1 = syslinux.cfg(5) = 2 :doctype: manpage 3 :revdate: 2012-10-28 4 :author: H. Peter Anvin 5 :author-email: hpa (a] zytor.com 6 :editor1: Gene Cumm 7 :editor1-email: gene.cumm (a] gmail.com 8 :editor1-revlast: 2012-10-28 9 :nbsp8:          10 :nbsp32: {nbsp8}{nbsp8}{nbsp8}{nbsp8} 11 :data-uri: 12 13 == NAME == 14 syslinux.cfg - *Syslinux* configuration file 15 16 17 == DESCRIPTION == 18 Configuration for the boot behavior and user experience of *Syslinux* 19 boot loaders, the format of display files and the boot prompt behavior. 20 21 Blank lines are ignored. 22 23 Note that the configuration file is not completely decoded. Syntax 24 different from the one described above may still work correctly in this 25 version of *Syslinux*, but may break in a future one. 26 27 28 == LOCATION/NAME == 29 *SYSLINUX* (before 4.00) used the configuration filename of 30 syslinux.cfg. *EXTLINUX* (merged into *SYSLINUX* as of 4.00) used the 31 filename extlinux.conf. Both default to searching for the config file 32 in the installed directory (containing ldlinux.sys/extlinux.sys). As of 33 4.00, *SYSLINUX* will search for extlinux.conf then syslinux.cfg in each 34 directory before falling back to the next directory. 35 36 As of 3.35, *SYSLINUX* also searches /boot/syslinux, /syslinux and /. 37 38 *ISOLINUX* (before 4.02) used the configuration filename of 39 isolinux.cfg, searching /boot/isolinux (starting 2.00), then /isolinux 40 and /. As of 4.02, *ISOLINUX* will search for isolinux.cfg then 41 syslinux.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:: 47 A line comment. As of version 3.10, the space between the *#* and the 48 comment is no longer required. 49 50 *MENU* any string:: 51 (3.00+) A directive for the simple menu system, treated as a comment 52 outside the menu. See menu.txt. 53 54 *INCLUDE* 'filename':: 55 Inserts the contents of another file at this point in the configuration 56 file. Files can currently be nested up to 16 levels deep, but it is not 57 guaranteed that more than 8 levels will be supported in the future. 58 59 *DEFAULT* 'kernel' 'options...':: 60 Sets 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 63 result in an override. 64 + 65 If no configuration file is present, or no *DEFAULT* or *UI* entry is 66 present in the config file, an error message is displayed and the 67 'boot:' prompt is shown (3.85+). 68 69 *UI* 'module' 'options...':: 70 Selects a specific user interface 'module' (typically menu.c32 or 71 vesamenu.c32). The command-line interface treats this as a directive 72 that overrides the *DEFAULT* directive to load this module instead at 73 startup, for an empty command line and at timeout and *PROMPT* directive 74 to not prompt (but these directives may have effects on other 75 configuration parsers). Multiple uses will result in an override. 76 77 *LABEL* 'mylabel':: 78 Begin a new *LABEL* clause. If 'mylabel' is entered as the kernel to 79 boot, *Syslinux* should instead boot "image" (specified by a directive 80 from *KERNEL-LIKE DIRECTIVES*) with any specified *DUAL-PURPOSE 81 DIRECTIVES* being used instead of the global instance. 82 + 83 'mylabel' must be unique. Currently the first instance is used but may 84 result in an error or undesired behavior. 'mylabel' ends at the first 85 character that is not a non-white-space printable character and should 86 be restricted to non-white-space typeable characters. Prior to version 87 3.32, this would transformed to a DOS compatible format of 8.3 with a 88 restricted character set. A *LABEL* clause must contain exactly 1 of 89 the *KERNEL-LIKE DIRECTIVES* and may contain 1 each of the *LABEL-ONLY 90 DIRECTIVES* or *DUAL-PURPOSE DIRECTIVES*. 91 + 92 Within a *LABEL*, using multiple *KERNEL-LIKE DIRECTIVES* or reuse of 93 *LABEL-ONLY DIRECTIVES* or *DUAL-PURPOSE DIRECTIVES* will result in an 94 override. Otherwise, multiple instances of the same directive will 95 result in the last being effective. 96 97 98 == DUAL-PURPOSE DIRECTIVES == 99 Use of any of the *DUAL-PURPOSE DIRECTIVES* as *GLOBAL DIRECTIVES* is 100 discouraged if there will be any non-Linux images loaded as *ALL* images 101 will get these, including those manually entered at the 'boot:' prompt. 102 103 *APPEND* 'options...':: 104 Add one or more options to the kernel command line. These are added 105 both for automatic and manual boots. The options are added at the very 106 beginning of the kernel command line, usually permitting explicitly 107 entered kernel options to override them. This is the equivalent of the 108 LILO "append" option. 109 + 110 Use of the parameter 'initrd=' supports multiple filenames separated by 111 commas (ie 'initrd=initrd_file1,initrd_file2') within a single instance. 112 This is mostly useful for initramfs, which can be composed of multiple 113 separate cpio or cpio.gz archives. 114 + 115 Note: all initrd files except the last one are zero-padded to a 4K page 116 boundary. This should not affect initramfs. 117 + 118 Note: Only the last effective 'initrd=' parameter is used for loading 119 initrd files. 120 121 *APPEND* -:: 122 Append nothing. *APPEND* with a single hyphen as argument in a *LABEL* 123 section 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) 129 The *SYSAPPEND* option was introduced in *Syslinux* 5.10; it is an 130 enhancement of a previous option *IPAPPEND* which was only available on 131 *PXELINUX*. 'bitmask' is interpreted as decimal format unless prefixed 132 with "0x" for hexadecimal or "0" (zero) for octal. The 'bitmask' is an 133 OR (sum) of the following integer options: 134 135 ifndef::doctype-manpage[[horizontal]] 136 *1*::: An option of the following format should be generated, based on 137 the input from the DHCP/BOOTP or PXE boot server and added to the kernel 138 command line(see note below; empty for non-PXELINUX variants): 139 + 140 ---- 141 ip=<client-ip>:<boot-server-ip>:<gw-ip>:<netmask> 142 ---- 143 + 144 NOTE: The use of option 1 is no substitute for running a DHCP client in 145 the booted system and should instead only be used to seed the client for 146 a request. Without regular renewals, the lease acquired by the PXE BIOS 147 will expire, making the IP address available for reuse by the DHCP 148 server. 149 + 150 *2*::: An option of the following format should be generated, in 151 dash-separated hexadecimal with leading hardware type (same as for the 152 configuration file; see pxelinux.txt.) and added to the kernel command 153 line, allowing an initrd program to determine from which interface the 154 system booted(empty for non-PXELINUX variants): 155 + 156 ---- 157 BOOTIF=<hardware-address-of-boot-interface> 158 ---- 159 + 160 *4*::: An option of the following format should be generated, in lower 161 case hexadecimal in the format normally used for UUIDs (same as for the 162 configuration file; see pxelinux.txt.) and added to the kernel command 163 line: 164 + 165 ---- 166 SYSUUID=<system uuid> 167 ---- 168 + 169 *8*::: (5.10+) indicate the CPU family and certain particularly 170 significant CPU feature bits: 171 + 172 ---- 173 CPU=<family><features> 174 ---- 175 + 176 The <family> is a single digit from 3 (i386) to 6 (i686 or higher.) The 177 following CPU features are currently reported; additional flags may be 178 added in the future: 179 + 180 .... 181 P Physical Address Extension (PAE) 182 V Intel Virtualization Technology (VT/VMX) 183 T Intel Trusted Exection Technology (TXT/SMX) 184 X Execution Disable (XD/NX) 185 L Long Mode (x86-64) 186 S AMD SMX virtualization 187 .... 188 + 189 *DMI*::: (5.10+) The following strings are derived from DMI/SMBIOS 190 information 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 + 208 If these strings contain white-space characters, they are replaced with 209 underscores (_). 