Re: [RFC PATCH] vfio: VFIO PCI driver for Qemu

[Andreas Hartmann <andihartmann@01019freenet.de>]

Avi Kivity wrote:
> On 07/25/2012 10:53 PM, Alex Williamson wrote:
>> On Wed, 2012-07-25 at 22:30 +0300, Avi Kivity wrote:
>>> On 07/25/2012 08:03 PM, Alex Williamson wrote:
>>>> This adds PCI based device assignment to Qemu using the Linux VFIO
>>>> userspace driver interface.  After setting up VFIO device access,
>>>> devices can be added to Qemu guests using the vfio-pci device
>>>> option:
>>>>
>>>>  -device vfio-pci,host=1:10.1,id=net0
>>>>
>>>>
>>>
>>> Let's use the same syntax as for kvm device assignment.  Then we can
>>> fall back on kvm when vfio is not available.  We can also have an
>>> optional parameter kernel-driver to explicitly select vfio or kvm.
>>
>> This seems confusing to me, pci-assign already has options like
>> prefer_msi, share_intx, and configfd that vfio doesn't.  I'm sure vfio
>> will eventually get options that pci-assign won't have.  How is a user
>> supposed to figure out what options are actually available from -device
>> pci-assign,? 
> 
> Read the documentation.
> 
>> Isn't this the same as asking to drop all model specific
>> devices and just use -device net,model=e1000... hey, we've been there
>> before ;)  Thanks,
> 
> It's not.  e1000 is a guest visible feature. vfio and kvm assignment do
> exactly the same thing, as far as the guest is concerned,

The big difference between vfio and old kvm assignment is: vfio does
work for PCI here, kvm doesn't!

Please let the users decide them self which tool to use!



Sorry,
kind regards,
Andreas