On 13/06/2016 23:41, Alex Bligh wrote: > That's one of the reasons that there is a proposal to add > STRUCTURED_READ to the spec (although I still haven't had time to > implement that for qemu), so that we have a newer approach that allows > for proper error handling without ambiguity on whether bogus bytes must > be sent on a failed read. But you'd have to convince me that ALL > existing NBD server and client implementations expect to handle a read > error without read payload, otherwise, I will stick with the notion that > the current spec wording is correct, and that read errors CANNOT be > gracefully recovered from unless BOTH sides transfer (possibly bogus) > bytes along with the error message, and which is why BOTH sides of the > protocol are warned that read errors usually result in a disconnection > rather than clean continuation, without the addition of STRUCTURED_READ.
I suspect that there are exactly two client implementations, namely Linux and QEMU's, and both do the right thing. What servers do doesn't matter, if all the clients agree. Paolo
