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

[Gerd Hoffmann]

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.

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

cheers,
  Gerd