Re: RFC: Hardware watchpoint register support for mips-linux.

[David Daney <ddaney@avtrex.com>]

Maciej W. Rozycki wrote:
> 
>  Well done! -- something I have meant to do for years, but never come to.  
> Out of curiousity -- does your kernel side support MIPS architecture style
> watchpoints only or does it work with the R4000-style watch registers as
> well?  I recall having a discussion with Daniel about how to support both
> in a reasonably abstract way long ago.  Either way thanks a lot, and I
> have an R4k machine handy, so I can see if I find some time to give it a
> shot.
> 

Currently it only handles mips32 style watch registers.  I have no 
documentation on the R4000 style registers.

I do however have an SGI Indy w/ R4400 which /proc/cpuinfo reports as 
having watch registers, but since there is a lack of documentation, I 
could not try it.

My plan for supporting different watch register formats is to have a 
format identifier that is read by GDB via PTRACE_GET_WATCH_REGS.  The 
rest of the information is a union of the known formats.

Currently it reports the number of registers and the active mask bits. 
But if R4000 does not fit with the mips32 register layout, its registers 
would be layed out in a different union member.

I hope that makes sense.

David Daney