Re: [PATCH 03/16] exec: Add cpu_probe_watchpoint

[Richard Henderson]

On 4/16/20 5:08 AM, Peter Maydell wrote:
>>  void cpu_check_watchpoint(CPUState *cpu, vaddr addr, vaddr len,
>>                            MemTxAttrs attrs, int flags, uintptr_t ra);
>> +bool cpu_probe_watchpoint(CPUState *cpu, vaddr addr, vaddr len, int flags);
> 
> Could we have a doc comment for the new function?
> 
>>  int cpu_watchpoint_address_matches(CPUState *cpu, vaddr addr, vaddr len);

Hah.  In the process of doing that, I notice that
cpu_watchpoint_address_matches actually does what I want.

I have added documentation for cpu_check_watchpoint and
cpu_watchpoint_address_matches and have dropped this new function.

> Clearly the insn emulation needs to do the right thing for
> guest architectural watchpoints, but should a gdb watchpoint
> also affect no-fault-load behaviour? I suppose making them
> both behave the same way is probably the least-surprising choice.

In both cases we need to interrupt the execution in order to actually honor the
watchpoint.  So yes, treating them the same seems the only reasonable way.


r~