Hi,
I'm trying to debug a problem that causes qemu-dm to lock up with Xen HVM
domains. We're using the qemu version that came with Xen 3.4.2. I know it's
old, but we're stuck with it for a little while yet.
I think the hang is related to thread synchronization and the xenstore, but I'm
not sure how it all fits together. In particular, I don't understand the lines
in xs.c that handle the watch_pipe, e.g.:
/* Kick users out of their select() loop. */
if (list_empty(&h->watch_list) &&
(h->watch_pipe[1] != -1))
while (write(h->watch_pipe[1], body, 1) != 1)
continue;
It looks to me like the other thread blocks while reading from the pipe, and
the write allows it to continue. But this code seems like it does the same
thing as the condvar_signal call that comes slightly after, and therefore it
seems like I could safely #ifndef USE_PTHREAD it out. Is this the case?
