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RE: Load Redboot RAM through serial
- To: "'Gary Thomas'" <gthomas at redhat dot com>
- Subject: RE: [ECOS] Load Redboot RAM through serial
- From: "Trenton D. Adams" <tadams at theone dot dnsalias dot com>
- Date: Thu, 20 Sep 2001 18:39:06 -0600
- Cc: "'Fabrice Gautier'" <Fabrice_Gautier at sdesigns dot com>, "'eCos Discussion'" <ecos-discuss at sourceware dot cygnus dot com>
>
>
> On Fri, 2001-09-21 at 08:56, Trenton D. Adams wrote:
> > How would you go about doing this though? The bootloader
> code in ROM
> > is not changeable and only loads 2K of code into SRAM for running.
> > Does eCos/RedBoot have a utility <2K that will load RedBoot
> into RAM
> > and run it?
>
> Here you're talking about the specifics of a paritcular chip[set].
>
> On the Cirrus Logic chips [your reference], we have to use a program
> provided by CL. We download this program using the
> "bootstrap" mode on the processor. That program then starts
> up a secondary process which loads RedBoot and writes it to
> FLASH. Of course, this mode of operation is very specific to
> that particular processor.
>
> I understand your problem though - you can't use the provided
> code (which came to us only in binary form) since the FLASH parts are
> different. In this case, it may be necessary to write a small
> replacement for the "download and FLASH" program which only
> downloads RedBoot and then runs it. This may prove difficult
> as IIRC the memory map changes when in bootstrap vs normal modes.
It's just a reverse chip select decoding anyhow so that's not too much
of a problem.
I was given the code from Cirrus Logic (source form) so I'm going to be
modifying it. That's what I'm doing in the "--entry=" topic. Trying to
compile/assemble it for loading. I'll probably modify the download
utility for the edb7xxx to load the boot code from a file instead of the
buffer. That way people will be able to integrate flash support for
whatever chips they want, and simply recompile the boot loader. I
talked to the guy there and he said the code is free and can be
integrated into the eCos repository. If you want to, email me privately
at "tadams@extremeeng.com", and I'll give you his email address. You
can talk to him about legalities.
>
> Another possibility to consider might be a special version of
> your hardware with the FLASH device in a socket which you
> could then remove and program remotely.
To late for that, the board is already layed out and almost populated!
:)