Answering questions that may arise related to the meaning of portions of an IEEE standard concerning specific applications.

IEEE Standards Interpretations for IEEE Std 1003.1b™-1993 IEEE Standard for Information Technology - Portable Operating System Interfaces (POSIX(R)) - Part 1: System Application Program Interface (API) - Amendment 1: Realtime Extension [C language]

Copyright © 1996 by the Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue New York, New York 10016-5997 USA All Rights Reserved.

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Interpretation Request #1
Topic: async IO Relevant Sections:

1. Does the sigev_notify field need to be filled in the sig argument to lio_listio? The generic section on the aiocb ( talks about the use of the sigev_notify field, however the section on lio_listio described different requirements using the same structure.
1b. If not, can it be filled in, and what is the behavior if for example the sigev_filed was set to SIGEV_NONE and the sigev_signo is non zero?
2. If a user puts valid values in the sigev_notify and sigev_signo fields in members of the aiocb list in a call to lio_listio() what happens? Are they ignored, do that happen as well as/instead of the event that is described by *sig argument.

Interpretation Response
1. The standard is clear that SIGEV_NOTIFY is ignored and a signal shall be sent. Conforming implementations must conform to this. This is different from the definition in section and which the interpretation committee views as a defect in the standard. This fact is being refered to the sponsor for consideration. The interpretation committee suggests that applications might wish to consistently set SIGEV_NOFTIFY and SIGEV_SIGNO so that the application would continue to work correctly if the standard is changed.
2. The standard is clear that in the case raised, that a signal is generated at the completion of each i/o operation where sigev_signo is non-zero and one is also generated when the entire set of operations is completed. Conforming implementations must conform to this.

Rationale for Interpretation