Syslinux 3 Changelog

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Changes in 3.86

  • chain.c32: fix chainloading the MBR of a hard disk (broken in 3.85).
  • mboot.c32: report the boot loader name in the information structure.
  • com32: set argv[0] in a com32 module.
  • core: add a workaround for a bug in Xen HVM older than version 3.3: disable halt on those platforms.
  • Fix problems where certain operations in com32 modules would cause the core to believe the system was idle.
  • MEMDISK: fix MBR detection when used with a DOSEMU header or an offset.
  • MEMDISK: generate the mBFT checksum correctly.

Changes in 3.85

  • gPXELINUX: updated to gPXE 1.0.0. gPXELINUX can now do NBP chainloading, and does not require a second DHCP.
  • vesamenu.c32: unbreak the default "grey hole" background.
  • We no longer have a built-in default of linux auto. Instead, if no DEFAULT or UI statement is found, or the configuration file is missing entirely, we drop to the boot: prompt with an error message (if NOESCAPE is set, we stop with a "boot failed" message; this is also the case for PXELINUX if the configuration file is not found.)
  • chain.c32: support chainloading Grub4DOS; patch by Gert Hulselmans.
  • New tool: sysdump.c32, can be used to produce system information for debugging via tftp or ymodem (serial port).
  • vga=current on the Linux command line is now supported.
  • chain.c32: support for Windows Recovery Console, via the cmldr= option.
  • chain.c32: should now support loading NTLDR from different type media than loaded from.
  • chain.c32: support chainloading to a FAT/NTFS partition with invalid "hidden sectors" via the sethidden option.
  • memdisk: fix the mBFT ACPI table.
  • vesamenu.c32: if the image is smaller than the screen, tile it across the whole screen.
  • mkdiskimage: -s option for producing a sparse image.
  • vesamenu.c32: support arbitrary resolution setting (beyond BIOS support) on some Intel-based video chipsets. This code is a modified version of the "915resolution" tool by Steve Tomljenovic; your mileage might vary.

Changes in 3.84

  • SYSLINUX: make the DOS installer work for MS-DOS 7.x/8.x (Win9x/ME) again.
  • HDT: updated to version 0.3.6 (numerous changes.)
  • mboot.c32: now supports video mode setting if requested by the image.
  • MEMDISK: Fix floppy images of PC-DOS.
  • MEMDISK: Add support for emulation of CD-ROM images; patch by Shao Miller.
  • MEMDISK: Comply with the Win9x "safe hook" standard, allowing a protected-mode driver.
  • MEMDISK: New "mBFT" ACPI table, by analogy with the iSCSI iBFT table. This allows detection from a protected-mode operating system without EDD support.
  • 32-bit version of the gfxboot loader (gfxboot.c32), so far experimental. This will replace in the future.
  • vesamenu.c32: new MENU RESOLUTION directive to set a screen resolution other than 640x480.
  • chain.c32: add support for loading isolinux.bin.
  • chain.c32: make sure to always return to text mode.
  • eltorito.sys: DOS driver for generic CD-ROMs; by Gary Tong and Bart Lagerweij.

Changes in 3.83

  • PXELINUX: clear memory before handing over to a chainloaded NBP. This may help avoid a bug in Windows RIS.
  • PXELINUX: fix localboot after NBP chainloading on certain BIOSes (including ASUS A8N-E, but possibly others.)
  • chain.c32: support chainloaded bootloaders on ISOLINUX.
  • PXELINUX: allow filenames up to 251 characters.
  • MEMDISK: fix problems booting from USB on Thinkpads, and possibly other machines or hardware combinations.
  • isohybrid: fix the -id option.
  • HDT: updated to version 0.3.4.
  • MEMDISK: the stack size is now configurable, with the stack= option.
  • Simple menu: fix Ctrl-W (word erase) in command-line edit.
  • Simple menu: fix crash on some platforms.
  • Gfxboot: fixes to the configuration file parsing.
  • PXELINUX: add a tool to override specific DHCP options via values hardcoded in the pxelinux.0 file. These hardcoded values can be either "before DHCP" (defaults if DHCP do not provide values), or "after DHCP" (overrides DHCP). The tool pxelinux-options can be used to set these options. This feature does not apply to gpxelinux.0; when used with gPXE this is better handled by modifying the embedded script.

