RE: Cache coherency and snooping

From: Imran Badr (imran.badr@cavium.com)
Date: Tue Aug 13 2002 - 20:56:38 EST

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I am looking at the linux kernel code. The driver in /drivers/char/agp uses
this same seqeuence to allocate non-cacheable memory page ( look at the
function static int agp_generic_create_gatt_table(void)).

I will give it a try on my mips based platform and let you guys know the
outcome.

Thanks to everyone for all the responses and guidance.
Imran.

-----Original Message-----
From: Rik van Riel [mailto:riel@conectiva.com.br]
Sent: Tuesday, August 13, 2002 6:38 PM
To: Imran Badr
Cc: 'Ralf Baechle'; 'Alan Cox'; linux-kernel@vger.kernel.org
Subject: RE: Cache coherency and snooping

On Tue, 13 Aug 2002, Imran Badr wrote:

> Please advise if following sequence of operations are going to help:
>
> alloc memory
> reserve the page
> flush every cache
> call ioremap_nocache

Won't work around hardware limitations. If the hardware
cannot turn off caching, all you could do is flush the
page to ram before every explicit IO request...

regards,

Rik

-- Bravely reimplemented by the knights who say "NIH".

http://www.surriel.com/ http://distro.conectiva.com/

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