Re: gdbstub initial code, v3

[Kevin Buettner <kevinb@redhat.com>]

On Thu, 12 Aug 2010 17:53:38 -0700 (PDT)
Roland McGrath <roland@redhat.com> wrote:

> > I've skimmed the code.  If I'm not mistaken, support for the 's', 'G',
> > and 'M' commands isn't implemented yet?  (That's single-step, write
> > registers, and write memory, all of which must be supported by a stub.)
> 
> Yes, that's fine.  For a starting place, having only reading support is OK.
> These bits are relatively trivial to fill in later as needed, so I think
> made plenty of sense for Oleg not to include them yet.

It certainly makes sense for Oleg to get communication between the
stub and gdb sorted out first.  As another early step, it also makes
sense to attempt to stop the process and determine its status.

Once that's sorted though, I should think that memory write and
single-step will become important to implement.  The 'M' (memory
write) packet may be used by GDB for inserting and removing
breakpoints.  (Or, alternately, Z0/z0 packets may be used.  I'd
rather see 'M' implemented first though.)  Single-step, whether
implemented as an 's' packet or 'vCont;s' packet, will be needed in
order to continue from a breakpoint as well as for single-stepping.

Implementation of the 'G' command (register write) is probably the
least important of the three that I mentioned earlier.

Kevin