Changes in 3.82

  • isohybrid: fix the -partok logic for loading from a partition.
  • ISOLINUX: deal with systems which return from INT 13h with interrupts disabled.
  • Do not invoke the idle handler during large file loads.
  • Simple menu: make ONTIMEOUT work with MENU HIDDEN.
  • PXELINUX: handle TFTP servers which have extra NULs at the end of an OACK packet.

Changes in 3.81

Changes in 3.81:

  • Shuffler: fix bug in real-mode entry. This affected a number of modules, probably in relatively unimportant ways, but it completely broke linux.c32.
  • Improved performance.
  • Attempt to halt the processor while idle. This can cause bad reponsiveness when using a serial console especially for automated input; if that ends up being a problem, use the new "NOHALT 1" configuration command.
  • linux.c32 now suppresses all messages if the "quiet" flag is specified.
  • isohybrid: add a variety of options, and a help message.
  • ISOLINUX: fix booting in hybrid mode when CBIOS is used.
  • Drop support for ACPI 3 extended memory flags.
  • Menu system: don't set the autocr flag on the serial console.
  • altmbr: fix handling of logical partitions.
  • altmbr: cap at 439 bytes so the partition select byte isn't part of the file.

Changes in 3.80

  • New shuffler mechanism and API.
  • Rewritten mboot.c32 module.
  • The syslinux_boot_linux() function has been simplified.
  • Don't hang trying to boot a "menu quit" label from the CLI.
  • Fix problem with boot-once "sticking" on some BIOSes.
  • isohybrid: fix problem with images over 2 GB in size.
  • APM poweroff module ( by Sebastian Herbszt.
  • ISOLINUX: fix the handling of large directories. Bug found and fixed by Steffen Winterfeldt.

Changes in 3.75

  • PXELINUX: fix the "keeppxe" option, which was broken in 3.74.
  • MEMDISK: correct the extraction of geometry information from the MBR of a hard disk image, again broken in 3.74.
  • extlinux(1) man page from Brian Pellin.
  • Simple menu: MENU SAVE is now controllable on a menu-by-menu or entry-by-entry basis.
  • gPXELINUX: fix interrupt-disabling bug.
  • HDT: fix lockup on machines with certain PCI configurations.

Changes in 3.74

  • New UI directive, which allows a more natural way to specify a menu system (or not.) With the UI directive specifying the menu system, the DEFAULT directive can be used to select the default entry inside the menus.
  • kbdmap.c32: new module to load a new keyboard map dynamically.
  • isohybrid: workaround bug in some versions of binutils.
  • Fix issue with the placement of the initrd on some machines.
  • ifcpu64: fix handling of less than three arguments.
  • Fix bug in the shuffle library when dealing with a very large number of fragments.
  • Documentation fixes by Vicente Jimenez Aguilar.
  • gPXE updated to version 0.9.7.
  • hdt.c32: Hardware Detection Tool, an interactive hardware analyzer module by Erwan Velu.
  • MEMDISK: enable automatic determination of the disk geometry for a large floppy disk image if (and only if) it is formatted with a FAT filesystem.
  • SYSLINUX: fix the handling of .bss files on FAT12/16.
  • Suppress the Loading ... message if "quiet" is specified on the kernel command line.
  • Fix the use of "CONSOLE 0" with menu.c32.
  • Allow COM32 modules to be aware of all memory even in the presence of a memory hole. The "linux.c32" module can be used to load a kernel (or memdisk) plus large initrd on such a system.
  • MBR: produce alternate MBR variants which force the drive number to hd0 (_f variants), or force the drive number to hd0 if the Ctrl key is pressed (_c variants.) Furthermore, add an MBR variant (altmbr*.bin) which ignores the active flag and instead boots the partition number specified in the byte at offset 439 decimal.
  • Add IPAPPEND strings to com32 modules, especially needed for linux.c32.
  • New MENU SAVE directive which saves the latest menu selection until the next boot. Currently only implemented for EXTLINUX.
  • *experimental* interface module to Steffen Winterfeldt's "gfxboot" graphical front end ( Module by Sebastian Herbszt.

Changes in 3.73

  • Upgrade gPXE to release version 0.9.5.
  • Fix a number of build errors on various platforms.
  • Handle systems with E820 "extended attributes" per ACPI 3. Someone "cleverly" decided to change the E820 spec in a backwards-incompatible manner!
  • MEMDISK: default to "safeint".
  • Adopt the moniker "The Syslinux Project", standard proper noun capitalization, to refer to the project as a whole. Thus, reserve the all-caps "SYSLINUX" to refer to the FAT loader.
  • mboot.c32: add "-solaris" option to pass DHCP information to the Solaris kernel; required for automatic Solaris boot without using Solaris' pxeboot program.
  • config.c32: trivial COM32 module to restart Syslinux with another configuration file from the command line (equivalent to the CONFIG command in the configuration file.)

Changes in 3.72

  • Include the module from Jeffery Hutzelman at Carnegie Mellon University. This allows chaining another PXE boot program while changing the DHCP packet passed to it.
  • Reorganize the Makefile system.
  • Major PCI core cleanups and other source cleanup.
  • gPXE code updated.
  • Try to avoid memory-snooping attacks on passwords. Note that if someone has root on the box, they generally don't need to compromise the boot loader...
  • ISOLINUX: fix crash when given a zero-length file.
  • sdi.c32: support gzipped SDI images.
  • ISOLINUX: support generating images which can be either a CD-ROM or a hard disk (USB disk, etc.) See doc/isolinux.txt for more information.
  • Remote gdb support for COM32 modules; patch from Stefan Hajnoczi.
  • Support beeps in F-key help in the simple menu system.
  • Tab display of labels, based on a patch from Sebastian Herbszt. Can be disabled with the NOCOMPLETE configuration command.
  • "menu default" can now be specified after "menu begin", to indicate that a specific submenu should be the default entry.

Changes in 3.71

  • Workaround for a VESA BIOS which tries to make DOS system calls(!!)
  • Simple menu: fix navigation around disabled entries (or at least try to...)
  • EXTLINUX: proper error message when confused about mount point.
  • MEMDISK: be smarter about incompletely disabled floppies in the BIOS and about being the only BIOS.
  • Optionally allow initrd to be specified on a separate line rather than as part of the "append" line. This is not recommended, but apparently makes life easier for some tools.
  • SYSLINUX: if no config file is present, set the current directory to the root directory (Sebastian Herbszt.)
  • chain.c32: option "hide" to support hiding and unhiding of primary partitions on the boot drive with DOS, Win, or OS/2 partition types (01, 04, 06, 07, 0b, 0c, 0e).
  • Unbreak the KBDMAP command (broken in 3.70).
  • EXTLINUX: fix the handling of the ADV when using CBIOS.
  • ifcpu64.c32: simple COM32 module to select a 32- or 64-bit kernel (and optionally 32-bit kernels with or without PAE.) Eventually we want a scripting language for this kind of stuff; a Lua module is under development.
  • Fix parsing of the SERIAL command without a baud rate specified.
  • chain.c32: error out when try to boot an unbootable partition.
  • SYSLINUX: when building the Win32 installer, search for MinGW under a large number of possible names.

