1# SPDX-License-Identifier: GPL-2.0 2# Select 32 or 64 bit 3config 64BIT 4 bool "64-bit kernel" if "$(ARCH)" = "x86" 5 default "$(ARCH)" != "i386" 6 ---help--- 7 Say yes to build a 64-bit kernel - formerly known as x86_64 8 Say no to build a 32-bit kernel - formerly known as i386 9 10config X86_32 11 def_bool y 12 depends on !64BIT 13 # Options that are inherently 32-bit kernel only: 14 select ARCH_WANT_IPC_PARSE_VERSION 15 select CLKSRC_I8253 16 select CLONE_BACKWARDS 17 select HAVE_DEBUG_STACKOVERFLOW 18 select MODULES_USE_ELF_REL 19 select OLD_SIGACTION 20 select GENERIC_VDSO_32 21 22config X86_64 23 def_bool y 24 depends on 64BIT 25 # Options that are inherently 64-bit kernel only: 26 select ARCH_HAS_GIGANTIC_PAGE 27 select ARCH_SUPPORTS_INT128 28 select ARCH_USE_CMPXCHG_LOCKREF 29 select HAVE_ARCH_SOFT_DIRTY 30 select MODULES_USE_ELF_RELA 31 select NEED_DMA_MAP_STATE 32 select SWIOTLB 33 select ARCH_HAS_SYSCALL_WRAPPER 34 35config FORCE_DYNAMIC_FTRACE 36 def_bool y 37 depends on X86_32 38 depends on FUNCTION_TRACER 39 select DYNAMIC_FTRACE 40 help 41 We keep the static function tracing (!DYNAMIC_FTRACE) around 42 in order to test the non static function tracing in the 43 generic code, as other architectures still use it. But we 44 only need to keep it around for x86_64. No need to keep it 45 for x86_32. For x86_32, force DYNAMIC_FTRACE. 46# 47# Arch settings 48# 49# ( Note that options that are marked 'if X86_64' could in principle be 50# ported to 32-bit as well. ) 51# 52config X86 53 def_bool y 54 # 55 # Note: keep this list sorted alphabetically 56 # 57 select ACPI_LEGACY_TABLES_LOOKUP if ACPI 58 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI 59 select ARCH_32BIT_OFF_T if X86_32 60 select ARCH_CLOCKSOURCE_DATA 61 select ARCH_CLOCKSOURCE_INIT 62 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI 63 select ARCH_HAS_CPU_FINALIZE_INIT 64 select ARCH_HAS_DEBUG_VIRTUAL 65 select ARCH_HAS_DEVMEM_IS_ALLOWED 66 select ARCH_HAS_ELF_RANDOMIZE 67 select ARCH_HAS_FAST_MULTIPLIER 68 select ARCH_HAS_FILTER_PGPROT 69 select ARCH_HAS_FORTIFY_SOURCE 70 select ARCH_HAS_GCOV_PROFILE_ALL 71 select ARCH_HAS_KCOV if X86_64 72 select ARCH_HAS_MEM_ENCRYPT 73 select ARCH_HAS_MEMBARRIER_SYNC_CORE 74 select ARCH_HAS_PMEM_API if X86_64 75 select ARCH_HAS_PTE_DEVMAP if X86_64 76 select ARCH_HAS_PTE_SPECIAL 77 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 78 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE 79 select ARCH_HAS_SET_MEMORY 80 select ARCH_HAS_SET_DIRECT_MAP 81 select ARCH_HAS_STRICT_KERNEL_RWX 82 select ARCH_HAS_STRICT_MODULE_RWX 83 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE 84 select ARCH_HAS_UBSAN_SANITIZE_ALL 85 select ARCH_HAVE_NMI_SAFE_CMPXCHG 86 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI 87 select ARCH_MIGHT_HAVE_PC_PARPORT 88 select ARCH_MIGHT_HAVE_PC_SERIO 89 select ARCH_STACKWALK 90 select ARCH_SUPPORTS_ACPI 91 select ARCH_SUPPORTS_ATOMIC_RMW 92 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 93 select ARCH_SUPPORTS_LTO_CLANG if X86_64 94 select ARCH_SUPPORTS_THINLTO if X86_64 95 select ARCH_USE_BUILTIN_BSWAP 96 select ARCH_USE_QUEUED_RWLOCKS 97 select ARCH_USE_QUEUED_SPINLOCKS 98 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 99 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 100 select ARCH_WANT_HUGE_PMD_SHARE 101 select ARCH_WANTS_THP_SWAP if X86_64 102 select BUILDTIME_EXTABLE_SORT 103 select CLKEVT_I8253 104 select CLOCKSOURCE_VALIDATE_LAST_CYCLE 105 select CLOCKSOURCE_WATCHDOG 106 select DCACHE_WORD_ACCESS 107 select EDAC_ATOMIC_SCRUB 108 select EDAC_SUPPORT 109 select GENERIC_CLOCKEVENTS 110 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) 111 select GENERIC_CLOCKEVENTS_MIN_ADJUST 112 select GENERIC_CMOS_UPDATE 113 select GENERIC_CPU_AUTOPROBE 114 select GENERIC_CPU_VULNERABILITIES 115 select GENERIC_EARLY_IOREMAP 116 select GENERIC_FIND_FIRST_BIT 117 select GENERIC_IOMAP 118 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP 119 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC 120 select GENERIC_IRQ_MIGRATION if SMP 121 select GENERIC_IRQ_PROBE 122 select GENERIC_IRQ_RESERVATION_MODE 123 select GENERIC_IRQ_SHOW 124 select GENERIC_PENDING_IRQ if SMP 125 select GENERIC_SMP_IDLE_THREAD 126 select GENERIC_STRNCPY_FROM_USER 127 select GENERIC_STRNLEN_USER 128 select GENERIC_TIME_VSYSCALL 129 select GENERIC_GETTIMEOFDAY 130 select GUP_GET_PTE_LOW_HIGH if X86_PAE 131 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64 132 select HAVE_ACPI_APEI if ACPI 133 select HAVE_ACPI_APEI_NMI if ACPI 134 select HAVE_ALIGNED_STRUCT_PAGE if SLUB 135 select HAVE_ARCH_AUDITSYSCALL 136 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE 137 select HAVE_ARCH_JUMP_LABEL 138 select HAVE_ARCH_JUMP_LABEL_RELATIVE 139 select HAVE_ARCH_KASAN if X86_64 140 select HAVE_ARCH_KGDB 141 select HAVE_ARCH_MMAP_RND_BITS if MMU 142 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT 143 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT 144 select HAVE_ARCH_PREL32_RELOCATIONS if !LTO_CLANG 145 select HAVE_ARCH_SECCOMP_FILTER 146 select HAVE_ARCH_THREAD_STRUCT_WHITELIST 147 select HAVE_ARCH_STACKLEAK 148 select HAVE_ARCH_TRACEHOOK 149 select HAVE_ARCH_TRANSPARENT_HUGEPAGE 150 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64 151 select HAVE_ARCH_VMAP_STACK if X86_64 152 select HAVE_ARCH_WITHIN_STACK_FRAMES 153 select HAVE_ASM_MODVERSIONS 154 select HAVE_CMPXCHG_DOUBLE 155 select HAVE_CMPXCHG_LOCAL 156 select HAVE_CONTEXT_TRACKING if X86_64 157 select HAVE_COPY_THREAD_TLS 158 select HAVE_C_RECORDMCOUNT 159 select HAVE_DEBUG_KMEMLEAK 160 select HAVE_DMA_CONTIGUOUS 161 select HAVE_DYNAMIC_FTRACE 162 select HAVE_DYNAMIC_FTRACE_WITH_REGS 163 select HAVE_EBPF_JIT 164 select HAVE_EFFICIENT_UNALIGNED_ACCESS 165 select HAVE_EISA 166 select HAVE_EXIT_THREAD 167 select HAVE_FAST_GUP 168 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE 169 select HAVE_FTRACE_MCOUNT_RECORD 170 select HAVE_FUNCTION_GRAPH_TRACER 171 select HAVE_FUNCTION_TRACER 172 select HAVE_GCC_PLUGINS 173 select HAVE_HW_BREAKPOINT 174 select HAVE_IDE 175 select HAVE_IOREMAP_PROT 176 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 177 select HAVE_IRQ_TIME_ACCOUNTING 178 select HAVE_KERNEL_BZIP2 179 select HAVE_KERNEL_GZIP 180 select HAVE_KERNEL_LZ4 181 select HAVE_KERNEL_LZMA 182 select HAVE_KERNEL_LZO 183 select HAVE_KERNEL_XZ 184 select HAVE_KPROBES 185 select HAVE_KPROBES_ON_FTRACE 186 select HAVE_FUNCTION_ERROR_INJECTION 187 select HAVE_KRETPROBES 188 select HAVE_KVM 189 select HAVE_LIVEPATCH if X86_64 190 select HAVE_MEMBLOCK_NODE_MAP 191 select HAVE_MIXED_BREAKPOINTS_REGS 192 select HAVE_MOD_ARCH_SPECIFIC 193 select HAVE_MOVE_PMD 194 select HAVE_NMI 195 select HAVE_OPROFILE 196 select HAVE_OPTPROBES 197 select HAVE_PCSPKR_PLATFORM 198 select HAVE_PERF_EVENTS 199 select HAVE_PERF_EVENTS_NMI 200 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI 201 select HAVE_PCI 202 select HAVE_PERF_REGS 203 select HAVE_PERF_USER_STACK_DUMP 204 select HAVE_RCU_TABLE_FREE if PARAVIRT 205 select HAVE_REGS_AND_STACK_ACCESS_API 206 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION 207 select HAVE_FUNCTION_ARG_ACCESS_API 208 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR 209 select HAVE_STACK_VALIDATION if X86_64 && !LTO_CLANG 210 select HAVE_RSEQ 211 select HAVE_SYSCALL_TRACEPOINTS 212 select HAVE_UNSTABLE_SCHED_CLOCK 213 select HAVE_USER_RETURN_NOTIFIER 214 select HAVE_GENERIC_VDSO 215 select HOTPLUG_SMT if SMP 216 select IRQ_FORCED_THREADING 217 select NEED_SG_DMA_LENGTH 218 select PCI_DOMAINS if PCI 219 select PCI_LOCKLESS_CONFIG if PCI 220 select PERF_EVENTS 221 select RTC_LIB 222 select RTC_MC146818_LIB 223 select SPARSE_IRQ 224 select SRCU 225 select SYSCTL_EXCEPTION_TRACE 226 select THREAD_INFO_IN_TASK 227 select USER_STACKTRACE_SUPPORT 228 select VIRT_TO_BUS 229 select X86_FEATURE_NAMES if PROC_FS 230 select PROC_PID_ARCH_STATUS if PROC_FS 231 232config INSTRUCTION_DECODER 233 def_bool y 234 depends on KPROBES || PERF_EVENTS || UPROBES 235 236config OUTPUT_FORMAT 237 string 238 default "elf32-i386" if X86_32 239 default "elf64-x86-64" if X86_64 240 241config ARCH_DEFCONFIG 242 string 243 default "arch/x86/configs/i386_defconfig" if X86_32 244 default "arch/x86/configs/x86_64_defconfig" if X86_64 245 246config LOCKDEP_SUPPORT 247 def_bool y 248 249config STACKTRACE_SUPPORT 250 def_bool y 251 252config MMU 253 def_bool y 254 255config ARCH_MMAP_RND_BITS_MIN 256 default 28 if 64BIT 257 default 8 258 259config ARCH_MMAP_RND_BITS_MAX 260 default 32 if 64BIT 261 default 16 262 263config ARCH_MMAP_RND_COMPAT_BITS_MIN 264 default 8 265 266config ARCH_MMAP_RND_COMPAT_BITS_MAX 267 default 16 268 269config SBUS 270 bool 271 272config GENERIC_ISA_DMA 273 def_bool y 274 depends on ISA_DMA_API 275 276config GENERIC_BUG 277 def_bool y 278 depends on BUG 279 select GENERIC_BUG_RELATIVE_POINTERS if X86_64 280 281config GENERIC_BUG_RELATIVE_POINTERS 282 bool 283 284config ARCH_MAY_HAVE_PC_FDC 285 def_bool y 286 depends on ISA_DMA_API 287 288config GENERIC_CALIBRATE_DELAY 289 def_bool y 290 291config ARCH_HAS_CPU_RELAX 292 def_bool y 293 294config ARCH_HAS_CACHE_LINE_SIZE 295 def_bool y 296 297config ARCH_HAS_FILTER_PGPROT 298 def_bool y 299 300config HAVE_SETUP_PER_CPU_AREA 301 def_bool y 302 303config NEED_PER_CPU_EMBED_FIRST_CHUNK 304 def_bool y 305 306config NEED_PER_CPU_PAGE_FIRST_CHUNK 307 def_bool y 308 309config ARCH_HIBERNATION_POSSIBLE 310 def_bool y 311 312config ARCH_SUSPEND_POSSIBLE 313 def_bool y 314 315config ARCH_WANT_GENERAL_HUGETLB 316 def_bool y 317 318config ZONE_DMA32 319 def_bool y if X86_64 320 321config AUDIT_ARCH 322 def_bool y if X86_64 323 324config ARCH_SUPPORTS_DEBUG_PAGEALLOC 325 def_bool y 326 327config KASAN_SHADOW_OFFSET 328 hex 329 depends on KASAN 330 default 0xdffffc0000000000 331 332config HAVE_INTEL_TXT 333 def_bool y 334 depends on INTEL_IOMMU && ACPI 335 336config X86_32_SMP 337 def_bool y 338 depends on X86_32 && SMP 339 340config X86_64_SMP 341 def_bool y 342 depends on X86_64 && SMP 343 344config X86_32_LAZY_GS 345 def_bool y 346 depends on X86_32 && !STACKPROTECTOR 347 348config ARCH_SUPPORTS_UPROBES 349 def_bool y 350 351config FIX_EARLYCON_MEM 352 def_bool y 353 354config DYNAMIC_PHYSICAL_MASK 355 bool 356 357config PGTABLE_LEVELS 358 int 359 default 5 if X86_5LEVEL 360 default 4 if X86_64 361 default 3 if X86_PAE 362 default 2 363 364config CC_HAS_SANE_STACKPROTECTOR 365 bool 366 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT 367 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC)) 368 help 369 We have to make sure stack protector is unconditionally disabled if 370 the compiler produces broken code. 371 372menu "Processor type and features" 373 374config ZONE_DMA 375 bool "DMA memory allocation support" if EXPERT 376 default y 377 help 378 DMA memory allocation support allows devices with less than 32-bit 379 addressing to allocate within the first 16MB of address space. 380 Disable if no such devices will be used. 381 382 If unsure, say Y. 383 384config SMP 385 bool "Symmetric multi-processing support" 386 ---help--- 387 This enables support for systems with more than one CPU. If you have 388 a system with only one CPU, say N. If you have a system with more 389 than one CPU, say Y. 390 391 If you say N here, the kernel will run on uni- and multiprocessor 392 machines, but will use only one CPU of a multiprocessor machine. If 393 you say Y here, the kernel will run on many, but not all, 394 uniprocessor machines. On a uniprocessor machine, the kernel 395 will run faster if you say N here. 396 397 Note that if you say Y here and choose architecture "586" or 398 "Pentium" under "Processor family", the kernel will not work on 486 399 architectures. Similarly, multiprocessor kernels for the "PPro" 400 architecture may not work on all Pentium based boards. 401 402 People using multiprocessor machines who say Y here should also say 403 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power 404 Management" code will be disabled if you say Y here. 405 406 See also <file:Documentation/x86/i386/IO-APIC.rst>, 407 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at 408 <http://www.tldp.org/docs.html#howto>. 409 410 If you don't know what to do here, say N. 411 412config X86_FEATURE_NAMES 413 bool "Processor feature human-readable names" if EMBEDDED 414 default y 415 ---help--- 416 This option compiles in a table of x86 feature bits and corresponding 417 names. This is required to support /proc/cpuinfo and a few kernel 418 messages. You can disable this to save space, at the expense of 419 making those few kernel messages show numeric feature bits instead. 420 421 If in doubt, say Y. 422 423config X86_X2APIC 424 bool "Support x2apic" 425 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST) 426 ---help--- 427 This enables x2apic support on CPUs that have this feature. 428 429 This allows 32-bit apic IDs (so it can support very large systems), 430 and accesses the local apic via MSRs not via mmio. 431 432 If you don't know what to do here, say N. 433 434config X86_MPPARSE 435 bool "Enable MPS table" if ACPI || SFI 436 default y 437 depends on X86_LOCAL_APIC 438 ---help--- 439 For old smp systems that do not have proper acpi support. Newer systems 440 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it 441 442config GOLDFISH 443 def_bool y 444 depends on X86_GOLDFISH 445 446config RETPOLINE 447 bool "Avoid speculative indirect branches in kernel" 448 default y 449 select STACK_VALIDATION if HAVE_STACK_VALIDATION 450 help 451 Compile kernel with the retpoline compiler options to guard against 452 kernel-to-user data leaks by avoiding speculative indirect 453 branches. Requires a compiler with -mindirect-branch=thunk-extern 454 support for full protection. The kernel may run slower. 