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Re: dynamic memory detection
- From: Robin Randhawa <robin dot randhawa at gmail dot com>
- To: alfred hitch <alfred dot hitch at gmail dot com>
- Cc: ecos-devel at ecos dot sourceware dot org
- Date: Wed, 11 May 2005 09:28:41 +0530
- Subject: Re: dynamic memory detection
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Hi.
While I do not have any hands on experience with the IXDP425, your post
reminded me of some work I had done for another board (one based on the
AMD Elan SC520 micro) to which I was porting the u-boot bootloader. I
used SDRAM sizing algorithms to determine stuff like :
1. The number of external SDRAM banks
2. The bank geometry
3. Column widths etc.
The net result was that the total amount of SDRAM was detectable at
runtime.
I do not have any devel experience with redboot, but being a bootloader
of certain pedigree (its always been a great help), I wonder why SDRAM
sizing and detection is not an option myself.
A bootloader would be expected to configure a board in preparation for
either an OS to take over safely or a standalone application. Either
ways, memory detection would be an added advantage and would not be too
costly in terms of the added footprint, which incidentally, would be one
of the concerns. The only issue could be the need for per-architecture,
per-processor support since SDRAM detection is quite a specific
technique, but eCos' beautifully modular design should easily allow
that.
Maybe the maintainers/developers would like to opine on this ?
Cheers,
Robin
On Tue, 2005-05-10 at 03:36 -0400, alfred hitch wrote:
> Hi All,
>
> I am working on a IXDP425 based plattform,
>
> If I understand it correctly there is no bios on it, and so for
> physical memory on the system, redboot has to depend on constant /
> #defines at compile time.
>
> What if one wants to dynamically detect these ?
> Why cannot we read the memory registers, while we are in redboot and
> set up things accordingly ??
>
> ( I remember doing something similar while playing around in netbsd,
> from smbus via open i/o ports it used to read the memory rows,
> coloumns etc and find out the size)
>
> I am sure there is some glitch in doing this, and I am missing
> something basic here,
> can someone please correct me here.
>
> Cheers,
> Alfred
>