Changes in 3.70

  • PXELINUX: Support enhanced capabilities when running on top of gPXE ( In particular, support URL-style syntax for filenames, and any protocol that gPXE supports (except, currently, iSCSI and AoE.) This feature is currently highly experimental.
  • Substantial infrastructure changes to support files whose length aren't known at open time (typically network connections.) Please note that the semantics of some of the comboot APIs have changed slightly; please see doc/comboot.txt.
  • PXELINUX: We no longer require a TFTP server which supports the tsize option for all transfers.
  • PXELINUX: Integrate with the gPXE source base; unified image now included as "gpxelinux.0".
  • The source tree has been restructured; files that were previously in the root have moved into the core, dos, gpxe, and utils directories.
  • "make install", "make netinstall", and "make extbootinstall" have been updated massively. "make install-all" now installs all three.
  • Change default dir for auxiliary files from /usr/lib/syslinux to /usr/share/syslinux.
  • SYSLINUX: VFAT long filename support.
  • MEMDISK: Any image less than 4096K (4 MB) is treated as a floppy disk. The geometry-guessing code will recognize all common extended formats, but it is still possible some very exotic formats need geometry specification. Large floppies and very small harddisks still need explicit specification.
  • chain.c32: option "swap" to support swapping of BIOS drive numbers. This is necessary to boot certain operating systems (DOS, Windows) from a secondary drive.
  • chain.c32: option "file=" to support loading a boot file from the SYSLINUX filesystem instead of loading the boot sector from the drive.
  • chain.c32: option "seg=" to control the load location.
  • chain.c32: option "ntldr=" as a shorthand for "seg=0x2000 file="; use this to load one of WinNT's loaders:
chain.c32 hd0 1 ntldr=/MiniNT/setupldr.bin

Note that the file needs to be in the SYSLINUX filesystem.

  • chain.32: options "freedos=" and "msdos="/"pcdos=" as shorthands for "seg=0x60 file=" and "seg=0x70 file=" respectively; use this to load FreeDOS's kernel.sys, MS-DOS's io.sys or PC-DOS's ibmbio.sys.
  • Change to the A20 algorithm which *MIGHT* help systems that have systems which freeze when Syslinux is used with USB keyboards. Note that this has been hard do verify, so I would greatly appreciate feedback on it.
  • Complex menu system: unbreak menus which has unnamed submenus, like complex.c.
  • Fix newline on the serial port for some com32 modules.
  • chain.c32: support "boot" as the drive specification, indicating the drive from which it was booted (for syslinux/extlinux).
  • SYSLINUX/EXTLINUX: support "localboot" with the same feature set as ISOLINUX.
  • Add an experimental MBR for GPT partition tables.
  • Use $(CC) when determining compile flags.
  • chain.c32: fix booting from logical partitions (Sergey Vlasov.)

Changes in 3.63

  • Fix errors in the PCI and DMI detection modules (Erwan Velu, Sebastian Herbszt).
  • Fix host dependencies and other issues in the build system.
  • PXELINUX: Allow class E addresses as unicast.
  • sdi.c32: module to load Microsoft System Deployment Images. For additional information, please see: RAM Boot Using SDI in Windows XP Embedded with Service Pack 1
  • EXTLINUX: Correct reading directories with deleted entries.
  • Shuffle library: correct the handling of certain geometries (an upward move with source material blocking the move); as required by sdi.c32 but theoretically possible for other formats as well.
  • Add "make netinstall" to install /tftpboot.
  • Fix some documentation files that didn't get moved/renamed.

