Starting with 1.47, changes marked with SYSLINUX/PXELINUX/ISOLINUX
apply to that specific program only; other changes apply to both.
Changes in 2.00:
* ALL: Add support for "COM32" (32-bit COMBOOT) images.
* ALL: Add an API for COMBOOT/COM32 images. See comboot.doc
for details. There is a C development environment for
COM32 being created; it should be ready at some point in
* Fix mbr.asm so that it actually works.
* SYSLINUX: The syslinux installer *SHOULD* now be safe to
run setuid root.
* PXELINUX: Fix bug where PXELINUX would override random
chunks of the UNDI code segment! Thanks to Kevin Tran for
finding this bug.
* ISOLINUX: Fix a bug related to slashes in pathnames.
* ISOLINUX: Fix a bug in handling initrds over 128 MB.
* ALL: Make the <Ctrl-V> key print out the version; this is
to help debugging.
* Add a small script, mkdiskimage, to create a DOS-formatted
hard disk image using mtools. This may be useful in
conjunction with MEMDISK.
* ISOLINUX: Search for a /boot/isolinux directory as well as
* ALL: Fix a bug related to very long configuration files.
* PXELINUX: Work around a NASM bug which would result in no
delay before reset if an error occurs.
Changes in 1.76:
* ISOLINUX: Remove code no longer used which caused hangs on
some Toshiba laptops.
Changes in 1.75:
* ALL: NASM 0.98.32 or later is now required to build
SYSLINUX from sources.
* SYSLINUX: put back in the workaround for the BIOS floppy
table. This seems to be a requirement for "extended" floppy
formats to work correctly.
* SYSLINUX: No longer warn if one is trying to boot on a 286
or older. The above BIOS workaround no longer fits if the
requirement to use only 8086-compatible code in the early
boot is maintained. It made sense in 1994, but in 2002 a
286 or older is a museum object.
* SYSLINUX: Use a downright bizarre, stateful algorithm to try
to guess the maximum transfer size. I am *hoping* this will
cut down on the number of systems for which -s is required
to work at any acceptable speed.
* ISOLINUX: Add a few more workarounds for various broken El
* Make sure .depend files aren't accidentally packed...
* ALL: Fix bugs in the extension-detect code; this caused
files like COMBOOT images and CD boot sectors to be
mis-identified as Linux kernels and rejected.
* ALL: Fix the return from COMBOOT.
* ALL: Do some of the early groundwork for supporting DOS
system calls in COMBOOT.
* Get rid of unnecessary "near" directives, making the code
* PXELINUX: Put the PXE stack back in the init state before
invoking a chain-loaded NBP.
* PXELINUX: Actually found the combination of calls that
allows some (most?) PXE 2+ stacks to be unloaded from memory
* PXELINUX: Add "keeppxe" command-line option to disable
the standard unloading of the PXE stack.
Changes in 1.74:
* SYSLINUX: fix bug that would cause valid kernel images to be
Changes in 1.73:
* Work on removing gratuitous differences between modules.
* Break up the source in common and module-specific files.
* PXELINUX: Allow chaining of other PXE NBPs.
* ISOLINUX: Allow loading "CD-ROM boot sectors".
* ALL: generalize the definition of a boot sector/NBP.
Changes in 1.72:
* PXELINUX, ISOLINUX: Fix bugs in the new core code.
Changes in 1.71:
* Fix a "brown paper bag" class bug in the new core code.
Changes in 1.70:
* Major code restructuring.
* Relax the conventional memory limits somewhat.
* MEMDISK: Set up the "version number string" pointer in the
* SYSLINUX: Fix, again, "the bug that won't die": the use of
the offset parameter with the SYSLINUX installer.
* SYSLINUX: Fix possible superblock corruption problem in the
Changes in 1.67:
* Handle bug in the location of initrd.
Changes in 1.66:
* MEMDISK: Make compile with newer versions of gcc.
Changes in 1.65:
* ISOLINUX: Support booting disk image files (to boot DOS or
other non-Linux operating systems), *IF* the BIOS works
correctly; unfortunately many BIOSes apparently don't.
* Support Linux boot protocol version 2.03 (explicitly
specify the initrd address limit.)
