Re: [Xen-users] GPLPV / Passing devices to HVM

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> just wondered after I read about devices passed through in HVM if the
> following if still true: (for Xen3.2.1)
>
> - a Domain running in HVM cannot get forwarded any other device than a
> USB device.

Correct.

> - the USB device forwarding is not too stable

I've heard variable reports about this; it's been a while since I've heard 
anything, which is sometimes a good thing :-)

> - PCI forwarding is not possible without processor support and Xen support.

For a PV guest you can do PCI forwarding without special hardware (but you 
have to trust that guest because abusing the PCI device could make it as 
powerful as dom0, with the ability to do anything on the machine).

For an HVM guest you need more than just processor support: for VT-d you 
currently need chipset support.  You need a Xen which can make use of the 
VT-d hardware, too.  The guest would not have to be Xen-aware or have any Xen 
additions installed into it, however.

> - The GPLPV tools won't change anything with that.
>
> Because if forwarding PCI devices to Xen HVM DomU would be possible that
> would be highly cool because it would enable me to use a PCIe-card that
> is definitly not supported with Linux in a Windows DomU where it is
> supported quite well.

I'm afraid that won't be possible for the moment.

Some guys at a company called Neocleus were working on passing through PCI 
devices (I think they were focused on graphics) to HVM guests without special 
hardware but I've not heard anything about this effort for a while so I don't 
know if it's still going.

Cheers,
Mark

> Thanks a lot for your information refresh :D
>
> Regards
> Joti
>
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