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

Tue Jan 6 19:55:57 UTC 2015
Johnny Hughes <johnny at centos.org>

On 01/05/2015 04:15 PM, Pasi Kärkkäinen wrote:
> On Tue, Dec 16, 2014 at 10:29:53PM +0200, Pasi Kärkkäinen wrote:
>>>
>>> * xend is now disabled by default.  You can enable it by running
>>> chkconfig.  xend has been removed from the tree entirely in Xen 4.5,
>>> so this should (hopefully) serve as a "wake-up-call" for people to
>>> begin the transition over to xend.
>>>
>>> * A lot have things have changed -- please to test this so we can get
>>> a good idea what may have broken.
>>>
>>
>> I'll test soon. Thanks a lot!
>>
> 
> 
> 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.

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