Re: [Xen-devel] Is: Wrap-up Was: VIRTIO - compatibility with different virtualization solutions

[Fabio Fantoni <fabio.fantoni@xxxxxxx>]

Il 10/03/2014 08:54, Daniel Kiper ha scritto:
> Hi,
>
> After some email exchange it looks that there is no consensus how VRITIO
> should work on Xen. There is some hand waiving and some preliminary tests
> but it is not sufficient to take final decision and put all needed stuff
> into upcoming VIRTIO specification release. However, it is certain that
> any solution which will be chosen in upcoming future MUST not break Xen
> security model, has a good performance and easily integrate with currently
> existing solutions. Additionally, it looks that that some terms (e.g.
> physical address) in VIRTIO specification shall be changed to something
> which is more platform independent (e.g. handle). Although such changes
> should not lead to changes in currently existing VIRTIO implementations.
>
> Taking into account above mentioned things I state that more research
> and development work is needed. I volunteer to lead this task. Hence
> I would like to propose that VIRTIO-46 task (Verify that VIRTIO devices
> could be implemented in Xen environment) should be opened and work on
> it should be deferred (from formal POV but that does not mean that work
> should be on hold in real) until next VIRTIO release. Additionally,
> I would like to rise VIRTIO on Xen issue during Xen Hackathon 2014 and
> in other avenues to discuss this with other stake holders of VIRTIO.
>
> Daniel
Thanks for your work about virtio.
For now xen uses virtio only with spice vdagent on hvm domUs (that use 
virtio-serial).
Virtio net and disks xl implementation is esperimental and old: 
http://wiki.xen.org/wiki/Virtio_On_Xen
Last year i did some test with virtio-net and I found one regression 
with qemu 1.6.
If can be useful some details from my old mails about:
> Based on my tests about virtio:
> - virtio-serial seems working out of box with windows domUs and also 
> with xen pv driver, on linux domUs with old kernel (tested 2.6.32) is 
> also working out of box but with newer kernel (tested >=3.2) require 
> pci=nomsi to work correctly and works also with xen pvhvm drivers, for 
> now I not found solution for msi problem, there are some posts about it.
> - virtio-net was working out of box but with recent qemu versions is 
> broken due qemu regression, I have narrowed down
> with bisect (one commit between 4 Jul 2013 and 22 Jul 2013) but I 
> unable to found the exact commit of regression because there are other 
> critical problems with xen in the range.
> - I not tested virtio-disk and I not know if is working with recent 
> xen and qemu version. 
About msi problem with virtio, xen and recent linux kernel see here:
http://lists.xen.org/archives/html/xen-devel/2014-02/msg00192.html

Recently I have not had time to test with qemu 2.
Certainly in the next few months I will further tests.
Let me know when there will be particular changesand Iwill test and try 
to help if possible.
Thanks for any reply.

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