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diff --git a/contrib/ntp/html/kern.htm b/contrib/ntp/html/kern.htm deleted file mode 100644 index 4139fb2..0000000 --- a/contrib/ntp/html/kern.htm +++ /dev/null @@ -1,122 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> -<html> -<head> -<meta name="generator" content="HTML Tidy, see www.w3.org"> -<title>Kernel Model for Precision Timekeeping</title> -</head> -<body> -<h3>Kernel Model for Precision Timekeeping</h3> - -<hr> -<img align="left" src="pic/alice61.gif" alt="gif"> <a href= -"http://www.eecis.udel.edu/~mills/pictures.htm">from <i>Pogo</i>, -Walt Kelly</a> - -<p>Exploding kernel<br clear="left"> -</p> - -<hr> -<p>The technical report [2], which is a major revision and update -of an earlier report [3], describes an engineering model for a -precision time-of-day function for a generic operating system. The -model is based on the principles of disciplined oscillators using -phase-lock loops (PLL) and frequency-lock loops (FLL) often found -in the engineering literature. The model uses a hybrid PLL/FLL -discipline algorithm implemented in the kernel. The hybrid loop -provides automatic time and frequency steering with update -intervals from a few seconds to over one day.</p> - -<p>The hybrid PLL/FLL has been implemented in the Unix kernels for -several operating systems, including FreeBSD and Linux and those -made by Sun Microsystems, Digital/Compaq and Hewlett Packard. The -modifications are currently included in the licensed kernels for -Digital Unix 4.0 (aka Tru64) and Sun Solaris 2.8. Since the -modifications involve proprietary kernel interface code, they -cannot be provided for other licensed kernels directly. Inquiries -should be directed to the manufacturer's representatives. The -software and documentation, including a simulator with code -segments almost identical to the implementations, but not involving -licensed code, is called <tt>nanokernel.tar.gz</tt> and available -via the web at <a href="http://www.ntp.org">www.ntp.org</a> or by -anonymous FTP from ftp.udel.edu in the <tt>pub/ntp/software</tt> -directory.</p> - -<p>Recently [1], the model has been re-implemented to support a -nanosecond system clock. The <tt>/usr/include/sys/timex.h</tt> -header file defines the applications programming interface (API) -routines and data structures. Implementations are available for -Linux, FreeBSD, SunOS and Tru64; however, only the Linux and -FreeBSD implementations, which are included in recent system -versions, are directly available. The software and documentation, -including a simulator with code segments almost identical to the -implementations, but not involving licensed code, is called <tt> -nanokernel.tar.gz</tt> and available via the web at <a href= -"http://www.ntp.org">www.ntp.org</a> or by anonymous FTP from -ftp.udel.edu in the <tt>pub/ntp/software</tt> directory.</p> - -<p>The model changes the way the system clock is adjusted in time -and frequency, as well as provides mechanisms to discipline its -time and frequency to an external precision timing source, such as -described in the <a href="pps.htm">Pulse-per-second (PPS) Signal -Interfacing</a> page. The model incorporates a generic system call -interface for use with the NTP or similar time synchronization -protocol. The NTP software daemons for Version 3 <tt>xntpd</tt> and -Version 4 <tt>ntpd</tt> use this API to provide synchronization -limited in principle only by the accuracy and stability of the -external timing source. There are two new system calls defined in -<tt>timex.h</tt>, <tt>ntp_gettime()</tt>, which returns a structure -including the current time, estimated error and maximum error, and -<tt>ntp_adjtime()</tt>, which provides a means to adjust kernel -variables, including the current time and frequency offsets.</p> - -<p>These kernel modifications are normally used in conjunction with -a kernel hardware interface such as described in the <a href= -"kernpps.htm">Kernel Programming Interface for Precision Time -Signals</a> page.</p> - -<h4>References</h4> - -<ol> - -<li><p>Mills, D.L., and P.-H. Kamp. The nanokernel. <i>Proc. Precision -Time and Time Interval (PTTI) Applications and Planning Meeting</i> -(Reston VA, November 2000). Paper: <a href= -"database/papers/nano/nano2.ps">PostScript</a> | <a href= -"http://www.eecis.udel.edu/~mills/database/papers/nano/nano2.pdf"> -PDF</a>, Slides: <a href= -"http://www.eecis.udel.edu/~mills/database/brief/nano/nano.htm"> -HTML</a> | <a href= -"http://www.eecis.udel.edu/~mills/database/brief/nano/nano.ps"> -PostScript</a> | <a href= -"http://www.eecis.udel.edu/~mills/database/brief/nano/nano.pdf"> -PDF</a> | <a href= -"http://www.eecis.udel.edu/~mills/database/brief/nano/nano.ppt"> -PowerPoint</a></p></li> - -<li><p>Mills, D.L. Unix kernel modifications for precision time -synchronization. Electrical Engineering Department Report 94-10-1, -University of Delaware, October 1994, 24 pp. Abstract: <a href= -"http://www.eecis.udel.edu/~mills/database/reports/kern/kerna.ps"> -PostScript</a> | <a href="database/reports/kern/kerna.pdf">PDF</a>, -Body: <a href= -"http://www.eecis.udel.edu/~mills/database/reports/kern/kernb.ps"> -PostScript</a> | <a href= -"http://www.eecis.udel.edu/~mills/database/reports/kern/kernb.pdf"> -PDF</a></p></li> - -<li><p>Mills, D.L. A kernel model for precision timekeeping. Network -Working Group Report RFC-1589, University of Delaware, March 1994. -31 pp. <a href= -"http://www.eecis.udel.edu/~mills/database/rfc/rfc1589.txt"> -ASCII</a></p></li> -</ol> - -<hr> -<a href="index.htm"><img align="left" src="pic/home.gif" alt= -"gif"></a> - -<address><a href="mailto:mills@udel.edu">David L. Mills -<mills@udel.edu></a></address> -</body> -</html> - |
