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Re: how to use TLB to prevent Linux accessing a particular memory region

To: veerasena reddy <veerasena_b@yahoo.co.in>
Subject: Re: how to use TLB to prevent Linux accessing a particular memory region
From: "J. Scott Kasten" <jscottkasten@yahoo.com>
Date: Tue, 16 Oct 2007 10:13:38 -0400 (EDT)
Cc: "linux-kernel.org" <linux-kernel@vger.kernel.org>, linux-mips <linux-mips@linux-mips.org>
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Really, it sounds more like you want a custom driver that "owns" that region of memory so it's marked as used and this driver is the gate keeper. I wonder if the console frame buffer driver for the mips ip32 arch might be a good example for you as it swallows a several meg chunk of memory for the display.

-S-

On Tue, 16 Oct 2007, veerasena reddy wrote:

Hi,

I have a board, which has two processors ( one is MIPS
on which Linux-2.6.18 kernel runs and another is DSP
based processor) and 32MB DDR.

Out of 32MB of DDR 8MB is reserved for use by DSP
processor. But the MIPS processor downloads firmware
into this reserved memory for the DSP.

Now, is it possible to use the TLB to prevent Linux
from accessing the reserved memory after the firmware
has been downloaded?

Also we'd need to remove those TLB entries if the
firmware would ever need to be reloaded to the DSP'
memory region.

What are the APIs to be used to achieve the above?


Thanks in advance.

Regards,
Veerasena.


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