From: Scott Wood <scottwood@freescale•com>
To: Aaron Pace <kodiakuppercut@gmail•com>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: Non-contiguous physical memory on 8572
Date: Thu, 02 Jul 2009 16:14:26 -0500 [thread overview]
Message-ID: <4A4D2332.1060607@freescale.com> (raw)
In-Reply-To: <bc81dc640907021311y1395ed15l2d50cebb3749c29f@mail.gmail.com>
Aaron Pace wrote:
> In MMU_init of arch/powerpc/mm/init_32.c, where the current code sets
> lmb.memory.cnt to zero, I instead walk through the memory regions and
> call lmb_reserve for each chunk of memory that lies in a 'hole'.
> There are then some minor fixups to make sure that total_memory and
> total_highmem get the right numbers. This small change allows all
> four gigabytes of memory to be accessed and used in my tests.
>
> Am I missing something obvious?
The main downsides that I see are wasted memory for bookkeeping of the
hole (how acceptable this is depends on how large the hole is relative
to the size of RAM -- it's a tradeoff against speed of looking up page
structs), and that the reserved area may still be mapped in the TLB
without the guarded bit set.
-Scott
next prev parent reply other threads:[~2009-07-02 21:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-02 20:11 Non-contiguous physical memory on 8572 Aaron Pace
2009-07-02 21:05 ` Kumar Gala
2009-07-02 21:14 ` Scott Wood [this message]
2009-07-02 21:56 ` Aaron Pace
2009-07-06 16:23 ` Scott Wood
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