* Handle small "pseudo-kernels"; images that use the Linux
kernel boot protocols but are less than 64K in size.
* MEMDISK: New subsystem; this is a driver which allows
legacy OSes to boot using an in-memory simulated disk.
See memdisk/memdisk.doc for more info.
* PXELINUX, ISOLINUX: Correctly handle files larger than 65535
blocks (32 MB for PXELINUX, 128 MB for ISOLINUX.)
* PXELINUX: Make a best-effort attempt at freeing all memory
claimed. From the looks of it, it will fail on most PXE
Changes in 1.64:
* Limited support for hardware flow control when using a
serial port console.
* Support specifying the serial port I/O address explicitly.
* Make DOS installer hopefully behave more nicely when used on
recent Windows versions.
* Fix returning to text mode when a font has been specified.
* Attempt to detect missing serial port hardware and disable
the serial port if there is nothing there.
Changes in 1.63:
* Make the ppmtolss16 program handle color conversion more
* Clean up "make install" target, honour INSTALLROOT if it
* SYSLINUX: Fix stack-smash bug identified by Steffen
* Hopefully fix return-to-text-mode on some graphics cards.
* ISOLINUX: Bug workaround for Award BIOS 4.51, and perhaps
other buggy BIOSes as well.
Changes in 1.62:
* PXELINUX: Allow the DHCP server to override the
configuration file name and pathname prefix, using
"site-specific" DHCP options.
* PXELINUX: Documentation fixes.
* PXELINUX: Fix the "ipappend" option; the last two values
were reversed vs. what the kernel expected.
* Introduce a way to return to text mode once we are already
in graphics mode. This may be useful for F-key help
* Fix several bugs in the way return to text mode was handled.
Changes in 1.61:
* ISOLINUX: Support full pathname searches. Max length for a
pathname is 255 characters. As a result, only 64 "label"
statements are supported in ISOLINUX.
* PXELINUX: Max filename length extended to 63 characters.
Changes in 1.60:
* Add support for graphical splash screens.
* Add mode control characters, which allows you to control
message display output depending on output mode (text,
graphics, or serial port.)
* ISOLINUX: New program, which boots Linux from a CD-ROM
without using floppy emulation mode. See isolinux.doc for
* PXELINUX: Don't search for boot sector file types, since
they don't work anyway.
* SYSLINUX: Document the LOCK command for Win9x, and the error
dialog box for WinNT/2K.
Changes in 1.54:
* PXELINUX: Fix code for finding !PXE from PXENV+. This was
due to a spec bug; match the most recent spec since that
seems to be what implementations actually do.
* SYSLINUX: Add some smarts to the boot sector, which
hopefully should reduce the number of systems which require
stupid mode ("syslinux -s").
* PXELINUX: Document further some of the pathologies with old
* When specifying a "default" command line, no longer
automatically appent "auto". See the "DEFAULT" command in
syslinux.doc for more information.
* PXELINUX: Clean up the allocation of local socket numbers.
Changes in 1.53:
* PXELINUX: Rename pxelinux.bin to pxelinux.0, to match what
most PXE servers seem to expect.
* PXELINUX: Update the DHCP/boot server setup documentation.
* PXELINUX: Support new "localboot" option for "label"
* PXELINUX: More robust parsing of DHCP/boot server packets.
* PXELINUX: Include a small utility program "gethostip" to
compute hexadecimal IP addresses.
Changes in 1.52:
* PXELINUX: Fix bugs introduced by new A20 code. (SYSLINUX
has also been changed for code consistency reasons, but I'm
pretty sure the changes are don't care on SYSLINUX.)
* Documentation updates.
* PXELINUX: Add "ipappend" option to generate an ip= option to
Changes in 1.51:
* PXELINUX: Not all PXE stacks fill in the IP address for a
type 3 cached info query. Use a type 2 cached info query
for this information (only.)
* Yet another attempt at A20 coding. Now support BIOS call
15:2401 as well, and handle machines which always have A20
* Support memory detection using INT 15h, AX=0E820h. BIOS
manufacturers have apparently gotten sloppy about keeping
INT 15h, AX=0E801h working properly.
