted during a Virtex II 1945 FPGA configuration sequence. The default time is 500 1946 ms. 1947 1948 CONFIG_SYS_FPGA_WAIT_BUSY 1949 1950 Maximum time to wait for BUSY to de-assert during 1951 Virtex II FPGA configuration. The default is 5 ms. 1952 1953 CONFIG_SYS_FPGA_WAIT_CONFIG 1954 1955 Time to wait after FPGA configuration. The default is 1956 200 ms. 1957 1958- Configuration Management: 1959 1960 CONFIG_IDENT_STRING 1961 1962 If defined, this string will be added to the U-Boot 1963 version information (U_BOOT_VERSION) 1964 1965- Vendor Parameter Protection: 1966 1967 U-Boot considers the values of the environment 1968 variables "serial#" (Board Serial Number) and 1969 "ethaddr" (Ethernet Address) to be parameters that 1970 are set once by the board vendor / manufacturer, and 1971 protects these variables from casual modification by 1972 the user. Once set, these variables are read-only, 1973 and write or delete attempts are rejected. You can 1974 change this behaviour: 1975 1976 If CONFIG_ENV_OVERWRITE is #defined in your config 1977 file, the write protection for vendor parameters is 1978 completely disabled. Anybody can change or delete 1979 these parameters. 1980 1981 Alternatively, if you define _both_ an ethaddr in the 1982 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default 1983 Ethernet address is installed in the environment, 1984 which can be changed exactly ONCE by the user. [The 1985 serial# is unaffected by this, i. e. it remains 1986 read-only.] 1987 1988 The same can be accomplished in a more flexible way 1989 for any variable by configuring the type of access 1990 to allow for those variables in the ".flags" variable 1991 or define CONFIG_ENV_FLAGS_LIST_STATIC. 1992 1993- Protected RAM: 1994 CONFIG_PRAM 1995 1996 Define this variable to enable the reservation of 1997 "protected RAM", i. e. RAM which is not overwritten 1998 by U-Boot. Define CONFIG_PRAM to hold the number of 1999 kB you want to reserve for pRAM. You can overwrite 2000 this default value by defining an environment 2001 variable "pram" to the number of kB you want to 2002 reserve. Note that the board info structure will 2003 still show the full amount of RAM. If pRAM is 2004 reserved, a new environment variable "mem" will 2005 automatically be defined to hold the amount of 2006 remaining RAM in a form that can be passed as boot 2007 argument to Linux, for instance like that: 2008 2009 setenv bootargs ... mem=\${mem} 2010 saveenv 2011 2012 This way you can tell Linux not to use this memory, 2013 either, which results in a memory region that will 2014 not be affected by reboots. 2015 2016 *WARNING* If your board configuration uses automatic 2017 detection of the RAM size, you must make sure that 2018 this memory test is non-destructive. So far, the 2019 following board configurations are known to be 2020 "pRAM-clean": 2021 2022 IVMS8, IVML24, SPD8xx, 2023 HERMES, IP860, RPXlite, LWMON, 2024 FLAGADM 2025 2026- Access to physical memory region (> 4GB) 2027 Some basic support is provided for operations on memory not 2028 normally accessible to U-Boot - e.g. some architectures 2029 support access to more than 4GB of memory on 32-bit 2030 machines using physical address extension or similar. 2031 Define CONFIG_PHYSMEM to access this basic support, which 2032 currently only supports clearing the memory. 2033 2034- Error Recovery: 2035 CONFIG_NET_RETRY_COUNT 2036 2037 This variable defines the number of retries for 2038 network operations like ARP, RARP, TFTP, or BOOTP 2039 before giving up the operation. If not defined, a 2040 default value of 5 is used. 2041 2042 CONFIG_ARP_TIMEOUT 2043 2044 Timeout waiting for an ARP reply in milliseconds. 2045 2046 CONFIG_NFS_TIMEOUT 2047 2048 Timeout in milliseconds used in NFS protocol. 2049 If you encounter "ERROR: Cannot umount" in nfs command, 2050 try longer timeout such as 2051 #define CONFIG_NFS_TIMEOUT 10000UL 2052 2053- Command Interpreter: 2054 CONFIG_SYS_PROMPT_HUSH_PS2 2055 2056 This defines the secondary prompt string, which is 2057 printed when the command interpreter needs more input 2058 to complete a command. Usually "> ". 2059 2060 Note: 2061 2062 In the current implementation, the local variables 2063 space and global environment variables space are 2064 separated. Local variables are those you define by 2065 simply typing `name=value'. To access a local 2066 variable later on, you have write `$name' or 2067 `${name}'; to execute the contents of a variable 2068 directly type `$name' at the command prompt. 2069 2070 Global environment variables are those you use 2071 setenv/printenv to work with. To run a command stored 2072 in such a variable, you need to use the run command, 2073 and you must not use the '$' sign to access them. 2074 2075 To store commands and special characters in a 2076 variable, please use double quotation marks 2077 surrounding the whole text of the variable, instead 2078 of the backslashes before semicolons and special 2079 symbols. 2080 2081- Command Line Editing and History: 2082 CONFIG_CMDLINE_PS_SUPPORT 2083 2084 Enable support for changing the command prompt string 2085 at run-time. Only static string is supported so far. 2086 The string is obtained from environment variables PS1 2087 and PS2. 2088 2089- Default Environment: 2090 CONFIG_EXTRA_ENV_SETTINGS 2091 2092 Define this to contain any number of null terminated 2093 strings (variable = value pairs) that will be part of 2094 the default environment compiled into the boot image. 2095 2096 For example, place something like this in your 2097 board's config file: 2098 2099 #define CONFIG_EXTRA_ENV_SETTINGS \ 2100 "myvar1=value1\0" \ 2101 "myvar2=value2\0" 2102 2103 Warning: This method is based on knowledge about the 2104 internal format how the environment is stored by the 2105 U-Boot code. This is NOT an official, exported 2106 interface! Although it is unlikely that this format 2107 will change soon, there is no guarantee either. 2108 You better know what you are doing here. 2109 2110 Note: overly (ab)use of the default environment is 2111 discouraged. Make sure to check other ways to preset 2112 the environment like the "source" command or the 2113 boot command first. 2114 2115 CONFIG_DELAY_ENVIRONMENT 2116 2117 Normally the environment is loaded when the board is 2118 initialised so that it is available to U-Boot. This inhibits 2119 that so that the environment is not available until 2120 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL 2121 this is instead controlled by the value of 2122 /config/load-environment. 2123 2124- TFTP Fixed UDP Port: 2125 CONFIG_TFTP_PORT 2126 2127 If this is defined, the environment variable tftpsrcp 2128 is used to supply the TFTP UDP source port value. 2129 If tftpsrcp isn't defined, the normal pseudo-random port 2130 number generator is used. 2131 2132 Also, the environment variable tftpdstp is used to supply 2133 the TFTP UDP destination port value. If tftpdstp isn't 2134 defined, the normal port 69 is used. 2135 2136 The purpose for tftpsrcp is to allow a TFTP server to 2137 blindly start the TFTP transfer using the pre-configured 2138 target IP address and UDP port. This has the effect of 2139 "punching through" the (Windows XP) firewall, allowing 2140 the remainder of the TFTP transfer to proceed normally. 2141 A better solution is to properly configure the firewall, 2142 but sometimes that is not allowed. 2143 2144 CONFIG_STANDALONE_LOAD_ADDR 2145 2146 This option defines a board specific value for the 2147 address where standalone program gets loaded, thus 2148 overwriting the architecture dependent default 2149 settings. 2150 2151- Frame Buffer Address: 2152 CONFIG_FB_ADDR 2153 2154 Define CONFIG_FB_ADDR if you want to use specific 2155 address for frame buffer. This is typically the case 2156 when using a graphics controller has separate video 2157 memory. U-Boot will then place the frame buffer at 2158 the given address instead of dynamically reserving it 2159 in system RAM by calling lcd_setmem(), which grabs 2160 the memory for the frame buffer depending on the 2161 configured panel size. 2162 2163 Please see board_init_f function. 2164 2165- Automatic software updates via TFTP server 2166 CONFIG_UPDATE_TFTP 2167 CONFIG_UPDATE_TFTP_CNT_MAX 2168 CONFIG_UPDATE_TFTP_MSEC_MAX 2169 2170 These options enable and control the auto-update feature; 2171 for a more detailed description refer to doc/README.update. 2172 2173- MTD Support (mtdparts command, UBI support) 2174 CONFIG_MTD_UBI_WL_THRESHOLD 2175 This parameter defines the maximum difference between the highest 2176 erase counter value and the lowest erase counter value of eraseblocks 2177 of UBI devices. When this threshold is exceeded, UBI starts performing 2178 wear leveling by means of moving data from eraseblock with low erase 2179 counter to eraseblocks with high erase counter. 2180 2181 The default value should be OK for SLC NAND flashes, NOR flashes and 2182 other flashes which have eraseblock life-cycle 100000 or more. 2183 However, in case of MLC NAND flashes which typically have eraseblock 2184 life-cycle less than 10000, the threshold should be lessened (e.g., 2185 to 128 or 256, although it does not have to be power of 2). 2186 2187 default: 4096 2188 2189 CONFIG_MTD_UBI_BEB_LIMIT 2190 This option specifies the maximum bad physical eraseblocks UBI 2191 expects on the MTD device (per 1024 eraseblocks). If the 2192 underlying flash does not admit of bad eraseblocks (e.g. NOR 2193 flash), this value is ignored. 2194 2195 NAND datasheets often specify the minimum and maximum NVM 2196 (Number of Valid Blocks) for the flashes' endurance lifetime. 2197 The maximum expected bad eraseblocks per 1024 eraseblocks 2198 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)", 2199 which gives 20 for most NANDs (MaxNVB is basically the total 2200 count of eraseblocks on the chip). 2201 2202 To put it differently, if this value is 20, UBI will try to 2203 reserve about 1.9% of physical eraseblocks for bad blocks 2204 handling. And that will be 1.9% of eraseblocks on the entire 2205 NAND chip, not just the MTD partition UBI attaches. This means 2206 that if you have, say, a NAND flash chip admits maximum 40 bad 2207 eraseblocks, and it is split on two MTD partitions of the same 2208 size, UBI will reserve 40 eraseblocks when attaching a 2209 partition. 2210 2211 default: 20 2212 2213 CONFIG_MTD_UBI_FASTMAP 2214 Fastmap is a mechanism which allows attaching an UBI device 2215 in nearly constant time. Instead of scanning the whole MTD device it 2216 only has to locate a checkpoint (called fastmap) on the device. 2217 The on-flash fastmap contains all information needed to attach 2218 the device. Using fastmap makes only sense on large devices where 2219 attaching by scanning takes long. UBI will not automatically install 2220 a fastmap on old images, but you can set the UBI parameter 2221 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note 2222 that fastmap-enabled images are still usable with UBI implementations 2223 without fastmap support. On typical flash devices the whole fastmap 2224 fits into one PEB. UBI will reserve PEBs to hold two fastmaps. 2225 2226 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT 2227 Set this parameter to enable fastmap automatically on images 2228 without a fastmap. 2229 default: 0 2230 2231 CONFIG_MTD_UBI_FM_DEBUG 2232 Enable UBI fastmap debug 2233 default: 0 2234 2235- SPL framework 2236 CONFIG_SPL 2237 Enable building of SPL globally. 2238 2239 CONFIG_SPL_LDSCRIPT 2240 LDSCRIPT for linking the SPL binary. 2241 2242 CONFIG_SPL_MAX_FOOTPRINT 2243 Maximum size in memory allocated to the SPL, BSS included. 2244 When defined, the linker checks that the actual memory 2245 used by SPL from _start to __bss_end does not exceed it. 2246 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE 2247 must not be both defined at the same time. 2248 2249 CONFIG_SPL_MAX_SIZE 2250 Maximum size of the SPL image (text, data, rodata, and 2251 linker lists sections), BSS excluded. 2252 When defined, the linker checks that the actual size does 2253 not exceed it. 2254 2255 CONFIG_SPL_RELOC_TEXT_BASE 2256 Address to relocate to. If unspecified, this is equal to 2257 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done). 2258 2259 CONFIG_SPL_BSS_START_ADDR 2260 Link address for the BSS within the SPL binary. 2261 2262 CONFIG_SPL_BSS_MAX_SIZE 2263 Maximum size in memory allocated to the SPL BSS. 2264 When defined, the linker checks that the actual memory used 2265 by SPL from __bss_start to __bss_end does not exceed it. 2266 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE 2267 must not be both defined at the same time. 2268 2269 CONFIG_SPL_STACK 2270 Adress of the start of the stack SPL will use 2271 2272 CONFIG_SPL_PANIC_ON_RAW_IMAGE 2273 When defined, SPL will panic() if the image it has 2274 loaded does not have a signature. 2275 Defining this is useful when code which loads images 2276 in SPL cannot guarantee that absolutely all read errors 2277 will be caught. 2278 An example is the LPC32XX MLC NAND driver, which will 2279 consider that a completely unreadable NAND block is bad, 2280 and thus should be skipped silently. 2281 2282 CONFIG_SPL_RELOC_STACK 2283 Adress of the start of the stack SPL will use after 2284 relocation. If unspecified, this is equal to 2285 CONFIG_SPL_STACK. 2286 2287 CONFIG_SYS_SPL_MALLOC_START 2288 Starting address of the malloc pool used in SPL. 2289 When this option is set the full malloc is used in SPL and 2290 it is set up by spl_init() and before that, the simple malloc() 2291 can be used if CONFIG_SYS_MALLOC_F is defined. 2292 2293 CONFIG_SYS_SPL_MALLOC_SIZE 2294 The size of the malloc pool used in SPL. 2295 2296 CONFIG_SPL_OS_BOOT 2297 Enable booting directly to an OS from SPL. 2298 See also: doc/README.falcon 2299 2300 CONFIG_SPL_DISPLAY_PRINT 2301 For ARM, enable an optional function to print more information 2302 about the running system. 