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Date: Thu, 10 Mar 2011 08:41:08 +0530
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From: "Jayachandran C." <c.jayachandran@gmail.com>
To: Adrian Chadd <adrian@freebsd.org>
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Cc: freebsd-mips@freebsd.org
Subject: Re: What to do when redboot lies about RAM?
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On Thu, Mar 10, 2011 at 8:13 AM, Adrian Chadd <adrian@freebsd.org> wrote:
> One of the Ubiquiti boards (LS-SR71) has redboot firmware that seems to lie
> about the amount of RAM it has.
>
> Although the board has 32 megabytes of RAM, Redboot only reports 16mb. Linux
> doesn't query redboot; it probes the amount of RAM by writing bits and
> reading them back until it finds where that fails.
>
> I've whacked together a quick hack to make this memory selection overridable
> in the kernel configuration.
> What would be the cleaner way? :)

Sibyte (mips/sibyte/sb_machdep.c) has a tunable hw.physmem for this.
That has an advantage that you do not have to re-compile the kernel to
change the memory setting.

There is also a MAXMEM option already in conf/options.mips which can
be used I think...

JC.