<para>Traditionally, FreeBSD has had what is called a

    <para>Traditionally, FreeBSD has had what is called a

      <quote>monolithic</quote> kernel.  This means that the kernel was one

      <quote>monolithic</quote> kernel.  This means that the kernel was one

      change the kernel's behavior then you had to compile a new kernel, and

      change the kernel's behavior then you had to compile a new kernel, and

      then reboot your computer with the new kernel.</para>

      then reboot your computer with the new kernel.</para>

      <listitem>

      <listitem>

	<para>Additional hardware support.  A custom kernel allows you to

	<para>Additional hardware support.  A custom kernel allows you to

	  present in the <literal>GENERIC</literal> kernel.</para>

	  present in the <literal>GENERIC</literal> kernel.</para>

      </listitem>

      </listitem>

    </itemizedlist>

    </itemizedlist>

      section slowly and carefully.</para>

      section slowly and carefully.</para>

    <note>

    <note>

    </note>

    </note>

    <para>You must now compile the source code for the kernel.  There are two

    <para>You must now compile the source code for the kernel.  There are two

    </itemizedlist>

    </itemizedlist>

    <procedure>

    <procedure>

      <step>

      <step>

	<para>Run &man.config.8; to generate the kernel source code.</para>

	<para>Run &man.config.8; to generate the kernel source code.</para>

    </procedure>

    </procedure>

    <procedure>

    <procedure>

	way</title>

	way</title>

      <step>

      <step>

    </indexterm>

    </indexterm>

    <para>If you have <emphasis>not</emphasis> upgraded your source

    <para>If you have <emphasis>not</emphasis> upgraded your source

      <application>CTM</application>, or used 

      <application>CTM</application>, or used 

      <application>anoncvs</application>), then you should use the 

      <application>anoncvs</application>), then you should use the 

      <command>config</command>, <maketarget>make depend</maketarget>,

      <command>config</command>, <maketarget>make depend</maketarget>,

  </sect1>

  </sect1>

  <sect1 id="kernelconfig-config">

  <sect1 id="kernelconfig-config">

    <indexterm>

    <indexterm>

      <primary>kernel</primary>

      <primary>kernel</primary>

      <secondary>LINT</secondary>

      <secondary>LINT</secondary>

      <secondary>config file</secondary>

      <secondary>config file</secondary>

    </indexterm>

    </indexterm>

      Each line contains a keyword and one or more arguments.  For

      Each line contains a keyword and one or more arguments.  For

      simplicity, most lines only contain one argument.  Anything

      simplicity, most lines only contain one argument.  Anything

      following a <literal>#</literal> is considered a comment and

      following a <literal>#</literal> is considered a comment and

    <para>Starting with FreeBSD 4.5, the system will auto-tune this setting

    <para>Starting with FreeBSD 4.5, the system will auto-tune this setting

      for you if you explicitly set it to <literal>0</literal><footnote>

      for you if you explicitly set it to <literal>0</literal><footnote>

	<para>The auto-tuning algorithm sets <literal>maxuser</literal> equal

	<para>The auto-tuning algorithm sets <literal>maxuser</literal> equal

	  maximum of 384.</para></footnote>.  If you are

	  maximum of 384.</para></footnote>.  If you are

      using an earlier version of FreeBSD, or you want to manage it

      using an earlier version of FreeBSD, or you want to manage it

      <literal>maxusers</literal> to at least 4, especially if you are

      <literal>maxusers</literal> to at least 4, especially if you are

      using the X Window System or compiling software.  The reason is that

      using the X Window System or compiling software.  The reason is that

      the most important table set by <literal>maxusers</literal> is the

      the most important table set by <literal>maxusers</literal> is the

    <note>

    <note>

      <para><literal>maxusers</literal> does <emphasis>not</emphasis>

      <para><literal>maxusers</literal> does <emphasis>not</emphasis>

	the maximum number of users you will likely have on your system

	the maximum number of users you will likely have on your system

	and how many processes each of them will be running.  One keyword

	and how many processes each of them will be running.  One keyword

	which <emphasis>does</emphasis> limit the number of simultaneous

	which <emphasis>does</emphasis> limit the number of simultaneous

    <programlisting>options          UFS_DIRHASH  #Improve performance on big directories</programlisting>

    <programlisting>options          UFS_DIRHASH  #Improve performance on big directories</programlisting>