2303 2304 CONFIG_SPL_INIT_MINIMAL 2305 Arch init code should be built for a very small image 2306 2307 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION 2308 Partition on the MMC to load U-Boot from when the MMC is being 2309 used in raw mode 2310 2311 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR 2312 Sector to load kernel uImage from when MMC is being 2313 used in raw mode (for Falcon mode) 2314 2315 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR, 2316 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS 2317 Sector and number of sectors to load kernel argument 2318 parameters from when MMC is being used in raw mode 2319 (for falcon mode) 2320 2321 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION 2322 Partition on the MMC to load U-Boot from when the MMC is being 2323 used in fs mode 2324 2325 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME 2326 Filename to read to load U-Boot when reading from filesystem 2327 2328 CONFIG_SPL_FS_LOAD_KERNEL_NAME 2329 Filename to read to load kernel uImage when reading 2330 from filesystem (for Falcon mode) 2331 2332 CONFIG_SPL_FS_LOAD_ARGS_NAME 2333 Filename to read to load kernel argument parameters 2334 when reading from filesystem (for Falcon mode) 2335 2336 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND 2337 Set this for NAND SPL on PPC mpc83xx targets, so that 2338 start.S waits for the rest of the SPL to load before 2339 continuing (the hardware starts execution after just 2340 loading the first page rather than the full 4K). 2341 2342 CONFIG_SPL_SKIP_RELOCATE 2343 Avoid SPL relocation 2344 2345 CONFIG_SPL_NAND_BASE 2346 Include nand_base.c in the SPL. Requires 2347 CONFIG_SPL_NAND_DRIVERS. 2348 2349 CONFIG_SPL_NAND_DRIVERS 2350 SPL uses normal NAND drivers, not minimal drivers. 2351 2352 CONFIG_SPL_NAND_IDENT 2353 SPL uses the chip ID list to identify the NAND flash. 2354 Requires CONFIG_SPL_NAND_BASE. 2355 2356 CONFIG_SPL_NAND_ECC 2357 Include standard software ECC in the SPL 2358 2359 CONFIG_SPL_NAND_SIMPLE 2360 Support for NAND boot using simple NAND drivers that 2361 expose the cmd_ctrl() interface. 2362 2363 CONFIG_SPL_UBI 2364 Support for a lightweight UBI (fastmap) scanner and 2365 loader 2366 2367 CONFIG_SPL_NAND_RAW_ONLY 2368 Support to boot only raw u-boot.bin images. Use this only 2369 if you need to save space. 2370 2371 CONFIG_SPL_COMMON_INIT_DDR 2372 Set for common ddr init with serial presence detect in 2373 SPL binary. 2374 2375 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT, 2376 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE, 2377 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS, 2378 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE, 2379 CONFIG_SYS_NAND_ECCBYTES 2380 Defines the size and behavior of the NAND that SPL uses 2381 to read U-Boot 2382 2383 CONFIG_SYS_NAND_U_BOOT_OFFS 2384 Location in NAND to read U-Boot from 2385 2386 CONFIG_SYS_NAND_U_BOOT_DST 2387 Location in memory to load U-Boot to 2388 2389 CONFIG_SYS_NAND_U_BOOT_SIZE 2390 Size of image to load 2391 2392 CONFIG_SYS_NAND_U_BOOT_START 2393 Entry point in loaded image to jump to 2394 2395 CONFIG_SYS_NAND_HW_ECC_OOBFIRST 2396 Define this if you need to first read the OOB and then the 2397 data. This is used, for example, on davinci platforms. 2398 2399 CONFIG_SPL_RAM_DEVICE 2400 Support for running image already present in ram, in SPL binary 2401 2402 CONFIG_SPL_PAD_TO 2403 Image offset to which the SPL should be padded before appending 2404 the SPL payload. By default, this is defined as 2405 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined. 2406 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL 2407 payload without any padding, or >= CONFIG_SPL_MAX_SIZE. 2408 2409 CONFIG_SPL_TARGET 2410 Final target image containing SPL and payload. Some SPLs 2411 use an arch-specific makefile fragment instead, for 2412 example if more than one image needs to be produced. 2413 2414 CONFIG_SPL_FIT_PRINT 2415 Printing information about a FIT image adds quite a bit of 2416 code to SPL. So this is normally disabled in SPL. Use this 2417 option to re-enable it. This will affect the output of the 2418 bootm command when booting a FIT image. 2419 2420- TPL framework 2421 CONFIG_TPL 2422 Enable building of TPL globally. 2423 2424 CONFIG_TPL_PAD_TO 2425 Image offset to which the TPL should be padded before appending 2426 the TPL payload. By default, this is defined as 2427 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined. 2428 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL 2429 payload without any padding, or >= CONFIG_SPL_MAX_SIZE. 2430 2431- Interrupt support (PPC): 2432 2433 There are common interrupt_init() and timer_interrupt() 2434 for all PPC archs. interrupt_init() calls interrupt_init_cpu() 2435 for CPU specific initialization. interrupt_init_cpu() 2436 should set decrementer_count to appropriate value. If 2437 CPU resets decrementer automatically after interrupt 2438 (ppc4xx) it should set decrementer_count to zero. 2439 timer_interrupt() calls timer_interrupt_cpu() for CPU 2440 specific handling. If board has watchdog / status_led 2441 / other_activity_monitor it works automatically from 2442 general timer_interrupt(). 2443 2444 2445Board initialization settings: 2446------------------------------ 2447 2448During Initialization u-boot calls a number of board specific functions 2449to allow the preparation of board specific prerequisites, e.g. pin setup 2450before drivers are initialized. To enable these callbacks the 2451following configuration macros have to be defined. Currently this is 2452architecture specific, so please check arch/your_architecture/lib/board.c 2453typically in board_init_f() and board_init_r(). 2454 2455- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f() 2456- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r() 2457- CONFIG_BOARD_LATE_INIT: Call board_late_init() 2458- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init() 2459 2460Configuration Settings: 2461----------------------- 2462 2463- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit. 2464 Optionally it can be defined to support 64-bit memory commands. 2465 2466- CONFIG_SYS_LONGHELP: Defined when you want long help messages included; 2467 undefine this when you're short of memory. 2468 2469- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default 2470 width of the commands listed in the 'help' command output. 2471 2472- CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to 2473 prompt for user input. 2474 2475- CONFIG_SYS_CBSIZE: Buffer size for input from the Console 2476 2477- CONFIG_SYS_PBSIZE: Buffer size for Console output 2478 2479- CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands 2480 2481- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to 2482 the application (usually a Linux kernel) when it is 2483 booted 2484 2485- CONFIG_SYS_BAUDRATE_TABLE: 2486 List of legal baudrate settings for this board. 2487 2488- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END: 2489 Begin and End addresses of the area used by the 2490 simple memory test. 2491 2492- CONFIG_SYS_MEMTEST_SCRATCH: 2493 Scratch address used by the alternate memory test 2494 You only need to set this if address zero isn't writeable 2495 2496- CONFIG_SYS_MEM_RESERVE_SECURE 2497 Only implemented for ARMv8 for now. 2498 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory 2499 is substracted from total RAM and won't be reported to OS. 2500 This memory can be used as secure memory. A variable 2501 gd->arch.secure_ram is used to track the location. In systems 2502 the RAM base is not zero, or RAM is divided into banks, 2503 this variable needs to be recalcuated to get the address. 2504 2505- CONFIG_SYS_MEM_TOP_HIDE: 2506 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header, 2507 this specified memory area will get subtracted from the top 2508 (end) of RAM and won't get "touched" at all by U-Boot. By 2509 fixing up gd->ram_size the Linux kernel should gets passed 2510 the now "corrected" memory size and won't touch it either. 2511 This should work for arch/ppc and arch/powerpc. Only Linux 2512 board ports in arch/powerpc with bootwrapper support that 2513 recalculate the memory size from the SDRAM controller setup 2514 will have to get fixed in Linux additionally. 2515 2516 This option can be used as a workaround for the 440EPx/GRx 2517 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't 2518 be touched. 2519 2520 WARNING: Please make sure that this value is a multiple of 2521 the Linux page size (normally 4k). If this is not the case, 2522 then the end address of the Linux memory will be located at a 2523 non page size aligned address and this could cause major 2524 problems. 2525 2526- CONFIG_SYS_LOADS_BAUD_CHANGE: 2527 Enable temporary baudrate change while serial download 2528 2529- CONFIG_SYS_SDRAM_BASE: 2530 Physical start address of SDRAM. _Must_ be 0 here. 2531 2532- CONFIG_SYS_FLASH_BASE: 2533 Physical start address of Flash memory. 2534 2535- CONFIG_SYS_MONITOR_BASE: 2536 Physical start address of boot monitor code (set by 2537 make config files to be same as the text base address 2538 (CONFIG_SYS_TEXT_BASE) used when linking) - same as 2539 CONFIG_SYS_FLASH_BASE when booting from flash. 2540 2541- CONFIG_SYS_MONITOR_LEN: 2542 Size of memory reserved for monitor code, used to 2543 determine _at_compile_time_ (!) if the environment is 2544 embedded within the U-Boot image, or in a separate 2545 flash sector. 2546 2547- CONFIG_SYS_MALLOC_LEN: 2548 Size of DRAM reserved for malloc() use. 2549 2550- CONFIG_SYS_MALLOC_F_LEN 2551 Size of the malloc() pool for use before relocation. If 2552 this is defined, then a very simple malloc() implementation 2553 will become available before relocation. The address is just 2554 below the global data, and the stack is moved down to make 2555 space. 2556 2557 This feature allocates regions with increasing addresses 2558 within the region. calloc() is supported, but realloc() 2559 is not available. free() is supported but does nothing. 2560 The memory will be freed (or in fact just forgotten) when 2561 U-Boot relocates itself. 2562 2563- CONFIG_SYS_MALLOC_SIMPLE 2564 Provides a simple and small malloc() and calloc() for those 2565 boards which do not use the full malloc in SPL (which is 2566 enabled with CONFIG_SYS_SPL_MALLOC_START). 2567 2568- CONFIG_SYS_NONCACHED_MEMORY: 2569 Size of non-cached memory area. This area of memory will be 2570 typically located right below the malloc() area and mapped 2571 uncached in the MMU. This is useful for drivers that would 2572 otherwise require a lot of explicit cache maintenance. For 2573 some drivers it's also impossible to properly maintain the 2574 cache. For example if the regions that need to be flushed 2575 are not a multiple of the cache-line size, *and* padding 2576 cannot be allocated between the regions to align them (i.e. 2577 if the HW requires a contiguous array of regions, and the 2578 size of each region is not cache-aligned), then a flush of 2579 one region may result in overwriting data that hardware has 2580 written to another region in the same cache-line. This can 2581 happen for example in network drivers where descriptors for 2582 buffers are typically smaller than the CPU cache-line (e.g. 2583 16 bytes vs. 32 or 64 bytes). 2584 2585 Non-cached memory is only supported on 32-bit ARM at present. 2586 2587- CONFIG_SYS_BOOTM_LEN: 2588 Normally compressed uImages are limited to an 2589 uncompressed size of 8 MBytes. If this is not enough, 2590 you can define CONFIG_SYS_BOOTM_LEN in your board config file 2591 to adjust this setting to your needs. 2592 2593- CONFIG_SYS_BOOTMAPSZ: 2594 Maximum size of memory mapped by the startup code of 2595 the Linux kernel; all data that must be processed by 2596 the Linux kernel (bd_info, boot arguments, FDT blob if 2597 used) must be put below this limit, unless "bootm_low" 2598 environment variable is defined and non-zero. In such case 2599 all data for the Linux kernel must be between "bootm_low" 2600 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment 2601 variable "bootm_mapsize" will override the value of 2602 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined, 2603 then the value in "bootm_size" will be used instead. 2604 2605- CONFIG_SYS_BOOT_RAMDISK_HIGH: 2606 Enable initrd_high functionality. If defined then the 2607 initrd_high feature is enabled and the bootm ramdisk subcommand 2608 is enabled. 2609 2610- CONFIG_SYS_BOOT_GET_CMDLINE: 2611 Enables allocating and saving kernel cmdline in space between 2612 "bootm_low" and "bootm_low" + BOOTMAPSZ. 2613 2614- CONFIG_SYS_BOOT_GET_KBD: 2615 Enables allocating and saving a kernel copy of the bd_info in 2616 space between "bootm_low" and "bootm_low" + BOOTMAPSZ. 2617 2618- CONFIG_SYS_MAX_FLASH_BANKS: 2619 Max number of Flash memory banks 2620 2621- CONFIG_SYS_MAX_FLASH_SECT: 2622 Max number of sectors on a Flash chip 2623 2624- CONFIG_SYS_FLASH_ERASE_TOUT: 2625 Timeout for Flash erase operations (in ms) 2626 2627- CONFIG_SYS_FLASH_WRITE_TOUT: 2628 Timeout for Flash write operations (in ms) 2629 2630- CONFIG_SYS_FLASH_LOCK_TOUT 2631 Timeout for Flash set sector lock bit operation (in ms) 2632 2633- CONFIG_SYS_FLASH_UNLOCK_TOUT 2634 Timeout for Flash clear lock bits operation (in ms) 2635 2636- CONFIG_SYS_FLASH_PROTECTION 2637 If defined, hardware flash sectors protection is used 2638 instead of U-Boot software protection. 2639 2640- CONFIG_SYS_DIRECT_FLASH_TFTP: 2641 2642 Enable TFTP transfers directly to flash memory; 2643 without this option such a download has to be 2644 performed in two steps: (1) download to RAM, and (2) 2645 copy from RAM to flash. 2646 2647 The two-step approach is usually more reliable, since 2648 you can check if the download worked before you erase 2649 the flash, but in some situations (when system RAM is 2650 too limited to allow for a temporary copy of the 2651 downloaded image) this option may be very useful. 2652 2653- CONFIG_SYS_FLASH_CFI: 2654 Define if the flash driver uses extra elements in the 2655 common flash structure for storing flash geometry. 2656 2657- CONFIG_FLASH_CFI_DRIVER 2658 This option also enables the building of the cfi_flash driver 2659 in the drivers directory 2660 2661- CONFIG_FLASH_CFI_MTD 2662 This option enables the building of the cfi_mtd driver 2663 in the drivers directory. The driver exports CFI flash 2664 to the MTD layer. 