Changes in 3.62

  • Clean up garbage after aborted. message.
  • Clean up filenames.
  • Support SHA256 and SHA512 encrypted passwords.
  • The shuffle library now can generate chained descriptors, thus allowing pretty much arbitrarily complex memory maps.
  • Handle command lines up to 2047 characters, the current Linux kernel limit.
  • vesamenu: support systems without linear framebuffer support (sigh, what is this, 1993?) and 15-bit RGB modes.
  • Move the label storage (for the command-line interface) to high memory, removing the size limit and freeing up 64K of low memory.
  • Get rid of 4096-entry limit in the simple menu system.
  • New hierarchial submenu support: see MENU BEGIN, MENU END, MENU GOTO in <a href="menu.php">doc/menu.txt</a>.
  • MENU QUIT allows creating a menu entry for returning to the command line.
  • ISOLINUX: Work around bug in certain Adaptec BIOSes, patch by Bruce Robson.
  • pngtopnm dependency removed from samples/ directory.
  • Text documentation files (in doc/) renamed *.doc -> *.txt.

Changes in 3.61

  • EXTLINUX: fix crash when accessing an empty file.
  • elf.c32: If a PHDR segment is present, load it.
  • Fix SHA-1 and MD5 passwords.
  • ISOLINUX: fix booting when mastered without mkisofs -boot-info-table (broken since 3.50, sigh...)
  • Handle BIOSes which emit multiple contiguous valid memory regions in the e820 map.

Changes in 3.60

  • Support for "auxilliary data vector", a small amount of writable storage. Currently only supported for EXTLINUX, but the infrastructure is there for the other derivatives, assuming a suitable storage location can be found.
  • EXTLINUX: boot-once support (--once, --clear-once, and --reset-adv).
  • A command is now required to the EXTLINUX installer, i.e. at least one of --install, --update, --once, --clear-once, or --reset-adv.

Changes in 3.55

  • PXELINUX: as per RFC 5071, PXELINUX no longer requires the use of the magic cookie option (208) for unencapsulated options. Currently it does not require it for vendor-encapsulated options (vendor-option-space) either, but that MAY be reverted in the future if it causes problems.
  • Documentation text files moved to a common "doc" directory; man pages from the Debian project added to the "man" directory.
  • Correct bug with self-overlapping memory areas when using the shuffle interface.

Changes in 3.54

  • Add "menu separator", "menu indent", "menu disabled" (see
  • vesamenu: fix handing of VESA modes with noncontiguous memory buffers. In particular, Qemu/KVM sets up such a mode when Cirrus Logic emulation is enabled (which is the default.)
  • Support for calling real mode functions using far calls, with argument on the stack. This was implemented to support the BIOS BBS specification, but subsequent experiments show that the at least one of the most common BIOS cores, Award, passes the presence check but doesn't actually implement the functionality.

Changes in 3.53

  • Fix bugs related to the $PnP BIOS functionality on some platforms.
  • PXELINUX: Fix the "naked" version of :: (suppress prefix.)
  • elf.c32: better error messages.
  • Faster operation under Intel VT virtualization.
  • PXELINUX: Fix DHCP bootfile option.
  • mkdiskimage: Support more than 1024 cylinders.
  • (Hopefully) fix installer on non-x86 platforms.
  • Fix shuffle_and_boot_rm, used by linux.c32.
  • Fix shuffle_and_boot_pm on 386/486.
  • ISOLINUX (at least): fix bss memory overwrite hang.
  • MBR: Fix booting from logical partitions.
  • Code cleanups.

Changes in 3.52

  • Handle capitalized F-key commands in the menu system.
  • Fix padding error when loading multiple ramdisks.
  • Workaround for VMware crashing when trying to print a message during early kernel boot (does not seem to work, consider deleting.)
  • chain.c32: add the ability to search for a specific MBR signature at runtime.
  • Fall back to the server identity option if the siaddr field in the DHCP header isn't set. This seems to match the behaviour of most PXE stacks.
  • mkdiskimage: give the generated disk image an MBR signature.
  • MEMDISK: Fix failures on some BIOSes.
  • Simple menu system: new "MENU HIDDEN" option to not display the menu unless the user presses a key.
  • Simple menu system: support MD5-encrypted passwords (modern Unix standard style, with "$1$" prefixes.)
  • pcitest.c32: now functions as a full "lspci". Thanks to Erwan Velu for this work.
  • MEMDISK: Make EDD actually work.
  • ISOLINUX: Fix for certain broken CD-ROM BIOSes which randomly corrupted register FS.
  • Simple menu system: fix memory overwrite bug that caused some systems to lock up or behave weirdly.
  • Fix building on 64-bit systems without a 32-bit libc installed.

