[CentOS-virt] Are xen and centos incompatible?

Tue Jun 10 13:15:16 UTC 2014
Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>

On Tue, Jun 10, 2014 at 04:44:23AM +0200, lee wrote:
> Konrad Rzeszutek Wilk <konrad.wilk at oracle.com> writes:
> > On Sat, Jun 07, 2014 at 02:44:54AM +0200, lee wrote:
> >> Hi,
> >> 
> >> I'm trying to pass a physical network interface through to a domU.
> >> 
> >> This seems to be impossible because the way xen wants to do it is
> >> incompatible with the way centos wants to do it.
> >
> > Huh?
> >> 
> >> I followed documentation on http://www.xen-support.com/?p=151 and tried
> >> booting with 'pciback.permissive pciback.hide=(06:00.0)'.  This gives a
> >> hint in dmesg "kernel: xen-pciback: backend is vpci", and the device is
> >> still visible in dom0.  So this obviously doesn't work.
> >
> > The device should be visible in the dom0 - even when it is for passthrough.
> Why should it be visible when it's hidden?

The 'hide' part is to hide it from the device drivers in the initial
domain - dom0. That is so that they will not try to use it - as we
plan to pass them to a guest. We need it in the dom0 to do admin type
work - FLR it, etc.

> > But irrespective of that - the steps mentioned there are out of date.
> > The correct option should be 'xen-pciback.hide=(06:00.0) xen-pciback.permissive=1'
> That's one of the problems: Xen is very poorly documented.

Any help in improving the documentations would be appreciated. Every month
we run 'Documentation days' and any work - either on Wiki, manuals, docs, etc
would be quite appreciated.

Please see http://wiki.xenproject.org/wiki/Xen_Project_Document_Days
> I replaced centos with debian and finally got it to work.  Things are
> much easier with debian.

Glad to hear you solved the problems.