Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD

["Chen, Tiejun" <tiejun.chen@intel.com>]

On 2014/6/26 10:00, Chen, Tiejun wrote:
> On 2014/6/26 7:04, Slutz, Donald Christopher wrote:
>> On 06/24/14 22:49, Chen, Tiejun wrote:
>>> On 2014/5/19 19:22, Gerd Hoffmann wrote:
>>>>    Hi,
>>>>
>>>>> I think '-vga none' just guarantees the qemu vga cards doesn't occupy
>>>>> 00:02.0, but this doesn't mean others use this specific slot since in
>>>>> qemu internal, we always pass -1 to assign a slot automatically to
>>>>> register a PCI device. So in some cases, we can't get this slot as we
>>>>> expect since that is already assigned previously before we need this.
>>>>
>>>> Yes, -vga, -net nic, -drive if=scsi (maybe more) can internally create
>>>> pci devices with auto slot assignment, which will occupy slot 2 indeed.
>>>> Use -device instead to create the devices.
>>>>
>>>>> PCI: slot 2 function 0 not available for xen-pci-passthrough, in use
>>>>> by xen-platform
>>>>
>>>> Ah, the xen platform device.  /me looks.  Ah, pc_xen_hvm_init creates
>>>> this automatically.  Two options here IMHO:
>>>>
>>>>    (1) Just move it somewhere else explicitly.  For example slot 3, or
>>>>        make it a southbridge function (say 00:01.7).
>>>>    (2) Don't create it automatically, instead expect management add it
>>>>        if needed, using -device xen-plaform,addr=...
>>>>
>>>
>>> Gerd,
>>>
>>> Sorry I return this discussion again.
>>>
>>> As we discussed here, we should never use -vga xxx to avoid occupying
>>> slot 2. Instead, we will just use -device to create that emulated vga
>>> device as you said like this:
>>>
>>> -device VGA,vgamem_mb=8,addr=0x4
>>>
>>> But looks this may issue another problem. That is we can't see
>>> anything until the vga driver is initialized. I means if we pass
>>> `-device VGA,vgamem_mb=8,addr=0x4', qemu doesn't expose any vga
>>> interface to BIOS. Right? Or I'm still missing something.
>>>
>>
>> I know for Xen that
>>
>> tools/firmware/hvmloader/acpi/dsdt.asl
>>
>> also needs to change:
>>
>>
>>               /* Make cirrues VGA S3 suspend/resume work in Windows
>> XP/2003 */
>>               Device (VGA)
>>               {
>> -               Name (_ADR, 0x00020000)
>> +               // Address of the VGA (device F function 0)
>> +               Name (_ADR, 0x000F0000)
>>

With this change I still didn't see anything.

Thanks
Tiejun

>>
>> is what I have for:
>>
>> -device VGA,vgamem_mb=8,addr=0xF.0x0
>>
>
> Do you mean we need to sync devfn with the passed address to work the
> emulated VGA before the real graphic device driver is called?
>
> Thanks
> Tiejun
>
>> I am not sure, but think that QEMU without Xen does this acpi
>> adjustment at run time.
>>
>>
>> I also change seabios's config to include more VGA support but
>> not sure it is needed.
>>
>>       -Don Slutz
>>
>>> Thanks
>>> Tiejun
>>>
>
>
>