2665 2666- CONFIG_SYS_FLASH_USE_BUFFER_WRITE 2667 Use buffered writes to flash. 2668 2669- CONFIG_FLASH_SPANSION_S29WS_N 2670 s29ws-n MirrorBit flash has non-standard addresses for buffered 2671 write commands. 2672 2673- CONFIG_SYS_FLASH_QUIET_TEST 2674 If this option is defined, the common CFI flash doesn't 2675 print it's warning upon not recognized FLASH banks. This 2676 is useful, if some of the configured banks are only 2677 optionally available. 2678 2679- CONFIG_FLASH_SHOW_PROGRESS 2680 If defined (must be an integer), print out countdown 2681 digits and dots. Recommended value: 45 (9..1) for 80 2682 column displays, 15 (3..1) for 40 column displays. 2683 2684- CONFIG_FLASH_VERIFY 2685 If defined, the content of the flash (destination) is compared 2686 against the source after the write operation. An error message 2687 will be printed when the contents are not identical. 2688 Please note that this option is useless in nearly all cases, 2689 since such flash programming errors usually are detected earlier 2690 while unprotecting/erasing/programming. Please only enable 2691 this option if you really know what you are doing. 2692 2693- CONFIG_SYS_RX_ETH_BUFFER: 2694 Defines the number of Ethernet receive buffers. On some 2695 Ethernet controllers it is recommended to set this value 2696 to 8 or even higher (EEPRO100 or 405 EMAC), since all 2697 buffers can be full shortly after enabling the interface 2698 on high Ethernet traffic. 2699 Defaults to 4 if not defined. 2700 2701- CONFIG_ENV_MAX_ENTRIES 2702 2703 Maximum number of entries in the hash table that is used 2704 internally to store the environment settings. The default 2705 setting is supposed to be generous and should work in most 2706 cases. This setting can be used to tune behaviour; see 2707 lib/hashtable.c for details. 2708 2709- CONFIG_ENV_FLAGS_LIST_DEFAULT 2710- CONFIG_ENV_FLAGS_LIST_STATIC 2711 Enable validation of the values given to environment variables when 2712 calling env set. Variables can be restricted to only decimal, 2713 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined, 2714 the variables can also be restricted to IP address or MAC address. 2715 2716 The format of the list is: 2717 type_attribute = [s|d|x|b|i|m] 2718 access_attribute = [a|r|o|c] 2719 attributes = type_attribute[access_attribute] 2720 entry = variable_name[:attributes] 2721 list = entry[,list] 2722 2723 The type attributes are: 2724 s - String (default) 2725 d - Decimal 2726 x - Hexadecimal 2727 b - Boolean ([1yYtT|0nNfF]) 2728 i - IP address 2729 m - MAC address 2730 2731 The access attributes are: 2732 a - Any (default) 2733 r - Read-only 2734 o - Write-once 2735 c - Change-default 2736 2737 - CONFIG_ENV_FLAGS_LIST_DEFAULT 2738 Define this to a list (string) to define the ".flags" 2739 environment variable in the default or embedded environment. 2740 2741 - CONFIG_ENV_FLAGS_LIST_STATIC 2742 Define this to a list (string) to define validation that 2743 should be done if an entry is not found in the ".flags" 2744 environment variable. To override a setting in the static 2745 list, simply add an entry for the same variable name to the 2746 ".flags" variable. 2747 2748 If CONFIG_REGEX is defined, the variable_name above is evaluated as a 2749 regular expression. This allows multiple variables to define the same 2750 flags without explicitly listing them for each variable. 2751 2752- CONFIG_ENV_ACCESS_IGNORE_FORCE 2753 If defined, don't allow the -f switch to env set override variable 2754 access flags. 2755 2756The following definitions that deal with the placement and management 2757of environment data (variable area); in general, we support the 2758following configurations: 2759 2760- CONFIG_BUILD_ENVCRC: 2761 2762 Builds up envcrc with the target environment so that external utils 2763 may easily extract it and embed it in final U-Boot images. 2764 2765BE CAREFUL! The first access to the environment happens quite early 2766in U-Boot initialization (when we try to get the setting of for the 2767console baudrate). You *MUST* have mapped your NVRAM area then, or 2768U-Boot will hang. 2769 2770Please note that even with NVRAM we still use a copy of the 2771environment in RAM: we could work on NVRAM directly, but we want to 2772keep settings there always unmodified except somebody uses "saveenv" 2773to save the current settings. 2774 2775BE CAREFUL! For some special cases, the local device can not use 2776"saveenv" command. For example, the local device will get the 2777environment stored in a remote NOR flash by SRIO or PCIE link, 2778but it can not erase, write this NOR flash by SRIO or PCIE interface. 2779 2780- CONFIG_NAND_ENV_DST 2781 2782 Defines address in RAM to which the nand_spl code should copy the 2783 environment. If redundant environment is used, it will be copied to 2784 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE. 2785 2786Please note that the environment is read-only until the monitor 2787has been relocated to RAM and a RAM copy of the environment has been 2788created; also, when using EEPROM you will have to use env_get_f() 2789until then to read environment variables. 2790 2791The environment is protected by a CRC32 checksum. Before the monitor 2792is relocated into RAM, as a result of a bad CRC you will be working 2793with the compiled-in default environment - *silently*!!! [This is 2794necessary, because the first environment variable we need is the 2795"baudrate" setting for the console - if we have a bad CRC, we don't 2796have any device yet where we could complain.] 2797 2798Note: once the monitor has been relocated, then it will complain if 2799the default environment is used; a new CRC is computed as soon as you 2800use the "saveenv" command to store a valid environment. 2801 2802- CONFIG_SYS_FAULT_ECHO_LINK_DOWN: 2803 Echo the inverted Ethernet link state to the fault LED. 2804 2805 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR 2806 also needs to be defined. 2807 2808- CONFIG_SYS_FAULT_MII_ADDR: 2809 MII address of the PHY to check for the Ethernet link state. 2810 2811- CONFIG_NS16550_MIN_FUNCTIONS: 2812 Define this if you desire to only have use of the NS16550_init 2813 and NS16550_putc functions for the serial driver located at 2814 drivers/serial/ns16550.c. This option is useful for saving 2815 space for already greatly restricted images, including but not 2816 limited to NAND_SPL configurations. 2817 2818- CONFIG_DISPLAY_BOARDINFO 2819 Display information about the board that U-Boot is running on 2820 when U-Boot starts up. The board function checkboard() is called 2821 to do this. 2822 2823- CONFIG_DISPLAY_BOARDINFO_LATE 2824 Similar to the previous option, but display this information 2825 later, once stdio is running and output goes to the LCD, if 2826 present. 2827 2828- CONFIG_BOARD_SIZE_LIMIT: 2829 Maximum size of the U-Boot image. When defined, the 2830 build system checks that the actual size does not 2831 exceed it. 2832 2833Low Level (hardware related) configuration options: 2834--------------------------------------------------- 2835 2836- CONFIG_SYS_CACHELINE_SIZE: 2837 Cache Line Size of the CPU. 2838 2839- CONFIG_SYS_CCSRBAR_DEFAULT: 2840 Default (power-on reset) physical address of CCSR on Freescale 2841 PowerPC SOCs. 2842 2843- CONFIG_SYS_CCSRBAR: 2844 Virtual address of CCSR. On a 32-bit build, this is typically 2845 the same value as CONFIG_SYS_CCSRBAR_DEFAULT. 2846 2847- CONFIG_SYS_CCSRBAR_PHYS: 2848 Physical address of CCSR. CCSR can be relocated to a new 2849 physical address, if desired. In this case, this macro should 2850 be set to that address. Otherwise, it should be set to the 2851 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR 2852 is typically relocated on 36-bit builds. It is recommended 2853 that this macro be defined via the _HIGH and _LOW macros: 2854 2855 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH 2856 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW) 2857 2858- CONFIG_SYS_CCSRBAR_PHYS_HIGH: 2859 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically 2860 either 0 (32-bit build) or 0xF (36-bit build). This macro is 2861 used in assembly code, so it must not contain typecasts or 2862 integer size suffixes (e.g. "ULL"). 2863 2864- CONFIG_SYS_CCSRBAR_PHYS_LOW: 2865 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is 2866 used in assembly code, so it must not contain typecasts or 2867 integer size suffixes (e.g. "ULL"). 2868 2869- CONFIG_SYS_CCSR_DO_NOT_RELOCATE: 2870 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be 2871 forced to a value that ensures that CCSR is not relocated. 2872 2873- Floppy Disk Support: 2874 CONFIG_SYS_FDC_DRIVE_NUMBER 2875 2876 the default drive number (default value 0) 2877 2878 CONFIG_SYS_ISA_IO_STRIDE 2879 2880 defines the spacing between FDC chipset registers 2881 (default value 1) 2882 2883 CONFIG_SYS_ISA_IO_OFFSET 2884 2885 defines the offset of register from address. It 2886 depends on which part of the data bus is connected to 2887 the FDC chipset. (default value 0) 2888 2889 If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and 2890 CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their 2891 default value. 2892 2893 if CONFIG_SYS_FDC_HW_INIT is defined, then the function 2894 fdc_hw_init() is called at the beginning of the FDC 2895 setup. fdc_hw_init() must be provided by the board 2896 source code. It is used to make hardware-dependent 2897 initializations. 2898 2899- CONFIG_IDE_AHB: 2900 Most IDE controllers were designed to be connected with PCI 2901 interface. Only few of them were designed for AHB interface. 2902 When software is doing ATA command and data transfer to 2903 IDE devices through IDE-AHB controller, some additional 2904 registers accessing to these kind of IDE-AHB controller 2905 is required. 2906 2907- CONFIG_SYS_IMMR: Physical address of the Internal Memory. 2908 DO NOT CHANGE unless you know exactly what you're 2909 doing! (11-4) [MPC8xx systems only] 2910 2911- CONFIG_SYS_INIT_RAM_ADDR: 2912 2913 Start address of memory area that can be used for 2914 initial data and stack; please note that this must be 2915 writable memory that is working WITHOUT special 2916 initialization, i. e. you CANNOT use normal RAM which 2917 will become available only after programming the 2918 memory controller and running certain initialization 2919 sequences. 2920 2921 U-Boot uses the following memory types: 2922 - MPC8xx: IMMR (internal memory of the CPU) 2923 2924- CONFIG_SYS_GBL_DATA_OFFSET: 2925 2926 Offset of the initial data structure in the memory 2927 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually 2928 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial 2929 data is located at the end of the available space 2930 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE - 2931 GENERATED_GBL_DATA_SIZE), and the initial stack is just 2932 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR + 2933 CONFIG_SYS_GBL_DATA_OFFSET) downward. 2934 2935 Note: 2936 On the MPC824X (or other systems that use the data 2937 cache for initial memory) the address chosen for 2938 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must 2939 point to an otherwise UNUSED address space between 2940 the top of RAM and the start of the PCI space. 2941 2942- CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27) 2943 2944- CONFIG_SYS_OR_TIMING_SDRAM: 2945 SDRAM timing 2946 2947- CONFIG_SYS_MAMR_PTA: 2948 periodic timer for refresh 2949 2950- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM, 2951 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP, 2952 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM, 2953 CONFIG_SYS_BR1_PRELIM: 2954 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH) 2955 2956- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE, 2957 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM, 2958 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM: 2959 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM) 2960 2961- CONFIG_PCI_ENUM_ONLY 2962 Only scan through and get the devices on the buses. 2963 Don't do any setup work, presumably because someone or 2964 something has already done it, and we don't need to do it 2965 a second time. Useful for platforms that are pre-booted 2966 by coreboot or similar. 2967 2968- CONFIG_PCI_INDIRECT_BRIDGE: 2969 Enable support for indirect PCI bridges. 2970 2971- CONFIG_SYS_SRIO: 2972 Chip has SRIO or not 2973 2974- CONFIG_SRIO1: 2975 Board has SRIO 1 port available 2976 2977- CONFIG_SRIO2: 2978 Board has SRIO 2 port available 2979 2980- CONFIG_SRIO_PCIE_BOOT_MASTER 2981 Board can support master function for Boot from SRIO and PCIE 2982 2983- CONFIG_SYS_SRIOn_MEM_VIRT: 2984 Virtual Address of SRIO port 'n' memory region 2985 2986- CONFIG_SYS_SRIOn_MEM_PHYxS: 2987 Physical Address of SRIO port 'n' memory region 2988 2989- CONFIG_SYS_SRIOn_MEM_SIZE: 2990 Size of SRIO port 'n' memory region 2991 2992- CONFIG_SYS_NAND_BUSWIDTH_16BIT 2993 Defined to tell the NAND controller that the NAND chip is using 2994 a 16 bit bus. 2995 Not all NAND drivers use this symbol. 2996 Example of drivers that use it: 2997 - drivers/mtd/nand/raw/ndfc.c 2998 - drivers/mtd/nand/raw/mxc_nand.c 2999 3000- CONFIG_SYS_NDFC_EBC0_CFG 3001 Sets the EBC0_CFG register for the NDFC. If not defined 3002 a default value will be used. 3003 3004- CONFIG_SPD_EEPROM 3005 Get DDR timing information from an I2C EEPROM. Common 3006 with pluggable memory modules such as SODIMMs 3007 3008 SPD_EEPROM_ADDRESS 3009 I2C address of the SPD EEPROM 3010 3011- CONFIG_SYS_SPD_BUS_NUM 3012 If SPD EEPROM is on an I2C bus other than the first 3013 one, specify here. Note that the value must resolve 3014 to something your driver can deal with. 3015 3016- CONFIG_SYS_DDR_RAW_TIMING 3017 Get DDR timing information from other than SPD. Common with 3018 soldered DDR chips onboard without SPD. DDR raw timing 3019 parameters are extracted from datasheet and hard-coded into 3020 header files or board specific files. 3021 3022- CONFIG_FSL_DDR_INTERACTIVE 3023 Enable interactive DDR debugging. See doc/README.fsl-ddr. 3024 3025- CONFIG_FSL_DDR_SYNC_REFRESH 3026 Enable sync of refresh for multiple controllers. 