Deep sleep modes on 7-BETA locks up syscons

[Kevin Oberman]

> Date: Thu, 08 Nov 2007 11:25:16 -0800
> From: Nate Lawson <nate at root.org>
> 
> Kevin Oberman wrote:
> > I have already sent much of this to -current@, but ACPI is clearly
> > involved and I'll admit that I don't fully understand all of the
> > implications of sleep (Cx) states.
> > 
> > Recently I discovered that I could no longer boot up on battery. (As it
> > turned out, I could not shut down, either.) The boot proceeds to devd
> > which kicks off power_profile which resets the cx_state. I use
> > performance_cx_lowest="HIGH" and economy_cx_lowest="LOW" which drops
> > cx_state to C4 when on battery. 
> > 
> > States of C1 and C2 don't cause a problem and C3 and C4 do. (C4 is only
> > available when on battery.)
> > 
> > At that point things slow to a crawl. I have never had the patience to
> > see if it would ever finish the boot, but it took many minutes just to
> > start ipfw and load the rules. When anything made it to the screen, it
> > appeared several lines at a time.
> > 
> > If I am up and switch cx_state to C3 or C4 while running X, things work
> > fine, but, if I exit X while the cx_state is still C3 or C4, the system
> > switches back to the vty and spits out a few lines before locking up
> > again. After several minutes I was able to log in to another vty and
> > change the cx_state which started things running normally.
> > 
> > This is a T43 (Pentium-M @2GHz) running ULE on 7-BETA2 of Nov. 4. The
> > problem has not been there for too long, but I can't say for sure when I
> > last ran on battery when not in X. 
> > 
> > I don't know if this is a syscons issue or some ugly interaction between
> > syscons and ULE or an ACPI issue.
> > 
> > If anyone else has seen this or has any ideas, I'd love to hear about it.
> 
> Does changing timers help?  sysctl kern.timecounter.hardware = TSC or
> other options from kern.timecounter.choice
> 
> I'm wondering if the local APIC timer is the problem.

Crap! I need to remember when I make fairly fundamental changes on my
system! I entirely forgot that I turned on APIC on my system for the
first time as it didn't work when I first got the system. I'm pretty
sure that this is what tickled it.

Unfortunately, setting the timecounter to TSC does not seem to make a
difference. :-( But I do appreciate the APIC suggestion. I'm about to
build a new kernel without APIC to confirm this.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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