[U-Boot-Users] Startup for ARM boards?
steven.scholz at imc-berlin.de
Thu Sep 25 09:34:52 CEST 2003
>>>>I will have a AT91RM9200 based board real soon now. But apparently the
>>>>eval board AT91RM9200DK uses a different approach. They have a
>>>>separate urloader to decompress and copy an U-Boot image into RAM and
>>>>then jump there...
> Actually this "urloader" is called Thunderboot and is a ripped version
> of ARMboot (a practice which seems to be quite fashionable these
> days.) I never got round to asking them for the sources, nor do I
> understand why they concealed it so pathetically :-) The flash images
> even contain references to ARMboot. Maybe you want to have a go at
Ehm. Nope. That's not what I meant.
They replace Thunderboot by their so called "AT91RM9200-Boot". Then they build a
U-Boot version for the eval board AT91RM9200DK and gzip it. The AT91RM9200-Boot
and the zipped version of AT91RM9200-U-Boot are stored in flash. Now all that
AT91RM9200-Boot does when power-on is init the hardware (especially SDRAM),
decompress u-boot.gz into SDRAM and jump to it.
"We chose, to put a compressed boot due to memory mapping constraints.
We need to keep a sector for environment variables the 8Kbyte-size sector is
IMHO this wasn't nessesary at all since they do seem to have flash with a few
small sectors. But nevermind.
They even provide a "AT91RM9200-Loader" which could be used to download the above
files via the DEBUG UNIT (DBGU).
I got these sources from Atmel. Now that I have these source I hope I can get
this working on my board as well. Then when this two-(or three)-step version
works I want to make U-Boot working like for all the other plattforms: init
SDRAM, relocate and start.
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