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Re: disk labels mismatch



pavicic wrote:
> Bob Proulx wrote:
> > > I would say that this is something that should be 
> > > changed. Grub simply should not read unmounted disks.  
> > 
> > This is actually a feature that other people rely upon to work.  For
> > example people who dual boot multiple systems expect the update-grub
> > script to search and automatically detect those other systems.  If
> > update-grub didn't locate those then these other people would have the
> > opposite problem to yours.  They would then no longer have an
> > automatically provided boot option for those systems.
> 
> Do you want to say that they can boot from a disk which is not mounted?

Yes.  Exactly so.  It is a very common case.

For the most common (nonfree) example would be people with both
MS-Windows and Debian GNU/Linux on the same system.  I will guess that
most people do not mount the MS-Windows filesystem on the Debian side
of things since it is not a default setting.  They would need to set
it up if they did want that.  Of course that is possible and I am sure
that many people do mount the windows filesystem on their Debian
system.  But definitely not everyone.  I think most would not and
would reboot to access the opposite files.

Another commonly seen configuration is to have two or more different
operating systems all mount /home.  The user may boot into any of a
selection of Debian, Red Hat, SuSE or other operating systems.  They
have each of those mount a single /home so that they share the $HOME
among all of those systems.  Because $HOME is shared those files are
always shared.  There is no need to mount the root file system of
those alternative operating systems.  Again although it is possible to
mount those all around I haven't seen that as the likely case.  Most
do not and simply share the /home in that case.

A point that I think may be getting missed is that there is a
separation in time and separation in environment between when grub
boots the system and when update-grub creates the menu for it.  These
are relatively far apart in time and environment.

At the time that grub boots *none* of the filesystems are mounted.
There isn't an operating system yet.  It must bootstrap itself along.
None of the filesystems are mounted.  It sets up the kernel and the
initrd and then starts the kernel running and only eventually do
things get mounted during the bootstrapping process.

At the time that update-grub runs the current operating system is
fully operational.  It is a completely different environment.  Some
are mounted and some are not.  But it can't require that other file
systems are mounted.  The most typical dual boot cases won't work
then.

Bob

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