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Subject: Re: Reserved pages in PowerPC
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Ankita Garg <ankita@in.ibm.com>
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Date: Thu, 16 Sep 2010 20:04:24 +1000
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On Thu, 2010-09-16 at 10:53 +0530, Ankita Garg wrote:
> 
> With some debugging I found that that section has reserved pages. On
> instrumenting the memblock_reserve() and reserve_bootmem() routines, I can see
> that many of the memory areas are reserved for kernel and initrd by the
> memblock reserve() itself. reserve_bootmem then looks at the pages already
> reserved and marks them reserved. However, for the very last section, I see
> that bootmem reserves it but I am unable to find a corresponding reservation
> by the memblock code.

It's probably RTAS (firmware runtime services). I'ts instanciated at
boot from prom_init and we do favor high addresses for it below 1G iirc.

Cheers,
Ben.