[U-Boot-Users] Debugging u-boot with BDI2000

Juergen Beisert jbeisert at eurodsn.de
Fri Jul 18 13:21:29 CEST 2003

Hello Wolfgang,

>>I'm trying to debug my u-boot with BDI. It's a 405GP based system.
>> In the telnet sessoin I can insert "reset run" and u-boot starts. When I
>> enter "reset halt" and then "go" it won't do anything. I have tried with
>> ddd
>What do you mean with "it won't do anything"? Who won't do  anything?
>The  BDI2000?  The  CPU?  What  makes  you  think the CPU does not do

At first I thought the 405GP cpu does not start. On my card is a LED display, 
so I can output some numbers very early in the startup process. With "reset 
halt", "go" the display never change its contents, with "reset run" it does.

>Are you sure your BDI2000 config file is OK for your board?

Good question. What should happen, to be shure? I have debugged a running 
Linux kernel with this configuration. So I think(!) the major settings are 

>  How  did you  configure  "RESET  type"  and  "STARTUP  mode"?  Is  your
> "START address" ok?

RESET is not set, defaults to "SYSTEM"
START is set to 0x0000'0000 (readed from a default file)

With "reset halt", "info" I see the CPU waiting at address 0xFFFF'FFFC, after 
one single step ("ti") it waits at address 0xFFFF'C0100. Seems ok.

>> When I step the mtmsr instruction ddd shows address 0x700, and the esr
>> register has 0x8800'0000 (illegal instruction occured?????).
>> Same when I place a breakpoint behind the mtmsr instruction und use "cont"
>> instead of "stepi".
>You  are  aware  that  you  cannot  single   step   through   certain
>instructions, aren't you?

If the mtmsr instruction is not "single step able", it should run, if I place 
a breakpoint behind this instruction (for example later in the C routines) 
and use "go" to run up the breakpoint. Or not?

>> What is the difference between "reset run" and "reset halt", "go"?

>"reset run" and "reset halt" change the startup  mode  to  "run"  and
>"halt",  respectively. "go" sets the PC and starts the target system.
>Ummm.. is there any specific part where the BDI2000 manual is unclear
>about this?

Perhaps my english is very bad. Question was: Why the cpu is running normal 
with "reset run", and did not run, when I enter "reset halt", enter a 
breakpoint and than "go" (it never reaches the breakpoint).

-- JB

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