1= syslinux.cfg(5) = 2:doctype: manpage 3:revdate: 2012-10-28 4:author: H. Peter Anvin 5:author-email: hpa@zytor.com 6:editor1: Gene Cumm 7:editor1-email: gene.cumm@gmail.com 8:editor1-revlast: 2012-10-28 9:nbsp8:          10:nbsp32: {nbsp8}{nbsp8}{nbsp8}{nbsp8} 11:data-uri: 12 13== NAME == 14syslinux.cfg - *Syslinux* configuration file 15 16 17== DESCRIPTION == 18Configuration for the boot behavior and user experience of *Syslinux* 19boot loaders, the format of display files and the boot prompt behavior. 20 21Blank lines are ignored. 22 23Note that the configuration file is not completely decoded. Syntax 24different from the one described above may still work correctly in this 25version of *Syslinux*, but may break in a future one. 26 27 28== LOCATION/NAME == 29*SYSLINUX* (before 4.00) used the configuration filename of 30syslinux.cfg. *EXTLINUX* (merged into *SYSLINUX* as of 4.00) used the 31filename extlinux.conf. Both default to searching for the config file 32in the installed directory (containing ldlinux.sys/extlinux.sys). As of 334.00, *SYSLINUX* will search for extlinux.conf then syslinux.cfg in each 34directory before falling back to the next directory. 35 36As of 3.35, *SYSLINUX* also searches /boot/syslinux, /syslinux and /. 37 38*ISOLINUX* (before 4.02) used the configuration filename of 39isolinux.cfg, searching /boot/isolinux (starting 2.00), then /isolinux 40and /. As of 4.02, *ISOLINUX* will search for isolinux.cfg then 41syslinux.cfg in /boot/isolinux before searching for the same files in 42/isolinux, /boot/syslinux, /syslinux, and /. 43 44 45== GLOBAL DIRECTIVES - MAIN == 46*#* comment:: 47A line comment. As of version 3.10, the space between the *#* and the 48comment is no longer required. 49 50*MENU* any string:: 51(3.00+) A directive for the simple menu system, treated as a comment 52outside the menu. See menu.txt. 53 54*INCLUDE* 'filename':: 55Inserts the contents of another file at this point in the configuration 56file. Files can currently be nested up to 16 levels deep, but it is not 57guaranteed that more than 8 levels will be supported in the future. 58 59*DEFAULT* 'kernel' 'options...':: 60Sets the default command line (which often references a LABEL). If 61*Syslinux* boots automatically, it will act just as if the entries after 62*DEFAULT* had been typed in at the 'boot:' prompt. Multiple uses will 63result in an override. 64+ 65If no configuration file is present, or no *DEFAULT* or *UI* entry is 66present in the config file, an error message is displayed and the 67'boot:' prompt is shown (3.85+). 68 69*UI* 'module' 'options...':: 70Selects a specific user interface 'module' (typically menu.c32 or 71vesamenu.c32). The command-line interface treats this as a directive 72that overrides the *DEFAULT* directive to load this module instead at 73startup, for an empty command line and at timeout and *PROMPT* directive 74to not prompt (but these directives may have effects on other 75configuration parsers). Multiple uses will result in an override. 76 77*LABEL* 'mylabel':: 78Begin a new *LABEL* clause. If 'mylabel' is entered as the kernel to 79boot, *Syslinux* should instead boot "image" (specified by a directive 80from *KERNEL-LIKE DIRECTIVES*) with any specified *DUAL-PURPOSE 81DIRECTIVES* being used instead of the global instance. 82+ 83'mylabel' must be unique. Currently the first instance is used but may 84result in an error or undesired behavior. 'mylabel' ends at the first 85character that is not a non-white-space printable character and should 86be restricted to non-white-space typeable characters. Prior to version 873.32, this would transformed to a DOS compatible format of 8.3 with a 88restricted character set. A *LABEL* clause must contain exactly 1 of 89the *KERNEL-LIKE DIRECTIVES* and may contain 1 each of the *LABEL-ONLY 90DIRECTIVES* or *DUAL-PURPOSE DIRECTIVES*. 