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Re: dynamic memory detection
- From: alfred hitch <alfred dot hitch at gmail dot com>
- To: Robin Randhawa <robin dot randhawa at gmail dot com>
- Cc: ecos-devel at ecos dot sourceware dot org
- Date: Wed, 11 May 2005 03:37:36 -0400
- Subject: Re: dynamic memory detection
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- Reply-to: alfred hitch <alfred dot hitch at gmail dot com>
Hi Robin,
thanks for your reply,
but could u please give more details on ur SDRAM sizing algo ?
how were u doing that ?
then I will see if I can do the same on IXDP or not ..
My fear is that I cannot as I was discussing with someone who has
worked extensively on x86 plattforms.
In there on northbridge there is a device generally which can be read
to find the size etc of dram ,
as of now I dont see any such stuff on ixp data sheet.
May be this is the reason that redboot etc dont have this as it might
not be a portable feature, but come to think of it, on boards where
one can, it should be implemented ?
can u tell how u did the sdram sizing thing ? I can infact choose
u-boot also as my bootloader that isnt the issue presently.
Alfred
On 5/10/05, Robin Randhawa <robin.randhawa@gmail.com> wrote:
> 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
> >
>
>