[U-Boot-Users] debug u-boot using bdi2000

[Brent Cook <bcook@bpointsys.com>]

On Friday 13 October 2006 13:48, Ben Warren wrote:
> On Fri, 2006-10-13 at 13:38 -0500, Timur Tabi wrote:
> > Ben Warren wrote:
> > > I don't know how well supported your CPU is (I've never heard of it,
> > > but that's not saying much)  Anyway, I've debugged ROM on a couple of
> > > different MPC8349s, but not with 100% success.  I can single-step with
> > > the BDI, and can single-step assembly code, but not C code using gdb.
> >
> > I don't know about PowerPC processors, but on x86, single-stepping
> > assembly code is completely different from single-stepping C code.  With
> > assembly, the debugger typically enables instruction interrupts, where an
> > interrupt is generated after each instruction is executed.  This does not
> > require modifying memory.
> >
> > With C code, a single line of C code is usually multiple assembly
> > instructions, so the debugger (gdb in this case) places a breakpoint at
> > the appropriate spot.
>
> That's some good insight, and would certainly explain my problem.
> Thanks!
>
> Ben

I find it really helpful when debugging C code in ROM to have the output 
of 'cross-compiler-objdump -d u-boot | less' handy for looking up functions 
and such. It's not too hard to get familiar with your CPU's ABI either, after 
a bit of this.