3027 3028- CONFIG_FSL_DDR_BIST 3029 Enable built-in memory test for Freescale DDR controllers. 3030 3031- CONFIG_SYS_83XX_DDR_USES_CS0 3032 Only for 83xx systems. If specified, then DDR should 3033 be configured using CS0 and CS1 instead of CS2 and CS3. 3034 3035- CONFIG_RMII 3036 Enable RMII mode for all FECs. 3037 Note that this is a global option, we can't 3038 have one FEC in standard MII mode and another in RMII mode. 3039 3040- CONFIG_CRC32_VERIFY 3041 Add a verify option to the crc32 command. 3042 The syntax is: 3043 3044 => crc32 -v <address> <count> <crc32> 3045 3046 Where address/count indicate a memory area 3047 and crc32 is the correct crc32 which the 3048 area should have. 3049 3050- CONFIG_LOOPW 3051 Add the "loopw" memory command. This only takes effect if 3052 the memory commands are activated globally (CONFIG_CMD_MEMORY). 3053 3054- CONFIG_MX_CYCLIC 3055 Add the "mdc" and "mwc" memory commands. These are cyclic 3056 "md/mw" commands. 3057 Examples: 3058 3059 => mdc.b 10 4 500 3060 This command will print 4 bytes (10,11,12,13) each 500 ms. 3061 3062 => mwc.l 100 12345678 10 3063 This command will write 12345678 to address 100 all 10 ms. 3064 3065 This only takes effect if the memory commands are activated 3066 globally (CONFIG_CMD_MEMORY). 3067 3068- CONFIG_SKIP_LOWLEVEL_INIT 3069 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain 3070 low level initializations (like setting up the memory 3071 controller) are omitted and/or U-Boot does not 3072 relocate itself into RAM. 3073 3074 Normally this variable MUST NOT be defined. The only 3075 exception is when U-Boot is loaded (to RAM) by some 3076 other boot loader or by a debugger which performs 3077 these initializations itself. 3078 3079- CONFIG_SKIP_LOWLEVEL_INIT_ONLY 3080 [ARM926EJ-S only] This allows just the call to lowlevel_init() 3081 to be skipped. The normal CP15 init (such as enabling the 3082 instruction cache) is still performed. 3083 3084- CONFIG_SPL_BUILD 3085 Set when the currently-running compilation is for an artifact 3086 that will end up in the SPL (as opposed to the TPL or U-Boot 3087 proper). Code that needs stage-specific behavior should check 3088 this. 3089 3090- CONFIG_TPL_BUILD 3091 Set when the currently-running compilation is for an artifact 3092 that will end up in the TPL (as opposed to the SPL or U-Boot 3093 proper). Code that needs stage-specific behavior should check 3094 this. 3095 3096- CONFIG_SYS_MPC85XX_NO_RESETVEC 3097 Only for 85xx systems. If this variable is specified, the section 3098 .resetvec is not kept and the section .bootpg is placed in the 3099 previous 4k of the .text section. 3100 3101- CONFIG_ARCH_MAP_SYSMEM 3102 Generally U-Boot (and in particular the md command) uses 3103 effective address. It is therefore not necessary to regard 3104 U-Boot address as virtual addresses that need to be translated 3105 to physical addresses. However, sandbox requires this, since 3106 it maintains its own little RAM buffer which contains all 3107 addressable memory. This option causes some memory accesses 3108 to be mapped through map_sysmem() / unmap_sysmem(). 3109 3110- CONFIG_X86_RESET_VECTOR 3111 If defined, the x86 reset vector code is included. This is not 3112 needed when U-Boot is running from Coreboot. 3113 3114- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE 3115 Option to disable subpage write in NAND driver 3116 driver that uses this: 3117 drivers/mtd/nand/raw/davinci_nand.c 3118 3119Freescale QE/FMAN Firmware Support: 3120----------------------------------- 3121 3122The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the 3123loading of "firmware", which is encoded in the QE firmware binary format. 3124This firmware often needs to be loaded during U-Boot booting, so macros 3125are used to identify the storage device (NOR flash, SPI, etc) and the address 3126within that device. 3127 3128- CONFIG_SYS_FMAN_FW_ADDR 3129 The address in the storage device where the FMAN microcode is located. The 3130 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro 3131 is also specified. 3132 3133- CONFIG_SYS_QE_FW_ADDR 3134 The address in the storage device where the QE microcode is located. The 3135 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro 3136 is also specified. 3137 3138- CONFIG_SYS_QE_FMAN_FW_LENGTH 3139 The maximum possible size of the firmware. The firmware binary format 3140 has a field that specifies the actual size of the firmware, but it 3141 might not be possible to read any part of the firmware unless some 3142 local storage is allocated to hold the entire firmware first. 3143 3144- CONFIG_SYS_QE_FMAN_FW_IN_NOR 3145 Specifies that QE/FMAN firmware is located in NOR flash, mapped as 3146 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the 3147 virtual address in NOR flash. 3148 3149- CONFIG_SYS_QE_FMAN_FW_IN_NAND 3150 Specifies that QE/FMAN firmware is located in NAND flash. 3151 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash. 3152 3153- CONFIG_SYS_QE_FMAN_FW_IN_MMC 3154 Specifies that QE/FMAN firmware is located on the primary SD/MMC 3155 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device. 3156 3157- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE 3158 Specifies that QE/FMAN firmware is located in the remote (master) 3159 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which 3160 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound 3161 window->master inbound window->master LAW->the ucode address in 3162 master's memory space. 3163 3164Freescale Layerscape Management Complex Firmware Support: 3165--------------------------------------------------------- 3166The Freescale Layerscape Management Complex (MC) supports the loading of 3167"firmware". 3168This firmware often needs to be loaded during U-Boot booting, so macros 3169are used to identify the storage device (NOR flash, SPI, etc) and the address 3170within that device. 3171 3172- CONFIG_FSL_MC_ENET 3173 Enable the MC driver for Layerscape SoCs. 3174 3175Freescale Layerscape Debug Server Support: 3176------------------------------------------- 3177The Freescale Layerscape Debug Server Support supports the loading of 3178"Debug Server firmware" and triggering SP boot-rom. 3179This firmware often needs to be loaded during U-Boot booting. 3180 3181- CONFIG_SYS_MC_RSV_MEM_ALIGN 3182 Define alignment of reserved memory MC requires 3183 3184Reproducible builds 3185------------------- 3186 3187In order to achieve reproducible builds, timestamps used in the U-Boot build 3188process have to be set to a fixed value. 3189 3190This is done using the SOURCE_DATE_EPOCH environment variable. 3191SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration 3192option for U-Boot or an environment variable in U-Boot. 3193 3194SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC. 3195 3196Building the Software: 3197====================== 3198 3199Building U-Boot has been tested in several native build environments 3200and in many different cross environments. Of course we cannot support 3201all possibly existing versions of cross development tools in all 3202(potentially obsolete) versions. In case of tool chain problems we 3203recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK) 3204which is extensively used to build and test U-Boot. 3205 3206If you are not using a native environment, it is assumed that you 3207have GNU cross compiling tools available in your path. In this case, 3208you must set the environment variable CROSS_COMPILE in your shell. 3209Note that no changes to the Makefile or any other source files are 3210necessary. For example using the ELDK on a 4xx CPU, please enter: 3211 3212 $ CROSS_COMPILE=ppc_4xx- 3213 $ export CROSS_COMPILE 3214 3215Note: If you wish to generate Windows versions of the utilities in 3216 the tools directory you can use the MinGW toolchain 3217 (http://www.mingw.org). Set your HOST tools to the MinGW 3218 toolchain and execute 'make tools'. For example: 3219 3220 $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools 3221 3222 Binaries such as tools/mkimage.exe will be created which can 3223 be executed on computers running Windows. 3224 3225U-Boot is intended to be simple to build. After installing the 3226sources you must configure U-Boot for one specific board type. This 3227is done by typing: 3228 3229 make NAME_defconfig 3230 3231where "NAME_defconfig" is the name of one of the existing configu- 3232rations; see boards.cfg for supported names. 3233 3234Note: for some board special configuration names may exist; check if 3235 additional information is available from the board vendor; for 3236 instance, the TQM823L systems are available without (standard) 3237 or with LCD support. You can select such additional "features" 3238 when choosing the configuration, i. e. 3239 3240 make TQM823L_defconfig 3241 - will configure for a plain TQM823L, i. e. no LCD support 3242 3243 make TQM823L_LCD_defconfig 3244 - will configure for a TQM823L with U-Boot console on LCD 3245 3246 etc. 3247 3248 3249Finally, type "make all", and you should get some working U-Boot 3250images ready for download to / installation on your system: 3251 3252- "u-boot.bin" is a raw binary image 3253- "u-boot" is an image in ELF binary format 3254- "u-boot.srec" is in Motorola S-Record format 3255 3256By default the build is performed locally and the objects are saved 3257in the source directory. One of the two methods can be used to change 3258this behavior and build U-Boot to some external directory: 3259 32601. Add O= to the make command line invocations: 3261 3262 make O=/tmp/build distclean 3263 make O=/tmp/build NAME_defconfig 3264 make O=/tmp/build all 3265 32662. Set environment variable KBUILD_OUTPUT to point to the desired location: 3267 3268 export KBUILD_OUTPUT=/tmp/build 3269 make distclean 3270 make NAME_defconfig 3271 make all 3272 3273Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment 3274variable. 3275 3276User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by 3277setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS. 3278For example to treat all compiler warnings as errors: 3279 3280 make KCFLAGS=-Werror 3281 3282Please be aware that the Makefiles assume you are using GNU make, so 3283for instance on NetBSD you might need to use "gmake" instead of 3284native "make". 3285 3286 3287If the system board that you have is not listed, then you will need 3288to port U-Boot to your hardware platform. To do this, follow these 3289steps: 3290 32911. Create a new directory to hold your board specific code. Add any 3292 files you need. In your board directory, you will need at least 3293 the "Makefile" and a "<board>.c". 32942. Create a new configuration file "include/configs/<board>.h" for 3295 your board. 32963. If you're porting U-Boot to a new CPU, then also create a new 3297 directory to hold your CPU specific code. Add any files you need. 32984. Run "make <board>_defconfig" with your new name. 32995. Type "make", and you should get a working "u-boot.srec" file 3300 to be installed on your target system. 33016. Debug and solve any problems that might arise. 3302 [Of course, this last step is much harder than it sounds.] 3303 3304 3305Testing of U-Boot Modifications, Ports to New Hardware, etc.: 3306============================================================== 3307 3308If you have modified U-Boot sources (for instance added a new board 3309or support for new devices, a new CPU, etc.) you are expected to 3310provide feedback to the other developers. The feedback normally takes 3311the form of a "patch", i.e. a context diff against a certain (latest 3312official or latest in the git repository) version of U-Boot sources. 3313 3314But before you submit such a patch, please verify that your modifi- 3315cation did not break existing code. At least make sure that *ALL* of 3316the supported boards compile WITHOUT ANY compiler warnings. To do so, 3317just run the buildman script (tools/buildman/buildman), which will 3318configure and build U-Boot for ALL supported system. Be warned, this 3319will take a while. Please see the buildman README, or run 'buildman -H' 3320for documentation. 3321 3322 3323See also "U-Boot Porting Guide" below. 3324 3325 3326Monitor Commands - Overview: 3327============================ 3328 3329go - start application at address 'addr' 3330run - run commands in an environment variable 3331bootm - boot application image from memory 3332bootp - boot image via network using BootP/TFTP protocol 3333bootz - boot zImage from memory 3334tftpboot- boot image via network using TFTP protocol 3335 and env variables "ipaddr" and "serverip" 3336 (and eventually "gatewayip") 3337tftpput - upload a file via network using TFTP protocol 3338rarpboot- boot image via network using RARP/TFTP protocol 3339diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd' 3340loads - load S-Record file over serial line 3341loadb - load binary file over serial line (kermit mode) 3342md - memory display 3343mm - memory modify (auto-incrementing) 3344nm - memory modify (constant address) 3345mw - memory write (fill) 3346cp - memory copy 3347cmp - memory compare 3348crc32 - checksum calculation 3349i2c - I2C sub-system 3350sspi - SPI utility commands 3351base - print or set address offset 3352printenv- print environment variables 3353setenv - set environment variables 3354saveenv - save environment variables to persistent storage 3355protect - enable or disable FLASH write protection 3356erase - erase FLASH memory 3357flinfo - print FLASH memory information 3358nand - NAND memory operations (see doc/README.nand) 3359bdinfo - print Board Info structure 3360iminfo - print header information for application image 3361coninfo - print console devices and informations 3362ide - IDE sub-system 3363loop - infinite loop on address range 3364loopw - infinite write loop on address range 3365mtest - simple RAM test 3366icache - enable or disable instruction cache 3367dcache - enable or disable data cache 3368reset - Perform RESET of the CPU 3369echo - echo args to console 3370version - print monitor version 3371help - print online help 3372? - alias for 'help' 3373 3374 3375Monitor Commands - Detailed Description: 3376======================================== 3377 3378TODO. 3379 3380For now: just type "help <command>". 