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Re: [RFC] Unified watchpoints for x86 platforms

> From: Mark Kettenis <>
> Date: 27 Feb 2001 12:28:43 +0100
> > 
> > For those who might not remember what those flags are: Each
> > hardware-assisted breakpoint or watchpoint should be enabled by
> > setting bits in the DR7 register.  A watchpoint can be enabled locally
> > or globally, depending on which bit in DR7 is set for that watchpoint.
> > A watchpoint that is enabled locally will only break if it is hit in
> > the current task.  A watchpoint that is enabled globally will break in
> > any task.
> Makes me wonder if global watchpoints would really work if hardware
> task switching isn't used.

I guess the answer depends on how exactly is the software task
switching implemented.  Namely, does it reset the GE and LE bits in
DR7 when the task switch happens.

> In principle a GDB command to control whether to enable watchpoints
> locally or globally wouldn't be a bad idea.  But I don't know any
> targets where this would be useful.  So if it isn't useful for DJGPP
> either, I wouldn't bother.  A comment about the issue at the right
> spot would be nice though.

That was my tendency as well.  Thanks for the feedback.

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