John Baldwin writes:
 > > 
 > > So its still stuck in msleep.   How is it supposed to get back to
 > > the panic'ed thread if a system thread wakes up and is not allowed to
 > > go back to sleep???
 > 
 > Hmmmmm.  Surprised we don't see this on other archs then (or maybe
 > we do...).  Probably when we have panic'd (and after we leave the
 > debugger and go into boot() or some such) we should take any non-P_SYSTEM
 > processes off the run queues and then remove the panicstr checks from
 > msleep() and the condition variable wait functions.

Do you have something like the following psuedo code in mind?
Perhaps placed just prior to the call to boot() in panic()?

foreach  p in (all procs in system) {
    if (p == curproc)
       continue
    if (p->p_flag & P_SYSTEM)
       continue;
    foreach td in (all threads in p)
        if (td->td_state == TDS_RUNQ)
           remrunqueue(td);
}

I assume a panic will IPI other processors and halt them in their
tracks so we don't need to worry too much about locking?

 > Perhaps better is to dink around in choosethread() so that if panicstr
 > is set, we throw away any threads get that aren't P_SYSTEM or have the
 > TDF_INPANIC flag set.  By throw away, I mean that we just ignore any such
 > threads and loop if we get one we want to throw away.

I think that I like your first idea better..

Drew

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