[libvirt] Trouble booting Xen VM with NFS root file system

[Daniel P. Berrange]

On Thu, Sep 10, 2009 at 03:15:44PM +0200, Matthias Schmidt wrote:
> Hi,
> 
> I'm currently trying to boot a Xen VM with the root file system on NFS
> via libvirt.  Previously we used a small python script and "xm create" to
> boot a number of VMs (which worked fine).  Now I'm trying to integrate
> that functionality in a python project which uses libvirt, but
> sadly booting the VMs fail.
> 
> The small script constructs a Xen command line which looks like the
> following:
> 
> create =("/usr/sbin/xm create /foo.cfg \
>  kernel=%s ramdisk=%s memory=64\
>  root=/dev/nfs nfs_server=%s nfs_root=%s name=%s vif='mac=%s'\
>  dhcp='dhcp' vcpus=1 extra='init=/stateless.sh xencons=tty1'\
>  ")%(vm_kernel, vm_ramdisk, vm_nfs_server, vm_nfs_root, hostname, vif)
> 
> kernel and ramdisk are the path to the installed version, vm_nfs_server is the
> IP address of the NFS server and vm_nfs_root the path to the operating system
> installation (which is a Debian Linux).  Firing up the script brings up
> all VMs with a read-only NFS root file system.
> 
> Now I tried to do this with libvirt, but all attempts failed with the
> following error popping up after the VM boots (after a certain
> time(out)):

It is hard to tell if this is just a configuration error, or an actual
libvirt Xen bug since there are a great many variables here. I think it
would be best to file a BZ against libvirt and include the following

 - The output of 'xm list --long GUESTNAME' when launched using 'xm'
 - The output of 'xm list --long GUESTNAME' when launched using libvirt
 - The /var/log/xen/xend.log file
 - The libvirt XML you used to launch the guest, or virsh dumpxml
 - The /foo.cfg file used with xm

Regards,
Daniel
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