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From: Jung-uk Kim <jkim@FreeBSD.org>
To: John Baldwin <jhb@freebsd.org>
Date: Mon, 11 May 2009 13:44:59 -0400
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Cc: Alan Amesbury <amesbury@umn.edu>, freebsd-acpi@freebsd.org,
	freebsd-stable@freebsd.org, Andriy Gapon <avg@icyb.net.ua>
Subject: Re: Garbled output from kgdb?
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On Monday 11 May 2009 09:52 am, John Baldwin wrote:
> On Tuesday 05 May 2009 5:43:01 pm Jung-uk Kim wrote:
> > On Tuesday 05 May 2009 04:09 pm, 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(). :-)
> >
> > The attached patch is for -STABLE.  Note that it is only compile
> > tested on amd64.
>
> This looks fine to test.  The patch has gratuitous style changes I
> wouldn't include in a commit though.

It should work but I don't plan to commit it any time soon. :-) In 
fact, the patch was meant to be a rewrite for new ACPI-CA, which 
actually has a real mutex.  Currently, mutex is emulated with 
semaphore.  The problem is semaphore has no concept of ownership 
while mutex does, i.e., any thread can acquire/release it without 
checking its ownership or order.  FYI, the OSL API (ACPI_MUTEX_TYPE) 
is finalized in ACPI-CA 20081204.

Jung-uk Kim