[U-Boot-Users] custom 8245 board & exceptions

Wolfgang Denk wd at denx.de
Tue Nov 5 12:51:03 CET 2002


in message <81A66F72DCACD511B0600002A551BFCB4E9CA3 at kuumex05.barco.com> you wrote:
> Our board is loosely based on the Sandpoint 8245 Unity board. The main
> difference is that it contains also a DSP and FPGA. The PowerPC related part
> is only composed of the MPC8245 running as PCI agent , 16MB of SDRAM, 2
> Flash ("primary" of 512KB and second one of 8MB) and the PCI bus (no serial
> port->no console) 
> I can Flash PPCBOOT with the BDI and use he SDRAM.
> I modified the putc and puts functions to write in a circular buffer located
> in RAM.

This is NOT a good idea. Console I/O is iused a long time before  the
RAM gets initialized, so you are provoking undefined behaviour.

> The problem is that that doesn't always work. I receive a "data storage
> interrupt" coming from  the function initdram.
> Note that the circular buffer is initialized just after initdram and that
> the position of the buffer and its data structure is hard wired in the
> program.

But console I/O is used long before that!

> I received before also a decrementer interrupt and I disabled the bit for
> it. I don't understand clearly the usefulness of this. Does it work like a
> watchdog ? 

I suggest you get yourself a BDI2000, which allows for good debugging
features, but also for a remote console feature which might be _very_
handy in your situation.

Ummm... and think about some form of  punishment  for  the  guys  who
designed  your  hardware.  A  board  without  a  serial  port is very

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
See us @ electronica 2002 in Munich, Nov 12-15, Hall A3, Booth A3.325 

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