Re: Is stub support for the 's' packet optional or required?

Daniel Jacobowitz
2003-02-18T20:23:35Z

On Tue, Feb 18, 2003 at 01:06:28PM -0700, Kevin Buettner wrote:
> On Feb 18, 11:51am, Daniel Jacobowitz wrote:
>
> > > [For remote MIPS/Linux targets, I've found some cases where GDB's
> > > implementation of software singlestep causes some undesirable behavior
> > > when doing the 'stepi' operation through some code that's hit by a number
> > > of threads. Yet, when software single step is implemented in the debug
> > > agent (and disabled in GDB), the debugging behavior is much more useful
> > > (and sensible).]
> >
> > Is it just slow, or do different things actually happen?
>
> Different things happen. Specifically, GDB was getting a SIGTRAP due to
> one of the other threads hitting the software single step breakpoint.
> This meant that I was unable to step through the function that I was
> attempting to debug when GDB was setting the software single step
> breakpoints. When I moved that functionality (software single step)
> to the debug agent, I was able to step through the code of interest
> without any problem.

That's a bug in software single step handling; I bet it shows up now
too, just less often (because of latency changes). I think it's as
simple as marking the single-step breakpoint thread-specific in the
normal way, but it might be a little more complicated...

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer