Merge of nickrob-async-20060513 to mainline?

[Nick Roberts]

 > Ideally you'd be able to reuse the signal handler logic (see the calls
 > to sigprocmask and sigsuspend) and thus not have a millisecond latency
 > and excessive spinning.  That's actually a pretty important feature,
 > because context switching to gdb every millisecond or so is going to
 > really hurt performance of the debuggee.

>From the event loop, GDB needs to detect that a process/thread has changed
status and check for user input.  If it does the first with sigsuspend, the
only way I can see how it can do the second is by using threads. This would
almost take us back to where we started.

-- 
Nick                                           http://www.inet.net.nz/~nickrob