455 456config X86_CPU_RESCTRL 457 bool "x86 CPU resource control support" 458 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD) 459 select KERNFS 460 help 461 Enable x86 CPU resource control support. 462 463 Provide support for the allocation and monitoring of system resources 464 usage by the CPU. 465 466 Intel calls this Intel Resource Director Technology 467 (Intel(R) RDT). More information about RDT can be found in the 468 Intel x86 Architecture Software Developer Manual. 469 470 AMD calls this AMD Platform Quality of Service (AMD QoS). 471 More information about AMD QoS can be found in the AMD64 Technology 472 Platform Quality of Service Extensions manual. 473 474 Say N if unsure. 475 476if X86_32 477config X86_BIGSMP 478 bool "Support for big SMP systems with more than 8 CPUs" 479 depends on SMP 480 ---help--- 481 This option is needed for the systems that have more than 8 CPUs 482 483config X86_EXTENDED_PLATFORM 484 bool "Support for extended (non-PC) x86 platforms" 485 default y 486 ---help--- 487 If you disable this option then the kernel will only support 488 standard PC platforms. (which covers the vast majority of 489 systems out there.) 490 491 If you enable this option then you'll be able to select support 492 for the following (non-PC) 32 bit x86 platforms: 493 Goldfish (Android emulator) 494 AMD Elan 495 RDC R-321x SoC 496 SGI 320/540 (Visual Workstation) 497 STA2X11-based (e.g. Northville) 498 Moorestown MID devices 499 500 If you have one of these systems, or if you want to build a 501 generic distribution kernel, say Y here - otherwise say N. 502endif 503 504if X86_64 505config X86_EXTENDED_PLATFORM 506 bool "Support for extended (non-PC) x86 platforms" 507 default y 508 ---help--- 509 If you disable this option then the kernel will only support 510 standard PC platforms. (which covers the vast majority of 511 systems out there.) 512 513 If you enable this option then you'll be able to select support 514 for the following (non-PC) 64 bit x86 platforms: 515 Numascale NumaChip 516 ScaleMP vSMP 517 SGI Ultraviolet 518 519 If you have one of these systems, or if you want to build a 520 generic distribution kernel, say Y here - otherwise say N. 521endif 522# This is an alphabetically sorted list of 64 bit extended platforms 523# Please maintain the alphabetic order if and when there are additions 524config X86_NUMACHIP 525 bool "Numascale NumaChip" 526 depends on X86_64 527 depends on X86_EXTENDED_PLATFORM 528 depends on NUMA 529 depends on SMP 530 depends on X86_X2APIC 531 depends on PCI_MMCONFIG 532 ---help--- 533 Adds support for Numascale NumaChip large-SMP systems. Needed to 534 enable more than ~168 cores. 535 If you don't have one of these, you should say N here. 536 537config X86_VSMP 538 bool "ScaleMP vSMP" 539 select HYPERVISOR_GUEST 540 select PARAVIRT 541 depends on X86_64 && PCI 542 depends on X86_EXTENDED_PLATFORM 543 depends on SMP 544 ---help--- 545 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is 546 supposed to run on these EM64T-based machines. Only choose this option 547 if you have one of these machines. 548 549config X86_UV 550 bool "SGI Ultraviolet" 551 depends on X86_64 552 depends on X86_EXTENDED_PLATFORM 553 depends on NUMA 554 depends on EFI 555 depends on KEXEC_CORE 556 depends on X86_X2APIC 557 depends on PCI 558 ---help--- 559 This option is needed in order to support SGI Ultraviolet systems. 560 If you don't have one of these, you should say N here. 561 562# Following is an alphabetically sorted list of 32 bit extended platforms 563# Please maintain the alphabetic order if and when there are additions 564 565config X86_GOLDFISH 566 bool "Goldfish (Virtual Platform)" 567 depends on X86_EXTENDED_PLATFORM 568 ---help--- 569 Enable support for the Goldfish virtual platform used primarily 570 for Android development. Unless you are building for the Android 571 Goldfish emulator say N here. 572 573config X86_INTEL_CE 574 bool "CE4100 TV platform" 575 depends on PCI 576 depends on PCI_GODIRECT 577 depends on X86_IO_APIC 578 depends on X86_32 579 depends on X86_EXTENDED_PLATFORM 580 select X86_REBOOTFIXUPS 581 select OF 582 select OF_EARLY_FLATTREE 583 ---help--- 584 Select for the Intel CE media processor (CE4100) SOC. 585 This option compiles in support for the CE4100 SOC for settop 586 boxes and media devices. 587 588config X86_INTEL_MID 589 bool "Intel MID platform support" 590 depends on X86_EXTENDED_PLATFORM 591 depends on X86_PLATFORM_DEVICES 592 depends on PCI 593 depends on X86_64 || (PCI_GOANY && X86_32) 594 depends on X86_IO_APIC 595 select SFI 596 select I2C 597 select DW_APB_TIMER 598 select APB_TIMER 599 select INTEL_SCU_IPC 600 select MFD_INTEL_MSIC 601 ---help--- 602 Select to build a kernel capable of supporting Intel MID (Mobile 603 Internet Device) platform systems which do not have the PCI legacy 604 interfaces. If you are building for a PC class system say N here. 605 606 Intel MID platforms are based on an Intel processor and chipset which 607 consume less power than most of the x86 derivatives. 608 609config X86_INTEL_QUARK 610 bool "Intel Quark platform support" 611 depends on X86_32 612 depends on X86_EXTENDED_PLATFORM 613 depends on X86_PLATFORM_DEVICES 614 depends on X86_TSC 615 depends on PCI 616 depends on PCI_GOANY 617 depends on X86_IO_APIC 618 select IOSF_MBI 619 select INTEL_IMR 620 select COMMON_CLK 621 ---help--- 622 Select to include support for Quark X1000 SoC. 623 Say Y here if you have a Quark based system such as the Arduino 624 compatible Intel Galileo. 625 626config X86_INTEL_LPSS 627 bool "Intel Low Power Subsystem Support" 628 depends on X86 && ACPI && PCI 629 select COMMON_CLK 630 select PINCTRL 631 select IOSF_MBI 632 ---help--- 633 Select to build support for Intel Low Power Subsystem such as 634 found on Intel Lynxpoint PCH. Selecting this option enables 635 things like clock tree (common clock framework) and pincontrol 636 which are needed by the LPSS peripheral drivers. 637 638config X86_AMD_PLATFORM_DEVICE 639 bool "AMD ACPI2Platform devices support" 640 depends on ACPI 641 select COMMON_CLK 642 select PINCTRL 643 ---help--- 644 Select to interpret AMD specific ACPI device to platform device 645 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets. 646 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is 647 implemented under PINCTRL subsystem. 648 649config IOSF_MBI 650 tristate "Intel SoC IOSF Sideband support for SoC platforms" 651 depends on PCI 652 ---help--- 653 This option enables sideband register access support for Intel SoC 654 platforms. On these platforms the IOSF sideband is used in lieu of 655 MSR's for some register accesses, mostly but not limited to thermal 656 and power. Drivers may query the availability of this device to 657 determine if they need the sideband in order to work on these 658 platforms. The sideband is available on the following SoC products. 659 This list is not meant to be exclusive. 660 - BayTrail 661 - Braswell 662 - Quark 663 664 You should say Y if you are running a kernel on one of these SoC's. 665 666config IOSF_MBI_DEBUG 667 bool "Enable IOSF sideband access through debugfs" 668 depends on IOSF_MBI && DEBUG_FS 669 ---help--- 670 Select this option to expose the IOSF sideband access registers (MCR, 671 MDR, MCRX) through debugfs to write and read register information from 672 different units on the SoC. This is most useful for obtaining device 673 state information for debug and analysis. As this is a general access 674 mechanism, users of this option would have specific knowledge of the 675 device they want to access. 676 677 If you don't require the option or are in doubt, say N. 678 679config X86_RDC321X 680 bool "RDC R-321x SoC" 681 depends on X86_32 682 depends on X86_EXTENDED_PLATFORM 683 select M486 684 select X86_REBOOTFIXUPS 685 ---help--- 686 This option is needed for RDC R-321x system-on-chip, also known 687 as R-8610-(G). 688 If you don't have one of these chips, you should say N here. 689 690config X86_32_NON_STANDARD 691 bool "Support non-standard 32-bit SMP architectures" 692 depends on X86_32 && SMP 693 depends on X86_EXTENDED_PLATFORM 694 ---help--- 695 This option compiles in the bigsmp and STA2X11 default 696 subarchitectures. It is intended for a generic binary 697 kernel. If you select them all, kernel will probe it one by 698 one and will fallback to default. 699 700# Alphabetically sorted list of Non standard 32 bit platforms 701 702config X86_SUPPORTS_MEMORY_FAILURE 703 def_bool y 704 # MCE code calls memory_failure(): 705 depends on X86_MCE 706 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags: 707 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH: 708 depends on X86_64 || !SPARSEMEM 709 select ARCH_SUPPORTS_MEMORY_FAILURE 710 711config STA2X11 712 bool "STA2X11 Companion Chip Support" 713 depends on X86_32_NON_STANDARD && PCI 714 select ARCH_HAS_PHYS_TO_DMA 715 select SWIOTLB 716 select MFD_STA2X11 717 select GPIOLIB 718 ---help--- 719 This adds support for boards based on the STA2X11 IO-Hub, 720 a.k.a. "ConneXt". The chip is used in place of the standard 721 PC chipset, so all "standard" peripherals are missing. If this 722 option is selected the kernel will still be able to boot on 723 standard PC machines. 724 725config X86_32_IRIS 726 tristate "Eurobraille/Iris poweroff module" 727 depends on X86_32 728 ---help--- 729 The Iris machines from EuroBraille do not have APM or ACPI support 730 to shut themselves down properly. A special I/O sequence is 731 needed to do so, which is what this module does at 732 kernel shutdown. 733 734 This is only for Iris machines from EuroBraille. 735 736 If unused, say N. 737 738config SCHED_OMIT_FRAME_POINTER 739 def_bool y 740 prompt "Single-depth WCHAN output" 741 depends on X86 742 ---help--- 743 Calculate simpler /proc/<PID>/wchan values. If this option 744 is disabled then wchan values will recurse back to the 745 caller function. This provides more accurate wchan values, 746 at the expense of slightly more scheduling overhead. 747 748 If in doubt, say "Y". 749 750menuconfig HYPERVISOR_GUEST 751 bool "Linux guest support" 752 ---help--- 753 Say Y here to enable options for running Linux under various hyper- 754 visors. This option enables basic hypervisor detection and platform 755 setup. 756 757 If you say N, all options in this submenu will be skipped and 758 disabled, and Linux guest support won't be built in. 759 760if HYPERVISOR_GUEST 761 762config PARAVIRT 763 bool "Enable paravirtualization code" 764 ---help--- 765 This changes the kernel so it can modify itself when it is run 766 under a hypervisor, potentially improving performance significantly 767 over full virtualization. However, when run without a hypervisor 768 the kernel is theoretically slower and slightly larger. 769 770config PARAVIRT_XXL 771 bool 772 773config PARAVIRT_DEBUG 774 bool "paravirt-ops debugging" 775 depends on PARAVIRT && DEBUG_KERNEL 776 ---help--- 777 Enable to debug paravirt_ops internals. Specifically, BUG if 778 a paravirt_op is missing when it is called. 779 780config PARAVIRT_SPINLOCKS 781 bool "Paravirtualization layer for spinlocks" 782 depends on PARAVIRT && SMP 783 ---help--- 784 Paravirtualized spinlocks allow a pvops backend to replace the 785 spinlock implementation with something virtualization-friendly 786 (for example, block the virtual CPU rather than spinning). 787 788 It has a minimal impact on native kernels and gives a nice performance 789 benefit on paravirtualized KVM / Xen kernels. 790 791 If you are unsure how to answer this question, answer Y. 792 793config X86_HV_CALLBACK_VECTOR 794 def_bool n 795 796source "arch/x86/xen/Kconfig" 797 798config KVM_GUEST 799 bool "KVM Guest support (including kvmclock)" 800 depends on PARAVIRT 801 select PARAVIRT_CLOCK 802 select ARCH_CPUIDLE_HALTPOLL 803 default y 804 ---help--- 805 This option enables various optimizations for running under the KVM 806 hypervisor. It includes a paravirtualized clock, so that instead 807 of relying on a PIT (or probably other) emulation by the 808 underlying device model, the host provides the guest with 809 timing infrastructure such as time of day, and system time 810 811config ARCH_CPUIDLE_HALTPOLL 812 def_bool n 813 prompt "Disable host haltpoll when loading haltpoll driver" 814 help 815 If virtualized under KVM, disable host haltpoll. 816 817config PVH 818 bool "Support for running PVH guests" 819 ---help--- 820 This option enables the PVH entry point for guest virtual machines 821 as specified in the x86/HVM direct boot ABI. 822 823config KVM_DEBUG_FS 824 bool "Enable debug information for KVM Guests in debugfs" 825 depends on KVM_GUEST && DEBUG_FS 826 ---help--- 827 This option enables collection of various statistics for KVM guest. 828 Statistics are displayed in debugfs filesystem. Enabling this option 829 may incur significant overhead. 830 831config PARAVIRT_TIME_ACCOUNTING 832 bool "Paravirtual steal time accounting" 833 depends on PARAVIRT 834 ---help--- 835 Select this option to enable fine granularity task steal time 836 accounting. Time spent executing other tasks in parallel with 837 the current vCPU is discounted from the vCPU power. To account for 838 that, there can be a small performance impact. 