Re: Patch 0/6] MIPS: Hardware watch register support for gdb (version 5).

[David Daney <ddaney@avtrex.com>]

David VomLehn wrote:
> David Daney wrote:
> 
>> To follow is my fifth pass at MIPS watch register support.
> 
> I'd like to add a feature request, understanding fully that the response 
> may very well be, "interesting idea, now show us a patch"--can we have 
> an interface that would allow kernel-space allocation of watchpoint 
> registers?
> 
> The rationale is that we have found it quite useful to have kernel and 
> driver code set watchpoints for debugging purposes. I would not expect 
> that kernel space code could grab watchpoint registers already in use by 
> ptrace, and that ptrace would be free to allocate all watchpoint 
> registers not in use for kernel space purposes, i.e. there would be no 
> watchpoint registers permanently allocated for kernel space usage.
> 

The current patch has an artificial limit of 4 registers that it would use.

I think adding this feature would be possible, but would rather make it 
part of a follow-on patch.

You would limit the number of registers available to ptrace and then 
handle the others specially in the do_watch handler.

David Daney