Re: Virtualized hardware and PCI

Avi Kivity
2007-02-18T09:54:10Z

Muli Ben-Yehuda wrote:
> On Sun, Feb 18, 2007 at 11:47:07AM +0200, Avi Kivity wrote:
>
>> Ronald Lew wrote:
>>
>>> Can Guest OS access abnormal PCI cards such as a fax card or a card designed
>>> for analog phones (like Digium cards)? Can the guest OS gain full access to
>>> the PCI card without going through the virtualization?
>>>
>> At present this is not supported. On current hardware it could be made
>> to work, but only with cards which don't do dma.
>>
>
> How would you handle device interrupts? take them in the host and then
> inject to the guest through the qemu device emulation?
>
>

Yes. Though I now see a problem: masking pci interrupts is not
standardized, so the host handler cannot shut up the interrupt by
itself, and of course it cannot rely on the guest doing so. So without
some knowledge of the device, all other pci devices that share the same
interrupt line are at risk.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.