Re: [Qemu-devel] Re: [PATCH 0/5] Debugger enhancements

[Paul Brook <paul@codesourcery.com>]

> I don't think it is a good idea to say that breakpoints/watchpoints
> apply to all processors. Such behavior should be handled at a higher level.
>
> It would also be interesting if the watchpoint/breakpoint implementation
> could be used to implement CPU watchpoints and breakpoints (I am
> thinking about the x86 DRx registers here).

Watchpoints and breakpoints are architecture independent debugger features. 
The gdb break/watchpoints should be independent of any user visible debug 
hardware.

I agree it probably makes sense for both to share an implementation though.

> If this is the wanted behavior then the same system as the Self
> Modifying Code on x86 should be used. Basically it consists in doing as
> a MMU fault and single stepping one instruction after. Unfortunately I
> fear the implementation will be complicated.

FWIW I'm planning on reviving the instruction counting patches and making some 
modifications to the mmio TLB handling, which should provide infrastructure 
for doing this in a better way.

Paul