This is the mail archive of the
ecos-discuss@sourceware.org
mailing list for the eCos project.
RE: MMU, chip select on AT91
- From: Jérémy Alles <jeremy dot alles at orange-ftgroup dot com>
- To: "'Andrew Lunn'" <andrew at lunn dot ch>
- Cc: "'eCos Discussion'" <ecos-discuss at ecos dot sourceware dot org>
- Date: Fri, 7 Mar 2008 16:54:08 +0100
- Subject: RE: [ECOS] MMU, chip select on AT91
Actually I solved this problem by disabling the MMU, but I'd like to fix
that and understand why it doesn't work when MMU is turned on.
MMU's initialization code looks like that (for the 0x30000000 address):
X_ARM_MMU_SECTION(0x300, 0x300, 256, ARM_UNCACHEABLE, ARM_UNBUFFERABLE,
ARM_ACCESS_PERM_RW_RW); /* External CS2 *
So it's look like a direct mapping is used. That's why I don't understand
why that does not work...
Regards,
Jeremy
-----Message d'origine-----
De?: ecos-discuss-owner@ecos.sourceware.org
[mailto:ecos-discuss-owner@ecos.sourceware.org] De la part de Andrew Lunn
Envoyé?: vendredi 7 mars 2008 11:14
À?: J?r?my Alles
Cc?: 'eCos Discussion'
Objet?: Re: [ECOS] MMU, chip select on AT91
On Fri, Mar 07, 2008 at 11:03:31AM +0100, J?r?my Alles wrote:
> Hi,
>
> I?m using a AT91 processor on a AT91RM9200DK board. I?m using a port that
> someone in my company did some years ago. Here is my problem: I would like
> to use the graphic possibilities of the board. In the development kit, I
> have an example driver (source code and bin file).
>
> If I run the bin file from Zooboot it works fine.
> If I build the driver (using arm-elf-gcc) and launch it from Redboot
(using
> eCos environment) it doesn?t work anymore.
>
> I?ve traced down the problem to the chip select line 2 (NCS2). This chip
> select should be enable when I access data at 0x30000000 but it?s not. I
was
> thinking that it might be a problem with the MMU initialization that is
done
> in eCos in AT91 common code.
There is no port for the AT91RM9200DK in anonymous CVS. Without the
code i cannot say what the MMU is doing. However it does sound like an
MMU problem.
Andrew
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss