1SYSLINUX(1) General Commands Manual SYSLINUX(1)
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6 syslinux - install the SYSLINUX bootloader on a FAT filesystem
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9 syslinux [OPTIONS] device
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12 Syslinux is a boot loader for the Linux operating system which operates
13 off an MS-DOS/Windows FAT filesystem. It is intended to simplify first-
14 time installation of Linux, and for creation of rescue and other spe‐
15 cial-purpose boot disks.
16 In order to create a bootable Linux floppy using Syslinux, prepare a
18 normal MS-DOS formatted floppy. Copy one or more Linux kernel files to
19 it, then execute the command:
20 syslinux --install /dev/fd0
22 This will alter the boot sector on the disk and copy a file named
24 ldlinux.sys into its root directory.
25 On boot time, by default, the kernel will be loaded from the image
27 named LINUX on the boot floppy. This default can be changed, see the
28 section on the syslinux configuration file.
29 If the Shift or Alt keys are held down during boot, or the Caps or
31 Scroll locks are set, syslinux will display a lilo(8) -style "boot:"
32 prompt. The user can then type a kernel file name followed by any ker‐
33 nel parameters. The SYSLINUX bootloader does not need to know about the
34 kernel file in advance; all that is required is that it is a file
35 located in the root directory on the disk.
36 Syslinux supports the loading of initial ramdisks (initrd) and the
38 bzImage kernel format.
39
41 -i, --install
42 Install SYSLINUX on a new medium, overwriting any previously
43 installed bootloader.
44 -U, --update
46 Install SYSLINUX on a new medium if and only if a version of
47 SYSLINUX is already installed.
48 -s, --stupid
50 Install a "safe, slow and stupid" version of SYSLINUX. This ver‐
51 sion may work on some very buggy BIOSes on which SYSLINUX would
52 otherwise fail. If you find a machine on which the -s option is
53 required to make it boot reliably, please send as much info
54 about your machine as you can, and include the failure mode.
55 -f, --force
57 Force install even if it appears unsafe.
58 -r, --raid
60 RAID mode. If boot fails, tell the BIOS to boot the next device
61 in the boot sequence (usually the next hard disk) instead of
62 stopping with an error message. This is useful for RAID-1 boot‐
63 ing.
64 -d, --directory subdirectory
66 Install the SYSLINUX control files in a subdirectory with the
67 specified name (relative to the root directory on the device).
68 -t, --offset offset
70 Indicates that the filesystem is at an offset from the base of
71 the device or file.
72 --once command
74 Declare a boot command to be tried on the first boot only.
75 -O, --clear-once
77 Clear the boot-once command.
78 -H, --heads head-count
80 Override the detected number of heads for the geometry.
81 -S, --sectors sector-count
83 Override the detected number of sectors for the geometry.
84 -z, --zipdrive
86 Assume zipdrive geometry (--heads 64 --sectors 32).
87
89 Configuration file
90 All the configurable defaults in SYSLINUX can be changed by putting a
91 file called syslinux.cfg in the install directory of the boot disk.
92 This is a text file in either UNIX or DOS format, containing one or
93 more of the following items (case is insensitive for keywords).
94 This list is out of date.
96 In the configuration file blank lines and comment lines beginning with
98 a hash mark (#) are ignored.
99 default kernel [ options ... ]
101 Sets the default command line. If syslinux boots automatically,
102 it will act just as if the entries after "default" had been
103 typed in at the "boot:" prompt.
104 If no DEFAULT or UI statement is found, or the configuration
106 file is missing entirely, SYSLINUX drops to the boot: prompt
107 with an error message (if NOESCAPE is set, it stops with a "boot
108 failed" message; this is also the case for PXELINUX if the con‐
109 figuration file is not found.)
110 NOTE: Until SYSLINUX 3.85, if no configuration file is present, or no
112 "default" entry is present in the configuration file, the
113 default is "linux auto".
114 Even earlier versions of SYSLINUX used to automatically
116 append the string "auto" to whatever the user specified using
117 the DEFAULT command. As of version 1.54, this is no longer
118 true, as it caused problems when using a shell as a substitute
119 for "init." You may want to include this option manually.