3381 3382 3383Environment Variables: 3384====================== 3385 3386U-Boot supports user configuration using Environment Variables which 3387can be made persistent by saving to Flash memory. 3388 3389Environment Variables are set using "setenv", printed using 3390"printenv", and saved to Flash using "saveenv". Using "setenv" 3391without a value can be used to delete a variable from the 3392environment. As long as you don't save the environment you are 3393working with an in-memory copy. In case the Flash area containing the 3394environment is erased by accident, a default environment is provided. 3395 3396Some configuration options can be set using Environment Variables. 3397 3398List of environment variables (most likely not complete): 3399 3400 baudrate - see CONFIG_BAUDRATE 3401 3402 bootdelay - see CONFIG_BOOTDELAY 3403 3404 bootcmd - see CONFIG_BOOTCOMMAND 3405 3406 bootargs - Boot arguments when booting an RTOS image 3407 3408 bootfile - Name of the image to load with TFTP 3409 3410 bootm_low - Memory range available for image processing in the bootm 3411 command can be restricted. This variable is given as 3412 a hexadecimal number and defines lowest address allowed 3413 for use by the bootm command. See also "bootm_size" 3414 environment variable. Address defined by "bootm_low" is 3415 also the base of the initial memory mapping for the Linux 3416 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and 3417 bootm_mapsize. 3418 3419 bootm_mapsize - Size of the initial memory mapping for the Linux kernel. 3420 This variable is given as a hexadecimal number and it 3421 defines the size of the memory region starting at base 3422 address bootm_low that is accessible by the Linux kernel 3423 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used 3424 as the default value if it is defined, and bootm_size is 3425 used otherwise. 3426 3427 bootm_size - Memory range available for image processing in the bootm 3428 command can be restricted. This variable is given as 3429 a hexadecimal number and defines the size of the region 3430 allowed for use by the bootm command. See also "bootm_low" 3431 environment variable. 3432 3433 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot 3434 3435 updatefile - Location of the software update file on a TFTP server, used 3436 by the automatic software update feature. Please refer to 3437 documentation in doc/README.update for more details. 3438 3439 autoload - if set to "no" (any string beginning with 'n'), 3440 "bootp" will just load perform a lookup of the 3441 configuration from the BOOTP server, but not try to 3442 load any image using TFTP 3443 3444 autostart - if set to "yes", an image loaded using the "bootp", 3445 "rarpboot", "tftpboot" or "diskboot" commands will 3446 be automatically started (by internally calling 3447 "bootm") 3448 3449 If set to "no", a standalone image passed to the 3450 "bootm" command will be copied to the load address 3451 (and eventually uncompressed), but NOT be started. 3452 This can be used to load and uncompress arbitrary 3453 data. 3454 3455 fdt_high - if set this restricts the maximum address that the 3456 flattened device tree will be copied into upon boot. 3457 For example, if you have a system with 1 GB memory 3458 at physical address 0x10000000, while Linux kernel 3459 only recognizes the first 704 MB as low memory, you 3460 may need to set fdt_high as 0x3C000000 to have the 3461 device tree blob be copied to the maximum address 3462 of the 704 MB low memory, so that Linux kernel can 3463 access it during the boot procedure. 3464 3465 If this is set to the special value 0xFFFFFFFF then 3466 the fdt will not be copied at all on boot. For this 3467 to work it must reside in writable memory, have 3468 sufficient padding on the end of it for u-boot to 3469 add the information it needs into it, and the memory 3470 must be accessible by the kernel. 3471 3472 fdtcontroladdr- if set this is the address of the control flattened 3473 device tree used by U-Boot when CONFIG_OF_CONTROL is 3474 defined. 3475 3476 i2cfast - (PPC405GP|PPC405EP only) 3477 if set to 'y' configures Linux I2C driver for fast 3478 mode (400kHZ). This environment variable is used in 3479 initialization code. So, for changes to be effective 3480 it must be saved and board must be reset. 3481 3482 initrd_high - restrict positioning of initrd images: 3483 If this variable is not set, initrd images will be 3484 copied to the highest possible address in RAM; this 3485 is usually what you want since it allows for 3486 maximum initrd size. If for some reason you want to 3487 make sure that the initrd image is loaded below the 3488 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment 3489 variable to a value of "no" or "off" or "0". 3490 Alternatively, you can set it to a maximum upper 3491 address to use (U-Boot will still check that it 3492 does not overwrite the U-Boot stack and data). 3493 3494 For instance, when you have a system with 16 MB 3495 RAM, and want to reserve 4 MB from use by Linux, 3496 you can do this by adding "mem=12M" to the value of 3497 the "bootargs" variable. However, now you must make 3498 sure that the initrd image is placed in the first 3499 12 MB as well - this can be done with 3500 3501 setenv initrd_high 00c00000 3502 3503 If you set initrd_high to 0xFFFFFFFF, this is an 3504 indication to U-Boot that all addresses are legal 3505 for the Linux kernel, including addresses in flash 3506 memory. In this case U-Boot will NOT COPY the 3507 ramdisk at all. This may be useful to reduce the 3508 boot time on your system, but requires that this 3509 feature is supported by your Linux kernel. 3510 3511 ipaddr - IP address; needed for tftpboot command 3512 3513 loadaddr - Default load address for commands like "bootp", 3514 "rarpboot", "tftpboot", "loadb" or "diskboot" 3515 3516 loads_echo - see CONFIG_LOADS_ECHO 3517 3518 serverip - TFTP server IP address; needed for tftpboot command 3519 3520 bootretry - see CONFIG_BOOT_RETRY_TIME 3521 3522 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR 3523 3524 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR 3525 3526 ethprime - controls which interface is used first. 3527 3528 ethact - controls which interface is currently active. 3529 For example you can do the following 3530 3531 => setenv ethact FEC 3532 => ping 192.168.0.1 # traffic sent on FEC 3533 => setenv ethact SCC 3534 => ping 10.0.0.1 # traffic sent on SCC 3535 3536 ethrotate - When set to "no" U-Boot does not go through all 3537 available network interfaces. 3538 It just stays at the currently selected interface. 3539 3540 netretry - When set to "no" each network operation will 3541 either succeed or fail without retrying. 3542 When set to "once" the network operation will 3543 fail when all the available network interfaces 3544 are tried once without success. 3545 Useful on scripts which control the retry operation 3546 themselves. 3547 3548 npe_ucode - set load address for the NPE microcode 3549 3550 silent_linux - If set then Linux will be told to boot silently, by 3551 changing the console to be empty. If "yes" it will be 3552 made silent. If "no" it will not be made silent. If 3553 unset, then it will be made silent if the U-Boot console 3554 is silent. 3555 3556 tftpsrcp - If this is set, the value is used for TFTP's 3557 UDP source port. 3558 3559 tftpdstp - If this is set, the value is used for TFTP's UDP 3560 destination port instead of the Well Know Port 69. 3561 3562 tftpblocksize - Block size to use for TFTP transfers; if not set, 3563 we use the TFTP server's default block size 3564 3565 tftptimeout - Retransmission timeout for TFTP packets (in milli- 3566 seconds, minimum value is 1000 = 1 second). Defines 3567 when a packet is considered to be lost so it has to 3568 be retransmitted. The default is 5000 = 5 seconds. 3569 Lowering this value may make downloads succeed 3570 faster in networks with high packet loss rates or 3571 with unreliable TFTP servers. 3572 3573 tftptimeoutcountmax - maximum count of TFTP timeouts (no 3574 unit, minimum value = 0). Defines how many timeouts 3575 can happen during a single file transfer before that 3576 transfer is aborted. The default is 10, and 0 means 3577 'no timeouts allowed'. Increasing this value may help 3578 downloads succeed with high packet loss rates, or with 3579 unreliable TFTP servers or client hardware. 3580 3581 vlan - When set to a value < 4095 the traffic over 3582 Ethernet is encapsulated/received over 802.1q 3583 VLAN tagged frames. 3584 3585 bootpretryperiod - Period during which BOOTP/DHCP sends retries. 3586 Unsigned value, in milliseconds. If not set, the period will 3587 be either the default (28000), or a value based on 3588 CONFIG_NET_RETRY_COUNT, if defined. This value has 3589 precedence over the valu based on CONFIG_NET_RETRY_COUNT. 3590 3591The following image location variables contain the location of images 3592used in booting. The "Image" column gives the role of the image and is 3593not an environment variable name. The other columns are environment 3594variable names. "File Name" gives the name of the file on a TFTP 3595server, "RAM Address" gives the location in RAM the image will be 3596loaded to, and "Flash Location" gives the image's address in NOR 3597flash or offset in NAND flash. 3598 3599*Note* - these variables don't have to be defined for all boards, some 3600boards currently use other variables for these purposes, and some 3601boards use these variables for other purposes. 3602 3603Image File Name RAM Address Flash Location 3604----- --------- ----------- -------------- 3605u-boot u-boot u-boot_addr_r u-boot_addr 3606Linux kernel bootfile kernel_addr_r kernel_addr 3607device tree blob fdtfile fdt_addr_r fdt_addr 3608ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr 3609 3610The following environment variables may be used and automatically 3611updated by the network boot commands ("bootp" and "rarpboot"), 3612depending the information provided by your boot server: 3613 3614 bootfile - see above 3615 dnsip - IP address of your Domain Name Server 3616 dnsip2 - IP address of your secondary Domain Name Server 3617 gatewayip - IP address of the Gateway (Router) to use 3618 hostname - Target hostname 3619 ipaddr - see above 3620 netmask - Subnet Mask 3621 rootpath - Pathname of the root filesystem on the NFS server 3622 serverip - see above 3623 3624 3625There are two special Environment Variables: 3626 3627 serial# - contains hardware identification information such 3628 as type string and/or serial number 3629 ethaddr - Ethernet address 3630 3631These variables can be set only once (usually during manufacturing of 3632the board). U-Boot refuses to delete or overwrite these variables 3633once they have been set once. 3634 3635 3636Further special Environment Variables: 3637 3638 ver - Contains the U-Boot version string as printed 3639 with the "version" command. This variable is 3640 readonly (see CONFIG_VERSION_VARIABLE). 3641 3642 3643Please note that changes to some configuration parameters may take 3644only effect after the next boot (yes, that's just like Windoze :-). 3645 3646 3647Callback functions for environment variables: 3648--------------------------------------------- 3649 3650For some environment variables, the behavior of u-boot needs to change 3651when their values are changed. This functionality allows functions to 3652be associated with arbitrary variables. On creation, overwrite, or 3653deletion, the callback will provide the opportunity for some side 3654effect to happen or for the change to be rejected. 3655 3656The callbacks are named and associated with a function using the 3657U_BOOT_ENV_CALLBACK macro in your board or driver code. 3658 3659These callbacks are associated with variables in one of two ways. The 3660static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC 3661in the board configuration to a string that defines a list of 3662associations. The list must be in the following format: 3663 3664 entry = variable_name[:callback_name] 3665 list = entry[,list] 3666 3667If the callback name is not specified, then the callback is deleted. 3668Spaces are also allowed anywhere in the list. 3669 3670Callbacks can also be associated by defining the ".callbacks" variable 3671with the same list format above. Any association in ".callbacks" will 3672override any association in the static list. You can define 3673CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the 3674".callbacks" environment variable in the default or embedded environment. 3675 3676If CONFIG_REGEX is defined, the variable_name above is evaluated as a 3677regular expression. This allows multiple variables to be connected to 3678the same callback without explicitly listing them all out. 3679 3680The signature of the callback functions is: 3681 3682 int callback(const char *name, const char *value, enum env_op op, int flags) 3683 3684* name - changed environment variable 3685* value - new value of the environment variable 3686* op - operation (create, overwrite, or delete) 3687* flags - attributes of the environment variable change, see flags H_* in 3688 include/search.h 3689 3690The return value is 0 if the variable change is accepted and 1 otherwise. 3691 3692Command Line Parsing: 3693===================== 3694 3695There are two different command line parsers available with U-Boot: 3696the old "simple" one, and the much more powerful "hush" shell: 3697 3698Old, simple command line parser: 3699-------------------------------- 3700 3701- supports environment variables (through setenv / saveenv commands) 3702- several commands on one line, separated by ';' 3703- variable substitution using "... ${name} ..." syntax 3704- special characters ('$', ';') can be escaped by prefixing with '\', 3705 for example: 3706 setenv bootcmd bootm \${address} 3707- You can also escape text by enclosing in single apostrophes, for example: 3708 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off' 3709 3710Hush shell: 3711----------- 3712 3713- similar to Bourne shell, with control structures like 3714 if...then...else...fi, for...do...done; while...do...done, 3715 until...do...done, ... 