Re: Freeze due to performance_cx_lowest=LOW

> Date: Sun, 28 May 2006 18:20:39 +0400
> From: Yar Tikhiy <yar_at_comp.chem.msu.su>
> Sender: owner-freebsd-current_at_freebsd.org
> 
> Hi,
> 
> A while ago I installed CURRENT on my new home PC and noticed that
> the system would hang hard at the boot time soon after setting
> cx_lowest to C3 according to the LOW setting in /etc/defaults/rc.conf.
> The last message on the console was each time: Mounting NFS file
> systems:.  Setting performance_cx_lowest to HIGH made the problem
> go away.
> 
> Now I've just tried again to return performance_cx_lowest to its
> modern default setting in a fresh CURRENT and found that the bug
> is still there.  Is it due to my ACPI HW being broken?  I'll be
> glad to show relevant debug output from my ACPI if told how to get
> it.  Thanks.

This problem has been discussed over on ACPI. It's a problem with the
local APIC timer which does not run in C3 or lower. Nate is looking at a
solution for the problem.

See his message on acpi_at_ on Sun, 07 May 2006 15:28:29 -0700.

The fixes are to either not use C3 (or C4 if it's available) or to
disable APIC.

For those who are not reading closely, DO NOT confuse APIC with ACPI!
They only look similar.

If the system is UP, there is no really no need for APIC.
-- 
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