to_xfer_partial, qPart, and EOF

[Daniel Jacobowitz]

On Wed, Jan 18, 2006 at 05:18:49PM -0800, Jim Blandy wrote:
> This, and a few other remote protocol wrinkles, are consequences of
> the mis-layering of the GDB protocol.  The protocol should simply
> specify that the entire block of data gets transmitted, and let lower
> layers handle retransmission and fragmentation.
> 
> I recognize it's probably not practical to fix this today, and maybe
> it never will be.  But I keep running into instances of this when I
> work on the remote protocol --- tracepoint definition packets needing
> to be broken up into pieces to avoid long packets; breakpoint packets
> needing to be idempotent, because they might be retransmitted; and so
> on --- so I wanted to mention it.  Perhaps someone will have a flash
> of super-coder powers some weekend.

I suspect we will need to redesign the protocol rather than just
layering on top of it, eventually.  Maybe not.  I don't know; I'm not
feeling that ambitious right now.

The two things I most often hear about as fundamental problems with the
existing protocol are:

  - multiple "channels" for output to/from the host, especially
    asynchronous channels (logging without stopping the target)

  - other asynchronous communication, e.g. collecting tracepoints
    or reading memory without stopping the target, where supported

> > Any comments on either of these plans?  Otherwise I will probably implement
> > them in the next couple of days.  I'm doing a lot of work in this area
> > at present.
> 
> Sounds great to me.

Thanks.

-- 
Daniel Jacobowitz
CodeSourcery