[U-Boot-Users] Debugging U-Boot on 440GP

Brian Padalino bpadalino at perigee.com
Thu Nov 27 01:02:45 CET 2003

Hi Wolfgang,

I removed basically everything from the INIT section and have found (through
single stepping still .. I am not sure why later breakpoints still don't
work yet) where my system's red light comes on.

init_baudrate() calls getenv_r() -- since I do not have a valid environment
table, it uses the default.  I modified my default environment to load the
baudrate first and it's during the envmatch() function that I end up getting
an error.

Even with baudrate at the beginning of the env table, it still falls through
everything to return(-1).  I find that confusing, but the strange part is
that it returns to some place around 0x05?????? which is too high for my
32MB of DDR on the board.

I am guessing I have to look at the stack placement, but I ran out of time
today to look at that, so tomorrow I think I will look at the stack pointer
placement and if I am, for some reason or another, blowing it up.

I am still upset I can't set hardware breakpoints farther in code that I
know I can reach and use the 'c' command instead of single stepping through
it all.  I am not setting too many breakpoints -- I keep it to the 2 that
the BDI supports.

So I suppose any extra help or pointers on the breakpoint situation would be

You know, I just realized -- why don't I just try to recompile u-boot to run
from RAM instead of trying to compile it and debug it to XIP?

Thanks for the help folks.

Brian Padalino

-----Original Message-----
From: u-boot-users-admin at lists.sourceforge.net
[mailto:u-boot-users-admin at lists.sourceforge.net]On Behalf Of Wolfgang
Sent: Wednesday, November 26, 2003 9:51 AM
To: Brian Padalino
Cc: U-Boot Mailing List
Subject: Re: [U-Boot-Users] Debugging U-Boot on 440GP

Dear Brian,

in message <AKELKEJDICNMBGAOOBLAGEPACHAA.bpadalino at perigee.com> you wrote:
> Lastly, I was thinking about this last night -- is the BDI too invasive in
> trying to figure out if U-Boot will boot properly?  It sets up the MMU and
> TLB by itself through it's init sequence, and I _think_ I am setting them
> properly in U-Boot, but I am not sure.  From what I saw in the code in

I have often recommended to use just a MINIMAL inti  script  for  the
BDI.  Don't  touch the memory controller. Just configure the absolute
necessary minimum (things like disabling a watchdog etc.).

> I guess I am just at a loss as to what these exception vectors mean

Then you will have to dig through a few books about the PowerPC

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
An optimist believes we live in the best world possible; a  pessimist
fears this is true.

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