Pulse-Per-Second API for UNIX-like Operating Systems, Version 1.0
RFC 2783
| Document | Type |
RFC - Informational
(March 2000; No errata)
Was draft-mogul-pps-api (individual)
|
|
|---|---|---|---|
| Authors | Jeffrey Mogul , David Mills , Ulrich Windl , Jonathan Stone , Jan Brittenson | ||
| Last updated | 2013-03-02 | ||
| Stream | Legacy stream | ||
| Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
| Stream | Legacy state | (None) | |
| Consensus Boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | RFC 2783 (Informational) | |
| Telechat date | |||
| Responsible AD | (None) | ||
| Send notices to | (None) | ||
Network Working Group J. Mogul
Request for Comments: 2783 Compaq WRL
Category: Informational D. Mills
University of Delaware
J. Brittenson
Sun
J. Stone
Stanford
U. Windl
Universitaet Regensburg
March 2000
Pulse-Per-Second API for UNIX-like Operating Systems, Version 1.0
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
RFC 1589 describes a UNIX kernel implementation model for high-
precision time-keeping. This model is meant for use in conjunction
with the Network Time Protocol (NTP, RFC 1305), or similar time
synchronization protocols. One aspect of this model is an accurate
interface to the high-accuracy, one pulse-per-second (PPS) output
typically available from precise time sources (such as a GPS or GOES
receiver). RFC 1589 did not define an API for managing the PPS
facility, leaving implementors without a portable means for using PPS
sources. This document specifies such an API.
Mogul, et al. Informational [Page 1]
RFC 2783 Pulse-Per-Second API March 2000
Table of Contents
1 Introduction................................................... 2
2 Data types for representing timestamps......................... 4
2.1 Resolution................................................... 4
2.2 Time scale................................................... 5
3 API............................................................ 5
3.1 PPS abstraction.............................................. 6
3.2 New data structures.......................................... 7
3.3 Mode bit definitions......................................... 10
3.4 New functions................................................ 12
3.4.1 New functions: obtaining PPS sources....................... 13
3.4.2 New functions: setting PPS parameters...................... 14
3.4.3 New functions: access to PPS timestamps.................... 16
3.4.4 New functions: disciplining the kernel timebase............ 18
3.5 Compliance rules............................................. 20
3.5.1 Functions.................................................. 20
3.5.2 Mode bits.................................................. 20
3.6 Examples..................................................... 21
4 Security Considerations........................................ 24
5 Acknowledgements............................................... 24
6 References..................................................... 25
7 Authors' Addresses............................................. 26
A. Extensions and related APIs................................... 27
A.1 Extension: Parameters for the "echo" mechanism............... 27
A.2 Extension: Obtaining information about external clocks....... 27
A.3 Extension: Finding a PPS source.............................. 28
B. Example implementation: PPSDISC Line discipline............... 29
B.1 Example...................................................... 29
C. Available implementations..................................... 30
Full Copyright Statement......................................... 31
1 Introduction
RFC 1589 [4] describes a model and programming interface for generic
operating system software that manages the system clock and timer
functions. The model provides improved accuracy and stability for
most workstations and servers using the Network Time Protocol (NTP)
[3] or similar time synchronization protocol. The model supports the
use of external timing sources, such as the precision pulse-per-
second (PPS) signals typically available from precise time sources
(such as a GPS or GOES receiver).
However, RFC 1589 did not define an application programming interface
(API) for the PPS facility. This document specifies such an
interface, for use with UNIX (or UNIX-like) operating systems. Such
systems often conform to the "Single UNIX Specification" [5],
sometimes known as POSIX.
Mogul, et al. Informational [Page 2]
RFC 2783 Pulse-Per-Second API March 2000
Show full document text