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 Notes: Labels are mangled as if they were DOS filenames, and
142 must be unique after mangling. For example, two labels
143 "v2.1.30" and "v2.1.31" will not be distinguishable.
144 The "image" doesn't have to be a Linux kernel; it can be
146 a boot sector or a COMBOOT file (see below.)
147 implicit flag_val
149 If flag_val is 0, do not load a kernel image unless it has been
150 explicitly named in a "label" statement. The default is 1.
151 timeout timeout
153 Indicates how long to wait at the "boot:" prompt until booting
154 automatically, in units of 1/10 s. The timeout is cancelled as
155 soon as the user types anything on the keyboard, the assumption
156 being that the user will complete the command line already
157 begun. A timeout of zero will disable the timeout completely,
158 this is also the default. The maximum possible timeout value is
159 35996; corresponding to just below one hour.
160 serial port [ baudrate ]
162 Enables a serial port to act as the console. "port" is a number
163 (0 = /dev/ttyS0 = COM1, etc.); if "baudrate" is omitted, the
164 baud rate defaults to 9600 bps. The serial parameters are hard‐
165 coded to be 8 bits, no parity, 1 stop bit.
166 For this directive to be guaranteed to work properly, it should
168 be the first directive in the configuration file.
169 font filename
171 Load a font in .psf format before displaying any output (except
172 the copyright line, which is output as ldlinux.sys itself is
173 loaded.) syslinux only loads the font onto the video card; if
174 the .psf file contains a Unicode table it is ignored. This only
175 works on EGA and VGA cards; hopefully it should do nothing on
176 others.
177 kbdmap keymap
179 Install a simple keyboard map. The keyboard remapper used is
180 very simplistic (it simply remaps the keycodes received from the
181 BIOS, which means that only the key combinations relevant in the
182 default layout - usually U.S. English - can be mapped) but
183 should at least help people with AZERTY keyboard layout and the
184 locations of = and , (two special characters used heavily on the
185 Linux kernel command line.)
186 The included program keytab-lilo.pl(8) from the lilo(8)
188 distribution can be used to create such keymaps.
189 display filename
191 Displays the indicated file on the screen at boot time (before
192 the boot: prompt, if displayed). Please see the section below on
193 DISPLAY files. If the file is missing, this option is simply
194 ignored.
195 prompt flag_val
197 If flag_val is 0, display the "boot:" prompt only if the Shift
198 or Alt key is pressed, or Caps Lock or Scroll lock is set (this
199 is the default). If flag_val is 1, always display the "boot:"
200 prompt.
201 f1 filename
203 f2 filename
204 ...
205 f9 filename
206 f10 filename
207 f11 filename
208 f12 filename
209 Displays the indicated file on the screen when a function key is
210 pressed at the "boot:" prompt. This can be used to implement
211 pre-boot online help (presumably for the kernel command line
212 options.)
213 When using the serial console, press <Ctrl-F><digit> to get to
215 the help screens, e.g. <Ctrl-F>2 to get to the f2 screen. For
216 f10-f12, hit <Ctrl-F>A, <Ctrl-F>B, <Ctrl-F>C. For compatiblity
217 with earlier versions, f10 can also be entered as <Ctrl-F>0.
218 Display file format
220 DISPLAY and function-key help files are text files in either DOS or
221 UNIX format (with or without <CR>). In addition, the following special
222 codes are interpreted:
223 <FF> = <Ctrl-L> = ASCII 12
225 Clear the screen, home the cursor. Note that the screen is
226 filled with the current display color.
227 <SI><bg><fg>, <SI> = <Ctrl-O> = ASCII 15
229 Set the display colors to the specified background and fore‐
230 ground colors, where <bg> and <fg> are hex digits, corresponding
231 to the standard PC display attributes:
232 0 = black 8 = dark grey
234 1 = dark blue 9 = bright blue
235 2 = dark green a = bright green
236 3 = dark cyan b = bright cyan
237 4 = dark red c = bright red
238 5 = dark purple d = bright purple
239 6 = brown e = yellow
240 7 = light grey f = white
241 Picking a bright color (8-f) for the background results in the
243 corresponding dark color (0-7), with the foreground flashing.
