Re: Is there an SGI person in this list?

["Martin K. Petersen" <mkp linuxcare com>]

>>>>> "Jean" == Jean Francois Martinez <jfm2 club-internet fr> writes:

Not speaking for SGI, but...

Jean> One of the things making use of XFS more difficult is that the
Jean> superior booter (GRUB) does not support XFS.  This makes harder
Jean> the task of a distribution vendor willing to move to XFS (he
Jean> will have to ensure /boot is using ext2 or Reiser).  It also
Jean> makes life harder for people willing to move to XFS but
Jean> unwilling to downgrade to LILO.

Jean> Is there a chance SGI would write an XFS back end for the GRUB
Jean> booter?

Unlikely.  Since grub needs to understand the entire layout of the XFS
filesystem, it effectively means re-implementing a lot of the
filesystem code in the bootloader.  And that is not a small task.

Adding support for an indirect block based filesystem like ext2 is a
lot easier.  On the other hand, chances are that your kernel image
will be one unfragmented extent in the XFS case.  And this could
potentially mean cutting corners in the implementation of a backend.

The reason lilo works with XFS is that it maps the kernel image block
by block and saves the locations.  This has the advantage that lilo
can leverage the existing XFS code in the kernel instead of
understanding the inner workings of the filesystem at runtime.

I'm not saying that grub is bad.  It's just that the grub approach to
booting (while more convenient for the user) is a lot harder to
implement.

Nothing prevents you from keeping your /boot partition on ext2,
though.  And since /boot is small, the fsck time in case of a crash
will be negligible anyway.

If you use the modified Red Hat installer we put out, you can select
filesystem type for your partitions during installation.  So if you
know you need grub, just tag /boot as being ext2 and Bob is your
uncle.

Implementing an XFS backend for grub is left as en exercise for the
reader:)

-- 
Martin K. Petersen, Principal Linux Consultant, Linuxcare, Inc.
mkp linuxcare com, http://www.linuxcare.com/
SGI XFS for Linux Developer, http://oss.sgi.com/projects/xfs/