[U-Boot-Users] U-Boot on MPC8280

Rod Boyce rod_boyce at stratexnet.com
Wed Jan 7 19:58:39 CET 2004

This is just my $0.02 worth but I have used our BDI2000 to debug User land
application, Kernel, and device drivers at the same time.  It is an
invaluable tool when tracking down both software and hardware bugs.  In fact
I will start hardware debugging with our BDI before cabling up a Logic
I can say that without a doubt if we had not use the BDI2000 in this way we
would have ended up redesigning the hardware to get around some perceived
limitations.  Instead I found the software bug and fixed it.  I did all this
in about 3-hours work as well.

I don't use the BDI all the time to debug user mode applications but when
you want to stop the hole processor it is invaluable.  To be able to step
through user code and then jump into the kernel on system calls is just

I cannot tell you how much time our BDI has saved us.  We also have a Vision
ICE in another office I am not completely familiar with the Vision Ice but
compared to the functionality I get from a BDI the Vision Ice is a very poor


-----Original Message-----
From: Wolfgang Denk [mailto:wd at denx.de]
Sent: Thursday, January 08, 2004 4:46 AM
To: David Aldrich
Cc: Matias Sundman (AL/EAB); u-boot-users at lists.sourceforge.net
Subject: Re: [U-Boot-Users] U-Boot on MPC8280 

Dear David,

in message
<0E8A20F2EB7BD7119C1F00508BB333780E5D7B at tmservermail02.t-modus.nec.co.uk>
you wrote:
> Is it true that the BDI is not suitable for user app debug?  Is this a

Yes, this is true. Well, you _can_ use  it,  but  you  have  manually
navigate  through  the  kernel virtual address space to find what you
are looking for. Sometimes  this  is  necessary  (typically  to  find
kernel  bugs),  but  this is definitely nothing to do for the average

> problem in practice?

No, it is not.

Kernel debugging and application debugging are two separate  weorlds,
like  kernel  address  space  and  user  address  space  are  clearly
separated. There is tools for both of them: for the firmware,  device
drivers  and  kernel  debugging  you  use  the  BDI2000, and for user
applications you use gdbserver or gdb.

Note that this does not mean  any  loss  of  productivity:  both  the
BDI2000  and  gdbserver  "speak" GDB remote protocol, so you will see
absolutely the same user interface.

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
"If the code and  the  comments  disagree,  then  both  are  probably
wrong."                                                - Norm Schryer

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