Re: Display of read/access watchpoints when HAVE_NONSTEPPABLE_WATCHPOINT

[Ulrich Weigand <weigand@i1.informatik.uni-erlangen.de>]

Mark Kettenis wrote:

>This patch breaks hardware watchpoints in SVR4-derived systems.  Those
>systems don't provide target_stopped_data_address().  The default
>target_stopped_data_address() will always return zero, which means
>that triggered watchpoints aren't properly caught.  This results in
>spurious SIGTRAPS.

The patch also breaks s390(x), for exactly this reason.

We don't define target_stopped_data_address, and *cannot* do so
because the hardware doesn't provide this information.

We do know whether a SIGTRAP was due to a (any) watchpoint or not,
however, and define STOPPED_BY_WATCHPOINT to indicate this.

(Since the hardware supports only write watchpoints, not read
or access watchpoints, this should -and used to- be enough for
gdb to find out what happened by manually checking watchpoint
values.)

The patch below uses STOPPED_BY_WATCHPOINT instead of 
target_stopped_data_address in bpstat_stop_status;
this get s390(x) watchpoints back functional.

Alternatively, we could also make the target_stopped_data_address
check only for read and access watch points, *not* for write
watchpoints ...

What do you think?


Index: gdb/breakpoint.c
===================================================================
RCS file: /cvs/src/src/gdb/breakpoint.c,v
retrieving revision 1.170
diff -c -p -r1.170 breakpoint.c
*** gdb/breakpoint.c	2 May 2004 00:21:41 -0000	1.170
--- gdb/breakpoint.c	4 May 2004 21:20:10 -0000
*************** bpstat_stop_status (CORE_ADDR bp_addr, p
*** 2631,2637 ****
  	&& !((b->type == bp_hardware_watchpoint
  	      || b->type == bp_read_watchpoint
  	      || b->type == bp_access_watchpoint)
! 	     && target_stopped_data_address () != 0)
  	&& b->type != bp_hardware_breakpoint
  	&& b->type != bp_catch_fork
  	&& b->type != bp_catch_vfork
--- 2631,2637 ----
  	&& !((b->type == bp_hardware_watchpoint
  	      || b->type == bp_read_watchpoint
  	      || b->type == bp_access_watchpoint)
! 	     && STOPPED_BY_WATCHPOINT ())
  	&& b->type != bp_hardware_breakpoint
  	&& b->type != bp_catch_fork
  	&& b->type != bp_catch_vfork

-- 
  Dr. Ulrich Weigand
  weigand@informatik.uni-erlangen.de