[CentOS-virt] Are xen and centos incompatible?

Tue Jun 10 02:44:23 UTC 2014
lee <lee at adminart.net>

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?

> But irrespective of that - the steps mentioned there are out of date.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.

I replaced centos with debian and finally got it to work.  Things are
much easier with debian.

>> Following http://wiki.xen.org/wiki/Xen_PCI_Passthrough:
> which is mentioned in that link.
>> [root at heimdall ~]# xl pci-assignable-add 06:00.0
>> xend is running, which may cause unpredictable results when using
>> this xl command.  Please shut down xend before continuing.
>> (This check can be overridden with the -f option.)
>> [root at heimdall ~]# 
>> There doesn't seem to be any documentation about what xend does or is
>> for and how to pass a physical network interface through with it.
> Did you just try using the same parameter but replace 'xl' with 'xm'?

I don't remember ... It seemed I had to use virsh since nothing else
worked on centos, and virsh doesn't let you seem to get networking stuff
to work.

Centos and xen just don't go along with each other.  The server is all
on debian now.

Knowledge is volatile and fluid.  Software is power.