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| author | roberto <roberto@FreeBSD.org> | 2002-11-04 19:36:11 +0000 |
|---|---|---|
| committer | roberto <roberto@FreeBSD.org> | 2002-11-04 19:36:11 +0000 |
| commit | a85d9ae25e8e8696677bc30feb6eaf7fc150e529 (patch) | |
| tree | 5071c8dbfd7605eec15909cabca2296957573ac7 /contrib/ntp/html/refclock.htm | |
| parent | 8d541346f2b91896a9ef53cafe2b81898978ccf3 (diff) | |
| download | FreeBSD-src-a85d9ae25e8e8696677bc30feb6eaf7fc150e529.zip FreeBSD-src-a85d9ae25e8e8696677bc30feb6eaf7fc150e529.tar.gz | |
Virgin import of ntpd 4.1.1b
Diffstat (limited to 'contrib/ntp/html/refclock.htm')
| -rw-r--r-- | contrib/ntp/html/refclock.htm | 430 |
1 files changed, 189 insertions, 241 deletions
diff --git a/contrib/ntp/html/refclock.htm b/contrib/ntp/html/refclock.htm index 079baba..df4af3a 100644 --- a/contrib/ntp/html/refclock.htm +++ b/contrib/ntp/html/refclock.htm @@ -1,254 +1,202 @@ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> <html> <head> -<meta name="generator" content="HTML Tidy, see www.w3.org"> -<title>Reference Clock Drivers</title> + + <meta name="generator" content="HTML Tidy, see www.w3.org"> + <title>Reference Clock Drivers</title> </head> -<body> + <body> + <h3>Reference Clock Drivers</h3> - -<img align="left" src="pic/stack1a.jpg" alt="gif">Master Time -Facility at the <a href="http://www.eecis.udel.edu/~mills/lab.htm"> -UDel Internet Research Laboratory</a>: <br clear="left"> -<hr> -<p>Support for most of the commonly available radio and modem -reference clocks is included in the default configuration of the -NTP daemon for Unix <tt>ntpd</tt>. Individual clocks can be -activated by configuration file commands, specifically the <tt> -server</tt> and <tt>fudge</tt> commands described in the <a href= -"ntpd.htm"><tt>ntpd</tt> program manual page</a>. The following -discussion presents Information on how to select and configure the -device drivers in a running Unix system.</p> - -<p>Many radio reference clocks can be set to display local time as -adjusted for timezone and daylight saving mode. For use with NTP -the clock must be set for Coordinated Universal Time (UTC) only. -Ordinarily, these adjustments are performed by the kernel, so the -fact that the clock runs on UTC will be transparent to the -user.</p> - -<p>Radio and modem clocks by convention have addresses in the form -127.127.<i>t.u</i>, where <i>t</i> is the clock type and <i>u</i> -is a unit number in the range 0-3 used to distinguish multiple -instances of clocks of the same type. Most of these clocks require -support in the form of a serial port or special bus peripheral, but -some can work directly from the audio codec found in some -workstations. The particular device is normally specified by adding -a soft link <tt>/dev/device<i>u</i></tt> to the particular hardware -device involved, where <i><tt>u</tt></i> correspond to the unit -number above.</p> - -<p>Most clock drivers communicate with the reference clock using a -serial port, usually at 9600 bps. There are several application -program interfaces (API) used in the various Unix and NT systems, -most of which can be detected at configuration time. Thus, it is -important that the NTP daemon and utilities be compiled on the -target system or clone. In some cases special features are -available, such as timestamping in the kernel or pulse-per-second -(PPS) interface. In most cases these features can be detected at -configuration time as well; however, the kernel may have to be -recompiled in order for them to work.</p> - -<p>The audio drivers are a special case. These include support for -the NIST time/frequency stations WWV and WWVH, the Canadian -time/frequency station CHU and generic IRIG signals. Currently, -support for the Solaris and SunOS audio API is included in the -distribution. It is left to the volunteer corps to extend this -support to other systems. Further information on hookup, debugging -and monitoring is given in the <a href="audio.htm">Audio -Drivers</a> page.