839 840 If in doubt, say N here. 841 842config PARAVIRT_CLOCK 843 bool 844 845config JAILHOUSE_GUEST 846 bool "Jailhouse non-root cell support" 847 depends on X86_64 && PCI 848 select X86_PM_TIMER 849 ---help--- 850 This option allows to run Linux as guest in a Jailhouse non-root 851 cell. You can leave this option disabled if you only want to start 852 Jailhouse and run Linux afterwards in the root cell. 853 854config ACRN_GUEST 855 bool "ACRN Guest support" 856 depends on X86_64 857 select X86_HV_CALLBACK_VECTOR 858 help 859 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is 860 a flexible, lightweight reference open-source hypervisor, built with 861 real-time and safety-criticality in mind. It is built for embedded 862 IOT with small footprint and real-time features. More details can be 863 found in https://projectacrn.org/. 864 865endif #HYPERVISOR_GUEST 866 867source "arch/x86/Kconfig.cpu" 868 869config HPET_TIMER 870 def_bool X86_64 871 prompt "HPET Timer Support" if X86_32 872 ---help--- 873 Use the IA-PC HPET (High Precision Event Timer) to manage 874 time in preference to the PIT and RTC, if a HPET is 875 present. 876 HPET is the next generation timer replacing legacy 8254s. 877 The HPET provides a stable time base on SMP 878 systems, unlike the TSC, but it is more expensive to access, 879 as it is off-chip. The interface used is documented 880 in the HPET spec, revision 1. 881 882 You can safely choose Y here. However, HPET will only be 883 activated if the platform and the BIOS support this feature. 884 Otherwise the 8254 will be used for timing services. 885 886 Choose N to continue using the legacy 8254 timer. 887 888config HPET_EMULATE_RTC 889 def_bool y 890 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y) 891 892config APB_TIMER 893 def_bool y if X86_INTEL_MID 894 prompt "Intel MID APB Timer Support" if X86_INTEL_MID 895 select DW_APB_TIMER 896 depends on X86_INTEL_MID && SFI 897 help 898 APB timer is the replacement for 8254, HPET on X86 MID platforms. 899 The APBT provides a stable time base on SMP 900 systems, unlike the TSC, but it is more expensive to access, 901 as it is off-chip. APB timers are always running regardless of CPU 902 C states, they are used as per CPU clockevent device when possible. 903 904# Mark as expert because too many people got it wrong. 905# The code disables itself when not needed. 906config DMI 907 default y 908 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK 909 bool "Enable DMI scanning" if EXPERT 910 ---help--- 911 Enabled scanning of DMI to identify machine quirks. Say Y 912 here unless you have verified that your setup is not 913 affected by entries in the DMI blacklist. Required by PNP 914 BIOS code. 915 916config GART_IOMMU 917 bool "Old AMD GART IOMMU support" 918 select IOMMU_HELPER 919 select SWIOTLB 920 depends on X86_64 && PCI && AMD_NB 921 ---help--- 922 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron 923 GART based hardware IOMMUs. 924 925 The GART supports full DMA access for devices with 32-bit access 926 limitations, on systems with more than 3 GB. This is usually needed 927 for USB, sound, many IDE/SATA chipsets and some other devices. 928 929 Newer systems typically have a modern AMD IOMMU, supported via 930 the CONFIG_AMD_IOMMU=y config option. 931 932 In normal configurations this driver is only active when needed: 933 there's more than 3 GB of memory and the system contains a 934 32-bit limited device. 935 936 If unsure, say Y. 937 938config CALGARY_IOMMU 939 bool "IBM Calgary IOMMU support" 940 select IOMMU_HELPER 941 select SWIOTLB 942 depends on X86_64 && PCI 943 ---help--- 944 Support for hardware IOMMUs in IBM's xSeries x366 and x460 945 systems. Needed to run systems with more than 3GB of memory 946 properly with 32-bit PCI devices that do not support DAC 947 (Double Address Cycle). Calgary also supports bus level 948 isolation, where all DMAs pass through the IOMMU. This 949 prevents them from going anywhere except their intended 950 destination. This catches hard-to-find kernel bugs and 951 mis-behaving drivers and devices that do not use the DMA-API 952 properly to set up their DMA buffers. The IOMMU can be 953 turned off at boot time with the iommu=off parameter. 954 Normally the kernel will make the right choice by itself. 955 If unsure, say Y. 956 957config CALGARY_IOMMU_ENABLED_BY_DEFAULT 958 def_bool y 959 prompt "Should Calgary be enabled by default?" 960 depends on CALGARY_IOMMU 961 ---help--- 962 Should Calgary be enabled by default? if you choose 'y', Calgary 963 will be used (if it exists). If you choose 'n', Calgary will not be 964 used even if it exists. If you choose 'n' and would like to use 965 Calgary anyway, pass 'iommu=calgary' on the kernel command line. 966 If unsure, say Y. 967 968config MAXSMP 969 bool "Enable Maximum number of SMP Processors and NUMA Nodes" 970 depends on X86_64 && SMP && DEBUG_KERNEL 971 select CPUMASK_OFFSTACK 972 ---help--- 973 Enable maximum number of CPUS and NUMA Nodes for this architecture. 974 If unsure, say N. 975 976# 977# The maximum number of CPUs supported: 978# 979# The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT, 980# and which can be configured interactively in the 981# [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range. 982# 983# The ranges are different on 32-bit and 64-bit kernels, depending on 984# hardware capabilities and scalability features of the kernel. 985# 986# ( If MAXSMP is enabled we just use the highest possible value and disable 987# interactive configuration. ) 988# 989 990config NR_CPUS_RANGE_BEGIN 991 int 992 default NR_CPUS_RANGE_END if MAXSMP 993 default 1 if !SMP 994 default 2 995 996config NR_CPUS_RANGE_END 997 int 998 depends on X86_32 999 default 64 if SMP && X86_BIGSMP 1000 default 8 if SMP && !X86_BIGSMP 1001 default 1 if !SMP 1002 1003config NR_CPUS_RANGE_END 1004 int 1005 depends on X86_64 1006 default 8192 if SMP && ( MAXSMP || CPUMASK_OFFSTACK) 1007 default 512 if SMP && (!MAXSMP && !CPUMASK_OFFSTACK) 1008 default 1 if !SMP 1009 1010config NR_CPUS_DEFAULT 1011 int 1012 depends on X86_32 1013 default 32 if X86_BIGSMP 1014 default 8 if SMP 1015 default 1 if !SMP 1016 1017config NR_CPUS_DEFAULT 1018 int 1019 depends on X86_64 1020 default 8192 if MAXSMP 1021 default 64 if SMP 1022 default 1 if !SMP 1023 1024config NR_CPUS 1025 int "Maximum number of CPUs" if SMP && !MAXSMP 1026 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 1027 default NR_CPUS_DEFAULT 1028 ---help--- 1029 This allows you to specify the maximum number of CPUs which this 1030 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum 1031 supported value is 8192, otherwise the maximum value is 512. The 1032 minimum value which makes sense is 2. 1033 1034 This is purely to save memory: each supported CPU adds about 8KB 1035 to the kernel image. 1036 1037config SCHED_SMT 1038 def_bool y if SMP 1039 1040config SCHED_MC 1041 def_bool y 1042 prompt "Multi-core scheduler support" 1043 depends on SMP 1044 ---help--- 1045 Multi-core scheduler support improves the CPU scheduler's decision 1046 making when dealing with multi-core CPU chips at a cost of slightly 1047 increased overhead in some places. If unsure say N here. 1048 1049config SCHED_MC_PRIO 1050 bool "CPU core priorities scheduler support" 1051 depends on SCHED_MC && CPU_SUP_INTEL 1052 select X86_INTEL_PSTATE 1053 select CPU_FREQ 1054 default y 1055 ---help--- 1056 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a 1057 core ordering determined at manufacturing time, which allows 1058 certain cores to reach higher turbo frequencies (when running 1059 single threaded workloads) than others. 1060 1061 Enabling this kernel feature teaches the scheduler about 1062 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the 1063 scheduler's CPU selection logic accordingly, so that higher 1064 overall system performance can be achieved. 1065 1066 This feature will have no effect on CPUs without this feature. 1067 1068 If unsure say Y here. 1069 1070config UP_LATE_INIT 1071 def_bool y 1072 depends on !SMP && X86_LOCAL_APIC 1073 1074config X86_UP_APIC 1075 bool "Local APIC support on uniprocessors" if !PCI_MSI 1076 default PCI_MSI 1077 depends on X86_32 && !SMP && !X86_32_NON_STANDARD 1078 ---help--- 1079 A local APIC (Advanced Programmable Interrupt Controller) is an 1080 integrated interrupt controller in the CPU. If you have a single-CPU 1081 system which has a processor with a local APIC, you can say Y here to 1082 enable and use it. If you say Y here even though your machine doesn't 1083 have a local APIC, then the kernel will still run with no slowdown at 1084 all. The local APIC supports CPU-generated self-interrupts (timer, 1085 performance counters), and the NMI watchdog which detects hard 1086 lockups. 1087 1088config X86_UP_IOAPIC 1089 bool "IO-APIC support on uniprocessors" 1090 depends on X86_UP_APIC 1091 ---help--- 1092 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an 1093 SMP-capable replacement for PC-style interrupt controllers. Most 1094 SMP systems and many recent uniprocessor systems have one. 1095 1096 If you have a single-CPU system with an IO-APIC, you can say Y here 1097 to use it. If you say Y here even though your machine doesn't have 1098 an IO-APIC, then the kernel will still run with no slowdown at all. 1099 1100config X86_LOCAL_APIC 1101 def_bool y 1102 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI 1103 select IRQ_DOMAIN_HIERARCHY 1104 select PCI_MSI_IRQ_DOMAIN if PCI_MSI 1105 1106config X86_IO_APIC 1107 def_bool y 1108 depends on X86_LOCAL_APIC || X86_UP_IOAPIC 1109 1110config X86_REROUTE_FOR_BROKEN_BOOT_IRQS 1111 bool "Reroute for broken boot IRQs" 1112 depends on X86_IO_APIC 1113 ---help--- 1114 This option enables a workaround that fixes a source of 1115 spurious interrupts. This is recommended when threaded 1116 interrupt handling is used on systems where the generation of 1117 superfluous "boot interrupts" cannot be disabled. 1118 1119 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ 1120 entry in the chipset's IO-APIC is masked (as, e.g. the RT 1121 kernel does during interrupt handling). On chipsets where this 1122 boot IRQ generation cannot be disabled, this workaround keeps 1123 the original IRQ line masked so that only the equivalent "boot 1124 IRQ" is delivered to the CPUs. The workaround also tells the 1125 kernel to set up the IRQ handler on the boot IRQ line. In this 1126 way only one interrupt is delivered to the kernel. Otherwise 1127 the spurious second interrupt may cause the kernel to bring 1128 down (vital) interrupt lines. 1129 1130 Only affects "broken" chipsets. Interrupt sharing may be 1131 increased on these systems. 1132 1133config X86_MCE 1134 bool "Machine Check / overheating reporting" 1135 select GENERIC_ALLOCATOR 1136 default y 1137 ---help--- 1138 Machine Check support allows the processor to notify the 1139 kernel if it detects a problem (e.g. overheating, data corruption). 1140 The action the kernel takes depends on the severity of the problem, 1141 ranging from warning messages to halting the machine. 1142 1143config X86_MCELOG_LEGACY 1144 bool "Support for deprecated /dev/mcelog character device" 1145 depends on X86_MCE 1146 ---help--- 1147 Enable support for /dev/mcelog which is needed by the old mcelog 1148 userspace logging daemon. Consider switching to the new generation 1149 rasdaemon solution. 1150 1151config X86_MCE_INTEL 1152 def_bool y 1153 prompt "Intel MCE features" 1154 depends on X86_MCE && X86_LOCAL_APIC 1155 ---help--- 1156 Additional support for intel specific MCE features such as 1157 the thermal monitor. 1158 1159config X86_MCE_AMD 1160 def_bool y 1161 prompt "AMD MCE features" 1162 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB 1163 ---help--- 1164 Additional support for AMD specific MCE features such as 1165 the DRAM Error Threshold. 1166 1167config X86_ANCIENT_MCE 1168 bool "Support for old Pentium 5 / WinChip machine checks" 1169 depends on X86_32 && X86_MCE 1170 ---help--- 1171 Include support for machine check handling on old Pentium 5 or WinChip 1172 systems. These typically need to be enabled explicitly on the command 1173 line. 1174 1175config X86_MCE_THRESHOLD 1176 depends on X86_MCE_AMD || X86_MCE_INTEL 1177 def_bool y 1178 1179config X86_MCE_INJECT 1180 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS 1181 tristate "Machine check injector support" 1182 ---help--- 1183 Provide support for injecting machine checks for testing purposes. 1184 If you don't know what a machine check is and you don't do kernel 1185 QA it is safe to say n. 1186 1187config X86_THERMAL_VECTOR 1188 def_bool y 1189 depends on X86_MCE_INTEL 1190 1191source "arch/x86/events/Kconfig" 1192 1193config X86_LEGACY_VM86 1194 bool "Legacy VM86 support" 1195 depends on X86_32 1196 ---help--- 1197 This option allows user programs to put the CPU into V8086 1198 mode, which is an 80286-era approximation of 16-bit real mode. 1199 1200 Some very old versions of X and/or vbetool require this option 1201 for user mode setting. Similarly, DOSEMU will use it if 1202 available to accelerate real mode DOS programs. However, any 1203 recent version of DOSEMU, X, or vbetool should be fully 1204 functional even without kernel VM86 support, as they will all 1205 fall back to software emulation. Nevertheless, if you are using 1206 a 16-bit DOS program where 16-bit performance matters, vm86 1207 mode might be faster than emulation and you might want to 1208 enable this option. 