91+ 92Within a *LABEL*, using multiple *KERNEL-LIKE DIRECTIVES* or reuse of 93*LABEL-ONLY DIRECTIVES* or *DUAL-PURPOSE DIRECTIVES* will result in an 94override. Otherwise, multiple instances of the same directive will 95result in the last being effective. 96 97 98== DUAL-PURPOSE DIRECTIVES == 99Use of any of the *DUAL-PURPOSE DIRECTIVES* as *GLOBAL DIRECTIVES* is 100discouraged if there will be any non-Linux images loaded as *ALL* images 101will get these, including those manually entered at the 'boot:' prompt. 102 103*APPEND* 'options...':: 104Add one or more options to the kernel command line. These are added 105both for automatic and manual boots. The options are added at the very 106beginning of the kernel command line, usually permitting explicitly 107entered kernel options to override them. This is the equivalent of the 108LILO "append" option. 109+ 110Use of the parameter 'initrd=' supports multiple filenames separated by 111commas (ie 'initrd=initrd_file1,initrd_file2') within a single instance. 112This is mostly useful for initramfs, which can be composed of multiple 113separate cpio or cpio.gz archives. 114+ 115Note: all initrd files except the last one are zero-padded to a 4K page 116boundary. This should not affect initramfs. 117+ 118Note: Only the last effective 'initrd=' parameter is used for loading 119initrd files. 120 121*APPEND* -:: 122Append nothing. *APPEND* with a single hyphen as argument in a *LABEL* 123section can be used to override a global *APPEND*. 124 125//[FIXME: Shorten subdefinitions] 126*SYSAPPEND* 'bitmask':: 127*IPAPPEND* 'bitmask':: 128(*SYSAPPEND*: 5.10+; *IPAPPEND*: *PXELINUX* only) 129The *SYSAPPEND* option was introduced in *Syslinux* 5.10; it is an 130enhancement of a previous option *IPAPPEND* which was only available on 131*PXELINUX*. 'bitmask' is interpreted as decimal format unless prefixed 132with "0x" for hexadecimal or "0" (zero) for octal. The 'bitmask' is an 133OR (sum) of the following integer options: 134 135ifndef::doctype-manpage[[horizontal]] 136*1*::: An option of the following format should be generated, based on 137the input from the DHCP/BOOTP or PXE boot server and added to the kernel 138command line(see note below; empty for non-PXELINUX variants): 139+ 140---- 141ip=<client-ip>:<boot-server-ip>:<gw-ip>:<netmask> 142---- 143+ 144NOTE: The use of option 1 is no substitute for running a DHCP client in 145the booted system and should instead only be used to seed the client for 146a request. Without regular renewals, the lease acquired by the PXE BIOS 147will expire, making the IP address available for reuse by the DHCP 148server. 149+ 150*2*::: An option of the following format should be generated, in 151dash-separated hexadecimal with leading hardware type (same as for the 152configuration file; see pxelinux.txt.) and added to the kernel command 153line, allowing an initrd program to determine from which interface the 154system booted(empty for non-PXELINUX variants): 155+ 156---- 157BOOTIF=<hardware-address-of-boot-interface> 158---- 159+ 160*4*::: An option of the following format should be generated, in lower 161case hexadecimal in the format normally used for UUIDs (same as for the 162configuration file; see pxelinux.txt.) and added to the kernel command 163line: 164+ 165---- 166SYSUUID=<system uuid> 167---- 168+ 169*8*::: (5.10+) indicate the CPU family and certain particularly 170significant CPU feature bits: 171+ 172---- 173CPU=<family><features> 174---- 175+ 176The <family> is a single digit from 3 (i386) to 6 (i686 or higher.) The 177following CPU features are currently reported; additional flags may be 178added in the future: 179+ 180.... 