ARM, MMU and IO space mapping

[Robert Jarzmik]

Sascha Hauer <s.hauer at pengutronix.de> writes:
> I remember Marc had some trouble with the mmu/cache implementation on
> PXA. I don't know the details though. Maybe you have to dig through
> the manuals/kernel code to find out the differences between the normal
> arm v5 and pxa.

Ah, I know what happens now, and it's tricky.
First of all, you're right, there's a flat uncached mapping, I was misled by
the function name "create_section", without looking closely at it. I thought
it created the first section, not all the 4096 1MBytes section of a 4GB
address space.
It would deserve a "create_sections" name, in plural form.

Now, for the serial UDC not working, there comes the fun.
What's happening is that I'm using a default environment, with the init
script in [1]. This script has an error somewhere.
In barebox_startup(), we have :
   if (!stat("/env/bin/init", &s)) {
      run_command("source /env/bin/init", 0);

And here is the trickery:
 - in the NOMMU case, the run_command() returns, and the code continues to the
   eternal loop of run_shell(), which calls console.getc(), which calls
   poller(), which call the UDC poll method
   => the gadget does work
   => I have a console, hurray !

 - in the MMU case, the run_command() never returns, and the poller method is
   never called. I traced that with my leds.
   => the gadget does *not* work

So the problem was not the IO mapping, but a difference in run_command() between
MMU and non-MMU config. Moreover, in non-MMU case, once my console is connected,
I see a message :
> running /env/bin/init...
> syntax error
I the MMU case, as the gadget doesn't work, I'm blind, so I can't really tell
what is happening and which is the impact of MMU over run_command()...

Cheers.

--
Robert

[1] Script:
#!/bin/sh

#led orange 1

PATH=/env/bin
export PATH

. /env/config

while [ -z $toto ]; do
    led orange 1
    readline "Give me a word" word
    echo "I've got your $word"
done