suspending execution within Xen

[Avi Kivity <avi.kivity@qumranet.com>]

I am trying to send a stream of events about one domain to another. so I
set up a ring between the monitoring domain and xen (not the monitored
domain). however I am having trouble blocking when buffer space runs
out.

the intuitive

   while (!buffer_space_available())
       do_block();

does not work; do_block() appears to return to guest context, not to the
while loop (is this correct?). the other alternative,

    while (!buffer_space_available())
	if (!test_and_set_bit(EDF_BLOCKED, &ed->ed_flags))
	    domain_sleep(ed);

freezes xen solid.

is there a way to do it? am I missing something obvious?

Avi