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Diffstat (limited to 'contrib/syslinux-4.02/doc/extlinux.txt')
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diff --git a/contrib/syslinux-4.02/doc/extlinux.txt b/contrib/syslinux-4.02/doc/extlinux.txt new file mode 100644 index 0000000..6974a51 --- /dev/null +++ b/contrib/syslinux-4.02/doc/extlinux.txt @@ -0,0 +1,132 @@ +EXTLINUX is a new Syslinux derivative, which boots from a Linux +ext2/ext3 filesystem. + +It works the same way as SYSLINUX (see doc/syslinux.txt), with a few +slight modifications. + +1. The installer is run on a *mounted* filesystem. Run the extlinux + installer on the directory in which you want extlinux installed: + + extlinux --install /boot + + Specify --install (-i) to install for the first time, or + --update (-U) to upgrade a previous installation. + + NOTE: this doesn't have to be the root directory of a filesystem. + If /boot is a filesystem, you can do: + + mkdir -p /boot/extlinux + extlinux --install /boot/extlinux + + ... to create a subdirectory and install extlinux in it. + /boot/extlinux is the recommended location for extlinux. + + +2. The configuration file is called "extlinux.conf", and is expected + to be found in the same directory as extlinux is installed in. + + +3. Pathnames can be absolute or relative; if absolute (with a leading + slash), they are relative to the root of the filesystem on which + extlinux is installed (/boot in the example above), if relative, + they are relative to the extlinux directory. + + extlinux supports subdirectories, but the total path length is + limited to 511 characters. + + +4. EXTLINUX now supports symbolic links. However, extremely long + symbolic links might hit the pathname limit. Also, please note + that absolute symbolic links are interpreted from the root *of the + filesystem*, which might be different from how the running system + would interpret it (e.g. in the case of a separate /boot + partition.) Therefore, use relative symbolic links if at all + possible. + + +5. EXTLINUX now has "boot-once" support. The boot-once information is + stored in an on-disk datastructure, part of extlinux.sys, called + the "Auxillary Data Vector". The Auxilliary Data Vector is also + available to COMBOOT/COM32 modules that want to store small amounts + of information. + + To set the boot-once information, do: + + extlinux --once 'command' /boot/extlinux + + where 'command' is any command you could enter at the Syslinux + command line. It will be executed on the next boot and then + erased. + + To clear the boot-once information, do: + + extlinux --clear-once /boot/extlinux + + If EXTLINUX is used on a RAID-1, this is recommended, since under + certain circumstances a RAID-1 rebuild can "resurrect" the + boot-once information otherwise. + + To clear the entire Auxillary Data Vector, do: + + extlinux --reset-adv /boot/extlinux + + This will erase all data stored in the ADV, including boot-once. + + The --once, --clear-once, and --reset-adv commands can be combined + with --install or --update, if desired. The ADV is preserved + across updates, unless --reset-adv is specified. + + +Note that EXTLINUX installs in the filesystem partition like a +well-behaved bootloader :) Thus, it needs a master boot record in the +partition table; the mbr.bin shipped with Syslinux should work well. +To install it just do: + + cat mbr.bin > /dev/XXX + +... where /dev/XXX is the appropriate master device, e.g. /dev/hda, +and make sure the correct partition in set active. + + +If you have multiple disks in a software RAID configuration, the +preferred way to boot is: + +- Create a separate RAID-1 partition for /boot. Note that the Linux + RAID-1 driver can span as many disks as you wish. + +- Install the MBR on *each disk*, and mark the RAID-1 partition + active. + +- Run "extlinux --raid --install /boot" to install extlinux. This + will install it on all the drives in the RAID-1 set, which means + you can boot any combination of drives in any order. + + + +It is not required to re-run the extlinux installer after installing +new kernels. If you are using ext3 journalling, however, it might be +desirable to do so, since running the extlinux installer will flush +the log. Otherwise a dirty shutdown could cause some of the new +kernel image to still be in the log. This is a general problem for +boot loaders on journalling filesystems; it is not specific to +extlinux. The "sync" command does not flush the log on the ext3 +filesystem. + + +The Syslinux Project boot loaders support chain loading other +operating systems via a separate module, chain.c32 (located in +com32/modules/chain.c32). To use it, specify a LABEL in the +configuration file with KERNEL chain.c32 and APPEND [hd|fd]<number> +[<partition>] + +For example: + +# Windows CE/ME/NT, a very dense operating system. +# Second partition (2) on the first hard disk (hd0); +# Linux would *typically* call this /dev/hda2 or /dev/sda2. +LABEL cement + KERNEL chain.c32 + APPEND hd0 2 + +See also doc/menu.txt. + |