    <para>This option includes some code to speed up disk operations on large

    <para>This option includes some code to speed up disk operations on large

      would normally keep this for a large server, or interactive workstation,

      would normally keep this for a large server, or interactive workstation,

      and remove it if you are using FreeBSD on a smaller system where memory

      and remove it if you are using FreeBSD on a smaller system where memory

      is at a premium and disk access speed is less important, such as a

      is at a premium and disk access speed is less important, such as a

    <programlisting>options          SOFTUPDATES  #Enable FFS soft updates support</programlisting>

    <programlisting>options          SOFTUPDATES  #Enable FFS soft updates support</programlisting>

      up write access on the disks.  They are enabled by default in the 4.X branch

      up write access on the disks.  They are enabled by default in the 4.X branch

      but may not be turned on.  Review the output from &man.mount.8; to see

      but may not be turned on.  Review the output from &man.mount.8; to see

      if you have them enabled.  If you do not see the soft-updates option then

      if you have them enabled.  If you do not see the soft-updates option then

      for new filesystems.</para>      

      for new filesystems.</para>      

    <programlisting>options          MFS          #Memory Filesystem

    <programlisting>options          MFS          #Memory Filesystem

    <programlisting>options          PROCFS       #Process filesystem</programlisting>

    <programlisting>options          PROCFS       #Process filesystem</programlisting>

      filesystem mounted on <filename>/proc</filename> which allows

      filesystem mounted on <filename>/proc</filename> which allows

      programs like &man.ps.1; to give you more information on what

      programs like &man.ps.1; to give you more information on what

      processes are running.</para>

      processes are running.</para>

    <programlisting>options          COMPAT_43    #Compatible with BSD 4.3 [KEEP THIS!]</programlisting>

    <programlisting>options          COMPAT_43    #Compatible with BSD 4.3 [KEEP THIS!]</programlisting>

    <para>Compatibility with 4.3BSD.  Leave this in; some programs will

    <para>Compatibility with 4.3BSD.  Leave this in; some programs will

    <programlisting>options          SCSI_DELAY=15000    #Delay (in ms) before probing SCSI</programlisting>

    <programlisting>options          SCSI_DELAY=15000    #Delay (in ms) before probing SCSI</programlisting>

      you can ignore this, otherwise you will probably want to lower this

      you can ignore this, otherwise you will probably want to lower this

      number, perhaps to 5 seconds, to speed up booting.  Of course, if

      number, perhaps to 5 seconds, to speed up booting.  Of course, if

      you do this, and FreeBSD has trouble recognizing your SCSI devices,

      you do this, and FreeBSD has trouble recognizing your SCSI devices,

    <programlisting>options          UCONSOLE            #Allow users to grab the console</programlisting>

    <programlisting>options          UCONSOLE            #Allow users to grab the console</programlisting>

    <para>Allow users to grab the console, which is useful for X users.

    <para>Allow users to grab the console, which is useful for X users.

      For example, you can create a console xterm by typing <command>xterm

      For example, you can create a console xterm by typing <command>xterm

      -C</command>, which will display any <command>write</command>,

      -C</command>, which will display any <command>write</command>,

      as any console messages sent by the kernel.</para>

      as any console messages sent by the kernel.</para>

    <programlisting>options          USERCONFIG          #boot -c editor</programlisting>

    <programlisting>options          USERCONFIG          #boot -c editor</programlisting>

    <programlisting>options 	P1003_1B		#Posix P1003_1B real-time extensions

    <programlisting>options 	P1003_1B		#Posix P1003_1B real-time extensions

options 	_KPOSIX_PRIORITY_SCHEDULING</programlisting>

options 	_KPOSIX_PRIORITY_SCHEDULING</programlisting>

      applications in the ports collection use these

      applications in the ports collection use these

      (such as <application>StarOffice</application>).</para>

      (such as <application>StarOffice</application>).</para>

    <para>This option enables ICMP error response bandwidth limiting.  You

    <para>This option enables ICMP error response bandwidth limiting.  You

      typically want this option as it will help protect the machine from

      typically want this option as it will help protect the machine from

    <indexterm>

    <indexterm>

      <primary>kernel options</primary>

      <primary>kernel options</primary>

    <programlisting>device          isa</programlisting>

    <programlisting>device          isa</programlisting>

      IBM PS/2 (Micro Channel Architecture), you cannot run FreeBSD at

      IBM PS/2 (Micro Channel Architecture), you cannot run FreeBSD at

    <programlisting>device          eisa</programlisting>

    <programlisting>device          eisa</programlisting>

    <programlisting>device          pci</programlisting>

    <programlisting>device          pci</programlisting>

    <para>Include this if you have a PCI motherboard.  This enables

    <para>Include this if you have a PCI motherboard.  This enables

      bus.</para>

      bus.</para>

    <programlisting># Floppy drives

    <programlisting># Floppy drives

    <programlisting>options         ATA_STATIC_ID           #Static device numbering</programlisting>