181P Physical Address Extension (PAE) 182V Intel Virtualization Technology (VT/VMX) 183T Intel Trusted Exection Technology (TXT/SMX) 184X Execution Disable (XD/NX) 185L Long Mode (x86-64) 186S AMD SMX virtualization 187.... 188+ 189*DMI*::: (5.10+) The following strings are derived from DMI/SMBIOS 190information if available: 191+ 192 Bit String Significance 193 ------------------------------------------------------------- 194 0x00010 SYSVENDOR= System vendor name 195 0x00020 SYSPRODUCT= System product name 196 0x00040 SYSVERSION= System version 197 0x00080 SYSSERIAL= System serial number 198 0x00100 SYSSKU= System SKU 199 0x00200 SYSFAMILY= System family 200 0x00400 MBVENDOR= Motherboard vendor name 201 0x00800 MBVERSION= Motherboard version 202 0x01000 MBSERIAL= Motherboard serial number 203 0x02000 MBASSET= Motherboard asset tag 204 0x04000 BIOSVENDOR= BIOS vendor name 205 0x08000 BIOSVERSION= BIOS version 206 0x10000 SYSFF= System form factor 207+ 208If these strings contain white-space characters, they are replaced with 209underscores (_). 210+ 211The system form factor value is a number defined in the SMBIOS 212specification, available at http://www.dmtf.org/. As of version 2.7.1 213of the specification, the following values are defined: 214+ 215 1 Other 216 2 Unknown 217 3 Desktop 218 4 Low profile desktop 219 5 Pizza box 220 6 Mini tower 221 7 Tower 222 8 Portble 223 9 Laptop 224 10 Notebook 225 11 Handheld 226 12 Docking station 227 13 All-in-one 228 14 Subnotebook 229 15 Space-saving 230 16 Lunch box 231 17 Main server chassis 232 18 Expansion chassis 233 19 Subchassis 234 20 Bus expansion chassis 235 21 Peripheral chassis 236 22 RAID chassis 237 23 Rack mount chasss 238 24 Sealed-case PC 239 25 Multi-system chassis 240 26 Compact PCI 241 27 Advanced TCI 242 28 Blade 243 29 Blade enclosure 244 245 246 247== KERNEL-LIKE DIRECTIVES == 248// Alpha sort after KERNEL and LINUX 249*KERNEL* 'image':: 250Load a kernel-like file 'image' with automatic filetype detection based 251on file extension, listed under the non-auto-detecting directives, 252defaulting to *LINUX*. 253 254//[FIXME: Should "'image' as " be removed entirely or added to all? 255*LINUX* is used as an example] 256*LINUX* 'image':: 257Load 'image' as a Linux-like kernel. MEMDISK is an example of a 258non-Linux kernel loaded in a Linux-like fashion. 259 260*BOOT* 'image':: 261(*ISOLINUX* only: .bin; *SYSLINUX* only: .bs) Load a boot sector. .bin 262is a "CD boot sector" and .bs is a regular disk boot sector. 263 264*BSS* 'image':: 265(*SYSLINUX* only: .bss) Load a BSS image, a .bs image with the DOS 266superblock patched in. 267 268*COMBOOT* 'image':: 269(.com, .cbt; Removed as of 5.00) Load a *Syslinux* COMBOOT image. .com 270images may also be runnable from DOS while .cbt images are not. See 271also *comboot.txt* 272 273*COM32* 'image':: 274(.c32) Load a *Syslinux* COM32 (32-bit *COMBOOT*) image. See also 275*comboot.txt* 276 277*CONFIG* 'image':: 278Load a new configuration file. The configuration file is read, the 279working directory is changed (if specified via an *APPEND*), then the 280configuration file is parsed. 281 282*FDIMAGE* 'image':: 283(Removed as of 4.05, added 1.65; *ISOLINUX* only: .img) Load a disk 284image. 285 286*LOCALBOOT* 'type':: 287(*PXELINUX* 1.53+; *ISOLINUX* ??3.10+; *SYSLINUX* 3.70+)Attempt a 288different local boot method. The special value -1 causes the boot 289loader to report failure to the BIOS, which, on recent BIOSes, should 290mean that the next boot device in the boot sequence should be activated. 291 Values other than those documented may produce undesired results. 292+ 293On *PXELINUX*, 'type' 0 means perform a normal boot. 