On Wed, Aug 30, 2023 at 04:23:36PM +0200, Ard Biesheuvel wrote:
> On Wed, 30 Aug 2023 at 16:18, Daniel Kiper <dkiper@net-space.pl> wrote:
> >
> > On Fri, Aug 25, 2023 at 05:50:58AM -0700, Oliver Steffen wrote:
> > > Quoting Vladimir 'phcoder' Serbinenko (2023-08-15 18:14:11)
> >
> > [...]
> >
> > > I am not sure what the best way forward is now, but we at least have the
> > > patches from Vladimir (thanks!).
> > >
> > > Pedro, Adrian, could you - if you get a chance - try them with a 4 byte
> > > alignment too?
> >
> > Yes, that would be perfect. If Itanium works then I suggest to align
> > GUIDs to 4 bytes. This alignment is used in the kernel for more than
> > 4 years and it looks nobody complains...
> >
> > Pedro, Adrian, could you change GUIDs alignment in Vladimir's patches to
> > 4 and test them on Itanium?
> >
>
> Note that itanium is a 64-bit architecture, whereas the potential
> alignment/padding issue I raised only occurs on 32-bit systems.
Yeah, I know. But IIRC your Linux kernel patch aligns GUIDs to 4 bytes
even on Itanium. So, how does it work on 64-bit architecture and nobody
complained for more than 4 years... Hmmm...
Unaligned access causes an exception. In GRUB it leads to unhandled exception. Linux catches exception and emulates unaligned access. It's typical for RISC platforms