Changes in 3.51

  • EXTLINUX: Fix failure to find the configuration file.

Changes in 3.50

  • New keywords allow the type of file to be specified in the configuration file.
  • It is now supported to load a different configuration file with the CONFIG keyword.
  • Fix API call 0x0019 (Read Disk.)
  • MENU AUTOBOOT, MENU TABMSG, MENU PASSPROMPT allows internationalization of menu messages.
  • A new feature, TEXT HELP, allows the administrator to set a multi-line help message for individual selections.
  • Fix API call 0x0012 (Cleanup, shuffle and boot.)
  • New API call "Cleanup, shuffle and boot to flat protected mode"
  • New API call "Cleanup, shuffle and boot to real mode", similar to API call 0x0012 but allows arbitrary register setting.
  • Introduce a library interface for loading arbitrary binary formats with relatively easily understood code. See the elf.c32 module for an example on how to use it.
  • New module elf.c32, to load a protected-mode ELF kernel.
  • MBR (old and new): Fix bug in CHS mode when LBA > 65535*sectors.
  • vesamenu: fix decoding of palettized PNG images.
  • Update the Linux kernel boot protocol.
  • PXELINUX: Press Ctrl-N at the boot prompt to read out the network info.
  • Instead of the (non-existent) MAC, use the client identifier for networks like Infiniband and Firewire/1394.
  • Add a new INCLUDE command to the core syslinux parser.
  • Allow binding help text to F11 and F12.
  • F-key help now available in the simple menu system.
  • Disabled the polling for ARP during idle. It is simply too slow on some (broken!) PXE stacks.
  • PXELINUX: also try to fetch the config file based on UUID.
  • SYSLINUX/EXTLINUX: New RAID mode (-r) which calls the BIOS to load the next device (typically the next drive) on boot failure.

Changes in 3.36

  • MEMDISK: Disable EDD by default on floppy disks. EDD can be enabled with the "edd" option and disabled with "noedd". This (hopefully) should make Ghost work again.
  • SYSLINUX: "unix" installer now uses Linux ioctls instead of using libfat.
  • New MBR which can boot from logical partitions.
  • SYSLINUX: Fix bug in detecting special extensions which was introduced in 3.35 :(
  • PXELINUX: Unbreak chainbooting FreeBSD (and possibly others.)

Changes in 3.35

  • MEMDISK: New "safeint" mode.
  • MEMDISK: Be more compliant with the PnP BIOS spec.
  • MEMDISK: Turn on EDD support by default.
  • MEMDISK: Try to work on some machines on which it would not work when there was no floppy drive in the system.
  • Simple menu system: fix serial console support (broken in 3.30).
  • SYSLINUX: Support subdirectories. Like ISOLINUX, the "current directory" is the directory in which syslinux.cfg is found; this is searched for in the sequence /boot/syslinux, /syslinux, /. As a side benefit, label names like "linux-2.6.18" and "linux-2.6.19" are now supported.

    To install ldlinux.sys in a subdirectory, pass the -d directory option to the SYSLINUX installer.

    This work was sponsored by (thanks, Tomas!)
  • New API call: read disk.
  • Invoke ONERROR on initrd load failure.

Changes in 3.31

  • The simple menu system (menu.c32 and vesamenu.c32) now support loading more than one configuration file at a time, using MENU INCLUDE or by specifying multiple filenames.
  • The MENU COLOR statement can now control the shadowing mode.

