mirror of https://github.com/tLDP/LDP
Only one console per technology type. Setting timezone. Use off parameter rather than comments in inittab. Cable lengths.
This commit is contained in:
gdt
parent
35e2b474fe
commit
614e6d32b7
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@ -5,7 +5,7 @@
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<title>Remote Serial Console HOWTO</title>
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<pubdate>v2.4 2002-10-03</pubdate>
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<pubdate>v2.5 2003-01-20</pubdate>
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<authorgroup>
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<author>
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@ -30,19 +30,31 @@
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<revhistory>
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<revision>
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<revnumber>2.4</revnumber> <date>2002-10-03</date>
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<revnumber>2.5</revnumber>
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<date>2003-01-20</date>
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<authorinitials>gdt</authorinitials> <revremark>Only one console
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per technology type. Setting timezone. Use off parameter rather
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than comments in inittab. Cable lengths.</revremark>
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</revision>
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<revision>
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<revnumber>2.4</revnumber>
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<date>2002-10-03</date>
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<authorinitials>gdt</authorinitials>
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<revremark>Kernel flow control bug, more cabling, Debian,
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Livingston Portmaster, typos (especially those found during
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translation to Japanese).</revremark>
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</revision>
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<revision>
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<revnumber>2.3</revnumber> <date>2002-07-11</date>
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<revnumber>2.3</revnumber>
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<date>2002-07-11</date>
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<authorinitials>gdt</authorinitials>
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<revremark>Updates for Red Hat Linux 7.3, corrections to serial
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port speeds and UARTs, ioctlsave.</revremark>
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</revision>
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<revision>
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<revnumber>2.2</revnumber>
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<date>2002-05-22</date>
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<authorinitials>gdt</authorinitials>
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<revremark>Minor changes</revremark>
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</revision>
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<revision>
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@ -150,9 +162,9 @@
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<title>Why use a serial console?</title>
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<para>For the average user a serial console has no advantage over a
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a console offered by a directly attached keyboard and screen.
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Serial consoles are much slower, taking up to a second to fill a 80
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column by 24 line screen. Serial consoles generally only support
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console offered by a directly attached keyboard and screen. Serial
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consoles are much slower, taking up to a second to fill a 80 column
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by 24 line screen. Serial consoles generally only support
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non-proportional <acronym>ASCII</acronym> text, with limited
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support for languages other than English. A new terminal can be
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more expensive than an old <acronym>PC</acronym>.</para>
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@ -1026,9 +1038,9 @@ setserial /dev/ttyS2 uart none port 0x0 irq 0
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console message to be read.</para>
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<para>Set the received end of line characters to
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<acronym>LF</acronym> <acronym>CR</acronym> (line feed then
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carriage return). Set the transmitted end of line characters to
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just <acronym>CR</acronym> (carriage return).</para>
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<acronym>CR</acronym> <acronym>LF</acronym> (carriage return then
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line feed). Set the transmitted end of line characters to just
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<acronym>CR</acronym> (carriage return).</para>
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<para>If you are using a terminal emulator then it is best to
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choose to emulate the popular <acronym>DEC</acronym>
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@ -1231,7 +1243,7 @@ setserial /dev/ttyS2 uart none port 0x0 irq 0
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<para>If you need to configure the boot loader to use the serial
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port then continue to <xref linkend="configure-boot-loader">.
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Otherwise go to directly to <xref linkend="configure-kernel"> to
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Otherwise go directly to <xref linkend="configure-kernel"> to
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configure the kernel; this is done by configuring the boot loader to
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pass boot parameters to the <systemitem
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class="osname">Linux</systemitem> kernel.</para>
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@ -1834,12 +1846,17 @@ serial 0 9600</programlisting>
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kernel</title>
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<para>The <systemitem class="osname">Linux</systemitem> kernel is
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configured to use a serial console by passing it the
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configured to select the console by passing it the
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<literal>console</literal> parameter. The
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<literal>console</literal> parameter can be given repeatedly; in
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that case output is sent to all consoles and input is taken from the
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last listed console. The last <literal>console</literal> is the one
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Linux uses as the <filename
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<literal>console</literal> parameter can be given repeatedly, but
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the parameter can only be given once for each console technology.
