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Re: to_xfer_partial, qPart, and EOF
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