[ECOS] eCos PowerPC Startup

["amassa at cts dot com" <amassa at cts dot com>]

Since I have been having so much trouble getting ecos running on my MBX
board I have stepped as far back to the beginning as possible.  I have been
stepping through the startup code (in vectors.s) on my MBX board because it
seems to be hanging each time.  I am using the EPPC-bug firmware to step
through each assembly line.

When I compile the code I see that the srec file is generated with an offset
of 0x10000 (if no exception vectors are copied) or 0x10100 (when exception
vectors are present).

I had to manually define CYGSEM_HAL_POWERPC_COPY_VECTORS in vectors.s
because it would not copy the vectors when I have it configured that way in
my ecos configuration.

I checked and found the correct assembly code present at the specified
address.

I ran the code in two different situations, the first was without any
exception vectors copied.  I stepped through the code and the board hung as
soon as I tried to branch from vectors.s in the _start routine to mbx.s in
the hal_hardware_init routine.

The next time I ran I didn't get very far at all.  The IP was at 0x10100
which is the reset vector.  I step through the vector which basically just
jumps to _start at address 0x12000.  As soon as I tried to step to the
branch instructions (bclr), the board hangs.

Any insight into what might be going on would be greatly appreciated.

Thanks,
Anthony