From: Scott Wood <scottwood@freescale.com>
To: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs.org>,
Surya Ravikiran <koduks@gmail.com>
Subject: Re: reg adjust_total_lowmem
Date: Fri, 26 Oct 2007 14:40:05 -0500 [thread overview]
Message-ID: <20071026194005.GA4571@loki.buserror.net> (raw)
In-Reply-To: <524E69ED-899B-452F-B593-44499C5181A3@kernel.crashing.org>
On Fri, Oct 26, 2007 at 10:04:19AM -0500, Kumar Gala wrote:
>
> On Oct 25, 2007, at 10:51 PM, Surya Ravikiran wrote:
>
> > Hi,
> >
> > I am trying to bootup a Linux kernel, on a FS eval board with 256M.
> > I pass the kernel argument mem=252M, and see that the kernel boots up
> > fine, but with much less memory, ~192M (the closes 64M multiple), and
> > I browsed through the code to see that the adjust_total_lowmem
> > function does not add up the residual memory to the total memory.
> > I am trying to understand why I cannot do this reserving of higher end
> > of the RAM during boot up,
> > I would appreciate your comments.
>
> The reason you have 192M is that lowmem is the total amount of memory
> that can be covered by up to three CAM entries. In the case of
> setting mem=252M that max that three CAM entries can cover is 192M (64
> +64+64). You should be able to access the other 60M via HIGHMEM.
Why doesn't it just use a 256M mapping, and not access the last 4M?
-Scott
next prev parent reply other threads:[~2007-10-26 19:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4dd2a2ce0710252051pe83a943q48f52d148f5a9603@mail.gmail.com>
2007-10-26 15:04 ` reg adjust_total_lowmem Kumar Gala
2007-10-26 19:40 ` Scott Wood [this message]
2007-10-26 20:50 ` Scott Wood
2007-10-26 21:17 ` Kumar Gala
2007-10-26 21:27 ` Scott Wood
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