freebsd-dev/contrib/ntp/html/kernpps.htm

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Kernel Programming Interface for Precision Time Signals
Network Performance Evaluation
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Kernel Programming Interface for Precision Time Signals
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<p>The technical report [1] describes a proposed application programming interface (API) for external precision time signals, such as the pulse-per-second (PPS) signal generated by some radio clocks and cesium oscillators. The report argues for a generic capability in the ubiquitous Unix kernel, which could be used for a wide variety of measurement applications, including network time synchronization and experiments involving performance measurement and evaluation of computer networks and transmission systems. The hardware to do this requires only a serial port and a modem control lead, such as the data carrier detect (DCD) lead, which can be driven by an external source via a level converter/pulse generator.

<p>Support for this API has been implemented in the NTP Version 4 software distribution. The <tt>/usr/include/sys/timepps.h</tt> header file defines the API interface routines and data structures. The API obsoletes previous APIs based on the <tt>tty_clock</tt> and <tt>ppsclock</tt> line disciplines and streams modules, which are no longer supported. The API used by the <a href=driver22.htm>PPS Clock Discipline</a> driver (type 22) to support PPS signals via either a serial port or parallel port, depending on the operating system. The API is supported in stock FreeBSD from 3.4 and with the addition of the <tt>PPSkit</tt> kernel software in Linux. Limited support for Solaris from 2.8 is available using the <tt>timepps.h.solaris</tt> header file included in this distribution. Copy this file to <tt>/usr/include/sys</tt> before configuring the distributution.

<p>The API is normally used in conjunction with the precision time kernel modifications described in the <a href=kern.htm>Kernel Model for Precision Timekeeping</a> page.

<h4>Reference</h4>

<ol>

<p><li>Mogul, J., D. Mills, J. Brittenson, J. Stone and U. Windl. Pulse-per-second API for Unix-like operating systems, version 1. Request for Comments RFC-2783, Internet Engineering Task Force, March 2000, 31 pp. <a href=http://www.eecis.udel.edu/~mills/database/rfc/rfc2783.txt>ASCII</a>

</ol>

<hr><a href=index.htm><img align=left src=pic/home.gif></a><address><a
href=mailto:mills@udel.edu> David L. Mills &lt;mills@udel.edu&gt;</a>
</address></a></body></html>
Virgin import of ntpd 4.0.98f 1999-12-09 13:01:21 +00:00			`<html><head><title>`
Virgin import of ntpd 4.1.0 2001-08-29 14:35:15 +00:00			`Kernel Programming Interface for Precision Time Signals`
Virgin import of ntpd 4.0.98f 1999-12-09 13:01:21 +00:00			`Network Performance Evaluation`
			`</title></head><body><h3>`
Virgin import of ntpd 4.1.0 2001-08-29 14:35:15 +00:00			`Kernel Programming Interface for Precision Time Signals`
Virgin import of ntpd 4.0.98f 1999-12-09 13:01:21 +00:00			`</h3><hr>`

Virgin import of ntpd 4.1.0 2001-08-29 14:35:15 +00:00			<p>The technical report [1] describes a proposed application programming interface (API) for external precision time signals, such as the pulse-per-second (PPS) signal generated by some radio clocks and cesium oscillators. The report argues for a generic capability in the ubiquitous Unix kernel, which could be used for a wide variety of measurement applications, including network time synchronization and experiments involving performance measurement and evaluation of computer networks and transmission systems. The hardware to do this requires only a serial port and a modem control lead, such as the data carrier detect (DCD) lead, which can be driven by an external source via a level converter/pulse generator.

			<p>Support for this API has been implemented in the NTP Version 4 software distribution. The <tt>/usr/include/sys/timepps.h</tt> header file defines the API interface routines and data structures. The API obsoletes previous APIs based on the <tt>tty_clock</tt> and <tt>ppsclock</tt> line disciplines and streams modules, which are no longer supported. The API used by the <a href=driver22.htm>PPS Clock Discipline</a> driver (type 22) to support PPS signals via either a serial port or parallel port, depending on the operating system. The API is supported in stock FreeBSD from 3.4 and with the addition of the <tt>PPSkit</tt> kernel software in Linux. Limited support for Solaris from 2.8 is available using the <tt>timepps.h.solaris</tt> header file included in this distribution. Copy this file to <tt>/usr/include/sys</tt> before configuring the distributution.

			`<p>The API is normally used in conjunction with the precision time kernel modifications described in the <a href=kern.htm>Kernel Model for Precision Timekeeping</a> page.`

			`<h4>Reference</h4>`

			`<ol>`

			`<p><li>Mogul, J., D. Mills, J. Brittenson, J. Stone and U. Windl. Pulse-per-second API for Unix-like operating systems, version 1. Request for Comments RFC-2783, Internet Engineering Task Force, March 2000, 31 pp. <a href=http://www.eecis.udel.edu/~mills/database/rfc/rfc2783.txt>ASCII</a>`

			`</ol>`
Virgin import of ntpd 4.0.98f 1999-12-09 13:01:21 +00:00
			`<hr><a href=index.htm><img align=left src=pic/home.gif></a><address><a`
			`href=mailto:mills@udel.edu> David L. Mills <mills@udel.edu></a>`
			`</address></a></body></html>`