    <programlisting>options         ATA_STATIC_ID           #Static device numbering</programlisting>

    <programlisting># ATA and ATAPI devices

    <programlisting># ATA and ATAPI devices

device          ata0        at isa? port IO_WD1 irq 14

device          ata0        at isa? port IO_WD1 irq 14

    <programlisting>device          atkbd0     at atkbdc? irq 1</programlisting>

    <programlisting>device          atkbd0     at atkbdc? irq 1</programlisting>

      <literal>atkbdc</literal> controller, provides access to the AT 84

      <literal>atkbdc</literal> controller, provides access to the AT 84

      keyboard or the AT enhanced keyboard which is connected to the AT

      keyboard or the AT enhanced keyboard which is connected to the AT

      keyboard controller.</para>

      keyboard controller.</para>

    <note>

    <note>

      <para>If you have an internal modem on COM4 and a serial port at

      <para>If you have an internal modem on COM4 and a serial port at

	COM2, you will have to change the IRQ of the modem to 2 (for

	COM2, you will have to change the IRQ of the modem to 2 (for

	from FreeBSD.  If you have a multiport serial card, check the

	from FreeBSD.  If you have a multiport serial card, check the

	manual page for &man.sio.4; for more information on the proper

	manual page for &man.sio.4; for more information on the proper

	values for these lines.  Some video cards (notably those based on

	values for these lines.  Some video cards (notably those based on

	<literal>0x*2e8</literal>, and since many cheap serial cards do

	<literal>0x*2e8</literal>, and since many cheap serial cards do

	not fully decode the 16-bit IO address space, they clash with

	not fully decode the 16-bit IO address space, they clash with

      <para>Each serial port is required to have a unique IRQ (unless you

      <para>Each serial port is required to have a unique IRQ (unless you

        are using one of the multiport cards where shared interrupts are

        are using one of the multiport cards where shared interrupts are

    <programlisting># Parallel port

    <programlisting># Parallel port

device          ppc0    at isa? irq 7</programlisting>

device          ppc0    at isa? irq 7</programlisting>

    <programlisting>device          ppbus      # Parallel port bus (required)</programlisting>

    <programlisting>device          ppbus      # Parallel port bus (required)</programlisting>

    <para>The general-purpose I/O (<quote>geek port</quote>) + IEEE1284

    <para>The general-purpose I/O (<quote>geek port</quote>) + IEEE1284

      I/O.</para>

      I/O.</para>

    <indexterm><primary>zip drive</primary></indexterm>

    <indexterm><primary>zip drive</primary></indexterm>

    <para>This is for an Iomega Zip drive.  It requires

    <para>This is for an Iomega Zip drive.  It requires

pseudo-device   pty           # Pseudo-ttys (telnet etc)</programlisting>

pseudo-device   pty           # Pseudo-ttys (telnet etc)</programlisting>

    <para>This is a <quote>pseudo-terminal</quote> or simulated login port.

    <para>This is a <quote>pseudo-terminal</quote> or simulated login port.

      <command>rlogin</command> sessions,

      <command>rlogin</command> sessions,

      <application>xterm</application>, and some other applications such

      <application>xterm</application>, and some other applications such

      as <application>emacs</application>.  A

      as <application>emacs</application>.  A

    <para>This is the Berkeley Packet Filter.  This pseudo-device allows

    <para>This is the Berkeley Packet Filter.  This pseudo-device allows

      network interfaces to be placed in promiscuous mode, capturing every

      network interfaces to be placed in promiscuous mode, capturing every

      packet on a broadcast network (e.g., an Ethernet).  These packets

      packet on a broadcast network (e.g., an Ethernet).  These packets

      program.</para>

      program.</para>

    <note>

    <note>

      <para>The <literal>bpf pseudo-device</literal> is also used by

      <para>The <literal>bpf pseudo-device</literal> is also used by

	&man.dhclient.8; to obtain the IP address of the default router

	&man.dhclient.8; to obtain the IP address of the default router

	(gateway) and so on.  If you use DHCP, leave this

	(gateway) and so on.  If you use DHCP, leave this

    </note>

    </note>

    <programlisting># USB support

    <programlisting># USB support