[maemo-leste] Broken u-boot on n900 hw (possibly CONFIG_POSITION_INDEPENDENT)

[Pali Rohár]

On Monday 10 October 2022 23:30:21 Sicelo wrote:
> On Sun, Oct 09, 2022 at 09:33:17PM +0200, Pali Rohár wrote:
> > Hello!
> > 
> > Current u-boot from master branch does not work on n900 hw. It does not
> > show anything on display, there just nokia logo.
> > 
> > In qemu it is working fine and all tests are passing. Also in qemu is
> > display working without any problem.
> > 
> > Could you help me to debug it? Maybe something is printed to serial
> > console? Or maybe serial console could be used for printf-debugging?
> > 
> > I just figured out that disabling CONFIG_POSITION_INDEPENDENT u-boot
> > option make it working again. But it requires to restoring older version
> > of lowlevel_init.S file which does not depend on POSITION_INDEPENDENT:
> > 
> >     git checkout 7c4ad9821758f98db127e9d6864671c906c02d3b -- board/nokia/rx51/lowlevel_init.S
> > 
> > And also setting CONFIG_SYS_TEXT_BASE=0x80008000 (to some value in RAM).
> 
> Hi
> 
> I have a really crude serial console setup in place now, but very little
> time, and even less experience with u-boot. I should be able to do the
> tests for you on Saturday night (UTC+2). Perhaps over IRC might be a
> good idea, in case I need some hand-holding, and if you still need the
> help by then.
> 
> Regards
> Sicelo

Well, I do not know where to start or how to instruct somebody who is
not experienced with u-boot debugging. I think that the first step
should be to look if U-Boot prints something on the serial console or
not. If it prints then try to find via printf-driven-debugging place
where it stuck. If it does not print anything on the console then try to
setup debug early console, check if it prints something now and do same
type of debugging. And if even early debug console does not work then
probably initialize serial console directly in lowlevel_init.S file,
prints something to serial, then move code for printing to later stage
and try to figure out what is broken...

Anybody else with serial console can look at it?

Or maybe look at the code if you spot some issue there?