Based on a old patch by Laszlo.
Time to get this in ...

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Message-id: 20170717101632.23247-1-kraxel@redhat.com