120 append options ...
122 Add one or more options to the kernel command line. These are
123 added both for automatic and manual boots. The options are added
124 at the very beginning of the kernel command line, usually per‐
125 mitting explicitly entered kernel options to override them. This
126 is the equivalent of the lilo(8)
127 "append" option.
128 label label
130 kernel image
131 append options ...
132 Indicates that if label is entered as the kernel to boot, sys‐
133 linux should instead boot image, and the specified "append"
134 options should be used instead of the ones specified in the
135 global section of the file (before the first "label" command.)
136 The default for image is the same as label, and if no "append"
137 is given the default is to use the global entry (if any). Use
138 "append -" to use no options at all. Up to 128 "label" entries
139 are permitted.
140 The "image" doesn't have to be a Linux kernel; it can be
142 a boot sector or a COMBOOT file (see below.)
143 implicit flag_val
145 If flag_val is 0, do not load a kernel image unless it has been
146 explicitly named in a "label" statement. The default is 1.
147 timeout timeout
149 Indicates how long to wait at the "boot:" prompt until booting
150 automatically, in units of 1/10 s. The timeout is cancelled as
151 soon as the user types anything on the keyboard, the assumption
152 being that the user will complete the command line already
153 begun. A timeout of zero will disable the timeout completely,
154 this is also the default. The maximum possible timeout value is
155 35996; corresponding to just below one hour.
156 serial port [ baudrate ]
158 Enables a serial port to act as the console. "port" is a number
159 (0 = /dev/ttyS0 = COM1, etc.); if "baudrate" is omitted, the
160 baud rate defaults to 9600 bps. The serial parameters are hard‐
161 coded to be 8 bits, no parity, 1 stop bit.
162 For this directive to be guaranteed to work properly, it should
164 be the first directive in the configuration file.
165 font filename
167 Load a font in .psf format before displaying any output (except
168 the copyright line, which is output as ldlinux.sys itself is
169 loaded.) syslinux only loads the font onto the video card; if
170 the .psf file contains a Unicode table it is ignored. This only
171 works on EGA and VGA cards; hopefully it should do nothing on
172 others.
173 kbdmap keymap
175 Install a simple keyboard map. The keyboard remapper used is
176 very simplistic (it simply remaps the keycodes received from the
177 BIOS, which means that only the key combinations relevant in the
178 default layout - usually U.S. English - can be mapped) but
179 should at least help people with AZERTY keyboard layout and the
180 locations of = and , (two special characters used heavily on the
181 Linux kernel command line.)
182 The included program keytab-lilo.pl(8) from the lilo(8)
184 distribution can be used to create such keymaps.
185 display filename
187 Displays the indicated file on the screen at boot time (before
188 the boot: prompt, if displayed). Please see the section below on
189 DISPLAY files. If the file is missing, this option is simply
190 ignored.
191 prompt flag_val
193 If flag_val is 0, display the "boot:" prompt only if the Shift
194 or Alt key is pressed, or Caps Lock or Scroll lock is set (this
195 is the default). If flag_val is 1, always display the "boot:"
196 prompt.
197 f1 filename
199 f2 filename
200 ...
201 f9 filename
202 f10 filename
203 f11 filename
204 f12 filename
205 Displays the indicated file on the screen when a function key is
206 pressed at the "boot:" prompt. This can be used to implement
207 pre-boot online help (presumably for the kernel command line
208 options.)
209 When using the serial console, press <Ctrl-F><digit> to get to
211 the help screens, e.g. <Ctrl-F>2 to get to the f2 screen. For
212 f10-f12, hit <Ctrl-F>A, <Ctrl-F>B, <Ctrl-F>C. For compatiblity
213 with earlier versions, f10 can also be entered as <Ctrl-F>0.
214 Display file format
216 DISPLAY and function-key help files are text files in either DOS or
217 UNIX format (with or without <CR>). In addition, the following special
218 codes are interpreted:
219 <FF> = <Ctrl-L> = ASCII 12
221 Clear the screen, home the cursor. Note that the screen is
222 filled with the current display color.
