linux-mips
[Top] [All Lists]

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

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: how to support more than 512MB RAM for MIPS32 ?
From: "Figo.zhang" <figo1802@gmail.com>
Date: Thu, 26 Nov 2009 00:17:01 +0800
Cc: Kevin Hickey <khickey@netlogicmicro.com>, linux-mips@linux-mips.org
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:subject:from:to:cc :in-reply-to:references:content-type:date:message-id:mime-version :x-mailer:content-transfer-encoding; bh=mfiShkuU2asD3QvquOVy1t80TLzI0BVmFMikoq0fgBI=; b=v/zRtgEEAK6eODaidC/QhkGjCvZ3mxdQ1nGzEf/CAb4uJH7u1bgWs04g1/SRI6Wfbn 20xBqcTZagL+CqRsJyy3ni5KQysvXCoQ1/pJFELm+anOwNZUFT8ym9z6MSmzgNYUpivn dHkJL2d75uFIRH3Vrrabqv4xU0khVakmLd4Vo=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=KeE9NUkE9Xmj9/kM0NOukfd/KI2funYUIgxbN/Y7mxzHFUHwuXOMSW0EnqGt3R+ydw E1zYul3sB6bG42siBEoiOxyn87afv2MN/0En64j0d2ra1KuCJ0H0w1Afo27N0SBAtrSB PM6ptU/WSEtrwTiR5lE9Hnn0TtkM+7185JXZ4=
In-reply-to: <20091125160047.GA10490@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <c6ed1ac50911242234p12817b55r1a062d59949308bf@mail.gmail.com> <1259159857.4675.11.camel@kh-d280-64> <1259163074.2049.6.camel@myhost> <20091125160047.GA10490@linux-mips.org>
Sender: linux-mips-bounce@linux-mips.org
On Wed, 2009-11-25 at 16:00 +0000, Ralf Baechle wrote:
> 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.
> 

HIGHMEM canot directly invoke __get_free_pages() to allocate pages, so
it would slow performance ?

Is it anyother solution in current linux-mips kernel? for example,
directly map extra RAM to 0x40000000~0x80000000, the user space
decreased, only 0x0~0x40000000.

Best,
Figo.zhang

>   Ralf



<Prev in Thread] Current Thread [Next in Thread>