Xen with libvirt and SR-IOV

[nospam at godawa.de]

Hi Jim,

thank you very much for your answers!

Unfortunately I was busy with some other things, so couldn't look at it 
earlier.

> That's an old libvirt, but there hasn't been a lot of changes to the PCI 
> passthrough code. One notable change that came with libvirt 6.8.0
> 
> https://gitlab.com/libvirt/libvirt/-/commit/9d15647dcb96831c93ac8c1d67c47265b5ed9072
> 
> However, that wouldn't be needed unless you were using the 'permissive' 
> setting in your xl config.

I see, current version is somewhere at 9.x. But I'm not sure, if it's 
possible to upgade the servers to a new version of libvirt, I assume, 
that I also would have to upgrade Xen to the latest version.


>>> I know it's not complete, but https://libvirt.org/formatdomain.html 
>>> makes an attempt to identify hypervisor support for the various 
>>> configuration settings.

I found this:

"if you are using a version of libvirt older than 0.9.11, you should use 
standard <hostdev> to assign the device to the guest instead of 
<interface type='hostdev'/>."

I think that 6.6 is newer than 0.9.11? Or do I have 0.6.6 in real?


> Ah, xen-pciback is already bound to the device, so no need for 
> managed='yes' in your device config. The 'managed' attribute tells 
> libvirt whether or not to manage attaching/detaching drivers to/from the 
> device. If you've done that elsewhere, set managed='no', or simply drop 
> the attribute since 'no' is the default. It's explained in the 'pci' 
> attribute of the hostdev element
> 
> https://libvirt.org/formatdomain.html#usb-pci-scsi-devices

I set this to "no", as you expected it didn't changed anything.


> Are there any errors from xen-pciback in dom0, or any hints in the 
> output of 'xl dmesg'? Also, it might be worth comparing the relevant 
> nodes in the output of xenstore-ls between VM started with xl and libvirt.

I already had compared some informations between XL and libvirt, see my 
very first message. Unfortunately there are no errors in the logs, it's 
just not working.

Any hints how to get further informations that might help debugging? Or 
could it just be a old bug in this version of libvirt?

Thanks a lot,
-- 

kind regards,

Thorolf