223 <SI><bg><fg>, <SI> = <Ctrl-O> = ASCII 15
225 Set the display colors to the specified background and fore‐
226 ground colors, where <bg> and <fg> are hex digits, corresponding
227 to the standard PC display attributes:
228 0 = black 8 = dark grey
230 1 = dark blue 9 = bright blue
231 2 = dark green a = bright green
232 3 = dark cyan b = bright cyan
233 4 = dark red c = bright red
234 5 = dark purple d = bright purple
235 6 = brown e = yellow
236 7 = light grey f = white
237 Picking a bright color (8-f) for the background results in the
239 corresponding dark color (0-7), with the foreground flashing.
240 colors are not visible over the serial console.
242 <CAN>filename<newline>, <CAN> = <Ctrl-X> = ASCII 24
244 If a VGA display is present, enter graphics mode and display the
245 graphic included in the specified file. The file format is an
246 ad hoc format called LSS16; the included Perl program "ppm‐
247 tolss16" can be used to produce these images. This Perl program
248 also includes the file format specification.
249 The image is displayed in 640x480 16-color mode. Once in graph‐
251 ics mode, the display attributes (set by <SI> code sequences)
252 work slightly differently: the background color is ignored, and
253 the foreground colors are the 16 colors specified in the image
254 file. For that reason, ppmtolss16 allows you to specify that
255 certain colors should be assigned to specific color indicies.
256 Color indicies 0 and 7, in particular, should be chosen with
258 care: 0 is the background color, and 7 is the color used for the
259 text printed by SYSLINUX itself.
260 <EM>, <EM> = <Ctrl-U> = ASCII 25
262 If we are currently in graphics mode, return to text mode.
263 <DLE>..<ETB>, <Ctrl-P>..<Ctrl-W> = ASCII 16-23
265 These codes can be used to select which modes to print a certain
266 part of the message file in. Each of these control characters
267 select a specific set of modes (text screen, graphics screen,
268 serial port) for which the output is actually displayed:
269 Character Text Graph Serial
271 ------------------------------------------------------
272 <DLE> = <Ctrl-P> = ASCII 16 No No No
273 <DC1> = <Ctrl-Q> = ASCII 17 Yes No No
274 <DC2> = <Ctrl-R> = ASCII 18 No Yes No
275 <DC3> = <Ctrl-S> = ASCII 19 Yes Yes No
276 <DC4> = <Ctrl-T> = ASCII 20 No No Yes
277 <NAK> = <Ctrl-U> = ASCII 21 Yes No Yes
278 <SYN> = <Ctrl-V> = ASCII 22 No Yes Yes
279 <ETB> = <Ctrl-W> = ASCII 23 Yes Yes Yes
280 For example:
282 <DC1>Text mode<DC2>Graphics mode<DC4>Serial port<ETB>
283 ... will actually print out which mode the console is in!
284 <SUB> = <Ctrl-Z> = ASCII 26
286 End of file (DOS convention).
287 Comboot Images and other operating systems
289 This version of syslinux supports chain loading of other operating sys‐
290 tems (such as MS-DOS and its derivatives, including Windows 95/98), as
291 well as COMBOOT-style standalone executables (a subset of DOS .COM
292 files; see separate section below.)
293 Chain loading requires the boot sector of the foreign operating system
295 to be stored in a file in the root directory of the filesystem.
296 Because neither Linux kernels, boot sector images, nor COMBOOT files
297 have reliable magic numbers, syslinux will look at the file extension.
298 The following extensions are recognised:
299 none or other Linux kernel image
301 CBT COMBOOT image (not runnable from DOS)
302 BSS Boot sector (DOS superblock will be patched in)
303 BS Boot sector
304 COM COMBOOT image (runnable from DOS)
305 For filenames given on the command line, syslinux will search for the
307 file by adding extensions in the order listed above if the plain file‐
308 name is not found. Filenames in KERNEL statements must be fully quali‐
309 fied.
