[libvirt] specifying cirrus ram size

[Serge Hallyn]

Hi,

In order to migrate a VM from an older system with qemu-kvm to a newer
one with qemu, the newer qemu needs to be told to use the same vga
ram size as qemu-kvm used, 8M.

virsh domxml-from-native suggests that the way to specify a
8mb cirrus vga ram size would be to add

<qemu:commandline>
 <qemu:arg value='-global'/>
 <qemu:arg value='cirrus-vga.vgamem_mb=8'/>
</qemu:commandline>

However whenever I edit a .xml to add this, it disappears.
I'm adding it right before the ending

</domain>

Am I doing something silly?

thanks,
-serge