Re: [reverse RFA] no singlestep-over-BP in reverse

Michael Snyder
2008-09-16T18:40:02Z

teawater wrote:
>
>
> On Tue, Sep 16, 2008 at 02:42, Daniel Jacobowitz <drow@false.org
> <mailto:drow@false.org>> wrote:
>
>
> If there is a breakpoint on the previous instruction, will you hit it
> before or after de-executing that instruction? It seems like this
> logic should be somehow still necessary... but I can't put my finger
> on when.
>
>
> I think is before exec the next instruction, the GDB will get breakpoint
> trap.
>
> But I found that there is a bug in inside record replay mode, I stop the
> GDB after exec the instruction.

Aha, let's figure out a test for this question.
It's rather important. ;-)

> Michael, how do you deal with the breakpoint in gdb-freeplay and vmware
> record?

Both use simulated hardware breakpoints. That is, they both
accept the Z0 message and emulate hardware breakpoint semantics
by watching the address of execution (one instruction at a time).