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


Pedro Alves wrote:
On Thursday 16 October 2008 22:15:30, Michael Snyder wrote:
What it looks like is that you try to write to memory
that's write-protected.

This is because most replay targets will treat all of memory
as write-protected when they are in replay mode.

Where this usually manifests is, you'll say "continue"
(probably for the first time since attaching to the target),
and it'll croak because it's trying to step over some
"invisible" breakpoint such as the one that handles
shared libraries.

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.


Teawater's "process replay" isn't a remote target, so it does
not use Z packet explicitly, but it does something similar --
in effect, it mimics the Z0 semantics.

VMware's development version uses Z0.

Ah, the record target
just ignores breakpoint insertions, and relies on forcing single-stepping
and checking breakpoint hits itself.

That's right.



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