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So <literal>console=tty0 console=lp0 console=ttyS0</literal> is
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acceptable but <literal>console=ttyS0 console=ttyS1</literal> will
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not work.</para>
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<para>When multiple consoles are listed output is sent to all
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consoles and input is taken from the last listed console. The last
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<literal>console</literal> is the one Linux uses as the <filename
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class="devicefile">/dev/console</filename> device.</para>
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<para>The syntax of the <literal>console</literal> parameter is
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@ -2193,6 +2210,26 @@ APPEND console=tty0 console=ttyS0,9600n8</programlisting>
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</screen>
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</figure>
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<para>A <application>getty</application> is also responsible for
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setting the time zone when a permanently-connected remote terminal
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is located beyond the machine's default time zone. The
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<application>getty</application> overrides the default timezone by
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setting the <envar>TZ</envar> environment variable. As with the
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<envar>TERM</envar> environment variable, a user connecting from a
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modem can interactively override the default time zone.</para>
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<figure id="getty-tz">
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<title>Interactively altering the connecting terminal's time zone</title>
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<screen>
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<prompt>bash$</prompt> <command>TZ=Australia/Adelaide</command>
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<prompt>bash$</prompt> <command>export TZ</command>
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</screen>
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</figure>
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<para>If you do not know your time zone name, run the
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<command>tzselect</command> utility to generate the appropiate
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contents for <envar>TZ</envar>.</para>
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<para>But first, let's see how <application>getty</application> gets
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started in the first place.</para>
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@ -2554,11 +2591,11 @@ port ttyS0
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<programlisting>
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1:2345:respawn:/sbin/mingetty tty1
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# Additional virtual terminals are not used
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# 2:2345:respawn:/sbin/mingetty tty2
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# 3:2345:respawn:/sbin/mingetty tty3
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# 4:2345:respawn:/sbin/mingetty tty4
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# 5:2345:respawn:/sbin/mingetty tty5
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# 6:2345:respawn:/sbin/mingetty tty6
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2:2345:off:/sbin/mingetty tty2
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3:2345:off:/sbin/mingetty tty3
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4:2345:off:/sbin/mingetty tty4
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5:2345:off:/sbin/mingetty tty5
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6:2345:off:/sbin/mingetty tty6
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</programlisting>
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</figure>
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@ -3092,7 +3129,7 @@ SAFE=yes</programlisting>
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<informalfigure>
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<screen format="linespecific">
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<prompt>bash#</prompt> <command>shutdown -h now</command></screen>
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<prompt>bash#</prompt> <command>shutdown -r now</command></screen>
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</informalfigure>
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<para>During reboot the terminal should see the usual boot loader
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@ -4528,23 +4565,17 @@ Transmit data ---------------------- Receive data</programlisting>
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</section> <!-- serial-pc-terminal -->
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<section id="serial-manufacture">
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<title>Making serial cables</title>
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<section id="serial-distance">
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<title>Lengths of serial cables</title>
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<para>If you use a serial console for densely-racked computers you
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will end up making a lot of null-modem serial cables. This section
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has some hints on making serial cables. If you are making more
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than ten cables and live in a city you will probably find it
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economic to have the cables made by a specialty cabling
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firm.</para>
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<para>The <acronym>RS-232</acronym> standard will drive at least 15
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metres of shielded cable. More precisely, an
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<para>The <acronym>RS-232</acronym> standard 9600bps port will
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drive 15 metres of shielded cable. More precisely, an
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<acronym>RS-232</acronym> line driver will operate against a
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capacitance of up to 2500 picoFarad. So if you select a cable with
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low capacitance you can drive further distances.</para>
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capacitance of up to 2500 picoFarad with low enough skew to allow a
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9600bps signal to be recovered.</para>
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<para>For example,
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<para>If you select a cable with lower capacitance you can drive
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further distances. For example,
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<citetitle><acronym>ANSI/TIA/EIA-568-A</acronym></citetitle>
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unshielded twisted pair category 5 cable has a maximum capacitiance
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of 55<acronym>pF</acronym> per metre, so this popular
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@ -4559,19 +4590,59 @@ Transmit data ---------------------- Receive data</programlisting>
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capacitance cables which can be driven up to
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100<acronym>m</acronym>.</para>
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<para>Attempt to minimise noise in your cabling design. Many BIOSs
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and boot loaders will wait forever if they receive a single
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character of line noise.</para>
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<para>Similarly, if you select a lower data rate you can drive
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further distances. <xref linkend="serial-manufacture-distance">
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shows the maximum distances over standard shielded cable at
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differing data rates.</para>
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<table frame="topbot" colsep="0" rowsep="0" id="serial-manufacture-distance">
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<title>Data rates and the maximum distances recommended in
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<citetitle>RS-232</citetitle></title>
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<tgroup cols="2">
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<colspec colname="bps" align="center">
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<colspec colname="m" align="center">
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<thead>
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<row>
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<entry colname="bps">Data rate (bps)</entry>
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<entry colname="m">Distance (m)</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry colname="bps"><para>2400</para></entry>
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<entry colname="m"><para>60</para></entry>
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</row>
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<row>
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<entry colname="bps"><para>4800</para></entry>
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<entry colname="m"><para>30</para></entry>
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</row>
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<row>
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<entry colname="bps"><para>9600</para></entry>
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<entry colname="m"><para>15</para></entry>
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</row>
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<row>
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<entry colname="bps"><para>19200</para></entry>
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<entry colname="m"><para>7.6</para></entry>
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</row>
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<row>
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<entry colname="bps"><para>38400</para></entry>
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<entry colname="m"><para>3.7</para></entry>
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</row>
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<row>
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<entry colname="bps"><para>56000</para></entry>
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<entry colname="m"><para>2.6</para></entry>
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</row>
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</tbody>
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</tgroup>
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</table> <!-- serial-manufacture-distance -->
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<para>If you are comfortable in working beyond specifications then
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you might note that the <acronym>RS-232</acronym> standard was
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initially designed to operate at a synchronous
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48<acronym>Kbps</acronym> and the cable requirements reflect this.
