Re: breakpoint extension for remote protocol

Stu Grossman
1998-12-10T21:46:00Z

Andrew Cagney writes:
> "J.T. Conklin" wrote:
>
> > Here is the protocol elements that I'm currently working with:
> >
> > Insert Breakpoint: B<type>, [,<length>]
> > returns: ?? - A cookie representing the breakpoint
> > EX - breakpoint type not supported
> > - no breakpoint contexts available
> > - invalid/unsupported address
> > - invalid/unsupported length
>
> FYI, there is already a semi-official use of `B' as a generic remote
> breakpoint operation. The syntax is:
>
> B ,S Set a breakpoint
> B ,C Clear a breakpoint

Where is this used? I see no evidence of this in devo's remote.c. Is it
hiding out on a branch somewhere? FYI, the syntax is bogus. It should use B
and b like the rest of the commands. Also, the protocol should support the
ability to set a breakpoint or watchpoint on a range of addresses. The command
format used by JT was developed by me many years ago, and should have been used
instead of this `semi-official' method which was apparantly done without
consultation of someone who understands how to develop this protocol.

> With regard to the general question of extending the remote-gdb protocol
> so that it supports a generic hardware breakpoint mechanism. I agree it
> is needed. It is a missing part of the overall toolkit.

I have discussed this with GDB folk in the past. If you want to hear what
needs to be done, ping me.

> Did you know
> that some targets actually implement hardware breakpoints by poking the
> registers directly?

Yes, and this is a complete sin.

Stu