GPE handler livelock

Moore, Robert robert.moore at
Mon Jan 7 10:35:38 PST 2008

No changes that I know of before 20070508.

You'll need to figure out why you are getting another GPE before the
_Lxx method completes. There was something like this on Linux with an HP
machine, perhaps Alexey can help.

As I recall, there was something nasty happening where the TZ trip
points had to be reset before the Notify() handler completed, but this
ended up causing another GPE, etc. etc.


>-----Original Message-----
>From: Nate Lawson [mailto:nate at]
>Sent: Monday, January 07, 2008 10:09 AM
>To: Moore, Robert
>Cc: Yousif Hassan; freebsd-acpi at
>Subject: Re: GPE handler livelock
>Bob, thanks for the reply.  That's exactly what my investigation is
>showing also.  It appears we're still on 20070320 so I'm not sure why
>this would affect us though.  Perhaps a similar change was already
>present?  In any case, we should see if an import fixes this.
>Moore, Robert wrote:
>> This sounds suspiciously like the changes we made to the Notify()
>> handling last year. We attempted to make the notify handler run
>> synchronously with the caller to Notify(), but this created more
>> problems than it solved. We ended up returning the behavior of Notify
>> handlers to be asynchronous:
>> 19 October 2007. Summary of changes for version 20071019:
>> 1) ACPI CA Core Subsystem:
>> Reverted a change to Notify handling that was introduced in version
>> 20070508. This version changed the Notify handling from asynchronous
>> fully synchronous (Device driver Notify handling with respect to the
>> Notify
>> ASL operator). It was found that this change caused more problems
>> it
>> solved and was removed by most users.
>>> -----Original Message-----
>>> From: owner-freebsd-acpi at [mailto:owner-freebsd-
>>> acpi at] On Behalf Of Yousif Hassan
>>> Sent: Sunday, January 06, 2008 12:18 PM
>>> To: Nate Lawson
>>> Cc: freebsd-acpi at
>>> Subject: Re: GPE handler livelock
>>> Nate wrote:
>>>> Thanks for digging into this.  I reviewed this and am trying to
>> figure
>>>> out why the _L00 handler never completes.  It keeps getting
>> by
>>>> the next one.  To help track this down, try removing these two
>>>> from the _L00 method and recompile your ASL:
>>>>    Acquire (\_TZ.C173, 0xFFFF)
>>>>    ...
>>>>    Release (\_TZ.C173)
>>>> For others who have this problem, instructions on how to recompile
>> and
>>>> load your custom ASL can be found here (11.16.4 and 5):
>> l
>>> I'm not sure if my situation is exactly what you're referring to in
>>> this note, but since my laptop is also an HP (nx6110), and since it
>> also
>>> hangs during thermal zone changes, I tried your suggestion.  It
>>> help, unfortunately.  I still get mutex problems when the thermal
>>> increases.  My ASL did not have precisely the Acquire call you
>>> but it did have a similar one in method _L00 called
>>> Acquire (\_TZ.C170, 0xFFFF) and Release (\_TZ.C170).  Also this pair
>>> of calls was also found in one other place (further down) in the
>>> I only removed the first pair in the method you instructed.
>>> FWIW, here are the debug error messages when the machine hangs:
>>> ACPI Exception (utmutex-0376): AE_TIME, Thread 28 could not acquire
>> Mutex
>>> [0] [20070320]
>>> ACPI Error (exutils-0180): Could not acquire AML Interpreter mutex
>>> [20070320]
>>> ACPI Error (utmutex-0421): Mutex [0] is not acquired, cannot release
>>> [20070320]
>>> ACPI Error (exutils-0250): Could not release AML Interpreter mutex
>>> [20070320]
>>> ACPI Exception (utmutex-0376): AE_TIME, Thread 28 could not acquire
>> Mutex
>>> [0] [20070320]
>>> ACPI Error (exutils-0180): Could not acquire AML Interpreter mutex
>>> [20070320]
>>> ACPI Error (psparse-0626): Method parse/execution failed
>> (Node
>>> 0xc321c220), AE_TIME
>>> ACPI Error (psparse-0626): Method parse/execution failed
>> [\_TZ_.TZ1_._TMP]
>>> (Node 0xc321b9c0), AE_TIME
>>> ... etc ...
>>> I put more info into PR 79080.
>>> Let me know if you want me to try anything else.
>>> --Yousif
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