* Don't issue <CR><LF> onto the serial port when we're doing
Changes in 1.50:
* Yet another A20-code update. It seems some "legacy-free"
machines and embedded gear simply don't have a KBC to talk
to, and that waiting for one will wait forever. Sigh.
Changes in 1.49:
* SYSLINUX: Implement a hack for BIOS drivers which hog significant
chunks of low memory during boot. (Note: PXELINUX already
had this modification. SYSLINUX does still require that the
low 512K is available; PXELINUX requires 384K. Machines
with a physical memory hole in the low 640K cannot boot
Linux no matter what.) Depending what the reason is for the
memory hole, a new kernel (2.4.0-test3-pre3 or later) may be
* SYSLINUX: Default installer binary now compiled against
glibc 2.1. If this is inappropriate for your system and you
still want to use the offical version of SYSLINUX, please
follow the instructions in "distrib.doc" to rebuild the
* SYSLINUX: Linux installer program now supports -o <offset>
option which does a loopback mount with the
-o loop,offset=<> option. Useful to run SYSLINUX on an
individual partition of a whole-harddisk image.
* Include the source code to a Master Boot Record (MBR)
functionally equivalent to the one installed DOS except it
includes EBIOS support, and should be resistant to geometry
changes. The MBR code is public domain.
* PXELINUX: Fix "double p" bug: if the tftp prefix was null,
all filenames would get a "p" preprended, e.g.
"ppxelinux.cfg" and "pvmlinux".
Changes in 1.48:
* PXELINUX: Workaround for PXE ROMs based on the Intel PXE PDK
3.0 build 071 and earlier: missing !PXE structure pointer.
* PXELINUX: Handle larger BOOTP/DHCP packages.
* PXELINUX: The command line passing was broken; fix.
* PXELINUX: Make COMBOOT images work.
* PXELINUX: Documentation on how to make booting work using
the PDK 3.0-derived clients, which aren't so generous as to
allow booting with only "PXEClient" specified.
Changes in 1.47:
* PXELINUX: RFC 1123 states that a TFTP implementation MUST
use adaptive timeout, "at least an exponential backoff of
retransmission timeout is necessary." Implement a very
simple exponential backoff for retransmits.
* PXELINUX: Updated documentation, including pointer to new
* PXELINUX: When sending ERROR due to bad OACK, use the proper
destination port number (why are TFTP port numbers so odd?)
* PXELINUX: If the boot dies in the middle somewhere,
eventually give up and reset the machine (unattended
Changes in 1.46:
* New program PXELINUX to do network booting using a
PXE-compliant (Pre-Execution Environment) network booting
PROM. See pxelinux.doc for details.
Changes in 1.45:
* Serial console support. See syslinux.doc for details.
Changes in 1.44:
* Change HIGHMEM_MAX to 38000000h to (hopefully) avoid the
kernel stepping on it; 3f000000h was apparently a higher
limit than the kernel used!
Changes in 1.43:
* Add sys2ansi.pl script to display the contents of a
colorized SYSLINUX file.
* Changed the io_delay once again, after a report that the
old delay port causes hangs on some systems.
Changes in 1.42:
* Frob the "fast A20 gate" port as well as the keyboard
controller; will this help systems with problems?
* Be even more paranoid about A20, unfortunately even this
seems to be not paranoid enough... what I don't understand
is that if there is hardware out there *this broken*, how
can it run Linux at all? Report an error message rather
than hang forever if A20 is stuck.
* Include some intermediate files in the distribution, plus
provide a "make installer" target for distributors to relink
the install programs only. I would prefer the syslinux boot
loader proper to be "binary clean" for debuggablity -- use
"make clean ; make installer" to rebuild the installers only.
Changes in 1.41:
* Don't get confused by directories, volume labels, or VFAT
* Use INT 15h, AX=0E801h to query memory size before trying
INT 15h, AH=88h. This not only provides more headroom
between the kernel and the initrd on large-memory machines,
but it appears some recent BIOSes actually have started
returning garbage for the AH=88h (older) call.
* Trust high memory beyond the 15 MB mark if the user has
specified it, or if obtained with INT 15h, AH=0E801h (with
no memory holes above 1 MB.)
Changes in 1.40:
* Increase A20M delay and put in a test to avoid problems on
certain IBM Thinkpads (thanks to Donnie Barnes of RedHat
for vital info on this one.)
