[U-Boot-Users] u-boot's own boot process

Seb James seb at peak.uklinux.net
Fri Aug 15 16:04:14 CEST 2003


I've got some hardware which has a problem somewhere. It's a board with 
a tqm823l on it and the tqm should happily boot u-boot. The module 
plugged into another board works fine, but in our new hardware the code 

I've checked out u-boot from cvs today, making it 0.4.5, and I applied a 
tqm8xx specific patch to boards/tqm8xx/flash.c which Wolfgang Denk 
posted in reply to a message a couple of days ago. I enabled debugging 
in config.mk and recompiled with no problems.

Running the code (using gdb through an Abatron BDI2000):

The problem occurs at program re-location. I set a breakpoint in 
cpu/mpc8xx/start.S thus:

(gdb) break start.S:575
Breakpoint 2 at 0x4000231c: file 
/eldk/ppc_8xx/usr/src/u-boot/cpu/mpc8xx/start.S, line 575.
(gdb) c

Breakpoint 2, relocate_code ()
    at /eldk/ppc_8xx/usr/src/u-boot/cpu/mpc8xx/start.S:575
575             addi    r0, r10, in_ram - _start + EXC_OFF_SYS_RESET
(gdb) s
576             mtlr    r0
(gdb) s
577             blr
(gdb) s
Program received signal SIGSTOP, Stopped (signal).
0x3ffffffc in ?? ()

And you can see where the trouble occurs (console output given below). 
It's just at the point in start.S where u-boot is relocated from flash 
to RAM (correct me if that's wrong).

Where's the code going from and to? In start.S I read that the code 
starts executing from flash, with the program counter starting at 0x100. 
What is boardinit? From start.S:

"board_init lies at a quite high address and when the cpu has jumped 
there, everything is ok."

Anyone have any ideas as to what might be wrong in the hardware to cause 
this behaviour?


Seb James

Here's the output at the terminal:

U-Boot 0.4.5 (Aug 15 2003 - 13:18:07)
CPU:   PPC823EZTnnB2 at 50 MHz: 16 kB I-Cache 8 kB D-Cache
Board: ### No HW ID - assuming TQM8xxL
DRAM:  16 MB
Top of RAM usable for U-Boot at: 01000000
Reserving 204k for U-Boot at: 00fcc000
Reserving 128k for malloc() at: 00fac000
Reserving 60 Bytes for Board Info at: 00fabfc4
Reserving 52 Bytes for Global Data at: 00fabf90
Stack Pointer at: 00fabf78
New Stack Pointer is: 00fabf78
A? " ?-&o?t*a?:.%?82x?F?A?H? ?e?h?d?r?i?a?d?
?#?G?t?f?a?h?b?n? ? ?i?e?@?0?%?8?
#? e?

(Then some more garbage is output until things stop).

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