1209 1210 Note that any app that works on a 64-bit kernel is unlikely to 1211 need this option, as 64-bit kernels don't, and can't, support 1212 V8086 mode. This option is also unrelated to 16-bit protected 1213 mode and is not needed to run most 16-bit programs under Wine. 1214 1215 Enabling this option increases the complexity of the kernel 1216 and slows down exception handling a tiny bit. 1217 1218 If unsure, say N here. 1219 1220config VM86 1221 bool 1222 default X86_LEGACY_VM86 1223 1224config X86_16BIT 1225 bool "Enable support for 16-bit segments" if EXPERT 1226 default y 1227 depends on MODIFY_LDT_SYSCALL 1228 ---help--- 1229 This option is required by programs like Wine to run 16-bit 1230 protected mode legacy code on x86 processors. Disabling 1231 this option saves about 300 bytes on i386, or around 6K text 1232 plus 16K runtime memory on x86-64, 1233 1234config X86_ESPFIX32 1235 def_bool y 1236 depends on X86_16BIT && X86_32 1237 1238config X86_ESPFIX64 1239 def_bool y 1240 depends on X86_16BIT && X86_64 1241 1242config X86_VSYSCALL_EMULATION 1243 bool "Enable vsyscall emulation" if EXPERT 1244 default y 1245 depends on X86_64 1246 ---help--- 1247 This enables emulation of the legacy vsyscall page. Disabling 1248 it is roughly equivalent to booting with vsyscall=none, except 1249 that it will also disable the helpful warning if a program 1250 tries to use a vsyscall. With this option set to N, offending 1251 programs will just segfault, citing addresses of the form 1252 0xffffffffff600?00. 1253 1254 This option is required by many programs built before 2013, and 1255 care should be used even with newer programs if set to N. 1256 1257 Disabling this option saves about 7K of kernel size and 1258 possibly 4K of additional runtime pagetable memory. 1259 1260config TOSHIBA 1261 tristate "Toshiba Laptop support" 1262 depends on X86_32 1263 ---help--- 1264 This adds a driver to safely access the System Management Mode of 1265 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does 1266 not work on models with a Phoenix BIOS. The System Management Mode 1267 is used to set the BIOS and power saving options on Toshiba portables. 1268 1269 For information on utilities to make use of this driver see the 1270 Toshiba Linux utilities web site at: 1271 <http://www.buzzard.org.uk/toshiba/>. 1272 1273 Say Y if you intend to run this kernel on a Toshiba portable. 1274 Say N otherwise. 1275 1276config I8K 1277 tristate "Dell i8k legacy laptop support" 1278 select HWMON 1279 select SENSORS_DELL_SMM 1280 ---help--- 1281 This option enables legacy /proc/i8k userspace interface in hwmon 1282 dell-smm-hwmon driver. Character file /proc/i8k reports bios version, 1283 temperature and allows controlling fan speeds of Dell laptops via 1284 System Management Mode. For old Dell laptops (like Dell Inspiron 8000) 1285 it reports also power and hotkey status. For fan speed control is 1286 needed userspace package i8kutils. 1287 1288 Say Y if you intend to run this kernel on old Dell laptops or want to 1289 use userspace package i8kutils. 1290 Say N otherwise. 1291 1292config X86_REBOOTFIXUPS 1293 bool "Enable X86 board specific fixups for reboot" 1294 depends on X86_32 1295 ---help--- 1296 This enables chipset and/or board specific fixups to be done 1297 in order to get reboot to work correctly. This is only needed on 1298 some combinations of hardware and BIOS. The symptom, for which 1299 this config is intended, is when reboot ends with a stalled/hung 1300 system. 1301 1302 Currently, the only fixup is for the Geode machines using 1303 CS5530A and CS5536 chipsets and the RDC R-321x SoC. 1304 1305 Say Y if you want to enable the fixup. Currently, it's safe to 1306 enable this option even if you don't need it. 1307 Say N otherwise. 1308 1309config MICROCODE 1310 bool "CPU microcode loading support" 1311 default y 1312 depends on CPU_SUP_AMD || CPU_SUP_INTEL 1313 select FW_LOADER 1314 ---help--- 1315 If you say Y here, you will be able to update the microcode on 1316 Intel and AMD processors. The Intel support is for the IA32 family, 1317 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The 1318 AMD support is for families 0x10 and later. You will obviously need 1319 the actual microcode binary data itself which is not shipped with 1320 the Linux kernel. 1321 1322 The preferred method to load microcode from a detached initrd is described 1323 in Documentation/x86/microcode.rst. For that you need to enable 1324 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the 1325 initrd for microcode blobs. 1326 1327 In addition, you can build the microcode into the kernel. For that you 1328 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE 1329 config option. 1330 1331config MICROCODE_INTEL 1332 bool "Intel microcode loading support" 1333 depends on MICROCODE 1334 default MICROCODE 1335 select FW_LOADER 1336 ---help--- 1337 This options enables microcode patch loading support for Intel 1338 processors. 1339 1340 For the current Intel microcode data package go to 1341 <https://downloadcenter.intel.com> and search for 1342 'Linux Processor Microcode Data File'. 1343 1344config MICROCODE_AMD 1345 bool "AMD microcode loading support" 1346 depends on MICROCODE 1347 select FW_LOADER 1348 ---help--- 1349 If you select this option, microcode patch loading support for AMD 1350 processors will be enabled. 1351 1352config MICROCODE_OLD_INTERFACE 1353 bool "Ancient loading interface (DEPRECATED)" 1354 default n 1355 depends on MICROCODE 1356 ---help--- 1357 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface 1358 which was used by userspace tools like iucode_tool and microcode.ctl. 1359 It is inadequate because it runs too late to be able to properly 1360 load microcode on a machine and it needs special tools. Instead, you 1361 should've switched to the early loading method with the initrd or 1362 builtin microcode by now: Documentation/x86/microcode.rst 1363 1364config X86_MSR 1365 tristate "/dev/cpu/*/msr - Model-specific register support" 1366 ---help--- 1367 This device gives privileged processes access to the x86 1368 Model-Specific Registers (MSRs). It is a character device with 1369 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. 1370 MSR accesses are directed to a specific CPU on multi-processor 1371 systems. 1372 1373config X86_CPUID 1374 tristate "/dev/cpu/*/cpuid - CPU information support" 1375 ---help--- 1376 This device gives processes access to the x86 CPUID instruction to 1377 be executed on a specific processor. It is a character device 1378 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to 1379 /dev/cpu/31/cpuid. 1380 1381choice 1382 prompt "High Memory Support" 1383 default HIGHMEM4G 1384 depends on X86_32 1385 1386config NOHIGHMEM 1387 bool "off" 1388 ---help--- 1389 Linux can use up to 64 Gigabytes of physical memory on x86 systems. 1390 However, the address space of 32-bit x86 processors is only 4 1391 Gigabytes large. That means that, if you have a large amount of 1392 physical memory, not all of it can be "permanently mapped" by the 1393 kernel. The physical memory that's not permanently mapped is called 1394 "high memory". 1395 1396 If you are compiling a kernel which will never run on a machine with 1397 more than 1 Gigabyte total physical RAM, answer "off" here (default 1398 choice and suitable for most users). This will result in a "3GB/1GB" 1399 split: 3GB are mapped so that each process sees a 3GB virtual memory 1400 space and the remaining part of the 4GB virtual memory space is used 1401 by the kernel to permanently map as much physical memory as 1402 possible. 1403 1404 If the machine has between 1 and 4 Gigabytes physical RAM, then 1405 answer "4GB" here. 1406 1407 If more than 4 Gigabytes is used then answer "64GB" here. This 1408 selection turns Intel PAE (Physical Address Extension) mode on. 1409 PAE implements 3-level paging on IA32 processors. PAE is fully 1410 supported by Linux, PAE mode is implemented on all recent Intel 1411 processors (Pentium Pro and better). NOTE: If you say "64GB" here, 1412 then the kernel will not boot on CPUs that don't support PAE! 1413 1414 The actual amount of total physical memory will either be 1415 auto detected or can be forced by using a kernel command line option 1416 such as "mem=256M". (Try "man bootparam" or see the documentation of 1417 your boot loader (lilo or loadlin) about how to pass options to the 1418 kernel at boot time.) 1419 1420 If unsure, say "off". 1421 1422config HIGHMEM4G 1423 bool "4GB" 1424 ---help--- 1425 Select this if you have a 32-bit processor and between 1 and 4 1426 gigabytes of physical RAM. 1427 1428config HIGHMEM64G 1429 bool "64GB" 1430 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6 1431 select X86_PAE 1432 ---help--- 1433 Select this if you have a 32-bit processor and more than 4 1434 gigabytes of physical RAM. 1435 1436endchoice 1437 1438choice 1439 prompt "Memory split" if EXPERT 1440 default VMSPLIT_3G 1441 depends on X86_32 1442 ---help--- 1443 Select the desired split between kernel and user memory. 1444 1445 If the address range available to the kernel is less than the 1446 physical memory installed, the remaining memory will be available 1447 as "high memory". Accessing high memory is a little more costly 1448 than low memory, as it needs to be mapped into the kernel first. 1449 Note that increasing the kernel address space limits the range 1450 available to user programs, making the address space there 1451 tighter. Selecting anything other than the default 3G/1G split 1452 will also likely make your kernel incompatible with binary-only 1453 kernel modules. 1454 1455 If you are not absolutely sure what you are doing, leave this 1456 option alone! 1457 1458 config VMSPLIT_3G 1459 bool "3G/1G user/kernel split" 1460 config VMSPLIT_3G_OPT 1461 depends on !X86_PAE 1462 bool "3G/1G user/kernel split (for full 1G low memory)" 1463 config VMSPLIT_2G 1464 bool "2G/2G user/kernel split" 1465 config VMSPLIT_2G_OPT 1466 depends on !X86_PAE 1467 bool "2G/2G user/kernel split (for full 2G low memory)" 1468 config VMSPLIT_1G 1469 bool "1G/3G user/kernel split" 1470endchoice 1471 1472config PAGE_OFFSET 1473 hex 1474 default 0xB0000000 if VMSPLIT_3G_OPT 1475 default 0x80000000 if VMSPLIT_2G 1476 default 0x78000000 if VMSPLIT_2G_OPT 1477 default 0x40000000 if VMSPLIT_1G 1478 default 0xC0000000 1479 depends on X86_32 1480 1481config HIGHMEM 1482 def_bool y 1483 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G) 1484 1485config X86_PAE 1486 bool "PAE (Physical Address Extension) Support" 1487 depends on X86_32 && !HIGHMEM4G 1488 select PHYS_ADDR_T_64BIT 1489 select SWIOTLB 1490 ---help--- 1491 PAE is required for NX support, and furthermore enables 1492 larger swapspace support for non-overcommit purposes. It 1493 has the cost of more pagetable lookup overhead, and also 1494 consumes more pagetable space per process. 1495 1496config X86_5LEVEL 1497 bool "Enable 5-level page tables support" 1498 select DYNAMIC_MEMORY_LAYOUT 1499 select SPARSEMEM_VMEMMAP 1500 depends on X86_64 1501 ---help--- 1502 5-level paging enables access to larger address space: 1503 upto 128 PiB of virtual address space and 4 PiB of 1504 physical address space. 1505 1506 It will be supported by future Intel CPUs. 1507 1508 A kernel with the option enabled can be booted on machines that 1509 support 4- or 5-level paging. 1510 1511 See Documentation/x86/x86_64/5level-paging.rst for more 1512 information. 1513 1514 Say N if unsure. 1515 1516config X86_DIRECT_GBPAGES 1517 def_bool y 1518 depends on X86_64 1519 ---help--- 1520 Certain kernel features effectively disable kernel 1521 linear 1 GB mappings (even if the CPU otherwise 1522 supports them), so don't confuse the user by printing 1523 that we have them enabled. 1524 1525config X86_CPA_STATISTICS 1526 bool "Enable statistic for Change Page Attribute" 1527 depends on DEBUG_FS 1528 ---help--- 1529 Expose statistics about the Change Page Attribute mechanims, which 1530 helps to determine the effectiveness of preserving large and huge 1531 page mappings when mapping protections are changed. 1532 1533config AMD_MEM_ENCRYPT 1534 bool "AMD Secure Memory Encryption (SME) support" 1535 depends on X86_64 && CPU_SUP_AMD 1536 select DYNAMIC_PHYSICAL_MASK 1537 select ARCH_USE_MEMREMAP_PROT 1538 select ARCH_HAS_FORCE_DMA_UNENCRYPTED 1539 ---help--- 1540 Say yes to enable support for the encryption of system memory. 1541 This requires an AMD processor that supports Secure Memory 1542 Encryption (SME). 1543 1544config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT 1545 bool "Activate AMD Secure Memory Encryption (SME) by default" 1546 depends on AMD_MEM_ENCRYPT 1547 ---help--- 1548 Say yes to have system memory encrypted by default if running on 1549 an AMD processor that supports Secure Memory Encryption (SME). 1550 1551 If set to Y, then the encryption of system memory can be 1552 deactivated with the mem_encrypt=off command line option. 1553 1554 If set to N, then the encryption of system memory can be 1555 activated with the mem_encrypt=on command line option. 1556 1557# Common NUMA Features 1558config NUMA 1559 bool "Numa Memory Allocation and Scheduler Support" 1560 depends on SMP 1561 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP) 1562 default y if X86_BIGSMP 1563 ---help--- 1564 Enable NUMA (Non Uniform Memory Access) support. 