[SeaBIOS] [Qemu-devel] [PATCH v3 5/5] docs: update documentation considering PCIE-PCI bridge

Marcel Apfelbaum marcel at redhat.com
Wed Aug 2 19:58:41 CEST 2017

On 02/08/2017 19:26, Michael S. Tsirkin wrote:
> On Wed, Aug 02, 2017 at 06:36:29PM +0300, Marcel Apfelbaum wrote:
>>>>>>> Can dmi-pci support shpc? why doesn't it? For compatibility?
>>>>>> I don't know why, but the fact that it doesn't is the reason libvirt
>>>>>> settled on auto-creating a dmi-pci bridge and a pci-pci bridge under
>>>>>> that for Q35. The reasoning was (IIRC Laine's words correctly) that the
>>>>>> dmi-pci bridge cannot receive hotplugged devices, while the pci-pci
>>>>>> bridge cannot be connected to the root complex. So both were needed.
>>>>>> Thanks
>>>>>> Laszlo
>>>>> OK. Is it true that dmi-pci + pci-pci under it will allow hotplug
>>>>> on Q35 if we just flip the bit in _OSC?
>>>> Marcel, what say you?... :)
>> Good news, works with:
>>     -device i82801b11-bridge,id=b1
>>     -device pci-bridge,id=b2,bus=b1,chassis_nr=1,msi=off
> And presumably it works for modern windows?
> OK, so it looks like patch 1 is merely a bugfix, I'll merge it for 2.10.

Tested with Win10, I think is OK to merge if for 2.10.

>> Notice bridge's msi=off until the following kernel bug will be merged:
>>    https://www.spinics.net/lists/linux-pci/msg63052.html
> Does libvirt support msi=off as a work-around?

Adding Laine, maybe he has the answer.


>> Thanks,
>> Marcel

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