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Date: Sat, 01 Dec 2012 11:10:00 +0200
From: Andriy Gapon <avg@FreeBSD.org>
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To: =?ISO-8859-1?Q?Jean-S=E9bastien_P=E9dron?= <dumbbell@FreeBSD.org>
Subject: Re: [rfc] bind curthread to target cpu for _CST change notification
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on 01/12/2012 11:02 Jean-Sébastien Pédron said the following:
> On 30.11.2012 12:14, Andriy Gapon wrote:
>> Here is my WIP: http://people.freebsd.org/~avg/acpi_cpu_notify.2.diff
> 
> Hi Andriy!
> 
> I tried your last patch and it fixed a page fault I had since r243404 (I 
> couldn't investigate the problem before this week-end).
> 
> This page fault corresponds to the point #2 of your patch ("avoid race 
> acpi_cpu_cx_cst and acpi_cpu_idle"). In my case, acpi_cpu_cx_cst is 
> triggered every 10 seconds (I don't know if it's expected). This frees 
> cx_ptr->p_lvlx each time (new in r243404), and concurrently, 
> CPU_GET_REG(cx_next->p_lvlx, 1) causes the page fault in acpi_cpu_idle().

Thank you for testing!  I will commit this patch soon.

> By the way, should _CST appear in a dump from acpidump(8)?

Yes, it depends... :-)
_CST could be defined in a dynamically loadable region.  If you do not see
_CST in the DSDT but see Load() calls, then that's the most likely explanation.

-- 
Andriy Gapon