1565 1566 The kernel will try to allocate memory used by a CPU on the 1567 local memory controller of the CPU and add some more 1568 NUMA awareness to the kernel. 1569 1570 For 64-bit this is recommended if the system is Intel Core i7 1571 (or later), AMD Opteron, or EM64T NUMA. 1572 1573 For 32-bit this is only needed if you boot a 32-bit 1574 kernel on a 64-bit NUMA platform. 1575 1576 Otherwise, you should say N. 1577 1578config AMD_NUMA 1579 def_bool y 1580 prompt "Old style AMD Opteron NUMA detection" 1581 depends on X86_64 && NUMA && PCI 1582 ---help--- 1583 Enable AMD NUMA node topology detection. You should say Y here if 1584 you have a multi processor AMD system. This uses an old method to 1585 read the NUMA configuration directly from the builtin Northbridge 1586 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead, 1587 which also takes priority if both are compiled in. 1588 1589config X86_64_ACPI_NUMA 1590 def_bool y 1591 prompt "ACPI NUMA detection" 1592 depends on X86_64 && NUMA && ACPI && PCI 1593 select ACPI_NUMA 1594 ---help--- 1595 Enable ACPI SRAT based node topology detection. 1596 1597# Some NUMA nodes have memory ranges that span 1598# other nodes. Even though a pfn is valid and 1599# between a node's start and end pfns, it may not 1600# reside on that node. See memmap_init_zone() 1601# for details. 1602config NODES_SPAN_OTHER_NODES 1603 def_bool y 1604 depends on X86_64_ACPI_NUMA 1605 1606config NUMA_EMU 1607 bool "NUMA emulation" 1608 depends on NUMA 1609 ---help--- 1610 Enable NUMA emulation. A flat machine will be split 1611 into virtual nodes when booted with "numa=fake=N", where N is the 1612 number of nodes. This is only useful for debugging. 1613 1614config NODES_SHIFT 1615 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP 1616 range 1 10 1617 default "10" if MAXSMP 1618 default "6" if X86_64 1619 default "3" 1620 depends on NEED_MULTIPLE_NODES 1621 ---help--- 1622 Specify the maximum number of NUMA Nodes available on the target 1623 system. Increases memory reserved to accommodate various tables. 1624 1625config ARCH_HAVE_MEMORY_PRESENT 1626 def_bool y 1627 depends on X86_32 && DISCONTIGMEM 1628 1629config ARCH_FLATMEM_ENABLE 1630 def_bool y 1631 depends on X86_32 && !NUMA 1632 1633config ARCH_DISCONTIGMEM_ENABLE 1634 def_bool n 1635 depends on NUMA && X86_32 1636 depends on BROKEN 1637 1638config ARCH_SPARSEMEM_ENABLE 1639 def_bool y 1640 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD 1641 select SPARSEMEM_STATIC if X86_32 1642 select SPARSEMEM_VMEMMAP_ENABLE if X86_64 1643 1644config ARCH_SPARSEMEM_DEFAULT 1645 def_bool X86_64 || (NUMA && X86_32) 1646 1647config ARCH_SELECT_MEMORY_MODEL 1648 def_bool y 1649 depends on ARCH_SPARSEMEM_ENABLE 1650 1651config ARCH_MEMORY_PROBE 1652 bool "Enable sysfs memory/probe interface" 1653 depends on X86_64 && MEMORY_HOTPLUG 1654 help 1655 This option enables a sysfs memory/probe interface for testing. 1656 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 1657 If you are unsure how to answer this question, answer N. 1658 1659config ARCH_PROC_KCORE_TEXT 1660 def_bool y 1661 depends on X86_64 && PROC_KCORE 1662 1663config ILLEGAL_POINTER_VALUE 1664 hex 1665 default 0 if X86_32 1666 default 0xdead000000000000 if X86_64 1667 1668config X86_PMEM_LEGACY_DEVICE 1669 bool 1670 1671config X86_PMEM_LEGACY 1672 tristate "Support non-standard NVDIMMs and ADR protected memory" 1673 depends on PHYS_ADDR_T_64BIT 1674 depends on BLK_DEV 1675 select X86_PMEM_LEGACY_DEVICE 1676 select LIBNVDIMM 1677 help 1678 Treat memory marked using the non-standard e820 type of 12 as used 1679 by the Intel Sandy Bridge-EP reference BIOS as protected memory. 1680 The kernel will offer these regions to the 'pmem' driver so 1681 they can be used for persistent storage. 1682 1683 Say Y if unsure. 1684 1685config HIGHPTE 1686 bool "Allocate 3rd-level pagetables from highmem" 1687 depends on HIGHMEM 1688 ---help--- 1689 The VM uses one page table entry for each page of physical memory. 1690 For systems with a lot of RAM, this can be wasteful of precious 1691 low memory. Setting this option will put user-space page table 1692 entries in high memory. 1693 1694config X86_CHECK_BIOS_CORRUPTION 1695 bool "Check for low memory corruption" 1696 ---help--- 1697 Periodically check for memory corruption in low memory, which 1698 is suspected to be caused by BIOS. Even when enabled in the 1699 configuration, it is disabled at runtime. Enable it by 1700 setting "memory_corruption_check=1" on the kernel command 1701 line. By default it scans the low 64k of memory every 60 1702 seconds; see the memory_corruption_check_size and 1703 memory_corruption_check_period parameters in 1704 Documentation/admin-guide/kernel-parameters.rst to adjust this. 1705 1706 When enabled with the default parameters, this option has 1707 almost no overhead, as it reserves a relatively small amount 1708 of memory and scans it infrequently. It both detects corruption 1709 and prevents it from affecting the running system. 1710 1711 It is, however, intended as a diagnostic tool; if repeatable 1712 BIOS-originated corruption always affects the same memory, 1713 you can use memmap= to prevent the kernel from using that 1714 memory. 1715 1716config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK 1717 bool "Set the default setting of memory_corruption_check" 1718 depends on X86_CHECK_BIOS_CORRUPTION 1719 default y 1720 ---help--- 1721 Set whether the default state of memory_corruption_check is 1722 on or off. 1723 1724config X86_RESERVE_LOW 1725 int "Amount of low memory, in kilobytes, to reserve for the BIOS" 1726 default 64 1727 range 4 640 1728 ---help--- 1729 Specify the amount of low memory to reserve for the BIOS. 1730 1731 The first page contains BIOS data structures that the kernel 1732 must not use, so that page must always be reserved. 1733 1734 By default we reserve the first 64K of physical RAM, as a 1735 number of BIOSes are known to corrupt that memory range 1736 during events such as suspend/resume or monitor cable 1737 insertion, so it must not be used by the kernel. 1738 1739 You can set this to 4 if you are absolutely sure that you 1740 trust the BIOS to get all its memory reservations and usages 1741 right. If you know your BIOS have problems beyond the 1742 default 64K area, you can set this to 640 to avoid using the 1743 entire low memory range. 1744 1745 If you have doubts about the BIOS (e.g. suspend/resume does 1746 not work or there's kernel crashes after certain hardware 1747 hotplug events) then you might want to enable 1748 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check 1749 typical corruption patterns. 1750 1751 Leave this to the default value of 64 if you are unsure. 1752 1753config MATH_EMULATION 1754 bool 1755 depends on MODIFY_LDT_SYSCALL 1756 prompt "Math emulation" if X86_32 1757 ---help--- 1758 Linux can emulate a math coprocessor (used for floating point 1759 operations) if you don't have one. 486DX and Pentium processors have 1760 a math coprocessor built in, 486SX and 386 do not, unless you added 1761 a 487DX or 387, respectively. (The messages during boot time can 1762 give you some hints here ["man dmesg"].) Everyone needs either a 1763 coprocessor or this emulation. 1764 1765 If you don't have a math coprocessor, you need to say Y here; if you 1766 say Y here even though you have a coprocessor, the coprocessor will 1767 be used nevertheless. (This behavior can be changed with the kernel 1768 command line option "no387", which comes handy if your coprocessor 1769 is broken. Try "man bootparam" or see the documentation of your boot 1770 loader (lilo or loadlin) about how to pass options to the kernel at 1771 boot time.) This means that it is a good idea to say Y here if you 1772 intend to use this kernel on different machines. 1773 1774 More information about the internals of the Linux math coprocessor 1775 emulation can be found in <file:arch/x86/math-emu/README>. 1776 1777 If you are not sure, say Y; apart from resulting in a 66 KB bigger 1778 kernel, it won't hurt. 1779 1780config MTRR 1781 def_bool y 1782 prompt "MTRR (Memory Type Range Register) support" if EXPERT 1783 ---help--- 1784 On Intel P6 family processors (Pentium Pro, Pentium II and later) 1785 the Memory Type Range Registers (MTRRs) may be used to control 1786 processor access to memory ranges. This is most useful if you have 1787 a video (VGA) card on a PCI or AGP bus. Enabling write-combining 1788 allows bus write transfers to be combined into a larger transfer 1789 before bursting over the PCI/AGP bus. This can increase performance 1790 of image write operations 2.5 times or more. Saying Y here creates a 1791 /proc/mtrr file which may be used to manipulate your processor's 1792 MTRRs. Typically the X server should use this. 1793 1794 This code has a reasonably generic interface so that similar 1795 control registers on other processors can be easily supported 1796 as well: 1797 1798 The Cyrix 6x86, 6x86MX and M II processors have Address Range 1799 Registers (ARRs) which provide a similar functionality to MTRRs. For 1800 these, the ARRs are used to emulate the MTRRs. 1801 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two 1802 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing 1803 write-combining. All of these processors are supported by this code 1804 and it makes sense to say Y here if you have one of them. 1805 1806 Saying Y here also fixes a problem with buggy SMP BIOSes which only 1807 set the MTRRs for the boot CPU and not for the secondary CPUs. This 1808 can lead to all sorts of problems, so it's good to say Y here. 1809 1810 You can safely say Y even if your machine doesn't have MTRRs, you'll 1811 just add about 9 KB to your kernel. 1812 1813 See <file:Documentation/x86/mtrr.rst> for more information. 1814 1815config MTRR_SANITIZER 1816 def_bool y 1817 prompt "MTRR cleanup support" 1818 depends on MTRR 1819 ---help--- 1820 Convert MTRR layout from continuous to discrete, so X drivers can 1821 add writeback entries. 1822 1823 Can be disabled with disable_mtrr_cleanup on the kernel command line. 1824 The largest mtrr entry size for a continuous block can be set with 1825 mtrr_chunk_size. 1826 1827 If unsure, say Y. 1828 1829config MTRR_SANITIZER_ENABLE_DEFAULT 1830 int "MTRR cleanup enable value (0-1)" 1831 range 0 1 1832 default "0" 1833 depends on MTRR_SANITIZER 1834 ---help--- 1835 Enable mtrr cleanup default value 1836 1837config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT 1838 int "MTRR cleanup spare reg num (0-7)" 1839 range 0 7 1840 default "1" 1841 depends on MTRR_SANITIZER 1842 ---help--- 1843 mtrr cleanup spare entries default, it can be changed via 1844 mtrr_spare_reg_nr=N on the kernel command line. 1845 1846config X86_PAT 1847 def_bool y 1848 prompt "x86 PAT support" if EXPERT 1849 depends on MTRR 1850 ---help--- 1851 Use PAT attributes to setup page level cache control. 1852 1853 PATs are the modern equivalents of MTRRs and are much more 1854 flexible than MTRRs. 1855 1856 Say N here if you see bootup problems (boot crash, boot hang, 1857 spontaneous reboots) or a non-working video driver. 1858 1859 If unsure, say Y. 1860 1861config ARCH_USES_PG_UNCACHED 1862 def_bool y 1863 depends on X86_PAT 1864 1865config ARCH_RANDOM 1866 def_bool y 1867 prompt "x86 architectural random number generator" if EXPERT 1868 ---help--- 1869 Enable the x86 architectural RDRAND instruction 1870 (Intel Bull Mountain technology) to generate random numbers. 1871 If supported, this is a high bandwidth, cryptographically 1872 secure hardware random number generator. 1873 1874config X86_SMAP 1875 def_bool y 1876 prompt "Supervisor Mode Access Prevention" if EXPERT 1877 ---help--- 1878 Supervisor Mode Access Prevention (SMAP) is a security 1879 feature in newer Intel processors. There is a small 1880 performance cost if this enabled and turned on; there is 1881 also a small increase in the kernel size if this is enabled. 1882 1883 If unsure, say Y. 1884 1885config X86_INTEL_UMIP 1886 def_bool y 1887 depends on CPU_SUP_INTEL 1888 prompt "Intel User Mode Instruction Prevention" if EXPERT 1889 ---help--- 1890 The User Mode Instruction Prevention (UMIP) is a security 1891 feature in newer Intel processors. If enabled, a general 1892 protection fault is issued if the SGDT, SLDT, SIDT, SMSW 1893 or STR instructions are executed in user mode. These instructions 1894 unnecessarily expose information about the hardware state. 1895 1896 The vast majority of applications do not use these instructions. 1897 For the very few that do, software emulation is provided in 1898 specific cases in protected and virtual-8086 modes. Emulated 1899 results are dummy. 1900 1901config X86_INTEL_MPX 1902 prompt "Intel MPX (Memory Protection Extensions)" 1903 def_bool n 1904 # Note: only available in 64-bit mode due to VMA flags shortage 1905 depends on CPU_SUP_INTEL && X86_64 1906 select ARCH_USES_HIGH_VMA_FLAGS 1907 ---help--- 1908 MPX provides hardware features that can be used in 1909 conjunction with compiler-instrumented code to check 1910 memory references. It is designed to detect buffer 1911 overflow or underflow bugs. 1912 1913 This option enables running applications which are 1914 instrumented or otherwise use MPX. It does not use MPX 1915 itself inside the kernel or to protect the kernel 1916 against bad memory references. 