Re: BBRAM

Jörn Engel
2002-11-19T18:23:21Z

On Tue, 19 November 2002 13:12:56 -0500, Richard Brunelle wrote:
>
> Hi, I have a question concerning a BBRAM from ST, the M48Z512A.
>
> I'm using the BBRAM mapped at 0xE0000 on a single board computer from
> VersaLogic. This BBRAM is pageable through access of a special register
> on the single board computer. I want to map the BBRAM as part of the
> file system.
>
> As I understand MTD is appropriate for this purpose, am I right?
>
> If yes, what are the options in the kernel configuration I need to
> enable to let the system access the device?
>
> My guess is CONFIG_MTD_MTDRAM with the appropriate position set to
> 0xE0000. In this case, what type of device should I see in /dev/?

I've been quite happy with the slram driver. The following options
should be enough:
CONFIG_MTD
CONFIG_MTD_CHAR
CONFIG_MTD_BLOCK
CONFIG_MTD_SLRAM

In the case of a monolithic kernel, you have to append something like
this:
slram=BBRAM,0xE0000,+0x8000
First parameter is the device name, second is the device start, third
is the device end or device length (length starts with +).

You have to make sure that the vm doesn't claim the same memory,
though. Maybe you also need something like mem=8M.

David, there is some Documentation floating around, but not in
/usr/src/linux/Documentation, where most people would expect it. What
would I have to do to change that? Commit to cvs? Bitkeeper tree?
Patch to you/Linus/Marcelo?

Jörn

--
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than for a secretaty.
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