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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