'type' 4 will 294perform a local boot with the Universal Network Driver Interface (UNDI) 295driver still resident in memory. Finally, 'type' 5 will perform a local 296boot with the entire PXE stack, including the UNDI driver, still 297resident in memory. All other values are undefined. If you don't know 298what the UNDI or PXE stacks are, don't worry -- you don't want them, 299just specify 0. 300+ 301On *ISOLINUX*/*SYSLINUX*, the 'type' specifies the local drive number to 302boot from; 0x00 is the primary floppy drive and 0x80 is the primary hard 303drive. 304 305*PXE* 'image':: 306(*PXELINUX* only: .0) Load a PXE NBP (Network Boot Program) image. The 307PXE protocol does not provide any means for specifiying or using a 308command line or initrd. 309 310 311== LABEL-ONLY DIRECTIVES == 312*INITRD* 'initrd_file':: 313(3.71+) An initrd can be specified in a separate statement (INITRD) 314instead of as part of the *APPEND* statement; this functionally appends 315"initrd=initrd_file" to the kernel command line. Like 'initrd=', this 316also supports multiple comma separated file names (see *APPEND*). 317 318 319== GLOBAL DIRECTIVES - SECONDARY == 320These are global directives that are of lesser importance, often 321affecting the user experience and not the boot process. 322 323*ALLOWOPTIONS* 'flag_val':: 324If 'flag_val' is 0, the user is not allowed to specify any arguments on 325the kernel command line. The only options recognized are those 326specified in an *APPEND*) statement. The default is 1. 327 328*IMPLICIT* 'flag_val':: 329If 'flag_val' is 0, do not load a kernel image unless it has been 330explicitly named in a *LABEL* statement. The default is 1. 331 332*TIMEOUT* 'timeout':: 333Indicates how long to wait at the 'boot:' prompt until booting 334automatically, in units of 1/10 s. The timeout is cancelled as soon as 335the user types anything on the keyboard, the assumption being that the 336user will complete the command line already begun. The timer is reset 337to 0 upon return from an unsuccessful attempt to boot or from a module. 338A timeout of zero (the default) will disable the timeout completely. 339 340*TOTALTIMEOUT* 'timeout':: 341Indicates how long to wait until booting automatically, in units of 3421/10 s. This timeout is *not* cancelled by user input, and can thus be 343used to deal with serial port glitches or "the user walked away" type 344situations. A timeout of zero (the default) will disable the timeout 345completely. 346+ 347Both *TIMEOUT* and *TOTALTIMEOUT* can be used together, for example: 348+ 349---- 350# Wait 5 seconds unless the user types something, but 351# always boot after 15 minutes. 352TIMEOUT 50 353TOTALTIMEOUT 9000 354---- 355 356// FIXME: be consistent 357*ONTIMEOUT* 'kernel options...':: 358Sets the command line invoked on a timeout (which often references a 359LABEL). If not specified, 'UI' (if used) or 'DEFAULT is used. 360 361*ONERROR* 'kernel options...':: 362If a kernel image is not found (either due to it not existing, or 363because *IMPLICIT* is set), run the specified command. The faulty 364command line is appended to the specified options, so if the *ONERROR* 365directive reads as: 366+ 367---- 368ONERROR xyzzy plugh 369---- 370+ 371and the command line as entered by the user is: 372+ 373---- 374foo bar baz 375---- 376+ 377*Syslinux* will execute the following as if entered by the user: 378+ 379---- 380xyzzy plugh foo bar baz 381---- 382 383*SERIAL* 'port [baudrate [flowcontrol]]':: 384Enables a serial port to act as the console. 'port' is a number (0 = 385/dev/ttyS0 = COM1, etc.) or an I/O port address (e.g. 0x3F8); if 386'baudrate' is omitted, the baud rate defaults to 9600 bps. The serial 387parameters are hardcoded to be 8 bits, no parity, 1 stop bit. 388+ 389'flowcontrol' is a combination of the following bits: 390+ 391.... 