210 + 211 The system form factor value is a number defined in the SMBIOS 212 specification, available at http://www.dmtf.org/. As of version 2.7.1 213 of 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':: 250 Load a kernel-like file 'image' with automatic filetype detection based 251 on file extension, listed under the non-auto-detecting directives, 252 defaulting 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':: 257 Load 'image' as a Linux-like kernel. MEMDISK is an example of a 258 non-Linux kernel loaded in a Linux-like fashion. 259 260 *BOOT* 'image':: 261 (*ISOLINUX* only: .bin; *SYSLINUX* only: .bs) Load a boot sector. .bin 262 is 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 266 superblock patched in. 267 268 *COMBOOT* 'image':: 269 (.com, .cbt; Removed as of 5.00) Load a *Syslinux* COMBOOT image. .com 270 images may also be runnable from DOS while .cbt images are not. See 271 also *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':: 278 Load a new configuration file. The configuration file is read, the 279 working directory is changed (if specified via an *APPEND*), then the 280 configuration file is parsed. 281 282 *FDIMAGE* 'image':: 283 (Removed as of 4.05, added 1.65; *ISOLINUX* only: .img) Load a disk 284 image. 285 286 *LOCALBOOT* 'type':: 287 (*PXELINUX* 1.53+; *ISOLINUX* ??3.10+; *SYSLINUX* 3.70+)Attempt a 288 different local boot method. The special value -1 causes the boot 289 loader to report failure to the BIOS, which, on recent BIOSes, should 290 mean that the next boot device in the boot sequence should be activated. 291 Values other than those documented may produce undesired results. 292 + 293 On *PXELINUX*, 'type' 0 means perform a normal boot. 'type' 4 will 294 perform a local boot with the Universal Network Driver Interface (UNDI) 295 driver still resident in memory. Finally, 'type' 5 will perform a local 296 boot with the entire PXE stack, including the UNDI driver, still 297 resident in memory. All other values are undefined. If you don't know 298 what the UNDI or PXE stacks are, don't worry -- you don't want them, 299 just specify 0. 300 + 301 On *ISOLINUX*/*SYSLINUX*, the 'type' specifies the local drive number to 302 boot from; 0x00 is the primary floppy drive and 0x80 is the primary hard 303 drive. 304 305 *PXE* 'image':: 306 (*PXELINUX* only: .0) Load a PXE NBP (Network Boot Program) image. The 307 PXE protocol does not provide any means for specifiying or using a 308 command 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) 314 instead of as part of the *APPEND* statement; this functionally appends 315 "initrd=initrd_file" to the kernel command line. Like 'initrd=', this 316 also supports multiple comma separated file names (see *APPEND*). 317 318 319 == GLOBAL DIRECTIVES - SECONDARY == 320 These are global directives that are of lesser importance, often 321 affecting the user experience and not the boot process. 322 323 *ALLOWOPTIONS* 'flag_val':: 324 If 'flag_val' is 0, the user is not allowed to specify any arguments on 325 the kernel command line. The only options recognized are those 326 specified in an *APPEND*) statement. The default is 1. 327 328 *IMPLICIT* 'flag_val':: 329 If 'flag_val' is 0, do not load a kernel image unless it has been 330 explicitly named in a *LABEL* statement. The default is 1. 331 332 *TIMEOUT* 'timeout':: 333 Indicates how long to wait at the 'boot:' prompt until booting 334 automatically, in units of 1/10 s. The timeout is cancelled as soon as 335 the user types anything on the keyboard, the assumption being that the 336 user will complete the command line already begun. The timer is reset 337 to 0 upon return from an unsuccessful attempt to boot or from a module. 338 A timeout of zero (the default) will disable the timeout completely. 