</p> - -<p>The local clock driver is also a special case. A server -configured with this driver can operate as a primary server to -synchronize other clients when no other external synchronization -sources are available. If the server is connected directly or -indirectly to the public Internet, there is some danger that it can -adversely affect the operation of unrelated clients. Carefully read -the <a href="driver1.htm">Undisciplined Local Clock</a> page and -respect the stratum limit.</p> - -<p>The local clock driver also supports an external synchronization -source such as a high resolution counter disciplined by a GPS -receiver, for example. Further information is on the <a href= -"extern.htm">External Clock Discipline and the Local Clock -Driver</a> page.</p> - + <img align="left" src="pic/stack1a.jpg" alt="gif"> +Master Time Facility at the <a + href="http://www.eecis.udel.edu/%7Emills/lab.htm"> UDel Internet Research +Laboratory</a>: <br clear="left"> + +<hr> +<p>Support for most of the commonly available radio and modem reference clocks +is included in the default configuration of the NTP daemon for Unix <tt>ntpd</tt>. +Individual clocks can be activated by configuration file commands, specifically +the <tt> server</tt> and <tt>fudge</tt> commands described in the <a + href="ntpd.htm"><tt>ntpd</tt> program manual page</a>. The following discussion +presents Information on how to select and configure the device drivers in +a running Unix system.</p> + +<p>Many radio reference clocks can be set to display local time as adjusted +for timezone and daylight saving mode. For use with NTP the clock must be +set for Coordinated Universal Time (UTC) only. Ordinarily, these adjustments +are performed by the kernel, so the fact that the clock runs on UTC will +be transparent to the user.</p> + +<p>Radio and modem clocks by convention have addresses in the form 127.127.<i>t.u</i>, +where <i>t</i> is the clock type and <i>u</i> is a unit number in the range +0-3 used to distinguish multiple instances of clocks of the same type. Most +of these clocks require support in the form of a serial port or special bus +peripheral, but some can work directly from the audio codec found in some +workstations. The particular device is normally specified by adding a soft +link <tt>/dev/device<i>u</i></tt> to the particular hardware device involved, +where <i><tt>u</tt></i> correspond to the unit number above.</p> + +<p>Most clock drivers communicate with the reference clock using a serial +port, usually at 9600 bps. There are several application program interfaces +(API) used in the various Unix and NT systems, most of which can be detected +at configuration time. Thus, it is important that the NTP daemon and utilities +be compiled on the target system or clone. In some cases special features +are available, such as timestamping in the kernel or pulse-per-second (PPS) +interface. In most cases these features can be detected at configuration +time as well; however, the kernel may have to be recompiled in order for +them to work.</p> + +<p>The audio drivers are a special case. These include support for the NIST +time/frequency stations WWV and WWVH, the Canadian time/frequency station +CHU and generic IRIG signals. Currently, support for the Solaris and SunOS +audio API is included in the distribution. It is left to the volunteer corps +to extend this support to other systems. Further information on hookup, debugging +and monitoring is given in the <a href="audio.htm">Audio Drivers</a> page.</p> + +<p>The local clock driver is also a special case. A server configured with +this driver can operate as a primary server to synchronize other clients +when no other external synchronization sources are available. If the server +is connected directly or indirectly to the public Internet, there is some +danger that it can adversely affect the operation of unrelated clients. Carefully +read the <a href="driver1.htm">Undisciplined Local Clock</a> page and respect +the stratum limit.</p> + +<p>The local clock driver also supports an external synchronization source +such as a high resolution counter disciplined by a GPS receiver, for example. +Further information is on the <a href="extern.htm">External Clock Discipline +and the Local Clock Driver</a> page.