3920x001 - Assert DTR 3930x002 - Assert RTS 3940x008 - Enable interrupts 3950x010 - Wait for CTS assertion 3960x020 - Wait for DSR assertion 3970x040 - Wait for RI assertion 3980x080 - Wait for DCD assertion 3990x100 - Ignore input unless CTS asserted 4000x200 - Ignore input unless DSR asserted 4010x400 - Ignore input unless RI asserted 4020x800 - Ignore input unless DCD asserted 403.... 404+ 405All other bits are reserved. 406+ 407Typical values are: 408+ 409.... 410 0 - No flow control (default) 4110x303 - Null modem cable detect 4120x013 - RTS/CTS flow control 4130x813 - RTS/CTS flow control, modem input 4140x023 - DTR/DSR flow control 4150x083 - DTR/DCD flow control 416.... 417+ 418For the *SERIAL* directive to be guaranteed to work properly, it should 419be the first directive in the configuration file. 420+ 421NOTE: 'port' values from 0 to 3 means the first four serial ports 422detected by the BIOS. They may or may not correspond to the legacy port 423values 0x3F8, 0x2F8, 0x3E8, 0x2E8. 424+ 425Enabling interrupts (setting the 0x008 bit) may give better 426responsiveness without setting the *NOHALT* option, but could 427potentially cause problems with buggy BIOSes. 428+ 429This option is "sticky" and is not automatically reset when loading a 430new configuration file with the CONFIG command. 431 432*NOHALT* 'flag_val':: 433If 'flag_val' is 1, don't halt the processor while idle. Halting the 434processor while idle significantly reduces the power consumption, but 435can cause poor responsiveness to the serial console, especially when 436using scripts to drive the serial console, as opposed to human 437interaction. 438 439*CONSOLE* 'flag_val':: 440If 'flag_val' is 0, disable output to the normal video console. If 441'flag_val' is 1, enable output to the video console (this is the 442default.) 443+ 444Some BIOSes try to forward this to the serial console and sometimes make 445a total mess thereof, so this option lets you disable the video console 446on these systems. 447 448*FONT* 'filename':: 449Load a font in .psf format before displaying any output (except the 450copyright line, which is output as ldlinux.sys itself is loaded.) 451*Syslinux* only loads the font onto the video card; if the .psf file 452contains a Unicode table it is ignored. This only works on EGA and VGA 453cards; hopefully it should do nothing on others. 454 455*KBDMAP* 'keymap':: 456Install a simple keyboard map. The keyboard remapper used is *very* 457simplistic (it simply remaps the keycodes received from the BIOS, which 458means that only the key combinations relevant in the default layout -- 459usually U.S. English -- can be mapped) but should at least help people 460with AZERTY keyboard layout and the locations of = and , (two special 461characters used heavily on the Linux kernel command line.) 462+ 463The included program keytab-lilo.pl from the LILO distribution can be 464used to create such keymaps. The file keytab-lilo.txt contains the 465documentation for this program. 466 467*DISPLAY* 'filename':: 468Displays the indicated file on the screen at boot time (before the boot: 469prompt, if displayed). Please see the section below on *DISPLAY* files. 470+ 471NOTE: If the file is missing, this option is simply ignored. 472 473*SAY* 'message':: 474Prints the message on the screen. 475 476*PROMPT* 'flag_val':: 477If 'flag_val' is 0, display the boot: prompt only if the Shift or Alt 478key is pressed, or Caps Lock or Scroll lock is set (this is the 479default). If 'flag_val' is 1, always display the boot: prompt. 480 481*NOESCAPE* 'flag_val':: 482If 'flag_val' is set to 1, ignore the Shift/Alt/Caps Lock/Scroll Lock 483escapes. Use this (together with PROMPT 0) to force the default boot 484alternative. 485 486*NOCOMPLETE* 'flag_val':: 487If 'flag_val' is set to 1, the Tab key does not display labels at the 488boot: prompt. 