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Re: [Nbd] [PATCH] doc: Specific error if NBD_OPT_GO refused without NBD_OPT_BLOCK_SIZE



On 19 Apr 2016, at 13:04, Eric Blake <eblake@...696...> wrote:

>>> 
>>> Question: Should we rearrange the various errors, so that
>>> NBD_REP_ERR_UNKNOWN and NBD_REP_ERR_BLOCK_SIZE_REQD are
>>> adjacent (since they are, for now, in the same extension
>>> branch), by hoising NBD_REP_ERR_SHUTDOWN to 2^32 + 6?  We
>>> don't yet have any released versions that use
>>> NBD_REP_ERR_SHUTDOWN, although it was added as normative text
>>> without going through the usual extension work.
> 
> Likewise for putting NBD_OPT_BLOCK_SIZE adjacent to NBD_OPT_GO if we
> keep block sizes as part of the INFO extension rather than its own.

So I think we can be pretty free and easy with the stuff in
extensions. But for things in master, I think we should try
not to change them once they are in. I know in this instance
it's a tiny thing, and it's only been a matter of days, but
it would also have only a tiny gain. Therefore I think not.

Incidentally I don't think normative text necessarily needs
to go through an 'extension' phase. For instance, if Wouter
agrees with us on synchronizing the options haggling phase,
we can't really have a 'synchronized option haggling'
extension (or whatever the opposite of an extension is).
I see extensions as a proving ground for protocol, um,
extensions that though we all like the idea, we know are
going to have lots of wrinkles to smooth out during
implementation. I don't think adding one error code
would fall into that category (not that I'm implying you
thought it did).

--
Alex Bligh




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