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.