RE: [PATCH v2 3/4] rsp: add 'E' to escaped characters

["Aktemur, Tankut Baris" <tankut.baris.aktemur@intel.com>]

Hi Ciaran,

On Thursday, March 14, 2024 2:47 PM, Ciaran Woodward wrote:
> Hi Tankut,
> 
> > Add 'E' to the list of escaped characters when sending/receiving
> > binary data.  This is a preparation for the next patch, to be able to
> > distinguish an error response from binary data that starts with 'E'.
> 
> I wonder if there is a better way to do this, given that this is for a totally
> new packet. My concerns are twofold:
> 
> 1. The other 'escaped' characters are part of the RSP packetization layer,
>    which is conceptually below the message processing. This new packet is
>    looking at both escaped and non-escaped message in order to figure out
>    which type of response it is looking at, which is (in my opinion)
>    unnecessary layer crossing.
> 
> 2. The idea of allowing this list to grow when there are other possible
>    solutions is just less scalable if other new binary packets are added
>    in the future.
> 
> Instead, I would propose a similar approach to other packets which would
> have the potential for 'ambiguous' replies, such as 'qCRC', 'qMemTags' etc.
> 
> That is: Always have a leading byte (not just in the error case) in order
> to disambiguate what type of reply the message contains.
> 
> So (for example) the message is something more like:
> 
> 'E NN' for an error
> 
> 'd XX...' for binary data
> 
> Does that sound reasonable?
> (Note that I am not a maintainer, so would appreciate other opinions!)
> 
> Thanks,
> Ciaran

My goal was to keep similarity to packets like 'm', 'g', 'p'.  Starting the reply with
a marker is certainly doable.  Let's see what the maintainers will say.  If that's the
direction, I can work on the change.

Thanks
-Baris



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