Re: [ppc-linux-nat]: set access flag for h/w watchpoint even if it is only read or write

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 7 Jul 2006 09:17:54 -0400
> From: Daniel Jacobowitz <drow@false.org>
> Cc: Wu Zhou <woodzltc@cn.ibm.com>, gdb-patches@sourceware.org
> 
> > Daniel, could you please point me to Ulrich's change, either in
> > ChangeLogs or in the sources?  I cannot find it forf some reason.
> 
> I must be mistaken; our S/390 support doesn't have any read watchpoints
> (I don't know if the architecture does or not).  In fact I can't find
> any architecture that does this.  But I immediately recognized
> the description of the problem... so it must have happened somewhere.

You are not dreaming, because I remember that as well.  Perhaps Ulrich
just suggested a change, but it wasn't accepted eventually.

> I can't find the discussion of it, but the gdbserver crisv32 port does
> the same thing:
> 
>   /* Read watchpoints are set as access watchpoints, because of GDB's
>      inability to deal with pure read watchpoints.  */
>   if (type == '3')
>     type = '4';
> 
> Here's some more about it:
>   http://sources.redhat.com/ml/gdb/2005-11/msg00231.html
> 
> In which I also claimed S/390 did it, which doesn't appear to be true,
> but at least I've had the same misconception for a while now.

Thanks for the pointers.  I think if we wish to change this, someone
will need to step forward and volunteer to submit a clean design of
how a back end could tell breakpoint.c that read watchpoints are
really supported, and how breakpoint.c could use that info to DTRT.