A question about All-stop and Non-stop

Pedro Alves pedro@codesourcery.com
Tue May 4 18:48:00 GMT 2010


On Tuesday 04 May 2010 10:25:28, xingxing pan wrote:
> Hi, Pedro.
> Dose GDB use syscall ptrace to single-step the thread while other
> threads are still stopped? 

On archs that support it, yes.

> I've read ARM's codes, it seems ARM's codes
> don't use ptrace to single-step, but just set a internal breakpoint
> and let all threads run.

Close.  On linux (and a couple of other OSs, where gdb knows the
backend doesn't support native single-step), it sets an internal
breakpoint, but only lets _one_ thread run.  For other random
targets, GDB leaves the target in charge of implementing single-step
however it wants (maybe with hardware support, maybe with internal
breakpoints, gdb doesn't need to know).

-- 
Pedro Alves



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