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The experience of enterprise network operators has been that
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structured cabling layout in buildings is limited by the 100m
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distance limitation of fast ethernet over category 5 cable, not by
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the practical distances achieved by RS-232 asynchronous signals at
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9600bps over category 5 cable.</para>
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you might note that the experience of enterprise network operators
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has been that structured cabling layout in buildings is limited by
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the 100m distance limitation of fast ethernet over category 5
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cable, not by the practical distances achieved by RS-232
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asynchronous signals at 9600bps over category 5 cable.</para>
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<para>For longer distances use an <acronym>RS-232</acronym> line
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driver; these will typically drive up to 2000 meters over category
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@ -4579,16 +4650,35 @@ Transmit data ---------------------- Receive data</programlisting>
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using fiber optical modems, the global telephony system, the mobile
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telephony system, satellite or radio.</para>
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</section>
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<section id="serial-manufacture">
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<title>Making serial cables</title>
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<para>If you use a serial console for densely-racked computers you
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will end up making a lot of null-modem serial cables. This section
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has some hints on making serial cables. If you are making more
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than ten cables and live in a city you will probably find it
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economic to have the cables made by a specialty cabling
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firm.</para>
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<para>Attempt to minimise noise in your cabling design. Many BIOSs
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and boot loaders will wait forever if they receive a single
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character of line noise. You might choose to use shielded UTP
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cables (these require special RJ-45 plugs but use standard RJ-45
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sockets).</para>
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<para>If the environment has a lot of radio frequency noise then
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use shielded cable and connectors. Connect the shield in the cable
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to the computer at <emphasis>one</emphasis> end. This can be done
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by connecting the drain wire of the shield it to the Protective
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Ground (if present) or by soldering the drain wire to the body of
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the connector. If there is a substantial amount of noise also
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place a ferrite core over the shielded cable at both ends of the
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cable. Follow the usual good practices of making the cable to the
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correct length and screwing home the D connectors into the
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chassis.</para>
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use traditional shielded cable and metal RS-232 connector shells.
