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Date: Thu, 13 Mar 2014 09:41:36 +0100
From: Laszlo Ersek <lersek@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 0/4] vga: new display devices
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: airlied@redhat.com, qemu-devel@nongnu.org

On 03/13/14 09:22, Gerd Hoffmann wrote:
>>     +---------->IS_PCI_VGA (Pci):
>>     |             "Found PCI VGA device"
> 
>>> +    k->class_id = PCI_CLASS_DISPLAY_OTHER;
>>
>> and from qemu's "include/hw/pci/pci_ids.h":
>>
>>> #define PCI_CLASS_DISPLAY_VGA            0x0300
>>> #define PCI_CLASS_DISPLAY_OTHER          0x0380
>>
>> I think this is the cause of the mismatch.
> 
> Yes, it is.  First byte (0x03) of the class says what it is, second byte
> of class (0x00 / 0x80) specifies the programming interface.
> 
> So, it is a display adapter, but it isn't vga compatible, therefore
> specifying PCI_CLASS_DISPLAY_VGA would be asking for trouble as trying
> to program it using the standard vga io ports isn't going to work ...
> 
> [ same picture with virtio-gpu btw:  The variant with the vga compat
>   bits declares itself as PCI_CLASS_DISPLAY_VGA whereas the variant
>   without is PCI_CLASS_DISPLAY_OTHER ]
> 
>> Does the following OVMF patch help?
>>
>>> -  if (IS_PCI_VGA (Pci)) {
>>> +  if (IS_PCI_DISPLAY (Pci)) {
> 
> Yes.

Please ping me when the series is merged and I will submit the patch
(possibly also correcting the related "Vga" references throughout the file).

Thanks
Laszlo