Re: [Qemu-devel] [PATCH 28/35] kvm: x86: Introduce kvmclock device to save/restore its state

[Markus Armbruster]

Gerd Hoffmann <address@hidden> writes:

> On 01/18/11 18:09, Anthony Liguori wrote:
>> On 01/18/2011 10:56 AM, Jan Kiszka wrote:
>>>
>>>> The device model topology is 100% a hidden architectural detail.
>>> This is true for the sysbus, it is obviously not the case for PCI and
>>> similarly discoverable buses. There we have a guest-explorable topology
>>> that is currently equivalent to the the qdev layout.
>>
>> But we also don't do PCI passthrough so we really haven't even explored
>> how that maps in qdev. I don't know if qemu-kvm has attempted to
>> qdev-ify it.
>
> It is qdev-ified.  It is a normal pci device from qdev's point of view.
>
> BTW: is there any reason why (vfio-based) pci passthrough couldn't
> work with tcg?
>
>> The -device interface is a stable interface. Right now, you don't
>> specify any type of identifier of the pci bus when you create a PCI
>> device. It's implied in the interface.
>
> Wrong.  You can specify the bus you want attach the device to via
> bus=<name>.  This is true for *every* device, including all pci
> devices. If unspecified qdev uses the first bus it finds.
>
> As long as there is a single pci bus only there is simply no need to
> specify it, thats why nobody does that today.  Once q35 finally
> arrives this will change of course.

As far as I know, libvirt does it already.