Changes in 3.30

  • libcom32 extended to support graphics mode and graphical console.
  • vesamenu.c32, new graphical version of the Simple Menu System, see
  • New com32 modules by Erwan Velu do selection based on CPUID or PCI devices present.
  • RPM spec: add syslinux-tftpboot module; move syslinux by default to the /usr/share/syslinux directory.
  • RPM spec: extlinux is now a separate package.

Changes in 3.20

  • EXTLINUX: New options --install (-i) and --update (-U), to make it clear if a boot loader should be installed or updated. For now, defaults to --install for compatibility; a future version will require one of these options.
  • New library functions to load and place files in memory.
  • mboot.c32 bug fixes.
  • Remove 8 MB kernel size restriction.
  • Add "klibc" target for building unix/syslinux and extlinux/extlinux with klcc (klibc-1.4.27 or later.)
  • PXELINUX: Fail (and eventually reboot) if no configuration file was found.
  • COM32 module by Erwan Velu to make decisions based on DMI info.
  • Fix issue where going back and forth between menus a lot would cause a hang.
  • ISOLINUX: Fix bug which made "cd boot sectors" not work.

Changes in 3.11

  • MEMDISK: Fix bug by which accessing the real floppy disk as B: in MS-DOS was broken.
  • Simple menu system: allow tweaking of the screen layout.
  • Simple menu system: better command-line editing, correctly handle command lines above 256 characters.
  • PXELINUX: revert memory allocation change that caused problems on some network cards.
  • MEMDISK: Try work around a bug on some BIOSes when no physical floppy disk is present in the system.
  • Enable the 16550A FIFOs, if present, when doing serial console.
  • New "totaltimeout" command establishes a timeout without regard for any user input.
  • Simple menu system: timeout behaviour now more in line with user expectations.
  • Simple menu system: "ontimeout" should now work correctly.

Changes in 3.10

  • gcc 4.0.1 compilation fixes.
  • Add support for querying the PCI BIOS in libcom32 (used by ethersel et al.)
  • Fix PCI handing (ethersel etc) on several old chipsets (and VMWare.)
  • Try to deal with systems with broken EBIOS.
  • New API call to do "localboot".
  • New API call to query features.
  • New API call to run kernel image, a lower-level call than "run command". See comboot.doc.
  • Fix for bug in EBIOS code discovered by Arwin Vosselman.
  • NOESCAPE security fix.
  • Comments are now recognized even without a space following #.
  • Fix incorrect handling of mixes of entries with and without MENU PASSWD.
  • The idle API call now harmlessly returns failure if it is a no-op. That way the caller can decide whether or not to bother invoking it again.
  • Temporarily disable the idle API call on PXELINUX, due to some platforms on which the idle API call seems to hang; this problem has not yet been debugged.
  • MEMDISK: the handling of DOSEMU-headered images was broken; fix it.
  • EXTLINUX: symlinks are now supported.
  • Simple menu system: N and P now work correctly as hotkeys.
  • MEMDISK: more BIOS bug workarounds.

Changes in 3.09

  • gcc4 compilation fix.
  • <BEL> (Ctrl-G) in message files now causes a beep.
  • Reduce the command line to 511 characters; 1023 caused memory overflows.

Changes in 3.08

  • SYSLINUX: Fix performance regression (-s mode always enabled.)
  • Add API function for idle loop.
  • libutil: Add do_idle() function for idle loop, make get_key() use it.
  • libutil: Add SHA-1 and base64 functions.
  • Simple menu system: add password support.
  • EXTLINUX: Sparse files now handled correctly.
  • EXTLINUX: Large directories now handled correctly.
  • ALL: At the prompt, Ctrl-X now forces text mode.
  • Fix configuration file parsing error, that could cause hangs.
  • Rewritten advanced menuing system from Murali Ganapathy.
  • MEMDISK: New "bigraw" mode to work around certain broken BIOS flash programs.
  • COM32 module to boot Multiboot systems, including Xen. See com32/modules/mboot.doc.
  • Max command line changed to 1023 characters. Note that the kernel proper still can only handle 255 characters without patching, and COM16 binaries can only handle 125 characters.

