8.0-RC1 panic attaching ppc

Alan Cox alc at cs.rice.edu
Mon Sep 28 17:25:17 UTC 2009

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.


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