grub / grub2 conflicts

Richard W.M. Jones rjones at
Thu Sep 15 15:56:43 UTC 2011

On Thu, Sep 15, 2011 at 04:25:41PM +0100, Matthew Garrett wrote:
> On Thu, Sep 15, 2011 at 04:21:36PM +0100, Richard W.M. Jones wrote:
> > On Thu, Sep 15, 2011 at 03:59:57PM +0100, Matthew Garrett wrote:
> > > We're talking about guest creation, aren't we?
> > 
> > No, we're talking about fixing and resizing existing guests, where
> > grub-install needs to be run to fix the bootloader.
> So how do you ensure that the version you run is the same version as the 
> package installed in the guest? Having those not match is an invitation 
> for bizarre failure down the line.

Well, this is interesting.

We're planning to snoop out whether the guest is using grub1 or grub2.
Previously this hasn't worked at all for (eg) Ubuntu guests.  This is
why providing grub2 in Fedora is great for us.

For grub1 guests, it has turned out not to matter which specific
version of grub [as long as it was grub1] was used, as apparently
grub-install updates all files needed in /boot/grub as appropriate.
Or at least we haven't come across a guest where this hasn't worked
(yet -- we could be in for a surprise).

I'm very interested in how to reinstall bootloaders *without* invoking
guest code.  Also in how to not break the bootloader when moving or
aligning the boot partition, which sometimes happens for reasons we
don't understand (but not on all grub1 guests, only on RHEL 5 era


Richard Jones, Virtualization Group, Red Hat
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