[U-Boot-Users] board bring up, mpc8555 custom board

[U-Boot-Users] board bring up, mpc8555 custom board

[Cam]

Hi

We have used u-boot-1.0 on our 8260 based boards with great success.

We are trying to bring up a new mpc8555 based board with u-boot-1.1.4 
but have run into some problems.

We have a BDI probe which is used for programming flash and exercising 
hardware using JTAG.

Using the BDI probe and a fairly extensive config file (which sets up 
TLBs and LAWBARs) we are able to step through the programmed u-boot 
although it has an alignment exception whilst running 
cpu/mpc85xx/start.S (at the part after the comment "Allocate Initial RAM 
in data cache"). We think it's an alignment exception because it jumps 
to the alignment exception handler address and continues briefly.

The u-boot code is modified from the mpc8560ads code, the main 
difference being the boot flash is 32Mb and we have no localbus SDRAM.

I have a suspicion that we shouldn't be trying to single step this 
initialisation code after the BDI has set up the hardware somewhat. I 
have tried a reduced BDI config file and it still doesn't work, and it 
no longer single steps.

Any suggestions how to proceed would be appreciated, does the alignment 
exception after allocating RAM suggest anything to anyone?

Thanks

-Cam

-- 

                                                                      <--
camilo@mesias.co.uk

[U-Boot-Users] board bring up, mpc8555 custom board

[Wolfgang Denk]

In message <43DB6042.9050000@mesias.co.uk> you wrote:
> 
> Using the BDI probe and a fairly extensive config file (which sets up 
> TLBs and LAWBARs) we are able to step through the programmed u-boot 

I'd like to point out that this is NOT the recommended way of  debug-
ging  U-Boot. It is usually much more efficient to use only a MINIMAL
config file for the BDI2000.

> although it has an alignment exception whilst running 
> cpu/mpc85xx/start.S (at the part after the comment "Allocate Initial RAM 
> in data cache"). We think it's an alignment exception because it jumps 
> to the alignment exception handler address and continues briefly.

It can be anything - including a consequence  of  your  inappropriate
BDI config file.

> I have a suspicion that we shouldn't be trying to single step this 
> initialisation code after the BDI has set up the hardware somewhat. I 

You shouldn't make the BDI initialize the HW in the first place.

> have tried a reduced BDI config file and it still doesn't work, and it 
> no longer single steps.

You have to work on the BDI  init  file  until  you  can  single-step
U-Boot right from the reset entry point. As long as this doesn't work
you cannot continue.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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