[U-Boot] mpc83xx U-boot questions

[Jerry Van Baren]

Yuke Tian wrote:
> Thanks.
> 
> To be specific, I followed the steps to build RTEMS:
> 1) Download a set of toolsets (gcc-4.2.3, binutils-2.18, newlib-1.16 and
> RTEMS specific patches) and build them or use the pre-built rpm toolset
> for RHLE5.

OK.

> 2) Download the RTEMS (4.9.0 for the latest version) and use the toolset
> to build RTEMS.

OK for RTEMS, it may be some work getting it to compile u-boot or linux. 
  Or maybe not.  Around here, ELDK dominates because it is easy to build 
u-boot and linux with it (thanks, Wolfgang!).  If you get serious about 
rebuilding u-boot or linux, I would strongly urge you to use ELDK to 
build the first one before trying to get RTEMS' toolset to work.  Rule 
#1 of engineering: change only ONE variable at a time!

> 3) Compile a RTEMS application,  tailed for specific BSP.  That is where
> I get .exe (it is ELF 32-bit MSB executable, PowerPC or cisco 4500,
> version 1 (SYSV), statically linked, not stripped).

That's good.

> I just want to use the vendor provided U-Boot to download the .exe
> and get it run.

I don't know anything about RTEMS and its BSP.  It may want to be burned 
into flash, replacing u-boot.  In that case, open your wallet and buy a 
JTAG debugger (e.g. BDI-3000).

----

If you want to use u-boot to load & go, you need to figure out where the 
.exe is loaded in memory and make sure it is in RAM, not by the start of 
RAM (interrupt vectors) or end of RAM (u-boot).  You probably will need 
to change the load location (Makefile or linker script *.lds).

You will need to figure out where RTEMS wants to live.  It may want to 
live at the start of RAM so it can take over the interrupt vectors.  You 
will need to figure out how to get it where it needs to be, if you 
cannot load it directly there.  You may be able to learn from how u-boot 
boots a vxWorks image?  That is the closest match that I can think of to 
how RTEMS will work.

You will also have to figure out how to make RTEMS support your board's 
I/O (serial first, ethernet second).

All of the above should be addressed more or less successfully by the 
BSP.  Whether your RTEMS+BSP plays well (or at all) with u-boot, I don't 
have a clue.  Since we (I) don't know much about RTEMS and the BSP you 
have, we (I) cannot say much specific.

> I didn't expect to rebuilt U-Boot, but that might be educational :-)          

It could be expensive too, if you don't have a JTAG debugger to recover 
from oopses. :-/

> Yuke

BTW, please bottom/inline post.
   <http://en.wikipedia.org/wiki/Posting_style#Bottom-posting>

Best regards,
gvb

> Jerry Van Baren wrote:
>> Yuke Tian wrote:
>>> Hi,
>>>
>>> Sorry to ask the stupid question. I did study the RTEMS for a while and
>>> am sure the tool set are correct (from ftp://www.rtems.com), otherwise
>>> they will not build RTEMS.  All the tools and development are done in
>>> linux (RHLE5).  I just got this board using U-boot and not sure about
>>> it. David's manual help a lot. Thanks.
>>>
>>> Yuke
>> I didn't call your question stupid, just clueless.  ;-)
>>
>> It sounds like you are coming up to speed rapidly, including providing
>> useful background information and asking smart questions.  You might
>> add the following to your reading list:
>>   <http://www.catb.org/esr/faqs/smart-questions.html>
>>
>> Best regards,
>> gvb
>>
>