Re: [Qemu-devel] [PATCH V13 3/4] pc: add a Virtual Machine Generation ID device

[Igor Mammedov]

On Wed, 25 Feb 2015 20:59:41 +0100
"Michael S. Tsirkin" <address@hidden> wrote:

> > diff --git a/hw/i386/acpi-dsdt.dsl b/hw/i386/acpi-dsdt.dsl
> > index a611e07..884038b 100644
> > --- a/hw/i386/acpi-dsdt.dsl
> > +++ b/hw/i386/acpi-dsdt.dsl
> > @@ -306,8 +306,6 @@ DefinitionBlock (
> >      Scope(\_GPE) {
> >          Name(_HID, "ACPI0006")
> >  
> > -        Method(_L00) {
> > -        }
> >          Method(_E01) {
> >              // PCI hotplug event
> >              Acquire(\_SB.PCI0.BLCK, 0xFFFF)
> > diff --git a/hw/i386/q35-acpi-dsdt.dsl b/hw/i386/q35-acpi-dsdt.dsl
> > index e1cee5d..9eb794c 100644
> > --- a/hw/i386/q35-acpi-dsdt.dsl
> > +++ b/hw/i386/q35-acpi-dsdt.dsl
> > @@ -414,8 +414,6 @@ DefinitionBlock (
> >      Scope(\_GPE) {
> >          Name(_HID, "ACPI0006")
> >  
> > -        Method(_L00) {
> > -        }
> >          Method(_L01) {
> >          }
> >          Method(_E02) {
> 
> What is this change doing?
It's replaced by \_GPE._E00 handler in SSDT if vmgenid device is present.
Implementation MUST provide control method _[LE]xx IF hardware utilizes
corresponding GPE event [ACPI 1.0b 5.6.2.2.3].
From that follows if GPE event is not used, the corresponding method doesn't
have to be present in \_GPE block. That goes along with \_GPE blocks I've
seen on real hardware also. (i.e. they provide only some handlers and do
not implement stubs for unused ones).

I've tested it with XPsp3/ws2012R2, it boots fine with vmgenid either
present or not.