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

[Marcel Apfelbaum <marcel@redhat.com>]

On 03/07/2016 02:36 PM, Michael S. Tsirkin wrote:
> 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?

Sure, I'll add a comment and re-post.

>
> 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?

Absolutely (in my opinion), Igor is OK if I'll submit a patch for it?
Since we're getting rid of old Q35 machines we don't care about compatibility here.

> -
>      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)?
>

I'll let Igor answer this.

Thanks,
Marcel

>>
>>>
>>> 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);
>>>