3716- supports environment ("global") variables (through setenv / saveenv 3717 commands) and local shell variables (through standard shell syntax 3718 "name=value"); only environment variables can be used with "run" 3719 command 3720 3721General rules: 3722-------------- 3723 3724(1) If a command line (or an environment variable executed by a "run" 3725 command) contains several commands separated by semicolon, and 3726 one of these commands fails, then the remaining commands will be 3727 executed anyway. 3728 3729(2) If you execute several variables with one call to run (i. e. 3730 calling run with a list of variables as arguments), any failing 3731 command will cause "run" to terminate, i. e. the remaining 3732 variables are not executed. 3733 3734Note for Redundant Ethernet Interfaces: 3735======================================= 3736 3737Some boards come with redundant Ethernet interfaces; U-Boot supports 3738such configurations and is capable of automatic selection of a 3739"working" interface when needed. MAC assignment works as follows: 3740 3741Network interfaces are numbered eth0, eth1, eth2, ... Corresponding 3742MAC addresses can be stored in the environment as "ethaddr" (=>eth0), 3743"eth1addr" (=>eth1), "eth2addr", ... 3744 3745If the network interface stores some valid MAC address (for instance 3746in SROM), this is used as default address if there is NO correspon- 3747ding setting in the environment; if the corresponding environment 3748variable is set, this overrides the settings in the card; that means: 3749 3750o If the SROM has a valid MAC address, and there is no address in the 3751 environment, the SROM's address is used. 3752 3753o If there is no valid address in the SROM, and a definition in the 3754 environment exists, then the value from the environment variable is 3755 used. 3756 3757o If both the SROM and the environment contain a MAC address, and 3758 both addresses are the same, this MAC address is used. 3759 3760o If both the SROM and the environment contain a MAC address, and the 3761 addresses differ, the value from the environment is used and a 3762 warning is printed. 3763 3764o If neither SROM nor the environment contain a MAC address, an error 3765 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case 3766 a random, locally-assigned MAC is used. 3767 3768If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses 3769will be programmed into hardware as part of the initialization process. This 3770may be skipped by setting the appropriate 'ethmacskip' environment variable. 3771The naming convention is as follows: 3772"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc. 3773 3774Image Formats: 3775============== 3776 3777U-Boot is capable of booting (and performing other auxiliary operations on) 3778images in two formats: 3779 3780New uImage format (FIT) 3781----------------------- 3782 3783Flexible and powerful format based on Flattened Image Tree -- FIT (similar 3784to Flattened Device Tree). It allows the use of images with multiple 3785components (several kernels, ramdisks, etc.), with contents protected by 3786SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory. 3787 3788 3789Old uImage format 3790----------------- 3791 3792Old image format is based on binary files which can be basically anything, 3793preceded by a special header; see the definitions in include/image.h for 3794details; basically, the header defines the following image properties: 3795 3796* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD, 3797 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks, 3798 LynxOS, pSOS, QNX, RTEMS, INTEGRITY; 3799 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS, 3800 INTEGRITY). 3801* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86, 3802 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit; 3803 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC). 3804* Compression Type (uncompressed, gzip, bzip2) 3805* Load Address 3806* Entry Point 3807* Image Name 3808* Image Timestamp 3809 3810The header is marked by a special Magic Number, and both the header 3811and the data portions of the image are secured against corruption by 3812CRC32 checksums. 3813 3814 3815Linux Support: 3816============== 3817 3818Although U-Boot should support any OS or standalone application 3819easily, the main focus has always been on Linux during the design of 3820U-Boot. 3821 3822U-Boot includes many features that so far have been part of some 3823special "boot loader" code within the Linux kernel. Also, any 3824"initrd" images to be used are no longer part of one big Linux image; 3825instead, kernel and "initrd" are separate images. This implementation 3826serves several purposes: 3827 3828- the same features can be used for other OS or standalone 3829 applications (for instance: using compressed images to reduce the 3830 Flash memory footprint) 3831 3832- it becomes much easier to port new Linux kernel versions because 3833 lots of low-level, hardware dependent stuff are done by U-Boot 3834 3835- the same Linux kernel image can now be used with different "initrd" 3836 images; of course this also means that different kernel images can 3837 be run with the same "initrd". This makes testing easier (you don't 3838 have to build a new "zImage.initrd" Linux image when you just 3839 change a file in your "initrd"). Also, a field-upgrade of the 3840 software is easier now. 3841 3842 3843Linux HOWTO: 3844============ 3845 3846Porting Linux to U-Boot based systems: 3847--------------------------------------- 3848 3849U-Boot cannot save you from doing all the necessary modifications to 3850configure the Linux device drivers for use with your target hardware 3851(no, we don't intend to provide a full virtual machine interface to 3852Linux :-). 3853 3854But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot). 3855 3856Just make sure your machine specific header file (for instance 3857include/asm-ppc/tqm8xx.h) includes the same definition of the Board 3858Information structure as we define in include/asm-<arch>/u-boot.h, 3859and make sure that your definition of IMAP_ADDR uses the same value 3860as your U-Boot configuration in CONFIG_SYS_IMMR. 3861 3862Note that U-Boot now has a driver model, a unified model for drivers. 3863If you are adding a new driver, plumb it into driver model. If there 3864is no uclass available, you are encouraged to create one. See 3865doc/driver-model. 3866 3867 3868Configuring the Linux kernel: 3869----------------------------- 3870 3871No specific requirements for U-Boot. Make sure you have some root 3872device (initial ramdisk, NFS) for your target system. 3873 3874 3875Building a Linux Image: 3876----------------------- 3877 3878With U-Boot, "normal" build targets like "zImage" or "bzImage" are 3879not used. If you use recent kernel source, a new build target 3880"uImage" will exist which automatically builds an image usable by 3881U-Boot. Most older kernels also have support for a "pImage" target, 3882which was introduced for our predecessor project PPCBoot and uses a 3883100% compatible format. 3884 3885Example: 3886 3887 make TQM850L_defconfig 3888 make oldconfig 3889 make dep 3890 make uImage 3891 3892The "uImage" build target uses a special tool (in 'tools/mkimage') to 3893encapsulate a compressed Linux kernel image with header information, 3894CRC32 checksum etc. for use with U-Boot. This is what we are doing: 3895 3896* build a standard "vmlinux" kernel image (in ELF binary format): 3897 3898* convert the kernel into a raw binary image: 3899 3900 ${CROSS_COMPILE}-objcopy -O binary \ 3901 -R .note -R .comment \ 3902 -S vmlinux linux.bin 3903 3904* compress the binary image: 3905 3906 gzip -9 linux.bin 3907 3908* package compressed binary image for U-Boot: 3909 3910 mkimage -A ppc -O linux -T kernel -C gzip \ 3911 -a 0 -e 0 -n "Linux Kernel Image" \ 3912 -d linux.bin.gz uImage 3913 3914 3915The "mkimage" tool can also be used to create ramdisk images for use 3916with U-Boot, either separated from the Linux kernel image, or 3917combined into one file. "mkimage" encapsulates the images with a 64 3918byte header containing information about target architecture, 3919operating system, image type, compression method, entry points, time 3920stamp, CRC32 checksums, etc. 3921 3922"mkimage" can be called in two ways: to verify existing images and 3923print the header information, or to build new images. 3924 3925In the first form (with "-l" option) mkimage lists the information 3926contained in the header of an existing U-Boot image; this includes 3927checksum verification: 3928 3929 tools/mkimage -l image 3930 -l ==> list image header information 3931 3932The second form (with "-d" option) is used to build a U-Boot image 3933from a "data file" which is used as image payload: 3934 3935 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \ 3936 -n name -d data_file image 3937 -A ==> set architecture to 'arch' 3938 -O ==> set operating system to 'os' 3939 -T ==> set image type to 'type' 3940 -C ==> set compression type 'comp' 3941 -a ==> set load address to 'addr' (hex) 3942 -e ==> set entry point to 'ep' (hex) 3943 -n ==> set image name to 'name' 3944 -d ==> use image data from 'datafile' 3945 3946Right now, all Linux kernels for PowerPC systems use the same load 3947address (0x00000000), but the entry point address depends on the 3948kernel version: 3949 3950- 2.2.x kernels have the entry point at 0x0000000C, 3951- 2.3.x and later kernels have the entry point at 0x00000000. 3952 3953So a typical call to build a U-Boot image would read: 3954 3955 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 3956 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \ 3957 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \ 3958 > examples/uImage.TQM850L 3959 Image Name: 2.4.4 kernel for TQM850L 3960 Created: Wed Jul 19 02:34:59 2000 3961 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3962 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 3963 Load Address: 0x00000000 3964 Entry Point: 0x00000000 3965 3966To verify the contents of the image (or check for corruption): 3967 3968 -> tools/mkimage -l examples/uImage.TQM850L 3969 Image Name: 2.4.4 kernel for TQM850L 3970 Created: Wed Jul 19 02:34:59 2000 3971 Image Type: PowerPC Linux Kernel Image (gzip compressed) 3972 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB 3973 Load Address: 0x00000000 3974 Entry Point: 0x00000000 3975 3976NOTE: for embedded systems where boot time is critical you can trade 3977speed for memory and install an UNCOMPRESSED image instead: this 3978needs more space in Flash, but boots much faster since it does not 3979need to be uncompressed: 3980 3981 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz 3982 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \ 3983 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \ 3984 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \ 3985 > examples/uImage.TQM850L-uncompressed 3986 Image Name: 2.4.4 kernel for TQM850L 3987 Created: Wed Jul 19 02:34:59 2000 3988 Image Type: PowerPC Linux Kernel Image (uncompressed) 3989 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB 3990 Load Address: 0x00000000 3991 Entry Point: 0x00000000 3992 3993 3994Similar you can build U-Boot images from a 'ramdisk.image.gz' file 3995when your kernel is intended to use an initial ramdisk: 3996 3997 -> tools/mkimage -n 'Simple Ramdisk Image' \ 3998 > -A ppc -O linux -T ramdisk -C gzip \ 3999 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd 4000 Image Name: Simple Ramdisk Image 4001 Created: Wed Jan 12 14:01:50 2000 4002 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 4003 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB 4004 Load Address: 0x00000000 4005 Entry Point: 0x00000000 4006 4007The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i" 4008option performs the converse operation of the mkimage's second form (the "-d" 4009option). Given an image built by mkimage, the dumpimage extracts a "data file" 4010from the image: 4011 4012 tools/dumpimage -i image -T type -p position data_file 4013 -i ==> extract from the 'image' a specific 'data_file' 4014 -T ==> set image type to 'type' 4015 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image' 4016 4017 4018Installing a Linux Image: 4019------------------------- 4020 4021To downloading a U-Boot image over the serial (console) interface, 4022you must convert the image to S-Record format: 4023 4024 objcopy -I binary -O srec examples/image examples/image.srec 4025 4026The 'objcopy' does not understand the information in the U-Boot 4027image header, so the resulting S-Record file will be relative to 4028address 0x00000000. To load it to a given address, you need to 4029specify the target address as 'offset' parameter with the 'loads' 4030command. 4031 4032Example: install the image to address 0x40100000 (which on the 4033TQM8xxL is in the first Flash bank): 4034 4035 => erase 40100000 401FFFFF 4036 4037 .......... done 4038 Erased 8 sectors 4039 4040 => loads 40100000 4041 ## Ready for S-Record download ... 4042 ~>examples/image.srec 4043 1 2 3 4 5 6 7 8 9 10 11 12 13 ... 4044 ... 4045 15989 15990 15991 15992 4046 [file transfer complete] 4047 [connected] 4048 ## Start Addr = 0x00000000 4049 4050 4051You can check the success of the download using the 'iminfo' command; 4052this includes a checksum verification so you can be sure no data 4053corruption happened: 4054 4055 => imi 40100000 4056 4057 ## Checking Image at 40100000 ... 4058 Image Name: 2.2.13 for initrd on TQM850L 4059 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4060 Data Size: 335725 Bytes = 327 kB = 0 MB 4061 Load Address: 00000000 4062 Entry Point: 0000000c 4063 Verifying Checksum ... OK 4064 4065 4066Boot Linux: 4067----------- 4068 4069The "bootm" command is used to boot an application that is stored in 4070memory (RAM or Flash). In case of a Linux kernel image, the contents 4071of the "bootargs" environment variable is passed to the kernel as 4072parameters. You can check and modify this variable using the 4073"printenv" and "setenv" commands: 4074 4075 4076 => printenv bootargs 4077 bootargs=root=/dev/ram 4078 4079 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 4080 4081 => printenv bootargs 4082 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 4083 4084 => bootm 40020000 4085 ## Booting Linux kernel at 40020000 ... 