Re: GDB stub question?

Paul Koning
2006-04-26T14:03:13Z

>>>>> "Daniel" == Daniel Jacobowitz <drow@false.org> writes:

>> Is there any way we could revert back to the old way (i.e) - set
>> breakpoint at the next address - continue - remove breakpoint.

Daniel> GDB has never done this to implement source single stepping,
Daniel> so I don't know what you want. You can't predict the next
Daniel> address that far ahead; what if the current line contains a
Daniel> branch?

Isn't there a "target side single step" optional packet -- so if the
stub supports that then gdb can just say "stepi" rather than the more
laborious process of setting one or two breakpoints and doing a
continue?

Daniel> You might want to look at the T packet response if you aren't
Daniel> already using it; supplying a few registers there can make
Daniel> stepping much faster.

I did that with our MIPS target -- yes it helps a lot. I think you
need SP and (if relevant on the target) FP, and maybe PC. A good way
to tell whether it's right is to see if gdb still asks for registers
after it gets the T packet. If yes, then one of the registers it
wanted immediately wasn't in the T packet.

paul