linux/Documentation/filesystems/bfs.rst
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   1.. SPDX-License-Identifier: GPL-2.0
   2
   3========================
   4BFS Filesystem for Linux
   5========================
   6
   7The BFS filesystem is used by SCO UnixWare OS for the /stand slice, which
   8usually contains the kernel image and a few other files required for the
   9boot process.
  10
  11In order to access /stand partition under Linux you obviously need to
  12know the partition number and the kernel must support UnixWare disk slices
  13(CONFIG_UNIXWARE_DISKLABEL config option). However BFS support does not
  14depend on having UnixWare disklabel support because one can also mount
  15BFS filesystem via loopback::
  16
  17    # losetup /dev/loop0 stand.img
  18    # mount -t bfs /dev/loop0 /mnt/stand
  19
  20where stand.img is a file containing the image of BFS filesystem.
  21When you have finished using it and umounted you need to also deallocate
  22/dev/loop0 device by::
  23
  24    # losetup -d /dev/loop0
  25
  26You can simplify mounting by just typing::
  27
  28    # mount -t bfs -o loop stand.img /mnt/stand
  29
  30this will allocate the first available loopback device (and load loop.o
  31kernel module if necessary) automatically. If the loopback driver is not
  32loaded automatically, make sure that you have compiled the module and
  33that modprobe is functioning. Beware that umount will not deallocate
  34/dev/loopN device if /etc/mtab file on your system is a symbolic link to
  35/proc/mounts. You will need to do it manually using "-d" switch of
  36losetup(8). Read losetup(8) manpage for more info.
  37
  38To create the BFS image under UnixWare you need to find out first which
  39slice contains it. The command prtvtoc(1M) is your friend::
  40
  41    # prtvtoc /dev/rdsk/c0b0t0d0s0
  42
  43(assuming your root disk is on target=0, lun=0, bus=0, controller=0). Then you
  44look for the slice with tag "STAND", which is usually slice 10. With this
  45information you can use dd(1) to create the BFS image::
  46
  47    # umount /stand
  48    # dd if=/dev/rdsk/c0b0t0d0sa of=stand.img bs=512
  49
  50Just in case, you can verify that you have done the right thing by checking
  51the magic number::
  52
  53    # od -Ad -tx4 stand.img | more
  54
  55The first 4 bytes should be 0x1badface.
  56
  57If you have any patches, questions or suggestions regarding this BFS
  58implementation please contact the author:
  59
  60Tigran Aivazian <aivazian.tigran@gmail.com>
  61