244 colors are not visible over the serial console.
246 <CAN>filename<newline>, <CAN> = <Ctrl-X> = ASCII 24
248 If a VGA display is present, enter graphics mode and display the
249 graphic included in the specified file. The file format is an
250 ad hoc format called LSS16; the included Perl program "ppm‐
251 tolss16" can be used to produce these images. This Perl program
252 also includes the file format specification.
253 The image is displayed in 640x480 16-color mode. Once in graph‐
255 ics mode, the display attributes (set by <SI> code sequences)
256 work slightly differently: the background color is ignored, and
257 the foreground colors are the 16 colors specified in the image
258 file. For that reason, ppmtolss16 allows you to specify that
259 certain colors should be assigned to specific color indicies.
260 Color indicies 0 and 7, in particular, should be chosen with
262 care: 0 is the background color, and 7 is the color used for the
263 text printed by SYSLINUX itself.
264 <EM>, <EM> = <Ctrl-U> = ASCII 25
266 If we are currently in graphics mode, return to text mode.
267 <DLE>..<ETB>, <Ctrl-P>..<Ctrl-W> = ASCII 16-23
269 These codes can be used to select which modes to print a certain
270 part of the message file in. Each of these control characters
271 select a specific set of modes (text screen, graphics screen,
272 serial port) for which the output is actually displayed:
273 Character Text Graph Serial
275 ------------------------------------------------------
276 <DLE> = <Ctrl-P> = ASCII 16 No No No
277 <DC1> = <Ctrl-Q> = ASCII 17 Yes No No
278 <DC2> = <Ctrl-R> = ASCII 18 No Yes No
279 <DC3> = <Ctrl-S> = ASCII 19 Yes Yes No
280 <DC4> = <Ctrl-T> = ASCII 20 No No Yes
281 <NAK> = <Ctrl-U> = ASCII 21 Yes No Yes
282 <SYN> = <Ctrl-V> = ASCII 22 No Yes Yes
283 <ETB> = <Ctrl-W> = ASCII 23 Yes Yes Yes
284 For example:
286 <DC1>Text mode<DC2>Graphics mode<DC4>Serial port<ETB>
287 ... will actually print out which mode the console is in!
288 <SUB> = <Ctrl-Z> = ASCII 26
290 End of file (DOS convention).
291 Comboot Images and other operating systems
293 This version of syslinux supports chain loading of other operating sys‐
294 tems (such as MS-DOS and its derivatives, including Windows 95/98), as
295 well as COMBOOT-style standalone executables (a subset of DOS .COM
296 files; see separate section below.)
297 Chain loading requires the boot sector of the foreign operating system
299 to be stored in a file in the root directory of the filesystem.
300 Because neither Linux kernels, boot sector images, nor COMBOOT files
301 have reliable magic numbers, syslinux will look at the file extension.
302 The following extensions are recognised:
303 none or other Linux kernel image
305 CBT COMBOOT image (not runnable from DOS)
306 BSS Boot sector (DOS superblock will be patched in)
307 BS Boot sector
308 COM COMBOOT image (runnable from DOS)
309 For filenames given on the command line, syslinux will search for the
311 file by adding extensions in the order listed above if the plain file‐
312 name is not found. Filenames in KERNEL statements must be fully quali‐
313 fied.
314 A COMBOOT file is a standalone executable in DOS .COM format. They can,
316 among other things, be produced by the Etherboot package by Markus
317 Gutschke and Ken Yap. The following requirements apply for these files
318 to be sufficiently "standalone" for syslinux to be able to load and run
319 them:
320 · The program must not execute any DOS calls (since there is no
322 DOS), although it may call the BIOS. The only exception is that
323 the program may execute INT 20h (Terminate Program) to return to
324 the syslinux prompt. Note especially that INT 21h AH=4Ch, INT
325 21h AH=31h or INT 27h are not supported.