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Connect the shield in the cable to the computer at
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<emphasis>one</emphasis> end. This can be done by connecting the
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drain wire of the shield it to the Protective Ground (if present)
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or by soldering the drain wire to the shell of the connector. If
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there is a substantial amount of noise also place a ferrite core
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over the shielded cable at both ends of the cable. Follow the
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usual good practices of making the cable to the correct length and
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screwing home the D connectors into the chassis.</para>
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<para>If you are making one of these cables and have some soldering
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skill, you can easily do the jumpering of the signal wires within
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@ -4935,7 +5025,7 @@ Press CTRL-A Z for help on special keys
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<section id="modem-hayes-speaker">
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<title>Configure silent connection</title>
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<title>Optionally, configure silent connection</title>
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<para>Most modems have a speaker. By default this is connected
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whilst a modem is connecting and negotiating a common protocol and
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@ -5701,7 +5791,7 @@ READY: press any key to continue...</guilabel>
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the block is sent again.</para>
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<para><application>Xmodem</application> is a simple protocol, as
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you would expect of a program written for 8-bit computers runing
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you would expect of a program written for 8-bit computers running
|
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<systemitem class="osname">CP/M</systemitem>. It has lots of
|
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inefficiencies and minor problems, such as rounding up the file
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size to the next 128 byte boundary. These deficiencies lead to an
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@ -5738,9 +5828,9 @@ Bytes Sent: 3072/ 10000 BPS:2185 ETA 00:09</guilabel>
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and <application>Ymodem</application>'s
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<command>ry</command>.</para>
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<para>A useful <application>Zmodem</application> capability is the
|
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ability to resume failed uploads and to send multiple files in a
|
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single upload session.</para>
|
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<para>Useful <application>Zmodem</application> abilities are
|
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resuming failed uploads and sending multiple files in a single
|
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upload session.</para>
|
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|
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<para>An implementation of <application>Xmodem</application>,
|
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<application>Ymodem</application> and
|
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|
|
@ -6905,12 +6995,13 @@ EOF
|
|||
are also buying the rights to the software. Some companies license
|
||||
their software and have contract terms which state that the license
|
||||
cannot be resold, but has to be repurchased from the company if the
|
||||
terminal server changes hands. Many companies require a current
|
||||
maintenance contract to obtain software updates. These maintenance
|
||||
agreements can be expensive, a common figure is 15% per annum of
|
||||
the manufacturer's retail price. You may be able to source a
|
||||
cheaper software updates from a third-party maintenance
|
||||
supplier.</para>
|
||||
terminal server changes hands.</para>
|
||||
|
||||
<para>Many vendors require a current maintenance contract to obtain
|
||||
software updates. These maintenance agreements can be expensive, a
|
||||
common figure is 15% per annum of the manufacturer's retail price.
|
||||
You may be able to source a cheaper software updates from a
|
||||
third-party maintenance supplier.</para>
|
||||
|
||||
<para>Many older terminal servers are no longer sold or supported
|
||||
by their vendors. Search the vendor's web site for “end of
|
||||
|
|
@ -7340,7 +7431,7 @@ alias char-major-10-144 nvram
|
|||
|
||||
<para>The revisions to this document for the second edition are
|
||||
copyright © AARNet Pty Ltd (Australian Company Number 084 540
|
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518), 2001‐2002. These parts were written by Glen Turner.
|
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518), 2001‐2003. These parts were written by Glen Turner.
|
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He asserts his moral rights to be identified as one of the authors
|
||||
of this work under the <citetitle>Copyright Act 1968 (Commonwealth
|
||||
of Australia)</citetitle>. The Australian Academic and Research
|
||||
|
|
@ -7547,6 +7638,19 @@ alias char-major-10-144 nvram
|
|||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term>Sue Bauer-Lee</term>
|
||||
<listitem>
|
||||
<para>Suggested using the <literal>off</literal> clause in
|
||||
<filename>/etc/inittab</filename> in <xref
|
||||
linkend="getty-mingetty-inittab"> rather than commenting or
|
||||
deleting the excess <application>mingetty</application>
|
||||
invocations. This has the advatage that no automated system
|
||||
administration tool will restore the excess
|
||||
<filename>inittab</filename> entries.</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
</variablelist>
|
||||
|
||||
</section> <!-- about-credits -->
|
||||
|
|
@ -7623,6 +7727,24 @@ alias char-major-10-144 nvram
|
|||
|
||||
</book> <!-- Remote-Serial-Console-HOWTO -->
|
||||
|
||||
<!-- Updating this HOWTO using CVS
|
||||
# Initialise
|
||||
mkdir cvs
|
||||
cd cvs
|
||||
export CVSROOT=:pserver:USERID@cvs.tldp.org:/cvsroot
|
||||
cvs -d $CVSROOT login
|
||||
mkdir -p LDP/howto/docbook
|
||||
cd LDP/howto/docbook
|
||||
cvs get Remote-Serial-Console-HOWTO.sgml
|
||||
|
||||
# Update HOWTO, by copying local updated copy over CVS original copy
|
||||
cd cvs/LDP/howto/docbook
|
||||
export CVSROOT=:pserver:USERID@cvs.tldp.org:/cvsroot
|
||||
cvs update Remote-Serial-Console-HOWTO.sgml
|
||||
cp ~/Remote-Serial-Console-HOWTO.sgml Remote-Serial-Console-HOWTO.sgml
|
||||
cvs ci -m 'COMMENT' Remote-Serial-Console-HOWTO.sgml
|
||||
mail submit@en.tldp.org
|
||||
-->
|
||||
|
||||
<!-- Keep this comment at the end of the file for Emacs's PSGML
|
||||
Local variables:
|
||||
|
|
|
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Reference in New Issue