</p> + <h4>Driver Calibration</h4> - -<p>Some drivers depending on longwave and shortwave radio services -need to know the radio propagation time from the transmitter to the -receiver, which can amount to some tens of milliseconds. This must -be calculated for each specific receiver location and requires the -geographic coordinates of both the transmitter and receiver. The -transmitter coordinates for various radio services are given in the -<a href="qth.htm">Stations, Frequencies and Geographic -Coordinates</a> page. Receiver coordinates can be obtained or -estimated from various sources. The actual calculations are beyond -the scope of this document.</p> - -<p>When more than one clock driver is supported, it is often the -case that each shows small systematic offset differences relative -to the rest. To reduce the effects of jitter when switching from -one driver to the another, it is useful to calibrate the drivers to -a common ensemble offset. The <tt>enable calibrate</tt> -configuration command in the <a href="miscopt.htm">Miscellaneous -Options</a> page is useful for this purpose. The calibration -function can also be enabled and disabled using the <tt>ntpdc</tt> -program utility.</p> - -<p>Most clock drivers use the <tt>time1</tt> value specified in the -<tt>fudge</tt> configuration command to provide the calibration -correction when this cannot be provided by the clock or interface. -When the calibration function is enabled, the <tt>time1</tt> value -is automatically adjusted to match the offset of the remote server -or local clock driver selected for synchronization. Ordinarily, the -NTP selection algorithm chooses the best from among all sources, -usually the best radio clock determined on the basis of stratum, -synchronization distance and jitter. The calibration function -adjusts the <tt>time1</tt> values for all clock drivers except this -source so that their indicated offsets tend to zero. If the -selected source is the kernel PPS discipline, the <tt>fudge + +<p>Some drivers depending on longwave and shortwave radio services need to +know the radio propagation time from the transmitter to the receiver, which +can amount to some tens of milliseconds. This must be calculated for each +specific receiver location and requires the geographic coordinates of both +the transmitter and receiver. The transmitter coordinates for various radio +services are given in the <a href="qth.htm">Stations, Frequencies and Geographic +Coordinates</a> page. Receiver coordinates can be obtained or estimated from +various sources. The actual calculations are beyond the scope of this document.</p> + +<p>When more than one clock driver is supported, it is often the case that +each shows small systematic offset differences relative to the rest. To reduce +the effects of jitter when switching from one driver to the another, it is +useful to calibrate the drivers to a common ensemble offset. The <tt>enable +calibrate</tt> configuration command in the <a href="miscopt.htm">Miscellaneous +Options</a> page is useful for this purpose. The calibration function can +also be enabled and disabled using the <tt>ntpdc</tt> program utility.</p> + +<p>Most clock drivers use the <tt>time1</tt> value specified in the <tt>fudge</tt> +configuration command to provide the calibration correction when this cannot +be provided by the clock or interface. When the calibration function is enabled, +the <tt>time1</tt> value is automatically adjusted to match the offset of +the remote server or local clock driver selected for synchronization. Ordinarily, +the NTP selection algorithm chooses the best from among all sources, usually +the best radio clock determined on the basis of stratum, synchronization +distance and jitter. The calibration function adjusts the <tt>time1</tt> +values for all clock drivers except this source so that their indicated offsets +tend to zero. If the selected source is the kernel PPS discipline, the <tt>fudge time1</tt> values for all clock drivers are adjusted.