Finish editorial review of Serial Console section.
Some reshuffling to avoid redundancy. Should undergo a tech review to make sure all the details are correct and updated for the supported versions of FreeBSD. Sponsored by: iXsystems
This commit is contained in:
Dru Lavigne
parent
87ef42fb8c
commit
b8194ebfd0
Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=44794
1 changed files with 99 additions and 142 deletions
|
|
@ -1879,6 +1879,19 @@ raisechar=^^</programlisting>
|
|||
keyboard and leaving the mouse plugged in can fool the
|
||||
keyboard probe into thinking the keyboard is still
|
||||
there.</para>
|
||||
|
||||
<note>
|
||||
<para>While most systems will boot without a keyboard, quite a
|
||||
few will not boot without a graphics adapter. Some systems
|
||||
can be configured to boot with no graphics adapter
|
||||
by changing the <quote>graphics adapter</quote>
|
||||
setting in the <acronym>BIOS</acronym> configuration to <quote>Not
|
||||
installed</quote>. Other systems do not support this option and will
|
||||
refuse to boot if there is no display hardware in the system.
|
||||
With these machines, leave some kind of graphics card plugged
|
||||
in, even if it is just a junky mono board. A monitor does not
|
||||
need to be attached.</para>
|
||||
</note>
|
||||
</step>
|
||||
|
||||
<step>
|
||||
|
|
@ -2082,164 +2095,108 @@ boot:</screen>
|
|||
<para>During the third stage of the boot process, one can still
|
||||
switch between the internal console and the serial console by
|
||||
setting appropriate environment variables in the boot loader.
|
||||
See <xref linkend="serialconsole-loader"/> for more
|
||||
See &man.loader.8; for more
|
||||
information.</para>
|
||||
</sect2>
|
||||
|
||||
<sect2 xml:id="serialconsole-tips">
|
||||
<title>Tips for the Serial Console</title>
|
||||
|
||||
<sect3>
|
||||
<title>Setting a Faster Serial Port Speed</title>
|
||||
|
||||
<para>By default, the serial port settings are 9600 baud, 8
|
||||
bits, no parity, and 1 stop bit. To change the default
|
||||
console speed, the following options are available:</para>
|
||||
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<para>Recompile the boot blocks with
|
||||
<varname>BOOT_COMCONSOLE_SPEED</varname> set to the new
|
||||
console speed.</para>
|
||||
|
||||
<para>If the serial console is configured in some other
|
||||
way than by booting with <option>-h</option>, or if the
|
||||
serial console used by the kernel is different from the
|
||||
one used by the boot blocks, add the following option
|
||||
to a custom kernel configuration file and compile a
|
||||
new kernel:</para>
|
||||
|
||||
<programlisting>options CONSPEED=19200</programlisting>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Add the <option>-S</option> boot option to
|
||||
<filename>/boot.config</filename>. See &man.boot.8; for
|
||||
a description of how to add options to
|
||||
<filename>/boot.config</filename> and a list of the
|
||||
supported options.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Enable <varname>comconsole_speed</varname> in
|
||||
<filename>/boot/loader.conf</filename>. This option
|
||||
depends on <varname>console</varname>,
|
||||
<varname>boot_serial</varname>, and
|
||||
<varname>boot_multicons</varname> being set in
|
||||
<filename>/boot/loader.conf</filename> too. An example
|
||||
of using <varname>comconsole_speed</varname> to change
|
||||
the serial console speed is:</para>
|
||||
|
||||
<programlisting>boot_multicons="YES"
|
||||
boot_serial="YES"
|
||||
comconsole_speed="115200"
|
||||
console="comconsole,vidconsole"</programlisting>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
</sect3>
|
||||
|
||||
<sect3 xml:id="serialconsole-ddb">
|
||||
<title>Entering the DDB Debugger from the Serial Line</title>
|
||||
|
||||
<para>To drop into the kernel debugger from the serial
|
||||
console, compile a custom kernel with the following options.
