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Date:      Tue, 16 Jul 2002 13:46:16 -0400 (EDT)
From:      Andrew Gallatin <gallatin@cs.duke.edu>
To:        Andrew Kolchoogin <andrew@snark.rinet.ru>
Cc:        current@freebsd.org
Subject:   Re: VOP_GETATTR panic on Alpha
Message-ID:  <15668.23528.719956.574605@grasshopper.cs.duke.edu>
In-Reply-To: <20020716145107.GA69162@snark.rinet.ru>
References:  <xzpele33kq0.fsf@flood.ping.uio.no> <20020716145107.GA69162@snark.rinet.ru>

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Andrew Kolchoogin writes:
 > Hi!
 > 
 > On Tue, Jul 16, 2002 at 02:45:11PM +0200, Dag-Erling Smorgrav wrote:
 > 
 > > The following panic is 100% reproducable - it happens whenever I boot
 > > a recent kernel on Alpha, just before init(8) starts getty(8) on the
 > > console:
 > sorry, kernel from today's sources at 17:38 works just fine.
 > 
 > Yet another question about kernel core dumps: what should I do to get one?-)
 > Why "panic" from debugger on i386 gives core dump and reboots the system
 > and "panic" from debugger on Alpha does not?
 > 

Because, as BDE says, that crashdumps work at all is mosty accidental.

On alpha, a random kernel thread is waking up, and is unable to go
back to sleep because of the panicstr hack msleep:

        mtx_lock_spin(&sched_lock);
        if (cold || panicstr) {
                /*
                 * After a panic, or during autoconfiguration,
                 * just give interrupts a chance, then just return;
                 * don't run any other procs or panic below,
                 * in case this is the idle process and already asleep.
                 */
                if (mtx != NULL && priority & PDROP)
                        mtx_unlock(mtx);
                mtx_unlock_spin(&sched_lock);
                return (0);
        }


We need to somehow let only interrupt threads and the panic'ed process
run after a panic.  I have no idea how to do this in a clean,
low-impact way.

Drew

PS: I was trying to make crashdumps fail on x86 by increasing HZ.  But
I cannot.   I have no idea why this only happens on alpha.

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