xen: blk & nic configuration via cmd line. (Gerd Hoffmann)

xen: blk & nic configuration via cmd line. (Gerd Hoffmann)

This patch makes qemu create backend and frontend device entries in
xenstore for devices configured on the command line.  It will use
qdisk and qnic backend names, so the qemu internal backends will
be used.

Disks can be created using -drive if=xen,file=...
Nics can be created using -net nic,macaddr=...

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7225 c046a42c-6fe2-441c-8c8c-71466251a162