hw watchpoint/breakpoint support for xscale

[Michael Snyder]

Jim Blandy wrote:
> 
> Mark Salter <msalter@redhat.com> writes:
> > > - request a protocol extension (some query packet)
> >
> > I think this is best. Query the board to find out how many hw
> > wathcpoints and hw breakpoints are supported. If the board
> > can't answer the query, then it doesn't support any.
> 
> Be careful!  The number of watchpoints can depend on their addresses
> and sizes.  For example, to set a watchpoint on a two-byte object at
> an odd address, the i386 code will set *two* hardware watchpoints ---
> one for each byte --- since the i386's watchpoints are always aligned
> on a multiple of their size.

I don't think the "number of watchpoints" macro has ever
been implemented correctly on most targets.  Frequently 
it evaluates to "1" or "0" (this is just from my
random access memory).