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

[Avi Kivity <avi@redhat.com>]

On 07/26/2012 12:28 PM, Andreas Hartmann wrote:
> 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!

Do we know why it doesn't work?

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

-device pci-assign,kernel-driver=vfio

(it will be the default in any case)

-- 
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