4086 Image Name: 2.2.13 for NFS on TQM850L 4087 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4088 Data Size: 381681 Bytes = 372 kB = 0 MB 4089 Load Address: 00000000 4090 Entry Point: 0000000c 4091 Verifying Checksum ... OK 4092 Uncompressing Kernel Image ... OK 4093 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000 4094 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2 4095 time_init: decrementer frequency = 187500000/60 4096 Calibrating delay loop... 49.77 BogoMIPS 4097 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000] 4098 ... 4099 4100If you want to boot a Linux kernel with initial RAM disk, you pass 4101the memory addresses of both the kernel and the initrd image (PPBCOOT 4102format!) to the "bootm" command: 4103 4104 => imi 40100000 40200000 4105 4106 ## Checking Image at 40100000 ... 4107 Image Name: 2.2.13 for initrd on TQM850L 4108 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4109 Data Size: 335725 Bytes = 327 kB = 0 MB 4110 Load Address: 00000000 4111 Entry Point: 0000000c 4112 Verifying Checksum ... OK 4113 4114 ## Checking Image at 40200000 ... 4115 Image Name: Simple Ramdisk Image 4116 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 4117 Data Size: 566530 Bytes = 553 kB = 0 MB 4118 Load Address: 00000000 4119 Entry Point: 00000000 4120 Verifying Checksum ... OK 4121 4122 => bootm 40100000 40200000 4123 ## Booting Linux kernel at 40100000 ... 4124 Image Name: 2.2.13 for initrd on TQM850L 4125 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4126 Data Size: 335725 Bytes = 327 kB = 0 MB 4127 Load Address: 00000000 4128 Entry Point: 0000000c 4129 Verifying Checksum ... OK 4130 Uncompressing Kernel Image ... OK 4131 ## Loading RAMDisk Image at 40200000 ... 4132 Image Name: Simple Ramdisk Image 4133 Image Type: PowerPC Linux RAMDisk Image (gzip compressed) 4134 Data Size: 566530 Bytes = 553 kB = 0 MB 4135 Load Address: 00000000 4136 Entry Point: 00000000 4137 Verifying Checksum ... OK 4138 Loading Ramdisk ... OK 4139 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000 4140 Boot arguments: root=/dev/ram 4141 time_init: decrementer frequency = 187500000/60 4142 Calibrating delay loop... 49.77 BogoMIPS 4143 ... 4144 RAMDISK: Compressed image found at block 0 4145 VFS: Mounted root (ext2 filesystem). 4146 4147 bash# 4148 4149Boot Linux and pass a flat device tree: 4150----------- 4151 4152First, U-Boot must be compiled with the appropriate defines. See the section 4153titled "Linux Kernel Interface" above for a more in depth explanation. The 4154following is an example of how to start a kernel and pass an updated 4155flat device tree: 4156 4157=> print oftaddr 4158oftaddr=0x300000 4159=> print oft 4160oft=oftrees/mpc8540ads.dtb 4161=> tftp $oftaddr $oft 4162Speed: 1000, full duplex 4163Using TSEC0 device 4164TFTP from server 192.168.1.1; our IP address is 192.168.1.101 4165Filename 'oftrees/mpc8540ads.dtb'. 4166Load address: 0x300000 4167Loading: # 4168done 4169Bytes transferred = 4106 (100a hex) 4170=> tftp $loadaddr $bootfile 4171Speed: 1000, full duplex 4172Using TSEC0 device 4173TFTP from server 192.168.1.1; our IP address is 192.168.1.2 4174Filename 'uImage'. 4175Load address: 0x200000 4176Loading:############ 4177done 4178Bytes transferred = 1029407 (fb51f hex) 4179=> print loadaddr 4180loadaddr=200000 4181=> print oftaddr 4182oftaddr=0x300000 4183=> bootm $loadaddr - $oftaddr 4184## Booting image at 00200000 ... 4185 Image Name: Linux-2.6.17-dirty 4186 Image Type: PowerPC Linux Kernel Image (gzip compressed) 4187 Data Size: 1029343 Bytes = 1005.2 kB 4188 Load Address: 00000000 4189 Entry Point: 00000000 4190 Verifying Checksum ... OK 4191 Uncompressing Kernel Image ... OK 4192Booting using flat device tree at 0x300000 4193Using MPC85xx ADS machine description 4194Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb 4195[snip] 4196 4197 4198More About U-Boot Image Types: 4199------------------------------ 4200 4201U-Boot supports the following image types: 4202 4203 "Standalone Programs" are directly runnable in the environment 4204 provided by U-Boot; it is expected that (if they behave 4205 well) you can continue to work in U-Boot after return from 4206 the Standalone Program. 4207 "OS Kernel Images" are usually images of some Embedded OS which 4208 will take over control completely. Usually these programs 4209 will install their own set of exception handlers, device 4210 drivers, set up the MMU, etc. - this means, that you cannot 4211 expect to re-enter U-Boot except by resetting the CPU. 4212 "RAMDisk Images" are more or less just data blocks, and their 4213 parameters (address, size) are passed to an OS kernel that is 4214 being started. 4215 "Multi-File Images" contain several images, typically an OS 4216 (Linux) kernel image and one or more data images like 4217 RAMDisks. This construct is useful for instance when you want 4218 to boot over the network using BOOTP etc., where the boot 4219 server provides just a single image file, but you want to get 4220 for instance an OS kernel and a RAMDisk image. 4221 4222 "Multi-File Images" start with a list of image sizes, each 4223 image size (in bytes) specified by an "uint32_t" in network 4224 byte order. This list is terminated by an "(uint32_t)0". 4225 Immediately after the terminating 0 follow the images, one by 4226 one, all aligned on "uint32_t" boundaries (size rounded up to 4227 a multiple of 4 bytes). 4228 4229 "Firmware Images" are binary images containing firmware (like 4230 U-Boot or FPGA images) which usually will be programmed to 4231 flash memory. 4232 4233 "Script files" are command sequences that will be executed by 4234 U-Boot's command interpreter; this feature is especially 4235 useful when you configure U-Boot to use a real shell (hush) 4236 as command interpreter. 4237 4238Booting the Linux zImage: 4239------------------------- 4240 4241On some platforms, it's possible to boot Linux zImage. This is done 4242using the "bootz" command. The syntax of "bootz" command is the same 4243as the syntax of "bootm" command. 4244 4245Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply 4246kernel with raw initrd images. The syntax is slightly different, the 4247address of the initrd must be augmented by it's size, in the following 4248format: "<initrd addres>:<initrd size>". 4249 4250 4251Standalone HOWTO: 4252================= 4253 4254One of the features of U-Boot is that you can dynamically load and 4255run "standalone" applications, which can use some resources of 4256U-Boot like console I/O functions or interrupt services. 4257 4258Two simple examples are included with the sources: 4259 4260"Hello World" Demo: 4261------------------- 4262 4263'examples/hello_world.c' contains a small "Hello World" Demo 4264application; it is automatically compiled when you build U-Boot. 4265It's configured to run at address 0x00040004, so you can play with it 4266like that: 4267 4268 => loads 4269 ## Ready for S-Record download ... 4270 ~>examples/hello_world.srec 4271 1 2 3 4 5 6 7 8 9 10 11 ... 4272 [file transfer complete] 4273 [connected] 4274 ## Start Addr = 0x00040004 4275 4276 => go 40004 Hello World! This is a test. 4277 ## Starting application at 0x00040004 ... 4278 Hello World 4279 argc = 7 4280 argv[0] = "40004" 4281 argv[1] = "Hello" 4282 argv[2] = "World!" 4283 argv[3] = "This" 4284 argv[4] = "is" 4285 argv[5] = "a" 4286 argv[6] = "test." 4287 argv[7] = "<NULL>" 4288 Hit any key to exit ... 4289 4290 ## Application terminated, rc = 0x0 4291 4292Another example, which demonstrates how to register a CPM interrupt 4293handler with the U-Boot code, can be found in 'examples/timer.c'. 4294Here, a CPM timer is set up to generate an interrupt every second. 4295The interrupt service routine is trivial, just printing a '.' 4296character, but this is just a demo program. The application can be 4297controlled by the following keys: 4298 4299 ? - print current values og the CPM Timer registers 4300 b - enable interrupts and start timer 4301 e - stop timer and disable interrupts 4302 q - quit application 4303 4304 => loads 4305 ## Ready for S-Record download ... 4306 ~>examples/timer.srec 4307 1 2 3 4 5 6 7 8 9 10 11 ... 4308 [file transfer complete] 4309 [connected] 4310 ## Start Addr = 0x00040004 4311 4312 => go 40004 4313 ## Starting application at 0x00040004 ... 4314 TIMERS=0xfff00980 4315 Using timer 1 4316 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0 4317 4318Hit 'b': 4319 [q, b, e, ?] Set interval 1000000 us 4320 Enabling timer 4321Hit '?': 4322 [q, b, e, ?] ........ 4323 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0 4324Hit '?': 4325 [q, b, e, ?] . 4326 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0 4327Hit '?': 4328 [q, b, e, ?] . 4329 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0 4330Hit '?': 4331 [q, b, e, ?] . 4332 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0 4333Hit 'e': 4334 [q, b, e, ?] ...Stopping timer 4335Hit 'q': 4336 [q, b, e, ?] ## Application terminated, rc = 0x0 4337 4338 4339Minicom warning: 4340================ 4341 4342Over time, many people have reported problems when trying to use the 4343"minicom" terminal emulation program for serial download. I (wd) 4344consider minicom to be broken, and recommend not to use it. Under 4345Unix, I recommend to use C-Kermit for general purpose use (and 4346especially for kermit binary protocol download ("loadb" command), and 4347use "cu" for S-Record download ("loads" command). See 4348http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3. 4349for help with kermit. 4350 4351 4352Nevertheless, if you absolutely want to use it try adding this 4353configuration to your "File transfer protocols" section: 4354 4355 Name Program Name U/D FullScr IO-Red. Multi 4356 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N 4357 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N 4358 4359 4360NetBSD Notes: 4361============= 4362 4363Starting at version 0.9.2, U-Boot supports NetBSD both as host 4364(build U-Boot) and target system (boots NetBSD/mpc8xx). 4365 4366Building requires a cross environment; it is known to work on 4367NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also 4368need gmake since the Makefiles are not compatible with BSD make). 4369Note that the cross-powerpc package does not install include files; 4370attempting to build U-Boot will fail because <machine/ansi.h> is 4371missing. This file has to be installed and patched manually: 4372 4373 # cd /usr/pkg/cross/powerpc-netbsd/include 4374 # mkdir powerpc 4375 # ln -s powerpc machine 4376 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h 4377 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST 4378 4379Native builds *don't* work due to incompatibilities between native 4380and U-Boot include files. 4381 4382Booting assumes that (the first part of) the image booted is a 4383stage-2 loader which in turn loads and then invokes the kernel 4384proper. Loader sources will eventually appear in the NetBSD source 4385tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the 4386meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz 4387 4388 4389Implementation Internals: 4390========================= 4391 4392The following is not intended to be a complete description of every 4393implementation detail. However, it should help to understand the 4394inner workings of U-Boot and make it easier to port it to custom 4395hardware. 4396 4397 4398Initial Stack, Global Data: 4399--------------------------- 4400 4401The implementation of U-Boot is complicated by the fact that U-Boot 4402starts running out of ROM (flash memory), usually without access to 4403system RAM (because the memory controller is not initialized yet). 4404This means that we don't have writable Data or BSS segments, and BSS 4405is not initialized as zero. To be able to get a C environment working 4406at all, we have to allocate at least a minimal stack. Implementation 4407options for this are defined and restricted by the CPU used: Some CPU 4408models provide on-chip memory (like the IMMR area on MPC8xx and 4409MPC826x processors), on others (parts of) the data cache can be 4410locked as (mis-) used as memory, etc. 4411 4412 Chris Hallinan posted a good summary of these issues to the 4413 U-Boot mailing list: 4414 4415 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)? 4416 From: "Chris Hallinan" <clh@net1plus.com> 4417 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET) 4418 ... 4419 4420 Correct me if I'm wrong, folks, but the way I understand it 4421 is this: Using DCACHE as initial RAM for Stack, etc, does not 4422 require any physical RAM backing up the cache. The cleverness 4423 is that the cache is being used as a temporary supply of 4424 necessary storage before the SDRAM controller is setup. It's 4425 beyond the scope of this list to explain the details, but you 4426 can see how this works by studying the cache architecture and 4427 operation in the architecture and processor-specific manuals. 4428 4429 OCM is On Chip Memory, which I believe the 405GP has 4K. It 4430 is another option for the system designer to use as an 4431 initial stack/RAM area prior to SDRAM being available. Either 4432 option should work for you. Using CS 4 should be fine if your 4433 board designers haven't used it for something that would 4434 cause you grief during the initial boot! It is frequently not 4435 used. 4436 4437 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere 4438 with your processor/board/system design. The default value 4439 you will find in any recent u-boot distribution in 4440 walnut.h should work for you. I'd set it to a value larger 4441 than your SDRAM module. If you have a 64MB SDRAM module, set 4442 it above 400_0000. Just make sure your board has no resources 4443 that are supposed to respond to that address! That code in 4444 start.S has been around a while and should work as is when 4445 you get the config right. 