Re: [RFA] set/show enable-software-singlestep

[Michael Snyder <msnyder@specifix.com>]

On Tue, 2008-06-24 at 21:07 +0100, Pedro Alves wrote:
> A Tuesday 24 June 2008 19:18:54, Michael Snyder wrote:
> > There may be cases where gdb would be inclined to use
> > software singlestep, but you might not want it to.  Examples:
> 
> I understand you want this for reverse debugging, so let me ask:
> 
> >  * "target remote" to a target such as a simulator that
> >    would be able to support normal singlestep.
> 
> Should the support be reported by the stub instead?, as in:
> 
> Can the target (stub/debug api) do single-stepping?  Yes, cool.
> No?  Bummer, will have to do software-singlestepping
> on the GDB's side.

Yes, that would certainly be cool -- automate the choice.
At the moment, I don't know of any stub that can report
that capability, so I'd like to be able to do it explicitly.


> E.g, another similar issue with displaced stepping:
> (hey you just touched that option :-) )

Yes, I was noticing that!  Sounds like a cool capability.

> I'm working with a target that supports stepping 
> off breakpoints on the stub side.  I was thinking of:
> 
>   Can the target (stub/debug api) step over breakpoints for me?
>   Yes, cool.  No?  Bummer, will have to do displaced-stepping
>   on the GDB's side.
> 
> >  * reverse debugging, where you can't predict the
> >    "come-from" address of a jump instruction.
> 
> Should software-singlestepping *always* be disabled
> while doing a reverse debug?  If so, why do we need the
> command?  Shouldn't it be enforced in the code?

Possibly.  I haven't gotten that far along in my thinking.
Just seemed like a reasonable starting point was to be
able to set it by hand.

And as I said, there might be other cases where you'd
like to do this other than reverse debugging.