1917 1918 Enabling this option will make the kernel larger: 1919 ~8k of kernel text and 36 bytes of data on a 64-bit 1920 defconfig. It adds a long to the 'mm_struct' which 1921 will increase the kernel memory overhead of each 1922 process and adds some branches to paths used during 1923 exec() and munmap(). 1924 1925 For details, see Documentation/x86/intel_mpx.rst 1926 1927 If unsure, say N. 1928 1929config X86_INTEL_MEMORY_PROTECTION_KEYS 1930 prompt "Intel Memory Protection Keys" 1931 def_bool y 1932 # Note: only available in 64-bit mode 1933 depends on CPU_SUP_INTEL && X86_64 1934 select ARCH_USES_HIGH_VMA_FLAGS 1935 select ARCH_HAS_PKEYS 1936 ---help--- 1937 Memory Protection Keys provides a mechanism for enforcing 1938 page-based protections, but without requiring modification of the 1939 page tables when an application changes protection domains. 1940 1941 For details, see Documentation/core-api/protection-keys.rst 1942 1943 If unsure, say y. 1944 1945choice 1946 prompt "TSX enable mode" 1947 depends on CPU_SUP_INTEL 1948 default X86_INTEL_TSX_MODE_OFF 1949 help 1950 Intel's TSX (Transactional Synchronization Extensions) feature 1951 allows to optimize locking protocols through lock elision which 1952 can lead to a noticeable performance boost. 1953 1954 On the other hand it has been shown that TSX can be exploited 1955 to form side channel attacks (e.g. TAA) and chances are there 1956 will be more of those attacks discovered in the future. 1957 1958 Therefore TSX is not enabled by default (aka tsx=off). An admin 1959 might override this decision by tsx=on the command line parameter. 1960 Even with TSX enabled, the kernel will attempt to enable the best 1961 possible TAA mitigation setting depending on the microcode available 1962 for the particular machine. 1963 1964 This option allows to set the default tsx mode between tsx=on, =off 1965 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more 1966 details. 1967 1968 Say off if not sure, auto if TSX is in use but it should be used on safe 1969 platforms or on if TSX is in use and the security aspect of tsx is not 1970 relevant. 1971 1972config X86_INTEL_TSX_MODE_OFF 1973 bool "off" 1974 help 1975 TSX is disabled if possible - equals to tsx=off command line parameter. 1976 1977config X86_INTEL_TSX_MODE_ON 1978 bool "on" 1979 help 1980 TSX is always enabled on TSX capable HW - equals the tsx=on command 1981 line parameter. 1982 1983config X86_INTEL_TSX_MODE_AUTO 1984 bool "auto" 1985 help 1986 TSX is enabled on TSX capable HW that is believed to be safe against 1987 side channel attacks- equals the tsx=auto command line parameter. 1988endchoice 1989 1990config EFI 1991 bool "EFI runtime service support" 1992 depends on ACPI 1993 select UCS2_STRING 1994 select EFI_RUNTIME_WRAPPERS 1995 select ARCH_USE_MEMREMAP_PROT 1996 ---help--- 1997 This enables the kernel to use EFI runtime services that are 1998 available (such as the EFI variable services). 1999 2000 This option is only useful on systems that have EFI firmware. 2001 In addition, you should use the latest ELILO loader available 2002 at <http://elilo.sourceforge.net> in order to take advantage 2003 of EFI runtime services. However, even with this option, the 2004 resultant kernel should continue to boot on existing non-EFI 2005 platforms. 2006 2007config EFI_STUB 2008 bool "EFI stub support" 2009 depends on EFI && !X86_USE_3DNOW 2010 select RELOCATABLE 2011 ---help--- 2012 This kernel feature allows a bzImage to be loaded directly 2013 by EFI firmware without the use of a bootloader. 2014 2015 See Documentation/admin-guide/efi-stub.rst for more information. 2016 2017config EFI_MIXED 2018 bool "EFI mixed-mode support" 2019 depends on EFI_STUB && X86_64 2020 ---help--- 2021 Enabling this feature allows a 64-bit kernel to be booted 2022 on a 32-bit firmware, provided that your CPU supports 64-bit 2023 mode. 2024 2025 Note that it is not possible to boot a mixed-mode enabled 2026 kernel via the EFI boot stub - a bootloader that supports 2027 the EFI handover protocol must be used. 2028 2029 If unsure, say N. 2030 2031config SECCOMP 2032 def_bool y 2033 prompt "Enable seccomp to safely compute untrusted bytecode" 2034 ---help--- 2035 This kernel feature is useful for number crunching applications 2036 that may need to compute untrusted bytecode during their 2037 execution. By using pipes or other transports made available to 2038 the process as file descriptors supporting the read/write 2039 syscalls, it's possible to isolate those applications in 2040 their own address space using seccomp. Once seccomp is 2041 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled 2042 and the task is only allowed to execute a few safe syscalls 2043 defined by each seccomp mode. 2044 2045 If unsure, say Y. Only embedded should say N here. 2046 2047source "kernel/Kconfig.hz" 2048 2049config KEXEC 2050 bool "kexec system call" 2051 select KEXEC_CORE 2052 ---help--- 2053 kexec is a system call that implements the ability to shutdown your 2054 current kernel, and to start another kernel. It is like a reboot 2055 but it is independent of the system firmware. And like a reboot 2056 you can start any kernel with it, not just Linux. 2057 2058 The name comes from the similarity to the exec system call. 2059 2060 It is an ongoing process to be certain the hardware in a machine 2061 is properly shutdown, so do not be surprised if this code does not 2062 initially work for you. As of this writing the exact hardware 2063 interface is strongly in flux, so no good recommendation can be 2064 made. 2065 2066config KEXEC_FILE 2067 bool "kexec file based system call" 2068 select KEXEC_CORE 2069 select BUILD_BIN2C 2070 depends on X86_64 2071 depends on CRYPTO=y 2072 depends on CRYPTO_SHA256=y 2073 ---help--- 2074 This is new version of kexec system call. This system call is 2075 file based and takes file descriptors as system call argument 2076 for kernel and initramfs as opposed to list of segments as 2077 accepted by previous system call. 2078 2079config ARCH_HAS_KEXEC_PURGATORY 2080 def_bool KEXEC_FILE 2081 2082config KEXEC_SIG 2083 bool "Verify kernel signature during kexec_file_load() syscall" 2084 depends on KEXEC_FILE 2085 ---help--- 2086 2087 This option makes the kexec_file_load() syscall check for a valid 2088 signature of the kernel image. The image can still be loaded without 2089 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 2090 there's a signature that we can check, then it must be valid. 2091 2092 In addition to this option, you need to enable signature 2093 verification for the corresponding kernel image type being 2094 loaded in order for this to work. 2095 2096config KEXEC_SIG_FORCE 2097 bool "Require a valid signature in kexec_file_load() syscall" 2098 depends on KEXEC_SIG 2099 ---help--- 2100 This option makes kernel signature verification mandatory for 2101 the kexec_file_load() syscall. 2102 2103config KEXEC_BZIMAGE_VERIFY_SIG 2104 bool "Enable bzImage signature verification support" 2105 depends on KEXEC_SIG 2106 depends on SIGNED_PE_FILE_VERIFICATION 2107 select SYSTEM_TRUSTED_KEYRING 2108 ---help--- 2109 Enable bzImage signature verification support. 2110 2111config CRASH_DUMP 2112 bool "kernel crash dumps" 2113 depends on X86_64 || (X86_32 && HIGHMEM) 2114 ---help--- 2115 Generate crash dump after being started by kexec. 2116 This should be normally only set in special crash dump kernels 2117 which are loaded in the main kernel with kexec-tools into 2118 a specially reserved region and then later executed after 2119 a crash by kdump/kexec. The crash dump kernel must be compiled 2120 to a memory address not used by the main kernel or BIOS using 2121 PHYSICAL_START, or it must be built as a relocatable image 2122 (CONFIG_RELOCATABLE=y). 2123 For more details see Documentation/admin-guide/kdump/kdump.rst 2124 2125config KEXEC_JUMP 2126 bool "kexec jump" 2127 depends on KEXEC && HIBERNATION 2128 ---help--- 2129 Jump between original kernel and kexeced kernel and invoke 2130 code in physical address mode via KEXEC 2131 2132config PHYSICAL_START 2133 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP) 2134 default "0x1000000" 2135 ---help--- 2136 This gives the physical address where the kernel is loaded. 2137 2138 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then 2139 bzImage will decompress itself to above physical address and 2140 run from there. Otherwise, bzImage will run from the address where 2141 it has been loaded by the boot loader and will ignore above physical 2142 address. 2143 2144 In normal kdump cases one does not have to set/change this option 2145 as now bzImage can be compiled as a completely relocatable image 2146 (CONFIG_RELOCATABLE=y) and be used to load and run from a different 2147 address. This option is mainly useful for the folks who don't want 2148 to use a bzImage for capturing the crash dump and want to use a 2149 vmlinux instead. vmlinux is not relocatable hence a kernel needs 2150 to be specifically compiled to run from a specific memory area 2151 (normally a reserved region) and this option comes handy. 2152 2153 So if you are using bzImage for capturing the crash dump, 2154 leave the value here unchanged to 0x1000000 and set 2155 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux 2156 for capturing the crash dump change this value to start of 2157 the reserved region. In other words, it can be set based on 2158 the "X" value as specified in the "crashkernel=YM@XM" 2159 command line boot parameter passed to the panic-ed 2160 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst 2161 for more details about crash dumps. 2162 2163 Usage of bzImage for capturing the crash dump is recommended as 2164 one does not have to build two kernels. Same kernel can be used 2165 as production kernel and capture kernel. Above option should have 2166 gone away after relocatable bzImage support is introduced. But it 2167 is present because there are users out there who continue to use 2168 vmlinux for dump capture. This option should go away down the 2169 line. 2170 2171 Don't change this unless you know what you are doing. 2172 2173config RELOCATABLE 2174 bool "Build a relocatable kernel" 2175 default y 2176 ---help--- 2177 This builds a kernel image that retains relocation information 2178 so it can be loaded someplace besides the default 1MB. 2179 The relocations tend to make the kernel binary about 10% larger, 2180 but are discarded at runtime. 2181 2182 One use is for the kexec on panic case where the recovery kernel 2183 must live at a different physical address than the primary 2184 kernel. 2185 2186 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address 2187 it has been loaded at and the compile time physical address 2188 (CONFIG_PHYSICAL_START) is used as the minimum location. 2189 2190config RANDOMIZE_BASE 2191 bool "Randomize the address of the kernel image (KASLR)" 2192 depends on RELOCATABLE 2193 default y 2194 ---help--- 2195 In support of Kernel Address Space Layout Randomization (KASLR), 2196 this randomizes the physical address at which the kernel image 2197 is decompressed and the virtual address where the kernel 2198 image is mapped, as a security feature that deters exploit 2199 attempts relying on knowledge of the location of kernel 2200 code internals. 2201 2202 On 64-bit, the kernel physical and virtual addresses are 2203 randomized separately. The physical address will be anywhere 2204 between 16MB and the top of physical memory (up to 64TB). The 2205 virtual address will be randomized from 16MB up to 1GB (9 bits 2206 of entropy). Note that this also reduces the memory space 2207 available to kernel modules from 1.5GB to 1GB. 2208 2209 On 32-bit, the kernel physical and virtual addresses are 2210 randomized together. They will be randomized from 16MB up to 2211 512MB (8 bits of entropy). 2212 2213 Entropy is generated using the RDRAND instruction if it is 2214 supported. If RDTSC is supported, its value is mixed into 2215 the entropy pool as well. If neither RDRAND nor RDTSC are 2216 supported, then entropy is read from the i8254 timer. The 2217 usable entropy is limited by the kernel being built using 2218 2GB addressing, and that PHYSICAL_ALIGN must be at a 2219 minimum of 2MB. As a result, only 10 bits of entropy are 2220 theoretically possible, but the implementations are further 2221 limited due to memory layouts. 2222 2223 If unsure, say Y. 2224 2225# Relocation on x86 needs some additional build support 2226config X86_NEED_RELOCS 2227 def_bool y 2228 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE) 2229 2230config PHYSICAL_ALIGN 2231 hex "Alignment value to which kernel should be aligned" 2232 default "0x200000" 2233 range 0x2000 0x1000000 if X86_32 2234 range 0x200000 0x1000000 if X86_64 2235 ---help--- 2236 This value puts the alignment restrictions on physical address 2237 where kernel is loaded and run from. Kernel is compiled for an 2238 address which meets above alignment restriction. 2239 2240 If bootloader loads the kernel at a non-aligned address and 2241 CONFIG_RELOCATABLE is set, kernel will move itself to nearest 2242 address aligned to above value and run from there. 2243 2244 If bootloader loads the kernel at a non-aligned address and 2245 CONFIG_RELOCATABLE is not set, kernel will ignore the run time 2246 load address and decompress itself to the address it has been 2247 compiled for and run from there. The address for which kernel is 2248 compiled already meets above alignment restrictions. Hence the 2249 end result is that kernel runs from a physical address meeting 2250 above alignment restrictions. 2251 2252 On 32-bit this value must be a multiple of 0x2000. On 64-bit 2253 this value must be a multiple of 0x200000. 2254 2255 Don't change this unless you know what you are doing. 2256 2257config DYNAMIC_MEMORY_LAYOUT 2258 bool 2259 ---help--- 2260 This option makes base addresses of vmalloc and vmemmap as well as 2261 __PAGE_OFFSET movable during boot. 2262 2263config RANDOMIZE_MEMORY 2264 bool "Randomize the kernel memory sections" 2265 depends on X86_64 2266 depends on RANDOMIZE_BASE 2267 select DYNAMIC_MEMORY_LAYOUT 2268 default RANDOMIZE_BASE 2269 ---help--- 2270 Randomizes the base virtual address of kernel memory sections 2271 (physical memory mapping, vmalloc & vmemmap). This security feature 2272 makes exploits relying on predictable memory locations less reliable. 2273 2274 The order of allocations remains unchanged. Entropy is generated in 2275 the same way as RANDOMIZE_BASE. Current implementation in the optimal 2276 configuration have in average 30,000 different possible virtual 2277 addresses for each memory section. 2278 2279 If unsure, say Y. 2280 2281config RANDOMIZE_MEMORY_PHYSICAL_PADDING 2282 hex "Physical memory mapping padding" if EXPERT 2283 depends on RANDOMIZE_MEMORY 2284 default "0xa" if MEMORY_HOTPLUG 2285 default "0x0" 2286 range 0x1 0x40 if MEMORY_HOTPLUG 2287 range 0x0 0x40 2288 ---help--- 2289 Define the padding in terabytes added to the existing physical 2290 memory size during kernel memory randomization. It is useful 2291 for memory hotplug support but reduces the entropy available for 2292 address randomization. 2293 2294 If unsure, leave at the default value. 2295 2296config HOTPLUG_CPU 2297 def_bool y 2298 depends on SMP 2299 2300config BOOTPARAM_HOTPLUG_CPU0 2301 bool "Set default setting of cpu0_hotpluggable" 2302 depends on HOTPLUG_CPU 2303 ---help--- 2304 Set whether default state of cpu0_hotpluggable is on or off. 2305 2306 Say Y here to enable CPU0 hotplug by default. If this switch 2307 is turned on, there is no need to give cpu0_hotplug kernel 2308 parameter and the CPU0 hotplug feature is enabled by default. 2309 2310 Please note: there are two known CPU0 dependencies if you want 2311 to enable the CPU0 hotplug feature either by this switch or by 2312 cpu0_hotplug kernel parameter. 2313 2314 First, resume from hibernate or suspend always starts from CPU0. 2315 So hibernate and suspend are prevented if CPU0 is offline. 2316 2317 Second dependency is PIC interrupts always go to CPU0. CPU0 can not 2318 offline if any interrupt can not migrate out of CPU0. There may 2319 be other CPU0 dependencies. 2320 2321 Please make sure the dependencies are under your control before 2322 you enable this feature. 2323 2324 Say N if you don't want to enable CPU0 hotplug feature by default. 2325 You still can enable the CPU0 hotplug feature at boot by kernel 2326 parameter cpu0_hotplug. 2327 2328config DEBUG_HOTPLUG_CPU0 2329 def_bool n 2330 prompt "Debug CPU0 hotplug" 2331 depends on HOTPLUG_CPU 2332 ---help--- 2333 Enabling this option offlines CPU0 (if CPU0 can be offlined) as 2334 soon as possible and boots up userspace with CPU0 offlined. User 2335 can online CPU0 back after boot time. 2336 2337 To debug CPU0 hotplug, you need to enable CPU0 offline/online 2338 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during 2339 compilation or giving cpu0_hotplug kernel parameter at boot. 2340 2341 If unsure, say N. 2342 2343config COMPAT_VDSO 2344 def_bool n 2345 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)" 2346 depends on COMPAT_32 2347 ---help--- 2348 Certain buggy versions of glibc will crash if they are 2349 presented with a 32-bit vDSO that is not mapped at the address 2350 indicated in its segment table. 2351 2352 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a 2353 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and 2354 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is 2355 the only released version with the bug, but OpenSUSE 9 2356 contains a buggy "glibc 2.3.2". 2357 2358 The symptom of the bug is that everything crashes on startup, saying: 2359 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! 2360 2361 Saying Y here changes the default value of the vdso32 boot 2362 option from 1 to 0, which turns off the 32-bit vDSO entirely. 2363 This works around the glibc bug but hurts performance. 2364 2365 If unsure, say N: if you are compiling your own kernel, you 2366 are unlikely to be using a buggy version of glibc. 2367 2368choice 2369 prompt "vsyscall table for legacy applications" 2370 depends on X86_64 2371 default LEGACY_VSYSCALL_XONLY 2372 help 2373 Legacy user code that does not know how to find the vDSO expects 2374 to be able to issue three syscalls by calling fixed addresses in 2375 kernel space. Since this location is not randomized with ASLR, 2376 it can be used to assist security vulnerability exploitation. 2377 2378 This setting can be changed at boot time via the kernel command 2379 line parameter vsyscall=[emulate|xonly|none]. 2380 2381 On a system with recent enough glibc (2.14 or newer) and no 2382 static binaries, you can say None without a performance penalty 2383 to improve security. 2384 2385 If unsure, select "Emulate execution only". 2386 2387 config LEGACY_VSYSCALL_EMULATE 2388 bool "Full emulation" 2389 help 2390 The kernel traps and emulates calls into the fixed vsyscall 2391 address mapping. This makes the mapping non-executable, but 2392 it still contains readable known contents, which could be 2393 used in certain rare security vulnerability exploits. This 2394 configuration is recommended when using legacy userspace 2395 that still uses vsyscalls along with legacy binary 2396 instrumentation tools that require code to be readable. 2397 2398 An example of this type of legacy userspace is running 2399 Pin on an old binary that still uses vsyscalls. 2400 2401 config LEGACY_VSYSCALL_XONLY 2402 bool "Emulate execution only" 2403 help 2404 The kernel traps and emulates calls into the fixed vsyscall 2405 address mapping and does not allow reads. This 2406 configuration is recommended when userspace might use the 2407 legacy vsyscall area but support for legacy binary 2408 instrumentation of legacy code is not needed. It mitigates 2409 certain uses of the vsyscall area as an ASLR-bypassing 2410 buffer. 2411 2412 config LEGACY_VSYSCALL_NONE 2413 bool "None" 2414 help 2415 There will be no vsyscall mapping at all. This will 2416 eliminate any risk of ASLR bypass due to the vsyscall 2417 fixed address mapping. Attempts to use the vsyscalls 2418 will be reported to dmesg, so that either old or 2419 malicious userspace programs can be identified. 2420 2421endchoice 2422 2423config CMDLINE_BOOL 2424 bool "Built-in kernel command line" 2425 ---help--- 2426 Allow for specifying boot arguments to the kernel at 2427 build time. On some systems (e.g. embedded ones), it is 2428 necessary or convenient to provide some or all of the 2429 kernel boot arguments with the kernel itself (that is, 2430 to not rely on the boot loader to provide them.) 2431 2432 To compile command line arguments into the kernel, 2433 set this option to 'Y', then fill in the 2434 boot arguments in CONFIG_CMDLINE. 2435 2436 Systems with fully functional boot loaders (i.e. non-embedded) 2437 should leave this option set to 'N'. 2438 2439config CMDLINE 2440 string "Built-in kernel command string" 2441 depends on CMDLINE_BOOL 2442 default "" 2443 ---help--- 2444 Enter arguments here that should be compiled into the kernel 2445 image and used at boot time. If the boot loader provides a 2446 command line at boot time, it is appended to this string to 2447 form the full kernel command line, when the system boots. 2448 2449 However, you can use the CONFIG_CMDLINE_OVERRIDE option to 2450 change this behavior. 2451 2452 In most cases, the command line (whether built-in or provided 2453 by the boot loader) should specify the device for the root 2454 file system. 2455 2456config CMDLINE_OVERRIDE 2457 bool "Built-in command line overrides boot loader arguments" 2458 depends on CMDLINE_BOOL 2459 ---help--- 2460 Set this option to 'Y' to have the kernel ignore the boot loader 2461 command line, and use ONLY the built-in command line. 2462 2463 This is used to work around broken boot loaders. This should 2464 be set to 'N' under normal conditions. 2465 2466config MODIFY_LDT_SYSCALL 2467 bool "Enable the LDT (local descriptor table)" if EXPERT 2468 default y 2469 ---help--- 2470 Linux can allow user programs to install a per-process x86 2471 Local Descriptor Table (LDT) using the modify_ldt(2) system 2472 call. This is required to run 16-bit or segmented code such as 2473 DOSEMU or some Wine programs. It is also used by some very old 2474 threading libraries. 2475 2476 Enabling this feature adds a small amount of overhead to 2477 context switches and increases the low-level kernel attack 2478 surface. Disabling it removes the modify_ldt(2) system call. 2479 2480 Saying 'N' here may make sense for embedded or server kernels. 2481 2482source "kernel/livepatch/Kconfig" 2483 2484endmenu 2485 2486config ARCH_HAS_ADD_PAGES 2487 def_bool y 2488 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG 2489 2490config ARCH_ENABLE_MEMORY_HOTPLUG 2491 def_bool y 2492 depends on X86_64 || (X86_32 && HIGHMEM) 2493 2494config ARCH_ENABLE_MEMORY_HOTREMOVE 2495 def_bool y 2496 depends on MEMORY_HOTPLUG 2497 2498config USE_PERCPU_NUMA_NODE_ID 2499 def_bool y 2500 depends on NUMA 2501 2502config ARCH_ENABLE_SPLIT_PMD_PTLOCK 2503 def_bool y 2504 depends on X86_64 || X86_PAE 2505 2506config GDS_FORCE_MITIGATION 2507 bool "Force GDS Mitigation" 2508 depends on CPU_SUP_INTEL 2509 default n 2510 help 2511 Gather Data Sampling (GDS) is a hardware vulnerability which allows 2512 unprivileged speculative access to data which was previously stored in 2513 vector registers. 2514 2515 This option is equivalent to setting gather_data_sampling=force on the 2516 command line. The microcode mitigation is used if present, otherwise 2517 AVX is disabled as a mitigation. On affected systems that are missing 2518 the microcode any userspace code that unconditionally uses AVX will 2519 break with this option set. 2520 2521 Setting this option on systems not vulnerable to GDS has no effect. 2522 2523 If in doubt, say N. 2524 2525config ARCH_ENABLE_HUGEPAGE_MIGRATION 2526 def_bool y 2527 depends on X86_64 && HUGETLB_PAGE && MIGRATION 2528 2529config ARCH_ENABLE_THP_MIGRATION 2530 def_bool y 2531 depends on X86_64 && TRANSPARENT_HUGEPAGE 2532 2533menu "Power management and ACPI options" 2534 2535config ARCH_HIBERNATION_HEADER 2536 def_bool y 2537 depends on HIBERNATION 2538 2539source "kernel/power/Kconfig" 2540 2541source "drivers/acpi/Kconfig" 2542 2543source "drivers/sfi/Kconfig" 2544 2545config X86_APM_BOOT 2546 def_bool y 2547 depends on APM 2548 2549menuconfig APM 2550 tristate "APM (Advanced Power Management) BIOS support" 2551 depends on X86_32 && PM_SLEEP 2552 ---help--- 2553 APM is a BIOS specification for saving power using several different 2554 techniques. This is mostly useful for battery powered laptops with 2555 APM compliant BIOSes. If you say Y here, the system time will be 2556 reset after a RESUME operation, the /proc/apm device will provide 2557 battery status information, and user-space programs will receive 2558 notification of APM "events" (e.g. battery status change). 2559 2560 If you select "Y" here, you can disable actual use of the APM 2561 BIOS by passing the "apm=off" option to the kernel at boot time. 2562 2563 Note that the APM support is almost completely disabled for 2564 machines with more than one CPU. 2565 2566 In order to use APM, you will need supporting software. For location 2567 and more information, read <file:Documentation/power/apm-acpi.rst> 2568 and the Battery Powered Linux mini-HOWTO, available from 2569 <http://www.tldp.org/docs.html#howto>. 2570 2571 This driver does not spin down disk drives (see the hdparm(8) 2572 manpage ("man 8 hdparm") for that), and it doesn't turn off 2573 VESA-compliant "green" monitors. 2574 2575 This driver does not support the TI 4000M TravelMate and the ACER 2576 486/DX4/75 because they don't have compliant BIOSes. Many "green" 2577 desktop machines also don't have compliant BIOSes, and this driver 2578 may cause those machines to panic during the boot phase. 2579 2580 Generally, if you don't have a battery in your machine, there isn't 2581 much point in using this driver and you should say N. If you get 2582 random kernel OOPSes or reboots that don't seem to be related to 2583 anything, try disabling/enabling this option (or disabling/enabling 2584 APM in your BIOS). 2585 2586 Some other things you should try when experiencing seemingly random, 2587 "weird" problems: 2588 2589 1) make sure that you have enough swap space and that it is 2590 enabled. 2591 2) pass the "no-hlt" option to the kernel 2592 3) switch on floating point emulation in the kernel and pass 2593 the "no387" option to the kernel 2594 4) pass the "floppy=nodma" option to the kernel 2595 5) pass the "mem=4M" option to the kernel (thereby disabling 2596 all but the first 4 MB of RAM) 2597 6) make sure that the CPU is not over clocked. 2598 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/> 2599 8) disable the cache from your BIOS settings 2600 9) install a fan for the video card or exchange video RAM 2601 10) install a better fan for the CPU 2602 11) exchange RAM chips 2603 12) exchange the motherboard. 