linux/Documentation/filesystems/bfs.txt
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

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BFS FILESYSTEM FOR LINUX
========================
The BFS filesystem is used by SCO UnixWare OS for the /stand slice, which
usually contains the kernel image and a few other files required for the
boot process.
In order to access /stand partition under Linux you obviously need to
know the partition number and the kernel must support UnixWare disk slices
(CONFIG_UNIXWARE_DISKLABEL config option). However BFS support does not
depend on having UnixWare disklabel support because one can also mount
BFS filesystem via loopback:
# losetup /dev/loop0 stand.img
# mount -t bfs /dev/loop0 /mnt/stand
where stand.img is a file containing the image of BFS filesystem.
When you have finished using it and umounted you need to also deallocate
/dev/loop0 device by:
# losetup -d /dev/loop0
You can simplify mounting by just typing:
# mount -t bfs -o loop stand.img /mnt/stand
this will allocate the first available loopback device (and load loop.o
kernel module if necessary) automatically. If the loopback driver is not
loaded automatically, make sure that your kernel is compiled with kmod
support (CONFIG_KMOD) enabled. Beware that umount will not
deallocate /dev/loopN device if /etc/mtab file on your system is a
symbolic link to /proc/mounts. You will need to do it manually using
"-d" switch of losetup(8). Read losetup(8) manpage for more info.
To create the BFS image under UnixWare you need to find out first which
slice contains it. The command prtvtoc(1M) is your friend:
# prtvtoc /dev/rdsk/c0b0t0d0s0
(assuming your root disk is on target=0, lun=0, bus=0, controller=0). Then you
look for the slice with tag "STAND", which is usually slice 10. With this
information you can use dd(1) to create the BFS image:
# umount /stand
# dd if=/dev/rdsk/c0b0t0d0sa of=stand.img bs=512
Just in case, you can verify that you have done the right thing by checking
the magic number:
# od -Ad -tx4 stand.img | more
The first 4 bytes should be 0x1badface.
If you have any patches, questions or suggestions regarding this BFS
implementation please contact the author:
Tigran A. Aivazian <tigran@veritas.com>