489 490// ...etc... 491*F1* 'filename':: 492*F2* 'filename':: 493*F3* 'filename':: 494*F4* 'filename':: 495*F5* 'filename':: 496*F6* 'filename':: 497*F7* 'filename':: 498*F8* 'filename':: 499*F9* 'filename':: 500*F10* 'filename':: 501*F11* 'filename':: 502*F12* 'filename':: 503Displays the indicated file on the screen when a function key is pressed 504at the boot: prompt. This can be used to implement pre-boot online help 505(presumably for the kernel command line options.) Please see the 506section below on DISPLAY files. 507+ 508When using the serial console, press <Ctrl-F><digit> to get to the help 509screens, e.g. <Ctrl-F><2> to get to the F2 screen. For F10-F12, hit 510<Ctrl-F><A>, <Ctrl-F>B, <Ctrl-F>C. For compatibility with earlier 511versions, F10 can also be entered as <Ctrl-F>0. 512 513*PATH* 'path':: 514(5.00+) Specify a space-separated (' '; 5.00-5.10 was a colon ':') list 515of directories to search when attempting to load modules. This directive 516is useful for specifying the directories containing the lib*.c32 library 517files as other modules may be dependent on these files, but may not 518reside in the same directory. Multiple instances will append additional 519paths. 520 521*SENDCOOKIES* 'bitmask':: 522(*PXELINUX* 5.10+) When downloading files over http, the SYSAPPEND 523strings are prepended with _Syslinux_ and sent to the server as cookies. 524The cookies are URL-encoded; whitespace is *not* replaced with 525underscores. 526+ 527This command limits the cookies send; 0 means no cookies. The default 528is -1, meaning send all cookies. 529+ 530This option is "sticky" and is not automatically reset when loading a 531new configuration file with the CONFIG command. 532 533 534== DISPLAY FILE FORMAT == 535DISPLAY and function-key help files are text files in either DOS or UNIX 536format (with or without <CR>). In addition, the following special codes 537are interpreted: 538 539//[FIXME]: #1 doesn't break; #2 as-is; #3 broken but not on right; #4 540identical to #3 541// horizontal extends the line's label, reducing the definition 542// tab or space to shift explanation ? align beginning or end? 543 544// ifndef::doctype-manpage[[horizontal]] 545*<FF>*:: {nbsp32} = <Ctrl-L> = ASCII 12 + 546Clear the screen, home the cursor. Note that the screen is filled with 547the current display color. 548 549*<FF>*:: 550= <Ctrl-L> = ASCII 12; Clear the screen, home the cursor. Note that the 551screen is filled with the current display color. 552 553*<FF>*:: <FF> = <Ctrl-L> = ASCII 12 554+ 555Clear the screen, home the cursor. Note that the screen is filled with 556the current display color. 557 558*<FF>*:: 559<FF> = <Ctrl-L> = ASCII 12 + 560Clear the screen, home the cursor. Note that the screen is filled with 561the current display color. 562 563*<SI>*'<bg><fg>':: <SI> = <Ctrl-O> = ASCII 15 564+ 565Set the display colors to the specified background and foreground 566colors, where <bg> and <fg> are the 2 hex digits representing 1 byte, 567corresponding to the standard PC display attributes: 568+ 569 0 = black 8 = dark grey 570 1 = dark blue 9 = bright blue 571 2 = dark green a = bright green 572 3 = dark cyan b = bright cyan 573 4 = dark red c = bright red 574 5 = dark purple d = bright purple 575 6 = brown e = yellow 576 7 = light grey f = white 577+ 578Picking a bright color (8-f) for the background results in the 579corresponding dark color (0-7), with the foreground flashing. 580+ 581Colors are not visible over the serial console. 582 583*<CAN>*'filename<newline>':: <CAN> = <Ctrl-X> = ASCII 24 584+ 585If a VGA display is present, enter graphics mode and display the graphic 586included in the specified file. The file format is an ad hoc format 587called LSS16; the included Perl program "ppmtolss16" can be used to 588produce these images. This Perl program also includes the file format 589specification. 