</p> - -<p>The adjustment function is an exponential average designed to -improve accuracy, so the function takes some time to converge. The -recommended procedure is to enable the function, let it run for an -hour or so, then edit the configuration file using the <tt> -time1</tt> values displayed by the <tt>ntpq</tt> utility and <tt> -clockvar</tt> command. Finally, disable the calibration function to -avoid possible future disruptions due to misbehaving clocks or -drivers.</p> - + +<p>The adjustment function is an exponential average designed to improve +accuracy, so the function takes some time to converge. The recommended procedure +is to enable the function, let it run for an hour or so, then edit the configuration +file using the <tt> time1</tt> values displayed by the <tt>ntpq</tt> utility +and <tt> clockvar</tt> command. Finally, disable the calibration function +to avoid possible future disruptions due to misbehaving clocks or drivers.</p> + <h4>Performance Enhancements</h4> - -<p>In general, performance can be improved, especially when more -than one clock driver is supported, to use the prefer peer function -described in the <a href="prefer.htm">Mitigation Rules and the <tt> -prefer</tt> Keyword</a> page. The prefer peer is ordinarily -designated the remote peer or local clock driver which provides the -best quality time. All other things equal, only the prefer peer -source is used to discipline the system clock and jitter-producing -"clockhopping" between sources is avoided. This is valuable when -more than one clock driver is present and especially valuable when -the PPS clock driver (type 22) is used. Support for PPS signals is -summarized in the <a href="pps.htm">Pulse-per-second (PPS) Signal -Interfacing</a> page.</p> - -<p>Where the highest performance is required, generally better than -one millisecond, additional hardware and/or software functions may -be required. Kernel modifications for precision time are described -in the <a href="kern.htm">A Kernel Model for Precision -Timekeeping</a> page. Special line discipline and streams modules + +<p>In general, performance can be improved, especially when more than one +clock driver is supported, to use the prefer peer function described in the +<a href="prefer.htm">Mitigation Rules and the <tt> prefer</tt> Keyword</a> +page. The prefer peer is ordinarily designated the remote peer or local clock +driver which provides the best quality time. All other things equal, only +the prefer peer source is used to discipline the system clock and jitter-producing +"clockhopping" between sources is avoided. This is valuable when more than +one clock driver is present and especially valuable when the PPS clock driver +(type 22) is used. Support for PPS signals is summarized in the <a + href="pps.htm">Pulse-per-second (PPS) Signal Interfacing</a> page.</p> + +<p>Where the highest performance is required, generally better than one millisecond, +additional hardware and/or software functions may be required. Kernel modifications +for precision time are described in the <a href="kern.htm">A Kernel Model +for Precision Timekeeping</a> page. Special line discipline and streams modules for use in capturing precision timestamps are described in the <a -href="ldisc.htm">Line Disciplines and Streams Drivers</a> page.</p> - + href="ldisc.htm">Line Disciplines and Streams Drivers</a> page.</p> + <h4>Comprehensive List of Clock Drivers</h4> - -<p>Following is a list showing the type and title of each driver -currently implemented. The compile-time identifier for each is -shown in parentheses. Click on a selected type for specific -description and configuration documentation, including the clock -address, reference ID, driver ID, device name and serial line -speed, and features (line disciplines, etc.). For those drivers -without specific documentation, please contact the author listed in -the <a href="copyright.htm">Copyright Notice</a> page.