j820, the saga

Francois-Rene Rideau fare@tunes.org
Sun Mar 28 00:28:56 CET 2004

Dear Oleg,

I fear I have no proficiency to answer the hardware questions
(though, if the RAM bank 1 has 2MB of VRAM, couldn't RAM bank 2 or 3
hold something else than 16MB of RAM? Couldn't we cheat a bit with
the hardware and work around in software?)

As for the software, here's my answer.
>> j820/init.S now properly uses ATAG. In jornada820.c, fixup is now empty.
> Can this code be merged into the general init.S instead of having the
> separate j820/init.S ?

Not really:
* we need know the size of the initrd, which must be quite separate
 from the zImage.
* we need know the size and location of memory and initrd,
 which the booting.php clearly tells us is a task for the boot loader.
* this j820/init.S can be construed as the last part of the bootloader.

> What about zeroing (filling with a known pattern)
> the whole memory and putting all internal processor registers to a
> known sane state ?
I'm not sure clearing memory would help;
however, if you know how to reset all internal IO registers, go ahead!

[ François-René ÐVB Rideau | Reflection&Cybernethics | http://fare.tunes.org ]
[  TUNES project for a Free Reflective Computing System  | http://tunes.org  ]
If the human mind were simple enough to understand,
we'd be too simple to understand it.
	-- Pat Bahn

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