From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?ISO-8859-1?Q?Andr=E9_Weidemann?= <Andre.Weidemann@web.de>
Subject: Re: IRQ issue on graphics card passthrough
Date: Sun, 05 Jun 2011 14:13:03 +0200
Message-ID: <4DEB72CF.4070608@web.de>
References: <4DEA704E.2080504@web.de> <4DEB3E9B.5000906@web.de>
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To: Jan Kiszka <jan.kiszka@web.de>
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Hi Jan,

On 05.06.2011 10:30, Jan Kiszka wrote:
> On 2011-06-04 19:50, Andr=E9 Weidemann wrote:
>> Hi,
>> as mentioned before I have successfully passed a graphics card from =
a
>> Linux host to VM using qemu-kvm.
>>
>> Shortly after starting the VM and before Windows7 initializes the
>> graphics card, "info pci" looks like this:
>>    Bus  0, device   4, function 0:
>>      VGA controller: PCI device 1002:6719
>>        IRQ 10.
>>        BAR0: 32 bit prefetchable memory at 0xe0000000 [0xefffffff].
>>        BAR2: 32 bit memory at 0xfeba0000 [0xfebbffff].
>>        BAR4: I/O at 0xc000 [0xc0ff].
>>        BAR6: 32 bit memory at 0xffffffffffffffff [0x0001fffe].
>>        id "radeon6950"
>>
>> After Windows has initialized the graphics card, "info pci" lists th=
e
>> following for the graphics card:
>>    Bus  0, device  4, function 0:
>>      VGA controller: PCI device 1002:6719
>>        IRQ 0.
>>        BAR0: 32 bit prefetchable memory at 0xe0000000 [0xefffffff].
>>        BAR2: 32 bit memory at 0xfeba0000 [0xfebbffff].
>>        BAR4: I/O at 0xc000 [0xc0ff].
>>        BAR6: 32 bit memory at 0xffffffffffffffff [0x0001fffe].
>>        id "radeon6950"
>>
>> Notice that the IRQ changed from 10 to 0...
>>
>> The graphics card's IRQ under Windows7 is displayed as:
>> "0xFFFFFFFE (-2)".
>
> That's not necessarily pointing to a problem, that just means Windows=
 is
> using the device in MSI mode. Does it do the same when running native=
ly?
>
>>
>> During another problem of assigning sound cards to a  VM, Jan Kiszka=
 has
>> pointed me to a patch that addresses an IRQ issue:
>> http://thread.gmane.org/gmane.comp.emulators.qemu/102540
>> Unfortuantely it does not help here.
>
> For sure, that patch addresses a legacy interrupt issue, nothing
> MSI-related.

It took me some time to get a native Windows7 running on that machine,=20
but you are right. The IRQ under Windows("0xFFFFFFF6 (-10)") is similar=
=20
to the one inside the VM ("0xFFFFFFFE (-2)").

Thank you for your reply.
  Andr=E9