[libvirt] questions on build qemu driver with non-root

[Daniel P. Berrange]

On Fri, Nov 27, 2009 at 12:33:49PM -0800, Shi Jin wrote:
> Hi there,
> 
> I have been successful in building the latest libvirt code from the git repository. The options I used to build is
> 
> ./autogen.sh  --prefix=/usr --sysconfdir=/etc --localstatedir=/var  --without-xen --with-qemu --with-qemu-user=oneadmin --with-qemu-group=oneadmin --without-uml --without-vbox --without-openvz --without-lxc
> 
> Please note that I have specified qemu user and group to be non-root.
> 
> So far the libvirtd service and virsh both seem to work fine but I have a few issues
> 1. Before running "virsh create", the image belongs to user oneadmin. During the run, it still does. But the as soon as I shutdown/destroy the instance, the image ownership changes to
> -rw-rw?????? 1 root root 
> I don't understand why. Is this a bug?
> 
> 2. From the documentation at http://libvirt.org/drvqemu.html, the  
>  directories /var/run/libvirt/qemu/, /var/lib/libvirt/qemu/ and 
> /var/cache/libvirt/qemu/ must all have their ownership set to 
> oneadmin:oneadmin. However, mine are still set to root:root and 
> it does not seem to affect the running of libvirt/qemu/kvm. For 
> example, 

The documentation is out-dated, it will set correct ownershiup on
those directories at libvirtd startup

> 3. The libvirtd service still shows the warning message:
> warning : qemudStartup:904 : Unable to create cgroup for driver: No such device or address
> I read from earlier posts that the --without-lxc option should get rid of this message.

CGroups are not something that is turned off at compile time, they will
always be present. This message simply means that you do not have the
cgroups controllers mounted on this host, so libvirt has disabled that
functionality at runtime. This means you won't be able to use any of
the schedular APIs with QEMU guests. Aside from that it is harmless,
so either ignore it, or setup cgroups as best suis you

Daniel
-- 
|: Red Hat, Engineering, London   -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org  -o-  http://virt-manager.org  -o-  http://ovirt.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|