[SeaBIOS] [PATCH] qemu: piix: PCI bridge ACPI hotplug support
Michael S. Tsirkin
mst at redhat.com
Tue Jun 11 10:18:13 CEST 2013
On Tue, Jun 11, 2013 at 10:00:36AM +0200, Gerd Hoffmann wrote:
> Hi,
>
> > Yes and not just because of windows guests.
> > ACPI spec is also very explicit that native hotplug is an optional
> > feature. Test suites such as WHQL are known to test spec compliance.
>
> /me looks a bit surprised.
>
> This pretty much implies that any shpc bridge needs a second interface
> to the hotplug functionality which can be driven via ACPI. Or the
> firmware somehow handles this using smm (not sure this works for the IRQ
> though).
>
> Do you know how this is handled by real hardware?
>
> cheers,
> Gerd
SHPC is not very widely deployed on a PC.
Since most hardware vendors do care about windows support,
the only way is a separate interface that is driven via ACPI.
You then need an ACPI specific register to switch to standard SHPC.
The SHPC spec even tells you as much.
--
MST
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