Re: [RFA] Displaced stepping just enable in non-stop mode

Michael Snyder
2008-10-17T19:49:45Z

Jakob Engblom wrote:
>>> I see, then this means that all the reverse targets in existance
>>> implement inserting breakpoints (target_insert_breakpoint, Z packet),
>>> instead of relying on memory breakpoints.
>> I believe that's true. Certainly it's true for gdb-freeplay.
>
> Do I understand to mean that the assumption is that the remote-capable target
> system
> Implements breakpoints by NOT modifying the code, but rather using some other
> mechanism that says that certain instructions in memory are breakpoints, and
> triggers them appropriately?
>
> This is what we do in Simics, and this assumptions makes sense to us.
> Breakpoints are implemented in the simulator, without any change to the target
> system.

That's right.

The serial protocol message is Z0/z0, and it instructs the target
to set/clear a breakpoint (rather than gdb inserting traps into
the text section explicitly).