4446 4447 -Chris Hallinan 4448 DS4.COM, Inc. 4449 4450It is essential to remember this, since it has some impact on the C 4451code for the initialization procedures: 4452 4453* Initialized global data (data segment) is read-only. Do not attempt 4454 to write it. 4455 4456* Do not use any uninitialized global data (or implicitly initialized 4457 as zero data - BSS segment) at all - this is undefined, initiali- 4458 zation is performed later (when relocating to RAM). 4459 4460* Stack space is very limited. Avoid big data buffers or things like 4461 that. 4462 4463Having only the stack as writable memory limits means we cannot use 4464normal global data to share information between the code. But it 4465turned out that the implementation of U-Boot can be greatly 4466simplified by making a global data structure (gd_t) available to all 4467functions. We could pass a pointer to this data as argument to _all_ 4468functions, but this would bloat the code. Instead we use a feature of 4469the GCC compiler (Global Register Variables) to share the data: we 4470place a pointer (gd) to the global data into a register which we 4471reserve for this purpose. 4472 4473When choosing a register for such a purpose we are restricted by the 4474relevant (E)ABI specifications for the current architecture, and by 4475GCC's implementation. 4476 4477For PowerPC, the following registers have specific use: 4478 R1: stack pointer 4479 R2: reserved for system use 4480 R3-R4: parameter passing and return values 4481 R5-R10: parameter passing 4482 R13: small data area pointer 4483 R30: GOT pointer 4484 R31: frame pointer 4485 4486 (U-Boot also uses R12 as internal GOT pointer. r12 4487 is a volatile register so r12 needs to be reset when 4488 going back and forth between asm and C) 4489 4490 ==> U-Boot will use R2 to hold a pointer to the global data 4491 4492 Note: on PPC, we could use a static initializer (since the 4493 address of the global data structure is known at compile time), 4494 but it turned out that reserving a register results in somewhat 4495 smaller code - although the code savings are not that big (on 4496 average for all boards 752 bytes for the whole U-Boot image, 4497 624 text + 127 data). 4498 4499On ARM, the following registers are used: 4500 4501 R0: function argument word/integer result 4502 R1-R3: function argument word 4503 R9: platform specific 4504 R10: stack limit (used only if stack checking is enabled) 4505 R11: argument (frame) pointer 4506 R12: temporary workspace 4507 R13: stack pointer 4508 R14: link register 4509 R15: program counter 4510 4511 ==> U-Boot will use R9 to hold a pointer to the global data 4512 4513 Note: on ARM, only R_ARM_RELATIVE relocations are supported. 4514 4515On Nios II, the ABI is documented here: 4516 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf 4517 4518 ==> U-Boot will use gp to hold a pointer to the global data 4519 4520 Note: on Nios II, we give "-G0" option to gcc and don't use gp 4521 to access small data sections, so gp is free. 4522 4523On NDS32, the following registers are used: 4524 4525 R0-R1: argument/return 4526 R2-R5: argument 4527 R15: temporary register for assembler 4528 R16: trampoline register 4529 R28: frame pointer (FP) 4530 R29: global pointer (GP) 4531 R30: link register (LP) 4532 R31: stack pointer (SP) 4533 PC: program counter (PC) 4534 4535 ==> U-Boot will use R10 to hold a pointer to the global data 4536 4537NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope, 4538or current versions of GCC may "optimize" the code too much. 4539 4540On RISC-V, the following registers are used: 4541 4542 x0: hard-wired zero (zero) 4543 x1: return address (ra) 4544 x2: stack pointer (sp) 4545 x3: global pointer (gp) 4546 x4: thread pointer (tp) 4547 x5: link register (t0) 4548 x8: frame pointer (fp) 4549 x10-x11: arguments/return values (a0-1) 4550 x12-x17: arguments (a2-7) 4551 x28-31: temporaries (t3-6) 4552 pc: program counter (pc) 4553 4554 ==> U-Boot will use gp to hold a pointer to the global data 4555 4556Memory Management: 4557------------------ 4558 4559U-Boot runs in system state and uses physical addresses, i.e. the 4560MMU is not used either for address mapping nor for memory protection. 4561 4562The available memory is mapped to fixed addresses using the memory 4563controller. In this process, a contiguous block is formed for each 4564memory type (Flash, SDRAM, SRAM), even when it consists of several 4565physical memory banks. 4566 4567U-Boot is installed in the first 128 kB of the first Flash bank (on 4568TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After 4569booting and sizing and initializing DRAM, the code relocates itself 4570to the upper end of DRAM. Immediately below the U-Boot code some 4571memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN 4572configuration setting]. Below that, a structure with global Board 4573Info data is placed, followed by the stack (growing downward). 4574 4575Additionally, some exception handler code is copied to the low 8 kB 4576of DRAM (0x00000000 ... 0x00001FFF). 4577 4578So a typical memory configuration with 16 MB of DRAM could look like 4579this: 4580 4581 0x0000 0000 Exception Vector code 4582 : 4583 0x0000 1FFF 4584 0x0000 2000 Free for Application Use 4585 : 4586 : 4587 4588 : 4589 : 4590 0x00FB FF20 Monitor Stack (Growing downward) 4591 0x00FB FFAC Board Info Data and permanent copy of global data 4592 0x00FC 0000 Malloc Arena 4593 : 4594 0x00FD FFFF 4595 0x00FE 0000 RAM Copy of Monitor Code 4596 ... eventually: LCD or video framebuffer 4597 ... eventually: pRAM (Protected RAM - unchanged by reset) 4598 0x00FF FFFF [End of RAM] 4599 4600 4601System Initialization: 4602---------------------- 4603 4604In the reset configuration, U-Boot starts at the reset entry point 4605(on most PowerPC systems at address 0x00000100). Because of the reset 4606configuration for CS0# this is a mirror of the on board Flash memory. 4607To be able to re-map memory U-Boot then jumps to its link address. 4608To be able to implement the initialization code in C, a (small!) 4609initial stack is set up in the internal Dual Ported RAM (in case CPUs 4610which provide such a feature like), or in a locked part of the data 4611cache. After that, U-Boot initializes the CPU core, the caches and 4612the SIU. 4613 4614Next, all (potentially) available memory banks are mapped using a 4615preliminary mapping. For example, we put them on 512 MB boundaries 4616(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash 4617on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is 4618programmed for SDRAM access. Using the temporary configuration, a 4619simple memory test is run that determines the size of the SDRAM 4620banks. 4621 4622When there is more than one SDRAM bank, and the banks are of 4623different size, the largest is mapped first. For equal size, the first 4624bank (CS2#) is mapped first. The first mapping is always for address 46250x00000000, with any additional banks following immediately to create 4626contiguous memory starting from 0. 4627 4628Then, the monitor installs itself at the upper end of the SDRAM area 4629and allocates memory for use by malloc() and for the global Board 4630Info data; also, the exception vector code is copied to the low RAM 4631pages, and the final stack is set up. 4632 4633Only after this relocation will you have a "normal" C environment; 4634until that you are restricted in several ways, mostly because you are 4635running from ROM, and because the code will have to be relocated to a 4636new address in RAM. 4637 4638 4639U-Boot Porting Guide: 4640---------------------- 4641 4642[Based on messages by Jerry Van Baren in the U-Boot-Users mailing 4643list, October 2002] 4644 4645 4646int main(int argc, char *argv[]) 4647{ 4648 sighandler_t no_more_time; 4649 4650 signal(SIGALRM, no_more_time); 4651 alarm(PROJECT_DEADLINE - toSec (3 * WEEK)); 4652 4653 if (available_money > available_manpower) { 4654 Pay consultant to port U-Boot; 4655 return 0; 4656 } 4657 4658 Download latest U-Boot source; 4659 4660 Subscribe to u-boot mailing list; 4661 4662 if (clueless) 4663 email("Hi, I am new to U-Boot, how do I get started?"); 4664 4665 while (learning) { 4666 Read the README file in the top level directory; 4667 Read http://www.denx.de/twiki/bin/view/DULG/Manual; 4668 Read applicable doc/*.README; 4669 Read the source, Luke; 4670 /* find . -name "*.[chS]" | xargs grep -i <keyword> */ 4671 } 4672 4673 if (available_money > toLocalCurrency ($2500)) 4674 Buy a BDI3000; 4675 else 4676 Add a lot of aggravation and time; 4677 4678 if (a similar board exists) { /* hopefully... */ 4679 cp -a board/<similar> board/<myboard> 4680 cp include/configs/<similar>.h include/configs/<myboard>.h 4681 } else { 4682 Create your own board support subdirectory; 4683 Create your own board include/configs/<myboard>.h file; 4684 } 4685 Edit new board/<myboard> files 4686 Edit new include/configs/<myboard>.h 4687 4688 while (!accepted) { 4689 while (!running) { 4690 do { 4691 Add / modify source code; 4692 } until (compiles); 4693 Debug; 4694 if (clueless) 4695 email("Hi, I am having problems..."); 4696 } 4697 Send patch file to the U-Boot email list; 4698 if (reasonable critiques) 4699 Incorporate improvements from email list code review; 4700 else 4701 Defend code as written; 4702 } 4703 4704 return 0; 4705} 4706 4707void no_more_time (int sig) 4708{ 4709 hire_a_guru(); 4710} 4711 4712 4713Coding Standards: 4714----------------- 4715 4716All contributions to U-Boot should conform to the Linux kernel 4717coding style; see the kernel coding style guide at 4718https://www.kernel.org/doc/html/latest/process/coding-style.html, and the 4719script "scripts/Lindent" in your Linux kernel source directory. 4720 4721Source files originating from a different project (for example the 4722MTD subsystem) are generally exempt from these guidelines and are not 4723reformatted to ease subsequent migration to newer versions of those 4724sources. 4725 4726Please note that U-Boot is implemented in C (and to some small parts in 4727Assembler); no C++ is used, so please do not use C++ style comments (//) 4728in your code. 4729 4730Please also stick to the following formatting rules: 4731- remove any trailing white space 4732- use TAB characters for indentation and vertical alignment, not spaces 4733- make sure NOT to use DOS '\r\n' line feeds 4734- do not add more than 2 consecutive empty lines to source files 4735- do not add trailing empty lines to source files 4736 4737Submissions which do not conform to the standards may be returned 4738with a request to reformat the changes. 4739 4740 4741Submitting Patches: 4742------------------- 4743 4744Since the number of patches for U-Boot is growing, we need to 4745establish some rules. Submissions which do not conform to these rules 4746may be rejected, even when they contain important and valuable stuff. 4747 4748Please see http://www.denx.de/wiki/U-Boot/Patches for details. 4749 4750Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>; 4751see https://lists.denx.de/listinfo/u-boot 4752 4753When you send a patch, please include the following information with 4754it: 4755 4756* For bug fixes: a description of the bug and how your patch fixes 4757 this bug. Please try to include a way of demonstrating that the 4758 patch actually fixes something. 4759 4760* For new features: a description of the feature and your 4761 implementation. 4762 4763* A CHANGELOG entry as plaintext (separate from the patch) 4764 4765* For major contributions, add a MAINTAINERS file with your 4766 information and associated file and directory references. 4767 4768* When you add support for a new board, don't forget to add a 4769 maintainer e-mail address to the boards.cfg file, too. 4770 4771* If your patch adds new configuration options, don't forget to 4772 document these in the README file. 4773 4774* The patch itself. If you are using git (which is *strongly* 4775 recommended) you can easily generate the patch using the 4776 "git format-patch". If you then use "git send-email" to send it to 4777 the U-Boot mailing list, you will avoid most of the common problems 4778 with some other mail clients. 4779 4780 If you cannot use git, use "diff -purN OLD NEW". If your version of 4781 diff does not support these options, then get the latest version of 4782 GNU diff. 4783 4784 The current directory when running this command shall be the parent 4785 directory of the U-Boot source tree (i. e. please make sure that 4786 your patch includes sufficient directory information for the 4787 affected files). 4788 4789 We prefer patches as plain text. MIME attachments are discouraged, 4790 and compressed attachments must not be used. 4791 4792* If one logical set of modifications affects or creates several 4793 files, all these changes shall be submitted in a SINGLE patch file. 4794 4795* Changesets that contain different, unrelated modifications shall be 4796 submitted as SEPARATE patches, one patch per changeset. 4797 4798 4799Notes: 4800 4801* Before sending the patch, run the buildman script on your patched 4802 source tree and make sure that no errors or warnings are reported 4803 for any of the boards. 4804 4805* Keep your modifications to the necessary minimum: A patch 4806 containing several unrelated changes or arbitrary reformats will be 4807 returned with a request to re-formatting / split it. 4808 4809* If you modify existing code, make sure that your new code does not 4810 add to the memory footprint of the code ;-) Small is beautiful! 4811 When adding new features, these should compile conditionally only 4812 (using #ifdef), and the resulting code with the new feature 4813 disabled must not need more memory than the old code without your 4814 modification. 4815 4816* Remember that there is a size limit of 100 kB per message on the 4817 u-boot mailing list. Bigger patches will be moderated. If they are 4818 reasonable and not too big, they will be acknowledged. But patches 4819 bigger than the size limit should be avoided. 4820