Changes in 3.07

  • Fix chainloading (chain.c32).
  • Fix zlib build problem.
  • Use a private copy of <linux/ext2_fs.h>.

Changes in 3.06

  • Fix typo that caused the ramdisk to load in the wrong place.

Changes in 3.05

  • New API function "shuffle and boot"; allows COM32 modules to load or construct (almost) arbitrarily complex objects, e.g. a kernel and its initrd/initramfs in pieces, and have the API core reorganize memory for booting. (A library API for this function will be introduced in a later version.)
  • The initrd= option now supports multiple filenames separated by commas. This is mostly useful for initramfs, which can be composed of multiple separate cpio or cpio.gz archives. (Note: all files except the last one are zero-padded to a 4K page boundary. This should not affect initramfs.)
  • EXTLINUX: Fix API function 000Ah (get derivative-specific info).
  • libcom32/ethersel: Support PCI Config Mechanism #2 on machines still infested with that hideous old hack.
  • SYSLINUX: Fix directory-parsing bug.

Changes in 3.02

  • SYSLINUX: The "unix" installer now sets the MS-DOS attributes (hidden, system, readonly.)
  • COM32 library: build the .lnx (test modules for running under Linux) as architecture native modules, in case i386 devel libraries aren't installed.
  • EXTLINUX: Hack for systems which don't have BLKGETSIZE64 defined in the standard header files.
  • Simple menu system: minor aestetic improvements, and try to work better over a serial console (speed, and readability on monochrome terminal emulators.)
  • New CONSOLE directive to control output on the video console (useful for dealing with some broken serial-forwarding BIOSes.)
  • New com32 module "ethersel" for searching for an Ethernet card and selecting the proper version of Etherboot.
  • EXTLINUX: Allow the user to override the detected geometry. Add help.

Changes in 3.01

  • EXTLINUX, SYSLINUX: Fix compile errors on some systems.
  • EXTLINUX: Default to zipdrive geometry (64 heads, 32 sectors) if no other geometry can be detected.

Changes in 3.00

  • SYSLINUX: Support FAT32 and EDD. As an unfortunate consequence, LDLINUX.SYS is no longer an ordinary file; it is block-mapped at install time, which means it can only be written using the syslinux installers.
  • SYSLINUX: Reorganize the source code for the installers; each one of the installers (dos, win32, unix, mtools) is now built in its own subdirectory. In particular, "mtools" is the unprivileged installer which uses mtools; "unix" is the privileged installer which uses system calls.
  • SYSLINUX: Completely rewritten DOS installer in C.
  • ALL: "label" statement information is now stored in a compressed format, which means that a lot more labels are permitted (500-1000 in a typical configuration, but depends on the complexity.)
  • EXTLINUX: New derivative, which boots from an ext2/ext3 filesystem.
  • SYSLINUX: The DOS and Win32 installers can now optionally write the boot sector to a file instead of the real boot sector. This is not supported in the Linux installers, however.
  • ALL: New NOESCAPE command, disables the "hold down the Shift key to display the prompt" behaviour.
  • New simple menu system, as an alternative to the advanced menu system already present. See for details.
  • PXELINUX: Filenames can now be prefixed with an IP address or DNS name plus :: (e.g. or, which downloads a file from an alternate TFTP server, or just a :: (e.g. ::filename), which suppresses the common pathname prefix. See pxelinux.doc.
  • SYSLINUX: Add an -m option to the DOS and Win32 installers to write an MBR and -a to mark the partition SYSLINUX is being installed on active.
  • MEMDISK: Give a way to query the boot loader type while running MEMDISK; see memdisk/memdisk.doc and sample/mdiskchk.c.
  • mkdiskimage: substantially improved mkdiskimage which, among other things, can now be used to initialize USB keys as zipdrives; see README.usbkey for more information.