Re: [Qemu-devel] [qemu PATCH for 2.10] i386: acpi: provide an XSDT instead of an RSDT

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jul 26, 2017 at 02:07:13PM +0100, Daniel P. Berrange wrote:
> On Wed, Jul 26, 2017 at 03:52:43PM +0300, Michael S. Tsirkin wrote:
> > On Wed, Jul 26, 2017 at 11:31:36AM +0200, Paolo Bonzini wrote:
> > > The tables that QEMU provides are not ACPI 1.0 compatible since commit
> > > 77af8a2b95 ("hw/i386: Use Rev3 FADT (ACPI 2.0) instead of Rev1 to improve
> > > guest OS support.", 2017-05-03).  This is visible with Windows 2000,
> > > which refuses to parse the rev3 FADT and fails to boot.
> > > 
> > > The recommended solution in this case is to build two FADTs, v1 being
> > > pointed to by the RSDT and v3 by the XSDT.  However, we leave this task
> > > to the firmware.  This patch simply switches the RSDT to the XSDT, which
> > > is valid for all ACPI 2.0-friendly operating systems and also leaves
> > > SeaBIOS the freedom to build an RSDT that points to the compatibility
> > > FADT.
> > > 
> > > When running Windows 2000 with an old BIOS, Windows would simply fall
> > > back to a non-ACPI HAL; however, the plan should be to include a BIOS with
> > > the new feature in 2.10.
> > > 
> > > Reported-by: Programmingkid <programmingkidx@gmail.com>
> > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> > 
> > I'm not against this but let's do it for q35 only please. PC is a legacy
> > machine type and let's just leave it alone.
> 
> We've already touched the PC machine type in 77af8a2b95 and that needs
> fixing to deal with the regressions it caused. Even if you call it
> "legacy", the PC machine is used by the vast majority of deployments
> that exist today & likely to be done for the foreseeable future too.
> 
> Regards,
> Daniel

Fine. So let's avoid making cosmetic changes there. Keep working things
working.

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