Re: [PATCH] use UUID to map system devices to grub devices

[Felix Zielcke]

Am Freitag, den 07.08.2009, 21:22 +0200 schrieb Robert Millan:
> On Fri, Aug 07, 2009 at 04:29:00PM +0200, Felix Zielcke wrote:
> > Am Freitag, den 07.08.2009, 13:27 +0200 schrieb Robert Millan:
> > > On Wed, Aug 05, 2009 at 08:18:29AM +0200, Felix Zielcke wrote:
> > > > Am Dienstag, den 04.08.2009, 23:19 +0200 schrieb Robert Millan:
> > > > > On Fri, Jul 31, 2009 at 06:26:51PM +0200, Felix Zielcke wrote:
> > > > > > 
> > > > > > If we'd do an arbitrary mapping then `grub-probe -t drive' would 
> > > > > > show
> > > > > > the wrong grub device.
> > > > > > But except from this I think that would be okay.
> > > > > 
> > > > > We can never garantee that `grub-probe -t drive' will show the 
> > > > > "right" drive,
> > > > > at least on i386-pc, because we don't know how is BIOS going to order 
> > > > > them.
> > > > 
> > > > Yes drive not, but the partition.
> > > 
> > > It's true, but we don't really make the distinction.  UUID search will 
> > > find
> > > a filesystem, which is in a partition (usually), and doesn't rely on 
> > > partitions
> > > being reliable.
> > > 
> > > That's fortunate!  It means we don't have to commit to partition numbers 
> > > being
> > > reliable, even if they are right now.
> > > 
> > > Because of this (unless I missed something), at the end of the day the
> > > unreliability issue you described doesn't translate into any real problem
> > > for us.  It just adds more to a problem we already solved.
> > > 
> > > > Unfortunately we don't have UUID support on every filesystem we support
> > > > like JFS. But I think it's not that commonly used.
> > > 
> > > Adding UUID support to new filesystems is very easy.  I did the first ones
> > > with just 5-10 minutes of research and a few lines of coding.
> > > 
> > > Would you like to do JFS ?
> > 
> > I did it now for JFS.
> > 
> > I tried it now out with dos_part set to p + 2 with my find_by_uuid patch
> > and now I get a `no such partition' error on my dmraid device.
> > So we can't use an arbitary mapping in grub_util_biosdisk_get_grub_dev
> 
> Why not?

well then we would need to change the partition table parsing code to
use the same arbitary mapping for GRUB_UTIL && LINUX then
grub_util_biosdisk_get_grub_dev and I think that's not really a proper
solution.


-- 
Felix Zielcke
Proud Debian Maintainer