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From: Jung-uk Kim <jkim@FreeBSD.org>
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Date: Tue, 5 May 2009 16:56:25 -0400
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Cc: freebsd-acpi@freebsd.org, Alan Amesbury <amesbury@umn.edu>,
	Andriy Gapon <avg@icyb.net.ua>, John Baldwin <jhb@freebsd.org>
Subject: Re: Garbled output from kgdb?
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On Tuesday 05 May 2009 04:23 pm, John Baldwin wrote:
> Jung-uk Kim wrote:
> > On Tuesday 05 May 2009 12:51 pm, Andriy Gapon wrote:
> >> BTW, this issue seems to be fixed in Jung-uk's acpi patches for
> >> newer acpica imports, but it is not fixed both in stable/7 and
> >> head.
> >
> > Yes, it was fixed in my patchsets long ago, which uses spin lock
> > for AcpiOsAcquireLock(). :-)
>
> I'm not sure all ACPI locks need to be spin locks, but any locks
> used by the idle code must be spin locks.

There are several types of ACPI locks internally and externally.  The 
AcpiOs{Create,Acquire,Release}Lock() is just one of them, which is a 
spin lock and it is mostly used for interrupt handlers, e.g., GPE and 
HW.  I have to say there were a lot of confusions between ACPI 
developers because it was not well-documented.  In fact, I personally 
had to exchange lengthy e-mails with Intel engineers to understand 
the meaning of these myself.  Now Intel has documented everything you 
need to know about ACPI-CA for OS developers:

http://git.moblin.org/cgit.cgi/acpica/tree/documents

> Regardless, are you going to import a newer ACPI-CA and commit your
> patches soon?  It sounds like several things are fixed in the
> outstanding patches by now including both this and the problem with
> the Alias() operator. 

Unfortunately, I don't have much time to work on it recently.  Couple 
of developers volunteered to do the actual import work although I 
haven't heard from them in a while. :-(

Jung-uk Kim