Configuration location and name
Note: In the following paragraphs, the "/" directory represents the root of the filesystem in which Syslinux (in its several variants) is (going to be) installed.
BIOS
SYSLINUX / EXTLINUX default to searching for the config file in the installed directory (containing ldlinux.sys or extlinux.sys).
[3.35+] SYSLINUX also searches for the config file in "/boot/syslinux/", "/syslinux/" and "/", in this order.
The first configuration file that is found stops the search and the configuration file is parsed / used.
[-3.xx] SYSLINUX uses syslinux.cfg as config file name. EXTLINUX (merged into SYSLINUX as of 4.00) used extlinux.conf.
[4.00+] In each searched-for directory, SYSLINUX searches first for extlinux.conf and then for syslinux.cfg before falling back to the next directory.
[-4.02] ISOLINUX uses isolinux.cfg as config file name, searching first in "/boot/isolinux/" [2.00+] , then in "/isolinux/" and then in "/".
[4.03+] ISOLINUX searches for isolinux.cfg and then for syslinux.cfg in "/boot/isolinux/" before searching for the same files in "/isolinux/", "/boot/syslinux/", "/syslinux/", and "/", in this order.
Since version 4.03, the resulting behavior is that the same
"/[[boot/]syslinux/]syslinux.cfg"
file can optionally be used for
SYSLINUX / EXTLINUX / ISOLINUX,
while specific isolinux.cfg
and/or extlinux.conf files would take precedence if present.
Since version 4.03, the resulting behavior is that
any of the respective config files (or even all of them)
— namely
isolinux.cfg, and/or
extlinux.conf, and/or
syslinux.cfg —
can optionally be located together in the same
"/[[boot/]syslinux/]"
directory.
UEFI
SYSLINUX
defaults to searching for
the configuration file in the installed directory, where
syslinux.efi
is located and containing also its corresponding
" ldlinux.* "
file.
[6.04+] In each searched-for directory, SYSLINUX searches first for either:
- syslia32.cfg when booting in EFI_ia32 mode
- syslx64.cfg when booting in EFI_x64 mode
and finally SYSLINUX searches for syslinux.cfg before falling back to the next directory.
The first configuration file that is found stops the search and the configuration file is parsed / used.
Note that syslinux.efi could be optionally renamed.
