Re: help string for "break" command

[Bob Rossi <bob_rossi at cox dot net>]

On Fri, Jan 12, 2007 at 03:19:31PM +0100, Mathieu Lacage wrote:
> On Fri, 2007-01-12 at 08:49 -0500, Daniel Jacobowitz wrote:
> > On Fri, Jan 12, 2007 at 02:45:16PM +0100, Mathieu Lacage wrote:
> > > Am I right in assuming that the gdb command "break" places exclusively
> > > so-called software-breakpoints while the command "hbreak" places a
> > > hardware-breakpoint (I am not sure I have figured out the details of the
> > > logic in gdb/breakpoint.c) ? 
> > 
> > Not 100%.  CVS versions of GDB will use hardware breakpoints
> > automatically if you try to set them in truly read-only memory.
> 
> I see the following comment in the CVS version:
>           /* If the explicitly specified breakpoint type
>              is not hardware breakpoint, check the memory map to see
>              if the breakpoint address is in read only memory or not.
>              Two important cases are:
>              - location type is not hardware breakpoint, memory
>              is readonly.  We change the type of the location to
>              hardware breakpoint.
>              - location type is hardware breakpoint, memory is read-write.
>              This means we've previously made the location hardware one, but
>              then the memory map changed, so we undo.
> 
>              When breakpoints are removed, remove_breakpoints will
>              use location types we've just set here, the only possible
>              problem is that memory map has changed during running program,
>              but it's not going to work anyway with current gdb.  */
> 
> and it seems to match the decision logic I see below.
> 
> Would there be opposition to an 'sbreak' command which would ensure that
> a software breakpoint is used _all the time_ ? 

Is the 'set breakpoint auto-hw off' helpful here?

http://sourceware.org/gdb/current/onlinedocs/gdb_6.html#SEC32

Bob Rossi