</p> - -<p><a href="driver1.htm">Type 1</a> Undisciplined Local Clock -(<tt>LOCAL</tt>)<br> -<a href="driver2.htm">Type 2</a> Trak 8820 GPS Receiver -(<tt>GPS_TRAK</tt>)<br> -<a href="driver3.htm">Type 3</a> PSTI/Traconex 1020 WWV/WWVH -Receiver (<tt>WWV_PST</tt>)<br> -<a href="driver4.htm">Type 4</a> Spectracom WWVB and GPS Receivers -(<tt>WWVB_SPEC</tt>)<br> -<a href="driver5.htm">Type 5</a> TrueTime GPS/GOES/OMEGA Receivers -(<tt>TRUETIME</tt>)<br> -<a href="driver6.htm">Type 6</a> IRIG Audio Decoder -(<tt>IRIG_AUDIO</tt>)<br> -<a href="driver7.htm">Type 7</a> Radio CHU Audio -Demodulator/Decoder (<tt>CHU</tt>)<br> -<a href="driver8.htm">Type 8</a> Generic Reference Driver -(<tt>PARSE</tt>)<br> -<a href="driver9.htm">Type 9</a> Magnavox MX4200 GPS Receiver -(<tt>GPS_MX4200</tt>)<br> -<a href="driver10.htm">Type 10</a> Austron 2200A/2201A GPS -Receivers (<tt>GPS_AS2201</tt>)<br> -<a href="driver11.htm">Type 11</a> Arbiter 1088A/B GPS Receiver -(<tt>GPS_ARBITER</tt>)<br> -<a href="driver12.htm">Type 12</a> KSI/Odetics TPRO/S IRIG -Interface (<tt>IRIG_TPRO</tt>)<br> -Type 13 Leitch CSD 5300 Master Clock Controller -(<tt>ATOM_LEITCH</tt>)<br> -Type 14 EES M201 MSF Receiver (<tt>MSF_EES</tt>)<br> -<a href="driver5.htm">Type 15</a> * TrueTime generic receivers<br> -<a href="driver16">Type 16</a> Bancomm GPS/IRIG Receiver -(<tt>GPS_BANCOMM</tt>)<br> -Type 17 Datum Precision Time System (<tt>GPS_DATUM</tt>)<br> -<a href="driver18.htm">Type 18</a> NIST Modem Time Service -(<tt>ACTS_NIST</tt>)<br> -<a href="driver19.htm">Type 19</a> Heath WWV/WWVH Receiver -(<tt>WWV_HEATH</tt>)<br> -<a href="driver20.htm">Type 20</a> Generic NMEA GPS Receiver -(<tt>NMEA</tt>)<br> -Type 21 TrueTime GPS-VME Interface (<tt>GPS_VME</tt>)<br> -<a href="driver22.htm">Type 22</a> PPS Clock Discipline -(<tt>PPS</tt>)<br> -<a href="driver23.htm">Type 23</a> PTB Modem Time Service -(<tt>ACTS_PTB</tt>)<br> -<a href="driver24.htm">Type 24</a> USNO Modem Time Service -(<tt>ACTS_USNO</tt>)<br> -<a href="driver5.htm">Type 25</a> * TrueTime generic receivers<br> -<a href="driver26.htm">Type 26</a> Hewlett Packard 58503A GPS -Receiver (<tt>GPS_HP</tt>)<br> -<a href="driver27.htm">Type 27</a> Arcron MSF Receiver -(<tt>MSF_ARCRON</tt>)<br> -<a href="driver28.htm">Type 28</a> Shared Memory Driver -(<tt>SHM</tt>)<br> -<a href="driver29.htm">Type 29</a> Trimble Navigation Palisade GPS -(<tt>GPS_PALISADE</tt>)<br> -<a href="driver30.htm">Type 30</a> Motorola UT Oncore GPS -(<tt>GPS_ONCORE</tt>)<br> -Type 31 Rockwell Jupiter GPS (<tt>GPS_JUPITER</tt>)<br> -<a href="driver32.htm">Type 32</a> Chrono-log K-series WWVB -receiver (<tt>CHRONOLOG</tt>)<br> -<a href="driver33.htm">Type 33</a> Dumb Clock (<tt>DUMBCLOCK</tt>)<br> -<a href="driver34.htm">Type 34</a> Ultralink WWVB Receivers (<tt>ULINK</tt>)<br> -<a href="driver35.htm">Type 35</a> Conrad Parallel Port Radio Clock -(<tt>PCF</tt>)<br> -<a href="driver36.htm">Type 36</a> Radio WWV/H Audio -Demodulator/Decoder (<tt>WWV</tt>)<br> -<a href="driver37.htm">Type 37</a> Forum Graphic GPS Dating station -(<tt>FG</tt>)<br> -<a href="driver38.htm">Type 38</a> hopf GPS/DCF77 6021/komp for -Serial Line (<tt>HOPF_S</tt>)<br> -<a href="driver39.htm">Type 39</a> hopf GPS/DCF77 6039 for PCI-Bus -(<tt>HOPF_P</tt>)<br> -<a href="driver40.htm">Type 40</a> JJY Receivers (<tt>JJY</tt>)<br> -</p> - - -<p>* All TrueTime receivers are now supported by one driver, type -5. Types 15 and 25 will be retained only for a limited time and may -be reassigned in future.</p> - + +<p>Following is a list showing the type and title of each driver currently +implemented. The compile-time identifier for each is shown in parentheses. +Click on a selected type for specific description and configuration documentation, +including the clock address, reference ID, driver ID, device name and serial +line speed, and features (line disciplines, etc.). For those drivers without +specific documentation, please contact the author listed in the <a + href="copyright.htm">Copyright Notice</a> page.