Re: [Qemu-devel] [PATCH] pc: drop external DSDT loading

[Michael S. Tsirkin]

On Fri, Aug 09, 2013 at 03:26:22PM +0200, Gerd Hoffmann wrote:
> On 08/09/13 14:38, Anthony Liguori wrote:
> > Gerd Hoffmann <address@hidden> writes:
> > 
> >> On 08/08/13 18:38, Anthony Liguori wrote:
> >>> This breaks migration and is unneeded with modern SeaBIOS.
> >>
> >> No.  Dropping for piix is fine.  It will break q35 though.
> > 
> > Can you elaborate?  When Michael and I discussed this I was under the
> > impression that latest SeaBIOS had full support for q35.
> 
> SeaBIOS has the piix acpi tables compiled in, for the snake of backward
> compatibility with old qemu versions which don't provide the acpi tables.
> 
> With the q35 merge seabios started to provide the apci tables via
> fw_cfg, for both q35 and piix, with the long-term goal to drop the
> internal tables some day even for piix.
> 
> Later on we figured table loading has live migration issues (due to bios
> binary being migrated but acpi tables are not, so you can end up with
> mismatches).
> 
> The idea to deal with that was to simply turn off acpi table loading for
> piix4, then wait for mst's acpi table patches which fix this for real
> (including migration).  Continue loading the tables on q35, ignoring the
> live migration issue as ahci renders q35 unmigratable anyway.

Sounds like a plan for 1.6.

> I assumed that happend already, but looks like it slipped though,
> otherwise you would not have posted that patch  ...
> 
> cheers,
>   Gerd