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Date: Fri, 01 Apr 2011 11:48:01 -0700
From: David Daney <ddaney@caviumnetworks.com>
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To: Michael Sundius <msundius@cisco.com>
CC: Kevin Cernekee <cernekee@gmail.com>, Ralf Baechle <ralf@linux-mips.org>,
        David VomLehn <dvomlehn@cisco.com>,
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        stable@kernel.org
Subject: Re: [PATCH v2] MIPS: Kernel crashes on boot with SPARSEMEM + HIGHMEM
 enabled
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On 04/01/2011 11:41 AM, Michael Sundius wrote:
> David Daney wrote:
>>
>>
>> I think this may do the same thing as my patch:
>>
>> http://patchwork.linux-mips.org/patch/1988/
>>
>> Although my patch had different motivations, and changes some other
>> things around too.
>>
>> David Daney
>>
> I'm not really sure why your kernel or initrd would be in memory was not
> within
> the range that had been accounted for. are you saying its in high mem?
>

Well the memory initialization code has a bunch of weird rules built in 
that prevent some memory from being used.

For example if the kernel resides in a different SPARSE page than the 
rest of memory bad things happen because memory_present() was not called 
on something that is later freed (when init memory is released).

If I try to put an initrd at a high physical address, the memory below 
that is not usable.

My three patches try to make some sense out of the whole thing.

David Daney