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Date: Mon, 28 Sep 2009 12:25:07 -0500
From: Alan Cox <alc@cs.rice.edu>
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Cc: Attilio Rao <attilio@freebsd.org>, alc@freebsd.org,
	freebsd-stable@freebsd.org, John Baldwin <jhb@freebsd.org>
Subject: Re: 8.0-RC1 panic attaching ppc
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Daniel O'Connor wrote:
> On Sun, 27 Sep 2009, Alan Cox wrote:
>   
>> Ok, now I can explain what is happening.  The kernel is using 1GB
>> pages to implement the direct map.  Unfortunately, pmap_extract()
>> doesn't know how to handle a 1GB page mapping.  pmap_kextract() only
>> works by an "accident" of its different implementation.  In other
>> words, it should not be relied upon to work either.
>>
>> Please revert whatever patch John gave you and try the attached
>> patch. It simply disables the use of 1GB page mapping by the direct
>> map.
>>     
>
> Your patch fixes (works around?) the problem.
>   

Thanks.  I've committed the patch.

Yes, it's a work around.  Fortunately(?), on my test machine, I don't 
see any measurable effect from disabling the use of 1GB pages by the 
direct map.

Alan