339 340 *TOTALTIMEOUT* 'timeout':: 341 Indicates how long to wait until booting automatically, in units of 342 1/10 s. This timeout is *not* cancelled by user input, and can thus be 343 used to deal with serial port glitches or "the user walked away" type 344 situations. A timeout of zero (the default) will disable the timeout 345 completely. 346 + 347 Both *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. 352 TIMEOUT 50 353 TOTALTIMEOUT 9000 354 ---- 355 356 // FIXME: be consistent 357 *ONTIMEOUT* 'kernel options...':: 358 Sets the command line invoked on a timeout (which often references a 359 LABEL). If not specified, 'UI' (if used) or 'DEFAULT is used. 360 361 *ONERROR* 'kernel options...':: 362 If a kernel image is not found (either due to it not existing, or 363 because *IMPLICIT* is set), run the specified command. The faulty 364 command line is appended to the specified options, so if the *ONERROR* 365 directive reads as: 366 + 367 ---- 368 ONERROR xyzzy plugh 369 ---- 370 + 371 and the command line as entered by the user is: 372 + 373 ---- 374 foo bar baz 375 ---- 376 + 377 *Syslinux* will execute the following as if entered by the user: 378 + 379 ---- 380 xyzzy plugh foo bar baz 381 ---- 382 383 *SERIAL* 'port [baudrate [flowcontrol]]':: 384 Enables 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 387 parameters are hardcoded to be 8 bits, no parity, 1 stop bit. 388 + 389 'flowcontrol' is a combination of the following bits: 390 + 391 .... 392 0x001 - Assert DTR 393 0x002 - Assert RTS 394 0x008 - Enable interrupts 395 0x010 - Wait for CTS assertion 396 0x020 - Wait for DSR assertion 397 0x040 - Wait for RI assertion 398 0x080 - Wait for DCD assertion 399 0x100 - Ignore input unless CTS asserted 400 0x200 - Ignore input unless DSR asserted 401 0x400 - Ignore input unless RI asserted 402 0x800 - Ignore input unless DCD asserted 403 .... 404 + 405 All other bits are reserved. 406 + 407 Typical values are: 408 + 409 .... 410 0 - No flow control (default) 411 0x303 - Null modem cable detect 412 0x013 - RTS/CTS flow control 413 0x813 - RTS/CTS flow control, modem input 414 0x023 - DTR/DSR flow control 415 0x083 - DTR/DCD flow control 416 .... 417 + 418 For the *SERIAL* directive to be guaranteed to work properly, it should 419 be the first directive in the configuration file. 420 + 421 NOTE: 'port' values from 0 to 3 means the first four serial ports 422 detected by the BIOS. They may or may not correspond to the legacy port 423 values 0x3F8, 0x2F8, 0x3E8, 0x2E8. 424 + 425 Enabling interrupts (setting the 0x008 bit) may give better 426 responsiveness without setting the *NOHALT* option, but could 427 potentially cause problems with buggy BIOSes. 428 + 429 This option is "sticky" and is not automatically reset when loading a 430 new configuration file with the CONFIG command. 431 432 *NOHALT* 'flag_val':: 433 If 'flag_val' is 1, don't halt the processor while idle. Halting the 434 processor while idle significantly reduces the power consumption, but 435 can cause poor responsiveness to the serial console, especially when 436 using scripts to drive the serial console, as opposed to human 437 interaction. 438 439 *CONSOLE* 'flag_val':: 440 If '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 442 default.) 443 + 444 Some BIOSes try to forward this to the serial console and sometimes make 445 a total mess thereof, so this option lets you disable the video console 446 on these systems. 447 448 *FONT* 'filename':: 449 Load a font in .psf format before displaying any output (except the 450 copyright line, which is output as ldlinux.sys itself is loaded.) 451 *Syslinux* only loads the font onto the video card; if the .psf file 452 contains a Unicode table it is ignored. This only works on EGA and VGA 453 cards; hopefully it should do nothing on others. 