Re: Hardware watchpoints; dealing with false triggers?

[Eli Zaretskii <eliz@is.elta.co.il>]

On Tue, 4 Dec 2001, Orjan Friberg wrote:

> > > And this is the key issue: could the interface to the target-specific
> > > code be extended to handle the concept of "actual watchpoint address"?
> > 
> > We already have this: it's called target_stopped_data_address.
> > breakpoint.c uses this macro to see which watchpoint, if any,
> > triggered.
> 
> Also great.  Thank you very much for your comments on this, Eli.

I need to correct myself: there's a subtle point I forgot to mention.  
The current code only calls target_stopped_data_address for read and 
access watchpoints (those set by `rwatch' and `awatch' commands), but not 
for regular, i.e. data-write, hardware watchpoints (those set by `watch' 
command).  Instead, GDB compares the previous and the current value of 
the watched expression, and if they differ, it decides that the 
corresponding watchpoint triggered, without ever considering the address!

I think it's a bug to do that with hardware watchpoints (as opposed to 
software watchpoints), so I'm trying to convince The Powers That Be to 
change that (in another thread called "Re: [RFC] Possible bug with i386 
watchpoints on several targets", which see).  But for now, that's how 
the code works.  Sorry I failed to mention that in my original message.