Document the device.hints(5) features in our handbook.

Requested by:	murray (through PR: 43529

en_US.ISO8859-1/books/handbook/boot/chapter.sgml

@@ -561,6 +561,79 @@ boot:</screen>
       <para> </para>
     </sect2> -->
   </sect1>
+  
+  <sect1 id="device-hints">
+    <sect1info>
+      <authorgroup>
+	<author>
+	  <firstname>Tom</firstname>
+	  <surname>Rhodes</surname>
+	  <contrib>Contributed by </contrib>
+	</author>
+      </authorgroup>
+      <!-- 18 OCT 2002 -->
+    </sect1info>
+    <indexterm>
+      <primary>device.hints</primary>
+    </indexterm>
+    <title>Device Hints</title>
+    
+    <para>During initial system startup, the boot &man.loader.8; will read the
+      device.hints(8) file.  This file stores kernel boot information
+      known as variables, sometimes referred to as <quote>device hints</quote>.</para>
+
+    <para>Setup of this file is one variable per line, using the standard hash
+      <quote>#</quote> as comment markers.  After system initialization, new
+      variables can be added using <command>set</command>, removed with
+      <command>unset</command>, and viewed with the <command>show</command>
+      commands.  Using the &man.kenv.1; command, you can dump all of these
+      variables.</para>
+
+    <para>These <quote>device hints</quote> are used by device drivers for device
+      control.  Syntax works as follows:</para>
+
+    <screen><userinput>hint.driver.unit.keyword="value"</userinput></screen>
+
+    <para>where driver is the device driver, unit is the unit number and keyword
+      is the hint keyword.  The keyword may consist of the following options:</para>
+
+    <itemizedlist>
+      <listitem>
+	<para>at: specifies the bus which the device is attached to.</para>
+      </listitem>
+
+      <listitem>
+	<para>port: specifies the start address of the <acronym>I/O</acronym>
+	  to be used.</para>
+      </listitem>
+
+      <listitem>
+	<para>irq: specifies the interrupt request number to be used.</para>
+      </listitem>
+
+      <listitem>
+	<para>drq: specifies the DMA channel number.</para>
+      </listitem>
+
+      <listitem>
+	<para>maddr: specifies the physical memory address occupied by the
+	  device.</para>
+      </listitem>
+
+      <listitem>
+	<para>flags: sets various flag bits for the device.</para>
+      </listitem>
+
+      <listitem>
+	<para>disabled: if set to <quote>1</quote> the device is disabled.</para>
+      </listitem>
+    </itemizedlist>
+
+    <para>Device drivers may accept (or require) more hints not listed here, viewing
+      their manual page is recommended.  For more information, consult the
+      device.hints(5), &man.kenv.1;, loader(5), and &man.loader.8;
+      manual pages.</para>
+  </sect1>
 
   <sect1 id="boot-init">
     <indexterm>