2604 2605 To compile this driver as a module, choose M here: the 2606 module will be called apm. 2607 2608if APM 2609 2610config APM_IGNORE_USER_SUSPEND 2611 bool "Ignore USER SUSPEND" 2612 ---help--- 2613 This option will ignore USER SUSPEND requests. On machines with a 2614 compliant APM BIOS, you want to say N. However, on the NEC Versa M 2615 series notebooks, it is necessary to say Y because of a BIOS bug. 2616 2617config APM_DO_ENABLE 2618 bool "Enable PM at boot time" 2619 ---help--- 2620 Enable APM features at boot time. From page 36 of the APM BIOS 2621 specification: "When disabled, the APM BIOS does not automatically 2622 power manage devices, enter the Standby State, enter the Suspend 2623 State, or take power saving steps in response to CPU Idle calls." 2624 This driver will make CPU Idle calls when Linux is idle (unless this 2625 feature is turned off -- see "Do CPU IDLE calls", below). This 2626 should always save battery power, but more complicated APM features 2627 will be dependent on your BIOS implementation. You may need to turn 2628 this option off if your computer hangs at boot time when using APM 2629 support, or if it beeps continuously instead of suspending. Turn 2630 this off if you have a NEC UltraLite Versa 33/C or a Toshiba 2631 T400CDT. This is off by default since most machines do fine without 2632 this feature. 2633 2634config APM_CPU_IDLE 2635 depends on CPU_IDLE 2636 bool "Make CPU Idle calls when idle" 2637 ---help--- 2638 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. 2639 On some machines, this can activate improved power savings, such as 2640 a slowed CPU clock rate, when the machine is idle. These idle calls 2641 are made after the idle loop has run for some length of time (e.g., 2642 333 mS). On some machines, this will cause a hang at boot time or 2643 whenever the CPU becomes idle. (On machines with more than one CPU, 2644 this option does nothing.) 2645 2646config APM_DISPLAY_BLANK 2647 bool "Enable console blanking using APM" 2648 ---help--- 2649 Enable console blanking using the APM. Some laptops can use this to 2650 turn off the LCD backlight when the screen blanker of the Linux 2651 virtual console blanks the screen. Note that this is only used by 2652 the virtual console screen blanker, and won't turn off the backlight 2653 when using the X Window system. This also doesn't have anything to 2654 do with your VESA-compliant power-saving monitor. Further, this 2655 option doesn't work for all laptops -- it might not turn off your 2656 backlight at all, or it might print a lot of errors to the console, 2657 especially if you are using gpm. 2658 2659config APM_ALLOW_INTS 2660 bool "Allow interrupts during APM BIOS calls" 2661 ---help--- 2662 Normally we disable external interrupts while we are making calls to 2663 the APM BIOS as a measure to lessen the effects of a badly behaving 2664 BIOS implementation. The BIOS should reenable interrupts if it 2665 needs to. Unfortunately, some BIOSes do not -- especially those in 2666 many of the newer IBM Thinkpads. If you experience hangs when you 2667 suspend, try setting this to Y. Otherwise, say N. 2668 2669endif # APM 2670 2671source "drivers/cpufreq/Kconfig" 2672 2673source "drivers/cpuidle/Kconfig" 2674 2675source "drivers/idle/Kconfig" 2676 2677endmenu 2678 2679 2680menu "Bus options (PCI etc.)" 2681 2682choice 2683 prompt "PCI access mode" 2684 depends on X86_32 && PCI 2685 default PCI_GOANY 2686 ---help--- 2687 On PCI systems, the BIOS can be used to detect the PCI devices and 2688 determine their configuration. However, some old PCI motherboards 2689 have BIOS bugs and may crash if this is done. Also, some embedded 2690 PCI-based systems don't have any BIOS at all. Linux can also try to 2691 detect the PCI hardware directly without using the BIOS. 2692 2693 With this option, you can specify how Linux should detect the 2694 PCI devices. If you choose "BIOS", the BIOS will be used, 2695 if you choose "Direct", the BIOS won't be used, and if you 2696 choose "MMConfig", then PCI Express MMCONFIG will be used. 2697 If you choose "Any", the kernel will try MMCONFIG, then the 2698 direct access method and falls back to the BIOS if that doesn't 2699 work. If unsure, go with the default, which is "Any". 2700 2701config PCI_GOBIOS 2702 bool "BIOS" 2703 2704config PCI_GOMMCONFIG 2705 bool "MMConfig" 2706 2707config PCI_GODIRECT 2708 bool "Direct" 2709 2710config PCI_GOOLPC 2711 bool "OLPC XO-1" 2712 depends on OLPC 2713 2714config PCI_GOANY 2715 bool "Any" 2716 2717endchoice 2718 2719config PCI_BIOS 2720 def_bool y 2721 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY) 2722 2723# x86-64 doesn't support PCI BIOS access from long mode so always go direct. 2724config PCI_DIRECT 2725 def_bool y 2726 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG)) 2727 2728config PCI_MMCONFIG 2729 bool "Support mmconfig PCI config space access" if X86_64 2730 default y 2731 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST) 2732 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG) 2733 2734config PCI_OLPC 2735 def_bool y 2736 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY) 2737 2738config PCI_XEN 2739 def_bool y 2740 depends on PCI && XEN 2741 select SWIOTLB_XEN 2742 2743config MMCONF_FAM10H 2744 def_bool y 2745 depends on X86_64 && PCI_MMCONFIG && ACPI 2746 2747config PCI_CNB20LE_QUIRK 2748 bool "Read CNB20LE Host Bridge Windows" if EXPERT 2749 depends on PCI 2750 help 2751 Read the PCI windows out of the CNB20LE host bridge. This allows 2752 PCI hotplug to work on systems with the CNB20LE chipset which do 2753 not have ACPI. 2754 2755 There's no public spec for this chipset, and this functionality 2756 is known to be incomplete. 2757 2758 You should say N unless you know you need this. 2759 2760config ISA_BUS 2761 bool "ISA bus support on modern systems" if EXPERT 2762 help 2763 Expose ISA bus device drivers and options available for selection and 2764 configuration. Enable this option if your target machine has an ISA 2765 bus. ISA is an older system, displaced by PCI and newer bus 2766 architectures -- if your target machine is modern, it probably does 2767 not have an ISA bus. 2768 2769 If unsure, say N. 2770 2771# x86_64 have no ISA slots, but can have ISA-style DMA. 2772config ISA_DMA_API 2773 bool "ISA-style DMA support" if (X86_64 && EXPERT) 2774 default y 2775 help 2776 Enables ISA-style DMA support for devices requiring such controllers. 2777 If unsure, say Y. 2778 2779if X86_32 2780 2781config ISA 2782 bool "ISA support" 2783 ---help--- 2784 Find out whether you have ISA slots on your motherboard. ISA is the 2785 name of a bus system, i.e. the way the CPU talks to the other stuff 2786 inside your box. Other bus systems are PCI, EISA, MicroChannel 2787 (MCA) or VESA. ISA is an older system, now being displaced by PCI; 2788 newer boards don't support it. If you have ISA, say Y, otherwise N. 2789 2790config SCx200 2791 tristate "NatSemi SCx200 support" 2792 ---help--- 2793 This provides basic support for National Semiconductor's 2794 (now AMD's) Geode processors. The driver probes for the 2795 PCI-IDs of several on-chip devices, so its a good dependency 2796 for other scx200_* drivers. 2797 2798 If compiled as a module, the driver is named scx200. 2799 2800config SCx200HR_TIMER 2801 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support" 2802 depends on SCx200 2803 default y 2804 ---help--- 2805 This driver provides a clocksource built upon the on-chip 2806 27MHz high-resolution timer. Its also a workaround for 2807 NSC Geode SC-1100's buggy TSC, which loses time when the 2808 processor goes idle (as is done by the scheduler). The 2809 other workaround is idle=poll boot option. 2810 2811config OLPC 2812 bool "One Laptop Per Child support" 2813 depends on !X86_PAE 2814 select GPIOLIB 2815 select OF 2816 select OF_PROMTREE 2817 select IRQ_DOMAIN 2818 select OLPC_EC 2819 ---help--- 2820 Add support for detecting the unique features of the OLPC 2821 XO hardware. 2822 2823config OLPC_XO1_PM 2824 bool "OLPC XO-1 Power Management" 2825 depends on OLPC && MFD_CS5535=y && PM_SLEEP 2826 ---help--- 2827 Add support for poweroff and suspend of the OLPC XO-1 laptop. 2828 2829config OLPC_XO1_RTC 2830 bool "OLPC XO-1 Real Time Clock" 2831 depends on OLPC_XO1_PM && RTC_DRV_CMOS 2832 ---help--- 2833 Add support for the XO-1 real time clock, which can be used as a 2834 programmable wakeup source. 2835 2836config OLPC_XO1_SCI 2837 bool "OLPC XO-1 SCI extras" 2838 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y 2839 depends on INPUT=y 2840 select POWER_SUPPLY 2841 ---help--- 2842 Add support for SCI-based features of the OLPC XO-1 laptop: 2843 - EC-driven system wakeups 2844 - Power button 2845 - Ebook switch 2846 - Lid switch 2847 - AC adapter status updates 2848 - Battery status updates 2849 2850config OLPC_XO15_SCI 2851 bool "OLPC XO-1.5 SCI extras" 2852 depends on OLPC && ACPI 2853 select POWER_SUPPLY 2854 ---help--- 2855 Add support for SCI-based features of the OLPC XO-1.5 laptop: 2856 - EC-driven system wakeups 2857 - AC adapter status updates 2858 - Battery status updates 2859 2860config ALIX 2861 bool "PCEngines ALIX System Support (LED setup)" 2862 select GPIOLIB 2863 ---help--- 2864 This option enables system support for the PCEngines ALIX. 2865 At present this just sets up LEDs for GPIO control on 2866 ALIX2/3/6 boards. However, other system specific setup should 2867 get added here. 2868 2869 Note: You must still enable the drivers for GPIO and LED support 2870 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs 2871 2872 Note: You have to set alix.force=1 for boards with Award BIOS. 2873 2874config NET5501 2875 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)" 2876 select GPIOLIB 2877 ---help--- 2878 This option enables system support for the Soekris Engineering net5501. 2879 2880config GEOS 2881 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)" 2882 select GPIOLIB 2883 depends on DMI 2884 ---help--- 2885 This option enables system support for the Traverse Technologies GEOS. 2886 2887config TS5500 2888 bool "Technologic Systems TS-5500 platform support" 2889 depends on MELAN 2890 select CHECK_SIGNATURE 2891 select NEW_LEDS 2892 select LEDS_CLASS 2893 ---help--- 2894 This option enables system support for the Technologic Systems TS-5500. 2895 2896endif # X86_32 2897 2898config AMD_NB 2899 def_bool y 2900 depends on CPU_SUP_AMD && PCI 2901 2902config X86_SYSFB 2903 bool "Mark VGA/VBE/EFI FB as generic system framebuffer" 2904 help 2905 Firmwares often provide initial graphics framebuffers so the BIOS, 2906 bootloader or kernel can show basic video-output during boot for 2907 user-guidance and debugging. Historically, x86 used the VESA BIOS 2908 Extensions and EFI-framebuffers for this, which are mostly limited 2909 to x86. 2910 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic 2911 framebuffers so the new generic system-framebuffer drivers can be 2912 used on x86. If the framebuffer is not compatible with the generic 2913 modes, it is advertised as fallback platform framebuffer so legacy 2914 drivers like efifb, vesafb and uvesafb can pick it up. 2915 If this option is not selected, all system framebuffers are always 2916 marked as fallback platform framebuffers as usual. 2917 2918 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will 2919 not be able to pick up generic system framebuffers if this option 2920 is selected. You are highly encouraged to enable simplefb as 2921 replacement if you select this option. simplefb can correctly deal 2922 with generic system framebuffers. But you should still keep vesafb 2923 and others enabled as fallback if a system framebuffer is 2924 incompatible with simplefb. 2925 2926 If unsure, say Y. 2927 2928endmenu 2929 2930 2931menu "Binary Emulations" 2932 2933config IA32_EMULATION 2934 bool "IA32 Emulation" 2935 depends on X86_64 2936 select ARCH_WANT_OLD_COMPAT_IPC 2937 select BINFMT_ELF 2938 select COMPAT_BINFMT_ELF 2939 select COMPAT_OLD_SIGACTION 2940 ---help--- 2941 Include code to run legacy 32-bit programs under a 2942 64-bit kernel. You should likely turn this on, unless you're 2943 100% sure that you don't have any 32-bit programs left. 2944 2945config IA32_AOUT 2946 tristate "IA32 a.out support" 2947 depends on IA32_EMULATION 2948 depends on BROKEN 2949 ---help--- 2950 Support old a.out binaries in the 32bit emulation. 2951 2952config X86_X32 2953 bool "x32 ABI for 64-bit mode" 2954 depends on X86_64 2955 ---help--- 2956 Include code to run binaries for the x32 native 32-bit ABI 2957 for 64-bit processors. An x32 process gets access to the 2958 full 64-bit register file and wide data path while leaving 2959 pointers at 32 bits for smaller memory footprint. 2960 2961 You will need a recent binutils (2.22 or later) with 2962 elf32_x86_64 support enabled to compile a kernel with this 2963 option set. 2964 2965config COMPAT_32 2966 def_bool y 2967 depends on IA32_EMULATION || X86_32 2968 select HAVE_UID16 2969 select OLD_SIGSUSPEND3 2970 2971config COMPAT 2972 def_bool y 2973 depends on IA32_EMULATION || X86_X32 2974 2975if COMPAT 2976config COMPAT_FOR_U64_ALIGNMENT 2977 def_bool y 2978 2979config SYSVIPC_COMPAT 2980 def_bool y 2981 depends on SYSVIPC 2982endif 2983 2984endmenu 2985 2986 2987config HAVE_ATOMIC_IOMAP 2988 def_bool y 2989 depends on X86_32 2990 2991config X86_DEV_DMA_OPS 2992 bool 2993 2994source "drivers/firmware/Kconfig" 2995 2996source "arch/x86/kvm/Kconfig" 2997