326 · Only the fields pspInt20 at offset 00h, pspNextParagraph at off‐
328 set 02h and pspCommandTail at offset 80h (contains the arguments
329 from the syslinux command line) in the PSP are supported. All
330 other fields will contain zero.
331 · The program must not modify any main memory outside its 64K seg‐
333 ment if it returns to syslinux via INT 20h.
334 Syslinux currently doesn't provide any form of API for the use of COM‐
336 BOOT files. If there is need, a future version may contain an INT
337 interface to some syslinux functions; please contact me if you have a
338 need or ideas for such an API.
339 Novice protection
341 Syslinux will attempt to detect if the user is trying to boot on a 286
342 or lower class machine, or a machine with less than 608K of low ("DOS")
343 RAM (which means the Linux boot sequence cannot complete). If so, a
344 message is displayed and the boot sequence aborted. Holding down the
345 Ctrl key while booting disables this feature.
346 The compile time and date of a specific syslinux version can be
348 obtained by the DOS command "type ldlinux.sys". This is also used as
349 the signature for the LDLINUX.SYS file, which must match the boot sec‐
350 tor
351 Any file that syslinux uses can be marked hidden, system or readonly if
353 so is convenient; syslinux ignores all file attributes. The SYSLINUX
354 installed automatically sets the readonly attribute on LDLINUX.SYS.
355 Bootable CD-ROMs
357 SYSLINUX can be used to create bootdisk images for El Torito-compatible
358 bootable CD-ROMs. However, it appears that many BIOSes are very buggy
359 when it comes to booting CD-ROMs. Some users have reported that the
360 following steps are helpful in making a CD-ROM that is bootable on the
361 largest possible number of machines:
362 · Use the -s (safe, slow and stupid) option to SYSLINUX
364 · Put the boot image as close to the beginning of the ISO 9660
366 filesystem as possible.
367 A CD-ROM is so much faster than a floppy that the -s option shouldn't
369 matter from a speed perspective.
370 Of course, you probably want to use ISOLINUX instead. See the documen‐
372 tation file isolinux.doc.
373 Booting from a FAT partition on a hard disk
375 SYSLINUX can boot from a FAT filesystem partition on a hard disk
376 (including FAT32). The installation procedure is identical to the pro‐
377 cedure for installing it on a floppy, and should work under either DOS
378 or Linux. To boot from a partition, SYSLINUX needs to be launched from
379 a Master Boot Record or another boot loader, just like DOS itself
380 would. A sample master boot sector (mbr.bin) is included with SYSLINUX.
381
383 I would appreciate hearing of any problems you have with SYSLINUX. I
384 would also like to hear from you if you have successfully used SYS‐
385 LINUX, especially if you are using it for a distribution.
386 If you are reporting problems, please include all possible information
388 about your system and your BIOS; the vast majority of all problems
389 reported turn out to be BIOS or hardware bugs, and I need as much
390 information as possible in order to diagnose the problems.
391 There is a mailing list for discussion among SYSLINUX users and for
393 announcements of new and test versions. To join, send a message to
394 majordomo@linux.kernel.org with the line:
395 subscribe syslinux
397 in the body of the message. The submission address is sys‐
399 linux@linux.kernel.org.
400
402 lilo(8), keytab-lilo.pl(8), fdisk(8), mkfs(8), superformat(1).
403
405 This manual page is a modified version of the original syslinux docu‐
406 mentation by H. Peter Anvin <hpa@zytor.com>. The conversion to a man‐
407 page was made by Arthur Korn <arthur@korn.ch>.
408SYSLINUX 19 July 2010 SYSLINUX(1)