[U-Boot-Users] Porting u-boot to custom MPC852T board.

[DavidHo at nanometrics.ca]

Hi,

I'm currently porting u-boot version 0.4.8 to our custom board running an
MPC852T.  The processor is configured to high-boot at 0xfff00000.  U-boot
is failing to execute any instructions in RAM after it has been relocated.
I did a CRC check on the code in RAM and compared that to the code in
flash.  I compared the memory dump of in_ram in RAM (which is the first
thing u-boot jumps to in RAM) and the same routine in flash.  They match
exactly.  Nothing seems to indicate that I have a problem writing and
reading to the SDRAM at these locations.

Stepping through relocate_code gave me the expected results.  I then put a
breakpoint at the branch location in RAM and tried tracing the instructions
there, but none of it made any sense to me.  I am pretty sure relocate_code
is branching to the right location in RAM.  This looks like a caching
problem because it seems like it is not fetching the instructions from
memory.  Does anyone have a similar problem with MPC866 family of
processors?

The code in ram just execute from address in_ram to in_ram+0x98 and
branches back to in_ram in an endless loop.  Does it appear to look like
some section of code that was previously ran from flash but was remain in
cache?

This portion of code modifies R3 to fff2dc00 which is definitely wrong
because in_ram tries to do a store to that location, which it is the high
boot flash memory region.

Regards,

David Ho
Nanometrics Inc.