</p> + +<p><a href="driver1.htm">Type 1</a> Undisciplined Local Clock (<tt>LOCAL</tt>)<br> + <a href="driver2.htm">Type 2</a> Trak 8820 GPS Receiver (<tt>GPS_TRAK</tt>)<br> + <a href="driver3.htm">Type 3</a> PSTI/Traconex 1020 WWV/WWVH Receiver (<tt>WWV_PST</tt>)<br> + <a href="driver4.htm">Type 4</a> Spectracom WWVB and GPS Receivers (<tt>WWVB_SPEC</tt>)<br> + <a href="driver5.htm">Type 5</a> TrueTime GPS/GOES/OMEGA Receivers (<tt>TRUETIME</tt>)<br> + <a href="driver6.htm">Type 6</a> IRIG Audio Decoder (<tt>IRIG_AUDIO</tt>)<br> + <a href="driver7.htm">Type 7</a> Radio CHU Audio Demodulator/Decoder (<tt>CHU</tt>)<br> + <a href="driver8.htm">Type 8</a> Generic Reference Driver (<tt>PARSE</tt>)<br> + <a href="driver9.htm">Type 9</a> Magnavox MX4200 GPS Receiver (<tt>GPS_MX4200</tt>)<br> + <a href="driver10.htm">Type 10</a> Austron 2200A/2201A GPS Receivers (<tt>GPS_AS2201</tt>)<br> + <a href="driver11.htm">Type 11</a> Arbiter 1088A/B GPS Receiver (<tt>GPS_ARBITER</tt>)<br> + <a href="driver12.htm">Type 12</a> KSI/Odetics TPRO/S IRIG Interface (<tt>IRIG_TPRO</tt>)<br> + Type 13 Leitch CSD 5300 Master Clock Controller (<tt>ATOM_LEITCH</tt>)<br> + Type 14 EES M201 MSF Receiver (<tt>MSF_EES</tt>)<br> + <a href="driver5.htm">Type 15</a> * TrueTime generic receivers<br> + <a href="driver16">Type 16</a> Bancomm GPS/IRIG Receiver (<tt>GPS_BANCOMM</tt>)<br> + Type 17 Datum Precision Time System (<tt>GPS_DATUM</tt>)<br> + <a href="driver18.htm">Type 18</a> NIST Modem Time Service (<tt>ACTS_NIST</tt>)<br> + <a href="driver19.htm">Type 19</a> Heath WWV/WWVH Receiver (<tt>WWV_HEATH</tt>)<br> + <a href="driver20.htm">Type 20</a> Generic NMEA GPS Receiver (<tt>NMEA</tt>)<br> + Type 21 TrueTime GPS-VME Interface (<tt>GPS_VME</tt>)<br> + <a href="driver22.htm">Type 22</a> PPS Clock Discipline (<tt>PPS</tt>)<br> + <a href="driver23.htm">Type 23</a> PTB Modem Time Service (<tt>ACTS_PTB</tt>)<br> + <a href="driver24.htm">Type 24</a> USNO Modem Time Service (<tt>ACTS_USNO</tt>)<br> + <a href="driver5.htm">Type 25</a> * TrueTime generic receivers<br> + <a href="driver26.htm">Type 26</a> Hewlett Packard 58503A GPS Receiver (<tt>GPS_HP</tt>)<br> + <a href="driver27.htm">Type 27</a> Arcron MSF Receiver (<tt>MSF_ARCRON</tt>)<br> + <a href="driver28.htm">Type 28</a> Shared Memory Driver (<tt>SHM</tt>)<br> + <a href="driver29.htm">Type 29</a> Trimble Navigation Palisade GPS (<tt>GPS_PALISADE</tt>)<br> + <a href="driver30.htm">Type 30</a> Motorola UT Oncore GPS (<tt>GPS_ONCORE</tt>)<br> + Type 31 Rockwell Jupiter GPS (<tt>GPS_JUPITER</tt>)<br> + <a href="driver32.htm">Type 32</a> Chrono-log K-series WWVB receiver (<tt>CHRONOLOG</tt>)<br> + <a href="driver33.htm">Type 33</a> Dumb Clock (<tt>DUMBCLOCK</tt>)<br> + <a href="driver34.htm">Type 34</a> Ultralink WWVB Receivers (<tt>ULINK</tt>)<br> + <a href="driver35.htm">Type 35</a> Conrad Parallel Port Radio Clock (<tt>PCF</tt>)<br> + <a href="driver36.htm">Type 36</a> Radio WWV/H Audio Demodulator/Decoder +(<tt>WWV</tt>)<br> + <a href="driver37.htm">Type 37</a> Forum Graphic GPS Dating station (<tt>FG</tt>)<br> + <a href="driver38.htm">Type 38</a> hopf GPS/DCF77 6021/komp for Serial Line +(<tt>HOPF_S</tt>)<br> + <a href="driver39.htm">Type 39</a> hopf GPS/DCF77 6039 for PCI-Bus (<tt>HOPF_P</tt>)<br> + <a href="driver40.htm">Type 40</a> JJY Receivers (<tt>JJY</tt>)<br> +<a href="driver44.htm">Type 44</a> NeoClock4X DCF77 / TDF receiver<br> + </p> + +<p>* All TrueTime receivers are now supported by one driver, type 5. Types +15 and 25 will be retained only for a limited time and may be reassigned +in future.</p> + <p>Additional Information</p> - -<p><a href="prefer.htm">Mitigation Rules and the <tt>prefer</tt> -Keyword</a><br> -<a href="rdebug.htm">Debugging Hints for Reference Clock -Drivers</a><br> -<a href="kern.htm">A Kernel Model for Precision Timekeeping</a><br> -<a href="ldisc.htm">Line Disciplines and Streams Drivers</a><br> -<a href="audio.htm">Reference Clock Audio Drivers</a><br> -<a href="pps.htm">Pulse-per-second (PPS) Signal Interfacing</a><br> -<a href="howto.htm">How To Write a Reference Clock Driver</a></p> - -<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> + +<p><a href="prefer.htm">Mitigation Rules and the <tt>prefer</tt> Keyword</a><br> + <a href="rdebug.htm">Debugging Hints for Reference Clock Drivers</a><br> + <a href="kern.htm">A Kernel Model for Precision Timekeeping</a><br> + <a href="ldisc.htm">Line Disciplines and Streams Drivers</a><br> + <a href="audio.htm">Reference Clock Audio Drivers</a><br> + <a href="pps.htm">Pulse-per-second (PPS) Signal Interfacing</a><br> + <a href="howto.htm">How To Write a Reference Clock Driver</a></p> + +<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> + <br> </body> </html> - |
