Re: libvirt and virt-manager default blktap driver name for file images, tap vs tap2?

[Jim Fehlig <jfehlig@suse.com>]

Pasi Kärkkäinen wrote:
> Hello,
>
> Does anyone know where/how to set the default libvirt blktap "driver name" for disk image files?
>
> If I have "blktap" module loaded in dom0 kernel, and I do this:
>
> virt-install -d -n blktaptest01 -r 2048 --vcpus=2 --disk /var/lib/libvirt/images/blktaptest01.img,size=8 --vnc -p -l "http://ftp.funet.fi/pub/mirrors/centos.org/6.4/os/x86_64"
>   

Does it work if you specify the driver name in the diskopts?  E.g.

  --disk /var/lib/libvirt/images/blktaptest01.img,size=8,driver_name=tap2

Regards,
Jim

> which results in this generated libvirt xml config for the VM:
>
>     <disk type='file' device='disk'>
>       <driver name='tap' type='aio'/>
>       <source file='/var/lib/libvirt/images/blktaptest01.img'/>
>       <target dev='xvda' bus='xen'/>
>     </disk>
>
> .. which doesn't seem to work for me with Xen 4.2.2 using xm/xend, and libvirt 0.10.x.
>
> The problem is there's no tapdisk process started in dom0, and the block device cannot be 
> initialized or accessed inside the VM. I have the same problem with virt-manager, 
> using the "new VM" wizard with disk image files.
>
> The correct "driver name" for libvirt is "tap2", which works for me, 
> so I need to manually edit the libvirt xml config to make the VM boot/work.
>
> This matches xm/xend behaviour with text config files for VMs. 
> I need to use tap2 there aswell on the disk = [] line.
>
> Where should I choose/set/patch the default libvirt driver name? Is that in libvirt sources,
> or in virt-install/virt-manager ? I tried reading the libvirt "xen" driver source, 
> but I couldn't find any "default" setting there.. 
>
> Thanks,
>
> -- Pasi
>
>
>