1 EXTLINUX is a new Syslinux derivative, which boots from a Linux 2 ext2/ext3 filesystem. 3 4 It works the same way as SYSLINUX (see doc/syslinux.txt), with a few 5 slight modifications. 6 7 1. The installer is run on a *mounted* filesystem. Run the extlinux 8 installer on the directory in which you want extlinux installed: 9 10 extlinux --install /boot 11 12 Specify --install (-i) to install for the first time, or 13 --update (-U) to upgrade a previous installation. 14 15 NOTE: this doesn't have to be the root directory of a filesystem. 16 If /boot is a filesystem, you can do: 17 18 mkdir -p /boot/extlinux 19 extlinux --install /boot/extlinux 20 21 ... to create a subdirectory and install extlinux in it. 22 /boot/extlinux is the recommended location for extlinux. 23 24 25 2. The configuration file is called "extlinux.conf", and is expected 26 to be found in the same directory as extlinux is installed in. 27 Since 4.00 "syslinux.cfg" is also tried if "extlinux.conf" is not 28 found. 29 30 31 3. Pathnames can be absolute or relative; if absolute (with a leading 32 slash), they are relative to the root of the filesystem on which 33 extlinux is installed (/boot in the example above), if relative, 34 they are relative to the extlinux directory. 35 36 extlinux supports subdirectories, but the total path length is 37 limited to 511 characters. 38 39 40 4. EXTLINUX now supports symbolic links. However, extremely long 41 symbolic links might hit the pathname limit. Also, please note 42 that absolute symbolic links are interpreted from the root *of the 43 filesystem*, which might be different from how the running system 44 would interpret it (e.g. in the case of a separate /boot 45 partition.) Therefore, use relative symbolic links if at all 46 possible. 47 48 49 5. EXTLINUX now has "boot-once" support. The boot-once information is 50 stored in an on-disk datastructure, part of extlinux.sys, called 51 the "Auxillary Data Vector". The Auxilliary Data Vector is also 52 available to COM32 modules that want to store small amounts of 53 information. 54 55 To set the boot-once information, do: 56 57 extlinux --once 'command' /boot/extlinux 58 59 where 'command' is any command you could enter at the Syslinux 60 command line. It will be executed on the next boot and then 61 erased. 62 63 To clear the boot-once information, do: 64 65 extlinux --clear-once /boot/extlinux 66 67 If EXTLINUX is used on a RAID-1, this is recommended, since under 68 certain circumstances a RAID-1 rebuild can "resurrect" the 69 boot-once information otherwise. 70 71 To clear the entire Auxillary Data Vector, do: 72 73 extlinux --reset-adv /boot/extlinux 74 75 This will erase all data stored in the ADV, including boot-once. 76 77 The --once, --clear-once, and --reset-adv commands can be combined 78 with --install or --update, if desired. The ADV is preserved 79 across updates, unless --reset-adv is specified. 80 81 82 Note that EXTLINUX installs in the filesystem partition like a 83 well-behaved bootloader :) Thus, it needs a master boot record in the 84 partition table; the mbr.bin shipped with Syslinux should work well. 85 To install it just do: 86 87 cat mbr.bin > /dev/XXX 88 89 ... where /dev/XXX is the appropriate master device, e.g. /dev/hda, 90 and make sure the correct partition in set active. 91 92 93 If you have multiple disks in a software RAID configuration, the 94 preferred way to boot is: 95 96 - Create a separate RAID-1 partition for /boot. Note that the Linux 97 RAID-1 driver can span as many disks as you wish. 98 99 - Install the MBR on *each disk*, and mark the RAID-1 partition 100 active. 101 102 - Run "extlinux --raid --install /boot" to install extlinux. This 103 will install it on all the drives in the RAID-1 set, which means 104 you can boot any combination of drives in any order. 105 106 107 108 It is not required to re-run the extlinux installer after installing 109 new kernels. If you are using ext3 journalling, however, it might be 110 desirable to do so, since running the extlinux installer will flush 111 the log. Otherwise a dirty shutdown could cause some of the new 112 kernel image to still be in the log. This is a general problem for 113 boot loaders on journalling filesystems; it is not specific to 114 extlinux. The "sync" command does not flush the log on the ext3 115 filesystem. 116 117 118 The Syslinux Project boot loaders support chain loading other 119 operating systems via a separate module, chain.c32 (located in 120 com32/modules/chain.c32). To use it, specify a LABEL in the 121 configuration file with KERNEL chain.c32 and APPEND [hd|fd]<number> 122 [<partition>] 123 124 For example: 125 126 # Windows CE/ME/NT, a very dense operating system. 127 # Second partition (2) on the first hard disk (hd0); 128 # Linux would *typically* call this /dev/hda2 or /dev/sda2. 129 LABEL cement 130 KERNEL chain.c32 131 APPEND hd0 2 132 133 See also doc/menu.txt. 134 135
