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Re: how to support more than 512MB RAM for MIPS32 ?

To: "Figo.zhang" <figo1802@gmail.com>
Subject: Re: how to support more than 512MB RAM for MIPS32 ?
From: Ralf Baechle <ralf@linux-mips.org>
Date: Wed, 25 Nov 2009 16:00:47 +0000
Cc: Kevin Hickey <khickey@netlogicmicro.com>, linux-mips@linux-mips.org
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References: <c6ed1ac50911242234p12817b55r1a062d59949308bf@mail.gmail.com> <1259159857.4675.11.camel@kh-d280-64> <1259163074.2049.6.camel@myhost>
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On Wed, Nov 25, 2009 at 11:31:14PM +0800, Figo.zhang wrote:

> how to do map extra RAM to any ouside I/O space?
> it is just motify:
> 
> 1. arch/mips/kernel/setup.c: bootm_init()function, motity the define
> "HIGHMEM_START", for me: 
> #define HIGHMEM_START 0x2000,0000   //512MB

Leave HIGHMEM_START unchanged; it should always be 512MB no matter what
the actual memory addresses of a particular platform are.  The kernel
needs to treat anything above 512MB differently because it's not
permanently mapped and HIGHMEM_START stands for this limit.

  Ralf

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