Date: Fri, 4 Jun 2004 09:35:12 -0700 (PDT) From: Nate Lawson <nate@root.org> To: John Baldwin <jhb@FreeBSD.org> Cc: David Gurvich <david.gurvich@verizon.net> Subject: Re: reboot or shutdown not working with -current Message-ID: <20040604093428.O50710@root.org> In-Reply-To: <200406041108.33170.jhb@FreeBSD.org> References: <714DBA6C-B565-11D8-B32B-000393AB07D8@verizon.net> <20040604105118.kpsgwcg4skgsgso0@www.sweetdreamsracing.biz> <200406041108.33170.jhb@FreeBSD.org>
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On Fri, 4 Jun 2004, John Baldwin wrote:
> On Friday 04 June 2004 10:51 am, Kenneth Culver wrote:
> > Quoting John Baldwin <jhb@FreeBSD.org>:
> > > On Thursday 03 June 2004 11:04 am, Dan Nelson wrote:
> > >> In the last episode (Jun 03), David Gurvich said:
> > >> > Recent cvsup has caused system to hang on reboot or shutdown,
> > >> > occasionally hangs on startup with detection of optical drive on 2nd
> > >> > ide. Anyone know how to get system logs in this situation?
> > >> > Motherboard is ASUS A7N266-VM. System worked reasonably with APIC
> > >> > turned off 5/26/2004.
> > >>
> > >> Back out sys/i386/i386/intr_machdep.c rev 1.6.
> > >
> > > Or for the real fix, try this:
> > >
> > > Index: acpi_cpu.c
> > > ===================================================================
> > > RCS file: /usr/cvs/src/sys/dev/acpica/acpi_cpu.c,v
> > > retrieving revision 1.36
> > > diff -u -r1.36 acpi_cpu.c
> > > --- acpi_cpu.c 7 May 2004 05:22:37 -0000 1.36
> > > +++ acpi_cpu.c 4 Jun 2004 14:44:33 -0000
> > > @@ -376,8 +376,7 @@
> > >
> > > /* Wait for all processors to exit acpi_cpu_idle(). */
> > > smp_rendezvous(NULL, NULL, NULL, NULL);
> > > - while (cpu_idle_busy > 0)
> > > - DELAY(1);
> > > + DELAY(1);
> > >
> > > return_VALUE (0);
> > > }
> >
> > You know that the reboot problems go away when
> > /usr/src/sys/i386/i386/intr_machdep.c is reverted from 1.16 to 1.15 right?
>
> Yes, because the real bug is above. Disabling interrupt preemption just masks
> it. The gory details are that almost all (in fact on UP, 100%) of context
> switches away from the idlethread are due to interrupts. When interrupt
> preemption is enabled, this means that idle threads are switched away from
> before they've had a chance to decrement the cpu_idle_busy counter in
> acpi_cpu_idle(). Thus, when the thread doing shutdown gets to this loop, it
> never terminates because the idlethread of the CPU executing the shutdown
> request never gets a chance to go back and decrement its idle_busy count. In
> truth, you don't actually need the loop, once you do the rendezvous, any
> other CPUs that are idle will wake up, exit acpi_cpu_idle() and re-enter
> after finding no runnable jobs. I tracked this down after a couple of hours
> on Wednesday but was very busy with ${REALJOB} work yesterday and haven't had
> a chance to send an e-mail out about this.
I'm swamped too. Please commit a #if 0 around the while () until I can
get to this.
Thanks,
Nate
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