|
||||
Note that while this is useful for remote diagnostics, it is
|
||||
also dangerous if a spurious BREAK is generated on the
|
||||
serial port.</para>
|
||||
|
||||
<programlisting>options BREAK_TO_DEBUGGER
|
||||
options DDB</programlisting>
|
||||
</sect3>
|
||||
|
||||
<sect3>
|
||||
<title>Getting a Login Prompt on the Serial Console</title>
|
||||
|
||||
<para>While this is not required, it is possible to get a
|
||||
<emphasis>login</emphasis> prompt over the serial line.
|
||||
First, make sure that the boot messages are displayed and it
|
||||
is possible to enter the kernel debugging session through
|
||||
the serial console.</para>
|
||||
|
||||
<para>Open <filename>/etc/ttys</filename> with a text editor
|
||||
and locate the lines:</para>
|
||||
|
||||
<programlisting>ttyu0 "/usr/libexec/getty std.9600" unknown off secure
|
||||
ttyu1 "/usr/libexec/getty std.9600" unknown off secure
|
||||
ttyu2 "/usr/libexec/getty std.9600" unknown off secure
|
||||
ttyu3 "/usr/libexec/getty std.9600" unknown off secure</programlisting>
|
||||
|
||||
<para><filename>ttyu0</filename> through
|
||||
<filename>ttyu3</filename> correspond to
|
||||
<filename>COM1</filename> through
|
||||
<filename>COM4</filename>. Change
|
||||
<literal>off</literal> to <literal>on</literal> for the
|
||||
desired port. If the speed of the serial port has been
|
||||
changed, change <literal>std.9600</literal> to match the
|
||||
new setting.</para>
|
||||
|
||||
<para>The terminal type can also be changed from
|
||||
<literal>unknown</literal> to the actual type of the serial
|
||||
terminal.</para>
|
||||
|
||||
<para>After editing the file, type <command>kill -HUP
|
||||
1</command> to make this change take effect.</para>
|
||||
</sect3>
|
||||
</sect2>
|
||||
|
||||
<sect2 xml:id="serialconsole-loader">
|
||||
<title>Changing Console from the Boot Loader</title>
|
||||
|
||||
<para>This line in <filename>/boot/loader.conf</filename>
|
||||
configures the boot loader and the kernel to use the serial
|
||||
console:</para>
|
||||
<note>
|
||||
<para>This line in <filename>/boot/loader.conf</filename> or
|
||||
<filename>/boot/loader.conf.local</filename>
|
||||
configures the boot loader and the kernel to send their boot messages to the serial
|
||||
console, regardless of the options in <filename>/boot.config</filename>:</para>
|
||||
|
||||
<programlisting>console="comconsole"</programlisting>
|
||||
|
||||
<para>This will take effect regardless of the settings in the
|
||||
boot block discussed in the previous section. This line should be the first line of
|
||||
<filename>/boot/loader.conf</filename> so as to see boot
|
||||
messages on the serial console as early as possible.</para>
|
||||
<para>That line should be the first line of
|
||||
<filename>/boot/loader.conf</filename> so that boot
|
||||
messages are displayed on the serial console as early as possible.</para>
|
||||
|
||||
<para>Likewise, to specify the internal console:</para>
|
||||
<para>If that line does not exist, or if it is set to
|
||||
<literal>console="vidconsole"</literal>, the boot loader and
|
||||
the kernel will use whichever console is
|
||||
indicated by <option>-h</option> in the boot block. See
|
||||
&man.loader.conf.5; for more information.</para>
|
||||
|
||||
<programlisting>console="vidconsole"</programlisting>
|
||||
|
||||
<para>If the boot loader environment variable
|
||||
<envar>console</envar> is not set, the boot loader, and
|
||||
subsequently the kernel, will use whichever console is
|
||||
indicated by <option>-h</option> in the boot block.</para>
|
||||
|
||||
<para>The console can be specified in
|
||||
<filename>/boot/loader.conf.local</filename> or in
|
||||
<filename>/boot/loader.conf</filename>.</para>
|
||||
|
||||
<para>See &man.loader.conf.5; for more information.</para>
|
||||
|
||||
<note>
|
||||
<para>At the moment, the boot loader has no option
|
||||
equivalent to <option>-P</option> in the boot block, and
|
||||
there is no provision to automatically select the internal
|
||||
console and the serial console based on the presence of
|
||||