* Support COMBOOT style boot command images.
* Support chain loading (foreign operating systems, e.g. DOS).
* Include a new "copybs" DOS utility to copy a boot sector to
a file (under Linux, use "dd".)
* Fix the DOS installer to work for disks over 32 MB.
* SYSLINUX should now handle disks with more than 65536 tracks.
Changes in 1.37:
* Fix a bug that caused "label" statements in syslinux.cfg to
not be handled properly.
* Updated the documentation. Among other things, we now allow
up to 128 "label" statements.
Changes in 1.36:
* Fix for booting old (pre-initrd) kernels.
* It seems at least some versions of OS/2 doesn't set up all
the fields in the superblock correctly. Account for that.
* Fix bug that caused boot failure when using the mem= option.
Changes in 1.35:
* Loading from partitions now should work properly. (Actually
tested, this time. You should even be able to dd a floppy
to a partition and boot from it.)
* Removed large workaround code for an alleged ancient BIOS
bug I have never actually seen. The -s option should work
on those machines, anyway.
* Support for simple keyboard remappings, same as used by
LILO (once again to support localization.) The program
keytab-lilo.pl from the LILO distribution included to
generate such maps.
* Added a "safe, slow and stupid" (-s) option to the
installers. This option will lobotomize the boot sector to
hopefully work on even very buggy BIOSes.
Changes in 1.34:
* Ability to load a VGA font on bootup (for localized Linux
Changes in 1.33:
* Bug fix in the Linux installer.
* Added a workaround for a bug in certain AMI/Intel BIOSes
when booting from CD-ROM.
* Documentation changes.
Changes in 1.32:
* FAT16 filesystems are now supported.
Changes in 1.31:
* Now compiles under Linux, using NASM, rather than using
Turbo Assembler under DOS. See http://www.cryogen.com/Nasm
for information about NASM.
* Linux-hosted SYSLINUX installer, as well as a
rewritten DOS installer (now is written in assembler, so we
don't need Turbo C.)
Changes in 1.30:
* Added support for loading bzImage and initrd loading, and made
SYSLINUX new-setup-code aware (SYSLINUX 1.30 id=0x31).
* Added LILO-style kernel labels; see the LABEL and IMPLICIT
keywords in README file.
* Added support for colorization of intro and help screens.
* The vga= option is now handled correctly.
* Massive rewrite of large chunks of the code in order to
support the first two new features.
Changes in 1.20:
* Added simple online help at the "boot:" prompt.
* Removed 2880K image as I no longer have access to such a
floppy drive. (Donations accepted!!)
* Decided to distribute the source in a subdirectory rather
than in a nested zipfile.
Changes in 1.11:
* Removed a sanity check which would cause booting to fail on
Phoenix BIOS version 4.03. Apparently this BIOS is buggy.
Changes in 1.10:
* Added configuration file SYSLINUX.CFG. This file contains all
configurable options, and can be edited from any OS which can
access an MS-DOS filesystem; there is no longer a need to run
SYSLINUX.EXE except to write the boot sector.
* Default command line now given by "default" line in config
* LINUXMSG.TXT and BOOTMSG.TXT hard-coded file names replaced by
"display" and "prompt" lines in config file.
* LILO-style option appending now supported ("append" line in
* Prompt timeout is now supported ("timeout" line in config
file). The timeout is cancelled when anything is typed on the
* Pressing <ESC> or <Ctrl-C> at the Loading... stage now aborts
the kernel loading in progress and returns the user to the
* The installer now automatically sets the READONLY flag on
* Added 2880K disk image.
Changes in 1.03:
* Fixed bug that would prevent booting from double-density
floppies and other DOS filesystems with multiple sectors per
* Added 720K disk image.
* Changed default kernel name on disk images to LINUX.
Changes in 1.02:
* Fixed bug that would garble the command line on recent kernels
with more than 4 sectors of setup code (this wasn't really a
*bug*; rather, a kernel change broke the code. Unfortunately
the Linux boot interface is still sorely undocumented).
* Added BOOTMSG.TXT file support (message file which does not
force display of the boot prompt).
Changes in 1.01:
* Fixed bug on some (most?) 386 BIOSes would require two boot