310 A COMBOOT file is a standalone executable in DOS .COM format. They can,
312 among other things, be produced by the Etherboot package by Markus
313 Gutschke and Ken Yap. The following requirements apply for these files
314 to be sufficiently "standalone" for syslinux to be able to load and run
315 them:
316 · The program must not execute any DOS calls (since there is no
318 DOS), although it may call the BIOS. The only exception is that
319 the program may execute INT 20h (Terminate Program) to return to
320 the syslinux prompt. Note especially that INT 21h AH=4Ch, INT
321 21h AH=31h or INT 27h are not supported.
322 · Only the fields pspInt20 at offset 00h, pspNextParagraph at off‐
324 set 02h and pspCommandTail at offset 80h (contains the arguments
325 from the syslinux command line) in the PSP are supported. All
326 other fields will contain zero.
327 · The program must not modify any main memory outside its 64K seg‐
329 ment if it returns to syslinux via INT 20h.
330 Syslinux currently doesn't provide any form of API for the use of COM‐
332 BOOT files. If there is need, a future version may contain an INT
333 interface to some syslinux functions; please contact me if you have a
334 need or ideas for such an API.
335 Novice protection
337 Syslinux will attempt to detect if the user is trying to boot on a 286
338 or lower class machine, or a machine with less than 608K of low ("DOS")
339 RAM (which means the Linux boot sequence cannot complete). If so, a
340 message is displayed and the boot sequence aborted. Holding down the
341 Ctrl key while booting disables this feature.
342 The compile time and date of a specific syslinux version can be
344 obtained by the DOS command "type ldlinux.sys". This is also used as
345 the signature for the LDLINUX.SYS file, which must match the boot sec‐
346 tor
347 Any file that syslinux uses can be marked hidden, system or readonly if
349 so is convenient; syslinux ignores all file attributes. The SYSLINUX
350 installed automatically sets the readonly attribute on LDLINUX.SYS.
351 Bootable CD-ROMs
353 SYSLINUX can be used to create bootdisk images for El Torito-compatible
354 bootable CD-ROMs. However, it appears that many BIOSes are very buggy
355 when it comes to booting CD-ROMs. Some users have reported that the
356 following steps are helpful in making a CD-ROM that is bootable on the
357 largest possible number of machines:
358 · Use the -s (safe, slow and stupid) option to SYSLINUX
360 · Put the boot image as close to the beginning of the ISO 9660
362 filesystem as possible.
363 A CD-ROM is so much faster than a floppy that the -s option shouldn't
365 matter from a speed perspective.
366 Of course, you probably want to use ISOLINUX instead. See the documen‐
368 tation file isolinux.doc.
369 Booting from a FAT partition on a hard disk
371 SYSLINUX can boot from a FAT filesystem partition on a hard disk
372 (including FAT32). The installation procedure is identical to the pro‐
373 cedure for installing it on a floppy, and should work under either DOS
374 or Linux. To boot from a partition, SYSLINUX needs to be launched from
375 a Master Boot Record or another boot loader, just like DOS itself
376 would. A sample master boot sector (mbr.bin) is included with SYSLINUX.
377
379 I would appreciate hearing of any problems you have with SYSLINUX. I
380 would also like to hear from you if you have successfully used SYS‐
381 LINUX, especially if you are using it for a distribution.
382 If you are reporting problems, please include all possible information
384 about your system and your BIOS; the vast majority of all problems
385 reported turn out to be BIOS or hardware bugs, and I need as much
386 information as possible in order to diagnose the problems.
387 There is a mailing list for discussion among SYSLINUX users and for
389 announcements of new and test versions. To join, send a message to
390 majordomo@linux.kernel.org with the line:
391 subscribe syslinux
393 in the body of the message. The submission address is sys‐
395 linux@linux.kernel.org.
396
398 lilo(8), keytab-lilo.pl(8), fdisk(8), mkfs(8), superformat(1).
399
401 This manual page is a modified version of the original syslinux docu‐
402 mentation by H. Peter Anvin <hpa@zytor.com>. The conversion to a man‐
403 page was made by Arthur Korn <arthur@korn.ch>.
404SYSLINUX 19 July 2010 SYSLINUX(1)