the keyboard.</para>
|
||||
</note>
|
||||
|
||||
<tip>
|
||||
<para>While it is not required, it is possible to provide a
|
||||
<command>login</command> prompt over the serial line. To
|
||||
configure this, edit the entry for the serial port in
|
||||
<filename>/etc/ttys</filename> using the instructions in
|
||||
<xref linkend="term-config"/>. If the speed of the serial port has been
|
||||
changed, change <literal>std.9600</literal> to match the
|
||||
new setting.</para>
|
||||
</tip>
|
||||
</sect2>
|
||||
|
||||
<sect2 xml:id="serialconsole-caveats">
|
||||
<title>Caveats</title>
|
||||
<sect2>
|
||||
<title>Setting a Faster Serial Port Speed</title>
|
||||
|
||||
<para>While most systems will boot without a keyboard, quite a
|
||||
few will not boot without a graphics adapter. Machines with
|
||||
AMI BIOSes can be configured to boot with no graphics adapter
|
||||
installed by changing the <quote>graphics adapter</quote>
|
||||
setting in the CMOS configuration to <quote>Not
|
||||
installed.</quote></para>
|
||||
<para>By default, the serial port settings are 9600 baud, 8
|
||||
bits, no parity, and 1 stop bit. To change the default
|
||||
console speed, use one of the following options:</para>
|
||||
|
||||
<para>However, many machines do not support this option and will
|
||||
refuse to boot if there is no display hardware in the system.
|
||||
With these machines, leave some kind of graphics card plugged
|
||||
in, even if it is just a junky mono board. A monitor does not
|
||||
need to be attached. One might also try installing an AMI
|
||||
BIOS.</para>
|
||||
</sect2>
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<para>Edit <filename>/etc/make.conf</filename> and set
|
||||
<varname>BOOT_COMCONSOLE_SPEED</varname> to the new
|
||||
console speed. Then, recompile and install the boot
|
||||
blocks and the boot loader:</para>
|
||||
|
||||
<screen>&prompt.root; <userinput>cd /sys/boot</userinput>
|
||||
&prompt.root; <userinput>make clean</userinput>
|
||||
&prompt.root; <userinput>make</userinput>
|
||||
&prompt.root; <userinput>make install</userinput></screen>
|
||||
|
||||
<para>If the serial console is configured in some other
|
||||
way than by booting with <option>-h</option>, or if the
|
||||
serial console used by the kernel is different from the
|
||||
one used by the boot blocks, add the following option, with the desired speed,
|
||||
to a custom kernel configuration file and compile a
|
||||
new kernel:</para>
|
||||
|
||||
<programlisting>options CONSPEED=<replaceable>19200</replaceable></programlisting>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Add the <option>-S <replaceable>19200</replaceable></option> boot option to
|
||||
<filename>/boot.config</filename>, replacing
|
||||
<replaceable>19200</replaceable> with the speed to use.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Add the following options to
|
||||
<filename>/boot/loader.conf</filename>. Replace
|
||||
<replaceable>115200</replaceable> with the speed to
|
||||
use.</para>
|
||||
|
||||
<programlisting>boot_multicons="YES"
|
||||
boot_serial="YES"
|
||||
comconsole_speed="<replaceable>115200</replaceable>"
|
||||
console="comconsole,vidconsole"</programlisting>
|
||||
</listitem>
|
||||
</itemizedlist>
|
||||
</sect2>
|
||||
|
||||
<sect2 xml:id="serialconsole-ddb">
|
||||
<title>Entering the DDB Debugger from the Serial Line</title>
|
||||
|
||||
<para>To configure the ability to drop into the kernel debugger from the serial
|
||||
console, add the following options to a custom kernel
|
||||
configuration file and compile the kernel using the
|
||||
instructions in <xref linkend="kernelconfig"/>.
|
||||
Note that while this is useful for remote diagnostics, it is
|
||||
also dangerous if a spurious BREAK is generated on the
|
||||
serial port. Refer to &man.ddb.4; and &man.ddb.8; for more
|
||||
information about the kernel debugger.</para>
|
||||
|
||||
<programlisting>options BREAK_TO_DEBUGGER
|
||||
options DDB</programlisting>
|
||||
</sect2>
|
||||
</sect1>
|
||||
</chapter>
|
||||
|
|
|
|||
Loading…
Reference in a new issue