454 455 *KBDMAP* 'keymap':: 456 Install a simple keyboard map. The keyboard remapper used is *very* 457 simplistic (it simply remaps the keycodes received from the BIOS, which 458 means that only the key combinations relevant in the default layout -- 459 usually U.S. English -- can be mapped) but should at least help people 460 with AZERTY keyboard layout and the locations of = and , (two special 461 characters used heavily on the Linux kernel command line.) 462 + 463 The included program keytab-lilo.pl from the LILO distribution can be 464 used to create such keymaps. The file keytab-lilo.txt contains the 465 documentation for this program. 466 467 *DISPLAY* 'filename':: 468 Displays the indicated file on the screen at boot time (before the boot: 469 prompt, if displayed). Please see the section below on *DISPLAY* files. 470 + 471 NOTE: If the file is missing, this option is simply ignored. 472 473 *SAY* 'message':: 474 Prints the message on the screen. 475 476 *PROMPT* 'flag_val':: 477 If 'flag_val' is 0, display the boot: prompt only if the Shift or Alt 478 key is pressed, or Caps Lock or Scroll lock is set (this is the 479 default). If 'flag_val' is 1, always display the boot: prompt. 480 481 *NOESCAPE* 'flag_val':: 482 If 'flag_val' is set to 1, ignore the Shift/Alt/Caps Lock/Scroll Lock 483 escapes. Use this (together with PROMPT 0) to force the default boot 484 alternative. 485 486 *NOCOMPLETE* 'flag_val':: 487 If 'flag_val' is set to 1, the Tab key does not display labels at the 488 boot: 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':: 503 Displays the indicated file on the screen when a function key is pressed 504 at the boot: prompt. This can be used to implement pre-boot online help 505 (presumably for the kernel command line options.) Please see the 506 section below on DISPLAY files. 507 + 508 When using the serial console, press <Ctrl-F><digit> to get to the help 509 screens, 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 511 versions, 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 515 of directories to search when attempting to load modules. This directive 516 is useful for specifying the directories containing the lib*.c32 library 517 files as other modules may be dependent on these files, but may not 518 reside in the same directory. Multiple instances will append additional 519 paths. 520 521 *SENDCOOKIES* 'bitmask':: 522 (*PXELINUX* 5.10+) When downloading files over http, the SYSAPPEND 523 strings are prepended with _Syslinux_ and sent to the server as cookies. 524 The cookies are URL-encoded; whitespace is *not* replaced with 525 underscores. 526 + 527 This command limits the cookies send; 0 means no cookies. The default 528 is -1, meaning send all cookies. 529 + 530 This option is "sticky" and is not automatically reset when loading a 531 new configuration file with the CONFIG command. 532 533 534 == DISPLAY FILE FORMAT == 535 DISPLAY and function-key help files are text files in either DOS or UNIX 536 format (with or without <CR>). In addition, the following special codes 537 are interpreted: 538 539 //[FIXME]: #1 doesn't break; #2 as-is; #3 broken but not on right; #4 540 identical 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 + 546 Clear the screen, home the cursor. Note that the screen is filled with 547 the current display color. 548 549 *<FF>*:: 550 = <Ctrl-L> = ASCII 12; Clear the screen, home the cursor. Note that the 551 screen is filled with the current display color. 552 553 *<FF>*:: <FF> = <Ctrl-L> = ASCII 12 554 + 555 Clear the screen, home the cursor. Note that the screen is filled with 556 the current display color. 557 558 *<FF>*:: 559 <FF> = <Ctrl-L> = ASCII 12 + 560 Clear the screen, home the cursor. Note that the screen is filled with 561 the current display color. 