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.