About the patch to add h/w watchpoint to ppc arch

[Wu Zhou <woodzltc@cn.ibm.com>]

Hello maintainers,

We have discussed a lot about this patch.  And I had made some modification
to the original to make it more acceptable.  I am now revisiting the patch
to see whether it is ok to check it in.

The latest patch is at:
  http://sourceware.org/ml/gdb-patches/2005-12/msg00250.html

It addressed the issue of getting the stopped data address. Eli said that it
made sense.  Others didn't replied.  Could I take this as no objection? :-)
Said that, I am still very open to different opinions.  Suggestion for 
improvement are highly appreciated!

I am not sure whether there are any other problems hindering its acceptance.
The patch didn't add anything more to nm.h now(Thanks Mark, Ulrich ... for 
suggesting ways to achieve this); It tested ok on p630(will try to find other
ppc machines to test this); It uses run-time check to see whether kernel
support DABR manipulation or whether target machine have DABR registers.

One issue might be that some 32-bits ppc cpu might have more than one DABRs
(I am not sure which ones have >1 DABRs, Daniel and Anton suggested that). 
But I think that this patch still works ok with any 32-bits ppc models.  
The reason is that the current 32-bits ppc kernel don't support 
PTRACE_SET_DEBUGREG, so the run-time check in ppc_linux_check_watch_resources
will fail and hence there won't be any difference than the unpatched GDB.
Any different opinion on this?

Another issue I can think of is that Anton's patch to return stopped data
address upon DABR hit is not in the upstream kernel yet.  But I believe 
that there won't be many objection for that, provided that it will only
impact debugger behavior. If it is a pre-requirement for this patch to go
into gdb, I can ping Anton to get his patch into kernel first.

Are there any other issues? Maybe some documents or testcase?  If it is
needed, I can add a testcase for rwatch/awatch or some words somewhere.

These are all I can think of at this time.  Did I miss something?  Your 
comments/suggestion are highly appreciated!

Regards
- Wu Zhou