[CentOS-virt] CentOS 6 Xen 4.4.1 packages available on virt6-testing / libvirt blktap2 problems

Tue Jan 6 20:07:43 UTC 2015
Pasi Kärkkäinen <pasik at iki.fi>

On Tue, Jan 06, 2015 at 01:55:57PM -0600, Johnny Hughes wrote:
> > 
> > Ok I just used a couple of hours testing Xen 4.4.1 rpms on CentOS 6.6 with Linux 3.10 dom0 kernel.
> > This session was all about xm/xend testing. I manually enabled xend first. 
> > 
> > 
> > What Works OK:
> > 	- Manually creating/managing guests with xm and domU cfgfiles in /etc/xen and LVM volumes as storage (phy backend).
> > 	- Manually creating/managing guests with xm and domU cfgfiles in /etc/xen and file images as storage (tap2:aio backend).
> > 	- Using virt-install to install PV domUs using LVM volumes as storage (phy backend).
> > 	- Using virt-manager to install PV domUs using LVM volumes as storage (phy backend).
> > 
> > What doesn't work:
> > 	- Using virt-manager to install PV domUs using file images as storage (tap:aio backend).
> > 
> > 
> > This libvirt/blktap2 file images failure with Xen 4.4 rpms is a regression from Xen 4.2 rpms, where blktap2 works OK with libvirt/virt-install/virt-manager.
> > 
> > The problem is most probably the fact that we had custom patches included in the xen4c6 libvirt rpms that we shipped with the Xen 4.2 rpms. 
> > We had to add two patches, one patch to fix the blktap2 backend type in libvirt, and one patch to fix the blktap2 backend type in virt-install or virt-manager, i'm not totally sure which one it was. Those patches should be included in the earlier libvirt source rpms, so we can check there. Or I can search thru my emails, because I hunted that down earlier aswell.
> > 
> > It seems we still need those patches with the latest libvirt rpms too.
> > 
> > The actual problem is libvirt/virt-manager tries to configure tap:aio: backend, which won't work.
> > It needs to be tap2:aio.
> > 
> > I get the exactly same behaviour with xm/xend. "tap:aio" stalls and fails. "tap2:aio" works OK.
> > 
> 
> Now with the new python-virtinst and then new kernel from here:
> 
> 
> http://people.centos.org/hughesjr/xen4-test/
> 
> But with the new libvirt-1.2 and xen 4.4 from this repo, everything
> seems to work with xend enabled.
> 

Yep, with the updated python-virtinst all works now, also with the Xen 4.4 rpms.

Thanks a lot!

-- Pasi