RE: [Xen-devel] xen 3.3.0 pv pci passthrough co-assigned problem

["Cui, Dexuan" <dexuan.cui@xxxxxxxxx>]

>> I didn't test the traditional PV-only PCI passthrough.  We only
>> specify a string "pci=['xx:xx.x']" in pv guest config file. How can
>> Xend tell whether we're using the traditional PCI passthrough or the
>> VT-d passthrough? Judging by the "iommu=pv or no-pv" xen parameter?
>> I'm not sure about that for now...
>
> No, I don't think the xen iommu parameter is the right flag to judge
> this. For example I can think of a setup where I wan't to run PV and
> HVM guests on the same dom0, both using PCI passthrough.
I think HVM geust can't use the traditional PCI passthrough; HVM guest can only 
use the VT-d/IOMMU passthrough.

>
> Doesn't the xend know if he starts a PV or a HVM guest? For example
> the option 'builder' or 'kernel' in the guest's config file should
> tell him. This assumes that vt-d passthrough is not possible with
> traditional PV - is it?
>
> Another way would be the use of traditional PCI passthrough if vt-d is
> disabled.
>
> And last but not least let the user/admin do the choice by an new
> parameter in the config file of the guest.
Yes. I think we should consider this.

> In fact I'm using PCI
> passthrough to divide subfunctions of a single pci board to diffrent
> guests (e.g. quad ethernet card).
>
> Is there a quick hack to get back the old behaviour for now?
>
Can you try applying the attached patch to your /usr/lib64/python/xen/ ?
Hope this can work for you at present.

Thanks,
-- Dexuan

Attachment: disable_co-assignment.patch
Description: disable_co-assignment.patch

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