xen does not have a register that, when written, will cause can_receive
to go from false to true. However, flushing the queue can be attempted
whenever the front-end raises its side of the Xen event channel. There
is a single event channel for tx and rx.
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Amos Kong <akong@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
a98b140223