Re: Faster stepping amidst breakpoints

[Daniel Jacobowitz <dan@codesourcery.com>]

On Thu, Feb 03, 2011 at 02:53:40PM -0800, Maxim Grigoriev wrote:
> 2) I think in the embedded-system world it does matter
>     when crashing / detaching GDB leaves target memory
>     and/or registers changed.

Yes - if your agent does breakpoint management using z/Z, then it has
the opportunity to clean up as long as the agent doesn't crash.  IMO
that's a reasonable expectation; if the agent crashes, your target is
probably in an unrecoverable state anyway.

> What I meant was a target agent, which can
> 
>     -- realize it's about to single-step over an inserted
>        breakpoint and then handle it properly ;
> 
>     -- watch out for shutting-down GDB communications,
>        while counting time-outs, and then return target to the
>        reliable state essentially making GDB non-intrusive.

I suggest separating these and dealing with them as separate concerns.

A related issue is watchpoints; different agents (and SoCs) handle
the current instruction after hitting a watchpoint differently.  For
instance, GDB assumes all MIPS targets have nonsteppable watchpoints
and we have one where that's clearly not true...

-- 
Daniel Jacobowitz
CodeSourcery