[lldb-dev] qfThreadInfo/qsThreadInfo stub impl and max packet size

Matthew Gardiner mg11 at csr.com
Thu May 22 00:45:39 PDT 2014

Todd Fiala wrote:
> It also seems like the qSupported request to the stub can take 
> client-side values pushed in as suffixes to the qSupported request. 
>  Is that the way to inform the stub of the client's max accepted 
> incoming packet length?
I can't see "PacketSize" listed as a gdbfeature, in the "GDB Remote 
Serial Protocol" appendix. (I assuming that the document lists 
gdbfeature and stubfeature as exclusive sets).

It's possible that the client is intended to tolerate large packets, 
since it is envisaged to run on a machine with sufficient memory to keep 
reallocing it's recv buffer. However, (I'm guessing here) the stub is 
intended to run on a more constrained environment, and where it may not 
be possible to allocate as much memory, and therefore is reliant on a 
statically allocated fixed-size buffer. As a consequence, the designers 
of the protocol may have decided that there must be a way to constrain 
the client, but that the stub need not be similarly constrained? Well, 
that's my take on it.


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