590+ 591The image is displayed in 640x480 16-color mode. Once in graphics mode, 592the display attributes (set by <SI> code sequences) work slightly 593differently: the background color is ignored, and the foreground colors 594are the 16 colors specified in the image file. For that reason, 595ppmtolss16 allows you to specify that certain colors should be assigned 596to specific color indicies. 597+ 598Color indicies 0 and 7, in particular, should be chosen with care: 0 is 599the background color, and 7 is the color used for the text printed by 600*Syslinux* itself. 601 602*<EM>*:: <EM> = <Ctrl-Y> = ASCII 25 + 603If we are currently in graphics mode, return to text mode. 604 605*<DLE>*..*<ETB>*:: <Ctrl-P>..<Ctrl-W> = ASCII 16-23 606+ 607These codes can be used to select which modes to print a certain part of 608the message file in. Each of these control characters select a specific 609set of modes (text screen, graphics screen, serial port) for which the 610output is actually displayed: 611+ 612 Character Text Graph Serial 613 ------------------------------------------------------ 614 <DLE> = <Ctrl-P> = ASCII 16 No No No 615 <DC1> = <Ctrl-Q> = ASCII 17 Yes No No 616 <DC2> = <Ctrl-R> = ASCII 18 No Yes No 617 <DC3> = <Ctrl-S> = ASCII 19 Yes Yes No 618 <DC4> = <Ctrl-T> = ASCII 20 No No Yes 619 <NAK> = <Ctrl-U> = ASCII 21 Yes No Yes 620 <SYN> = <Ctrl-V> = ASCII 22 No Yes Yes 621 <ETB> = <Ctrl-W> = ASCII 23 Yes Yes Yes 622+ 623For example, the following will actually print out which mode the 624console is in: 625+ 626 <DC1>Text mode<DC2>Graphics mode<DC4>Serial port<ETB> 627 628*<SUB>*:: <SUB> = <Ctrl-Z> = ASCII 26 629+ 630End of file (DOS convention). 631 632*<BEL>*:: <BEL> = <Ctrl-G> = ASCII 7 + 633Beep the speaker. 634 635 636== BOOT LOADER IDS USED == 637The Linux boot protocol supports a "boot loader ID", a single byte where 638the upper nybble specifies a boot loader family (3 = *Syslinux*) and the 639lower nybble is version or, in the case of *Syslinux*, media: 640 641 0x31 (49) = SYSLINUX 642 0x32 (50) = PXELINUX 643 0x33 (51) = ISOLINUX 644 0x34 (52) = EXTLINUX 645 646In recent versions of Linux, this ID is available as 647/proc/sys/kernel/bootloader_type. 648 649 650== NOVICE PROTECTION == 651*Syslinux* will attempt to detect booting on a machine with too little 652memory, which means the Linux boot sequence cannot complete. If so, a 653message is displayed and the boot sequence aborted. Holding down the 654Ctrl key while booting disables this feature. 655 656Any file that *Syslinux* uses can be marked hidden, system or readonly 657if so is convenient; *Syslinux* ignores all file attributes. The 658*SYSLINUX* installer automatically sets the readonly/hidden/system 659attributes on LDLINUX.SYS. 660 661== EXAMPLE == 662Here are some sample config files: 663---- 664# SERIAL 0 115200 665DEFAULT linux 666PROMPT 1 667TIMEOUT 600 668 669LABEL linux 670 LINUX vmlinuz 671 APPEND initrd=initrd1.gz,initrd2.gz 672 673LABEL m 674 COM32 menu.c32 675---- 676In this example, serial port use is disabled but can be enabled by 677uncommenting the first line and utilize serial port 0 at 115200 bps. If 678'linux' is typed on the command line, the kernel-like file 'vmlinuz' is 679executed as a Linux kernel, initrd files initrd1.gz and initrd2.gz are 680loaded as initial ramdisk files (like cpio.gz files for initramfs). If 681'm' is typed on the command line, the COM32 module 'menu.c32' is 682executed to launch a menu system. 683 684 685 686== KNOWN BUGS == 687include::com-bug.txt[] 688 689 690== BUG REPORTS == 691include::com-rpt.txt[] 692 693 694== AUTHOR == 695This AsciiDoc derived document is a modified version of the original 696*SYSLINUX* documentation by {author} <{author-email}>. The conversion 697to an AsciiDoc was made by {editor1} <{editor1-email}> 698