[okl4-developer] Debugging tips for a new platform

[Geoffrey Lee]

On Thu, Jun 19, 2008 at 12:53:09PM +1000, Joshua Root wrote:
> Hi all,
> 
> I'm porting OKL4 2.1.1-fix7 to the Linksys NSLU2 (aka Slug), which is a 
> big-endian XScale platform, IXP420-based. I've referenced the ixp4xx 
> platform code from the old N1 version of L4, and the current pxa code, 
> and have produced something which compiles and links, but the image 
> produces no serial output when run.

Josh - 

There is a platforms/pxa/tools/machines.py where you put specific
platform description for the PXA.  This tells it where the memory
is located, as well as other platform-specific descriptions.  Most
of these are for Iguana, though.

For PXA, you will need to define the subplatform, because there
are minor differences on how certain operations are handled in
say, between PXA255 and PXA270.

The head.spp should work unmodified, we utilize the PXA-based
gumstix extensively.  That runs in little endian though, but 
I don't think that is the specific issue.

I just took a brief look at the Skyeye source code and it seems there
is support for running in big endian mode.  If you specify the -e
parameter it infers it from the ELF file automatically.  You may
want to take a look whether it is worth trying out Skyeye, as
it can give you instruction traces, and from there, you can narrow
down where to look further.

	-gl



> 
> I used the head.spp from pxa unmodified, would you expect that to work? 
> Are there likely to be any issues with big-endianness outside the 
> platform code? I've double-checked the KDB serial code and it looks 
> right. Basically I'm looking for debugging tips. What am I most likely 
> to have got wrong? :)
> 
> TIA,
> Josh
> 
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