562 563 *<SI>*'<bg><fg>':: <SI> = <Ctrl-O> = ASCII 15 564 + 565 Set the display colors to the specified background and foreground 566 colors, where <bg> and <fg> are the 2 hex digits representing 1 byte, 567 corresponding 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 + 578 Picking a bright color (8-f) for the background results in the 579 corresponding dark color (0-7), with the foreground flashing. 580 + 581 Colors are not visible over the serial console. 582 583 *<CAN>*'filename<newline>':: <CAN> = <Ctrl-X> = ASCII 24 584 + 585 If a VGA display is present, enter graphics mode and display the graphic 586 included in the specified file. The file format is an ad hoc format 587 called LSS16; the included Perl program "ppmtolss16" can be used to 588 produce these images. This Perl program also includes the file format 589 specification. 590 + 591 The image is displayed in 640x480 16-color mode. Once in graphics mode, 592 the display attributes (set by <SI> code sequences) work slightly 593 differently: the background color is ignored, and the foreground colors 594 are the 16 colors specified in the image file. For that reason, 595 ppmtolss16 allows you to specify that certain colors should be assigned 596 to specific color indicies. 597 + 598 Color indicies 0 and 7, in particular, should be chosen with care: 0 is 599 the background color, and 7 is the color used for the text printed by 600 *Syslinux* itself. 601 602 *<EM>*:: <EM> = <Ctrl-Y> = ASCII 25 + 603 If we are currently in graphics mode, return to text mode. 604 605 *<DLE>*..*<ETB>*:: <Ctrl-P>..<Ctrl-W> = ASCII 16-23 606 + 607 These codes can be used to select which modes to print a certain part of 608 the message file in. Each of these control characters select a specific 609 set of modes (text screen, graphics screen, serial port) for which the 610 output 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 + 623 For example, the following will actually print out which mode the 624 console is in: 625 + 626 <DC1>Text mode<DC2>Graphics mode<DC4>Serial port<ETB> 627 628 *<SUB>*:: <SUB> = <Ctrl-Z> = ASCII 26 629 + 630 End of file (DOS convention). 631 632 *<BEL>*:: <BEL> = <Ctrl-G> = ASCII 7 + 633 Beep the speaker. 634 635 636 == BOOT LOADER IDS USED == 637 The Linux boot protocol supports a "boot loader ID", a single byte where 638 the upper nybble specifies a boot loader family (3 = *Syslinux*) and the 639 lower 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 645 646 In 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 652 memory, which means the Linux boot sequence cannot complete. If so, a 653 message is displayed and the boot sequence aborted. Holding down the 654 Ctrl key while booting disables this feature. 655 656 Any file that *Syslinux* uses can be marked hidden, system or readonly 657 if so is convenient; *Syslinux* ignores all file attributes. The 658 *SYSLINUX* installer automatically sets the readonly/hidden/system 659 attributes on LDLINUX.SYS. 660 661 == EXAMPLE == 662 Here are some sample config files: 663 ---- 664 # SERIAL 0 115200 665 DEFAULT linux 666 PROMPT 1 667 TIMEOUT 600 668 669 LABEL linux 670 LINUX vmlinuz 671 APPEND initrd=initrd1.gz,initrd2.gz 672 673 LABEL m 674 COM32 menu.c32 675 ---- 676 In this example, serial port use is disabled but can be enabled by 677 uncommenting 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 679 executed as a Linux kernel, initrd files initrd1.gz and initrd2.gz are 680 loaded 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 682 executed to launch a menu system. 683 684 685 686 == KNOWN BUGS == 687 include::com-bug.txt[] 688 689 690 == BUG REPORTS == 691 include::com-rpt.txt[] 692 693 694 == AUTHOR == 695 This AsciiDoc derived document is a modified version of the original 696 *SYSLINUX* documentation by {author} <{author-email}>. The conversion 697 to an AsciiDoc was made by {editor1} <{editor1-email}> 698
