Bug#891434: grub-efi: System fails to boot after "No space left on device" on EFI variable storage

[Niels Thykier]

On Fri, 14 Dec 2018 10:22:49 +0100 Ralf Jung <post at ralfj.de> wrote:
> Hi,
> 
> > Fixing this does seem like it would be a good idea for general
> > robustness against dodgy firmware (this is not the first iteration of
> > problems along these lines).  It would take some development work, but
> > hopefully not too much.
> > 
> > Things that GRUB can't do, as far as I can tell:
> > 
> >  * I don't think there's a way for GRUB to check whether it will be
> >    possible to recreate a boot entry later; as I understand it, that
> >    depends on various low-level details, including firmware-specific
> >    quirks.
> >    
> >  * Even detecting that nothing changed would require cooperation from
> >    efibootmgr, since the encoding of the EFI variable is an
> >    implementation detail there (so we can't just read it out and
> >    compare), and efibootmgr doesn't expose a way for GRUB to say "set
> >    this configuration, but only if it's different from what's already
> >    there".
> > 
> > However, I think GRUB can at least manage to delete all but one entry
> > from the same distributor rather than all of them, and if it finds one
> > remaining entry then it can modify that rather than writing a brand new
> > variable.  As I understand it, that would probably be enough to fix this
> > bug?
> 
> Assuming that modification works even when the variable storage is (close to)
> full, then yes, that would at least keep the device bootable which would be a
> big improvement.
> 
> Kind regards,
> Ralf
> 
> 

Hi Colin,

Thanks for proposing this solution. :)

I also think it would be a good solution for now that will hopefully
avoid most of these errors. :)

Thanks,
~Niels