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Re: [Xen-devel] [Q] Is qemu used when we use VTd?

Tian, Kevin wrote:
>> From: Akio Takebe
>> Sent: 2008年9月11日 19:48
>> Can we directly use MMCONFIG for PCI-Express card 
>> pass-throughed by VT-d on HVM?
> You can't. MMCONFIG in no sense vary from old I/O port
> style, as just a means to access PCI configuration space.
> Note that PCI configuration space access has to be trapped
> as it determines which devices, and also config space
> content to be observed by HVM guest. Normally you'd need
> some virtualization on config space content, such as BARs.
> Thus even by presenting MMCONFIG capability to HVM
> guest, you still need trap those access falling in that range.
I suspect MMCONFIG is needed to access Extended PCI
configuration space of PCI-Express. Probably PCI-Express card
can work without those access.
But we can't use full features of PCI-Express cards, right?

Best Regards,

Akio Takebe

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