Re: [Qemu-devel] [PATCH] hw/acpi: fix Q35 support for legacy Windows OS

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

On Mon, Mar 07, 2016 at 01:06:43PM +0100, Igor Mammedov wrote:
> On Sun,  6 Mar 2016 14:17:56 +0200
> Marcel Apfelbaum <marcel@redhat.com> wrote:
> 
> > Legacy Windows operating systems like Windows XP and Windows 2003
> > require _DIS method to be present for all interrupt links.
> > 
> > PC machines already have a no-op implemented for GSI links, add
> > it also in Q35.
> Maybe I don't see but only LINKS has no-op _DIS, the rest of
> links have _DIS that does something. According to spec
> _STA must return disabled status after _DIS has been called.

A no-op _DIS is OK as long as the interrupt can not be disabled.
Marcel, how about a comment explaining this?

BTW, going over it again:
- we really need to set separate UIDs for them, might
  be a good idea to fix that, might it not?
- 
    method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
    aml_append(method, aml_create_dword_field(aml_arg(0), aml_int(5), "PRRI"));
    aml_append(method, aml_store(aml_name("PRRI"), reg));
    aml_append(dev, method);

should this be serialized as it creates a local name (PRRI)?

> 
> > 
> > Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
> > ---
> > 
> > Hi,
> > 
> > I tested this patch with WinXP and Win 2003, but also with Win 10, and Fedora.
> > This solves a BSOD early in the setup process.
> > 
> > WinXP/2003 can be tested using:
> >      -device piix3-ide,id=legacyide \
> >      -drive file=winxp-q35.qcow2,if=none,id=disk -device ide-hd,drive=disk,bus=legacyide.0 \
> >      -drive file=xp_sp3.iso,if=none,id=cdrom -device ide-cd,drive=cdrom,bus=legacyide.1 
> > 
> > Please note that you have to use the piix3-ide because Win2003 (and probably XP)
> > does not have Q35 AHCI drivers inbox.
> > 
> > Thanks,
> > Marcel
> > 
> >  hw/i386/acpi-build.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index 52c9470..4c66568 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -1509,6 +1509,9 @@ static Aml *build_gsi_link_dev(const char *name, uint8_t uid, uint8_t gsi)
> >  
> >      aml_append(dev, aml_name_decl("_CRS", crs));
> >  
> > +    method = aml_method("_DIS", 0, AML_NOTSERIALIZED);
> > +    aml_append(dev, method);
> > +
> >      method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
> >      aml_append(dev, method);
> >