About the patch to add h/w watchpoint to ppc arch
Wu Zhou
woodzltc@cn.ibm.com
Fri Jan 6 05:41:00 GMT 2006
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
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