Re: Linux not adhering to BIOS Drive boot order?

[Andreas Dilger <adilger@turbolinux.com>]

David Balazic writes:
> Andreas Dilger <adilger@turbolinux.com> wrote :
> > In the end I re-wrote most of the patch, so
> > that we resolve ROOT_DEV before calling mount_root(), just to be a bit
> > more consistent. I will release a new patch for 2.2.18 and 2.4.0 after
> > David Balazic has a look at it.
> 
> Cool, send it to me !

Need to test it a bit first (i.e. at least compile it)...

> > I know a bit about LILO, so I should be able to get the "root=LABEL=" to
> > work there as well.   
> 
> There were no problems with the original patch with LILO.
> You just must use append="root=xxxxx" instead of simply
> root=xxx , because LILO tries to be "smart" .... at least the
> version I used then did.

Actually, there are 2 ways to go about this: LILO could do the UUID/LABEL
resolution at the time lilo is run (to store root dev into kernel), and
_also_ append "root=LABEL=X" to kernel options, so that if the kernel
can't resolve the UUID/LABEL (i.e. no support for this option) we can fall
back to the root dev from when LILO was run.

> > One reason why this may NOT ever make it into the kernel is that I know
> > "kernel poking at devices" is really frowned upon.
> 
> This an ugly hack , if you ask me. The identificators ( be it labels ,
> UUIDs or whatever ) should be outside the partitions. Otherwise cases with
> swap partitions , <any FS that doesn't support labels/UUIDs> unformatted
> partitions etc. can not be handled.

LVM now has UUID-like identifiers for all "partitions" (Logical Volumes),
although they are not really accessible by any tools right now. The "LABEL"
is actually the LV name, so it is used directly all the time:

/dev/vgroot/lvroot	/	ext3	defaults	1	1
/dev/vgroot/lvswap	none	swap	sw,pri=100	0	0

This obviates most of the reason for the UUID/LABEL support, but not
everyone runs LVM (yet ;-) and ext2 UUID/LABELs are still useful.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert
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