Change the recipe for wrapper kernel module dependencies to use the explicit soft-dependency support added to kmod. While I'm here, rewrite a bunch of the chapter-7 udev processing documentation, now that we use devtmpfs.

Fixes #3010.



git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@9727 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter01/changelog.xml

@@ -37,6 +37,18 @@
 
 -->
 
+    <listitem>
+      <para>2012-02-04</para>
+      <itemizedlist>
+        <listitem>
+          <para>[bryan] - Fix up text in section 7.4 ("device and module
+          handling"), and change the recommendation for wrapper modules to
+          use kmod's support for soft post-dependencies instead.  Fixes
+          <ulink url="&lfs-ticket-root;3010">#3010</ulink>.</para>
+        </listitem>
+      </itemizedlist>
+    </listitem>
+
     <listitem>
       <para>2012-02-02</para>
       <itemizedlist>

chapter07/udev.xml

@@ -32,9 +32,9 @@
   <para>Using the Udev method, only those devices which are detected by the
   kernel get device nodes created for them. Because these device nodes will be
   created each time the system boots, they will be stored on a <systemitem
-  class="filesystem">tmpfs</systemitem> file system (a virtual file system that
+  class="filesystem">devtmpfs</systemitem> file system (a virtual file system
-  resides entirely in system memory). Device nodes do not require much space, so
+  that resides entirely in system memory). Device nodes do not require much
-  the memory that is used is negligible.</para>
+  space, so the memory that is used is negligible.</para>
 
   <sect2>
     <title>History</title>
@@ -87,8 +87,8 @@
       class="filesystem">sysfs</systemitem> filesystem is mounted (on <filename
       class="directory">/sys</filename>), data which the built-in drivers
       registered with <systemitem class="filesystem">sysfs</systemitem> are
-      available to userspace processes and to <command>udevd</command> for device
+      available to userspace processes and to <command>udevd</command> for
-      node creation.</para>
+      processing (including modifications to device nodes).</para>
 
     </sect3>
 
@@ -132,24 +132,31 @@
     <sect3>
       <title>Device Node Creation</title>
 
-      <para>To obtain the right major and minor number for a device, Udev
+      <para>As of Udev-&udev-version;, <command>udevd</command> no longer
-      relies on the information provided by <systemitem
+      creates device files in <filename class="directory">/dev</filename>.
-      class="filesystem">sysfs</systemitem> in <filename
+      Instead, this must be handled in the kernel, by the <systemitem
-      class="directory">/sys</filename>.  For example,
+      class="filesystem">devtmpfs</systemitem> filesystem.  Any driver that
-      <filename>/sys/class/tty/vcs/dev</filename> contains the string
+      wishes to register a device node will go through <systemitem
-      <quote>7:0</quote>. This string is used by <command>udevd</command> to
+      class="filesystem">devtmpfs</systemitem> (via the driver core) to do it.
-      create a device node with major number <emphasis>7</emphasis> and minor
+      When a <systemitem class="filesystem">devtmpfs</systemitem> instance is
-      <emphasis>0</emphasis>. The names and permissions of the nodes created
+      mounted on <filename class="directory">/dev</filename>, the device node
-      under the <filename class="directory">/dev</filename> directory are
+      will initially be created with a fixed name, permissions, and owner.</para>
-      determined by rules specified in the files within the <filename
+
-      class="directory">/etc/udev/rules.d/</filename> directory. These are
+      <para>A short time later, the kernel will send a uevent to <command>
-      numbered in a similar fashion to the LFS-Bootscripts package. If
+      udevd</command>.  Based on the rules specified in the files within the
-      <command>udevd</command> can't find a rule for the device it is creating,
+      <filename class="directory">/etc/udev/rules.d</filename>, <filename
-      it will default permissions to <emphasis>660</emphasis> and ownership to
+      class="directory">/lib/udev/rules.d</filename>, and <filename
-      <emphasis>root:root</emphasis>. Documentation on the syntax of the Udev
+      class="directory">/run/udev/rules.d</filename> directories, <command>
-      rules configuration files are available in
+      udevd</command> will create additional symlinks to the device node,
-      <filename>/usr/share/doc/udev-&udev-version;/writing_udev_rules/index.html</filename>
+      or change its permissions, owner, or group, or modify the internal
-      </para>
+      <command>udevd</command> database entry for that object.</para>
+
+      <para>The rules in these three directories are numbered in a similar
+      fashion to the LFS-Bootscripts package, and all three directories are
+      merged together. If <command>udevd</command> can't find a rule for the
+      device it is creating, it will leave the permissions and ownership at
+      whatever <systemitem class="filesystem">devtmpfs</systemitem> used
+      initially.</para>
 
     </sect3>
 
@@ -247,12 +254,17 @@
       enhances the functionality of <emphasis>snd-pcm</emphasis> by making the
       sound cards available to OSS applications), configure
       <command>modprobe</command> to load the wrapper after Udev loads the
-      wrapped module. To do this, add an <quote>install</quote> line in any
+      wrapped module. To do this, add a <quote>softdep</quote> line in any
       <filename>/etc/modprobe.d/<replaceable>&lt;filename&gt;</replaceable>.conf</filename>
       file. For example:</para>
 
-<screen role="nodump"><literal>install snd-pcm /sbin/modprobe -i snd-pcm ; \
+<screen role="nodump"><literal>softdep snd-pcm post: snd-pcm-oss</literal></screen>
-    /sbin/modprobe snd-pcm-oss ; true</literal></screen>
+
+      <para>Note that the <quote>softdep</quote> command also allows
+      <literal>pre:</literal> dependencies, or a mixture of both
+      <literal>pre:</literal> and <literal>post:</literal>.  See the
+      <filename>modprobe.d(5)</filename> manual page for more information
+      on <quote>softdep</quote> syntax and capabilities.</para>
 
       <para>If the module in question is not a wrapper and is useful by itself,
       configure the <command>modules</command> bootscript to load this

general.ent

@@ -1,5 +1,5 @@
-<!ENTITY version "SVN-20120202">
+<!ENTITY version "SVN-20120204">
-<!ENTITY releasedate "Feb 2, 2012">
+<!ENTITY releasedate "Feb 4, 2012">
 <!ENTITY copyrightdate "1999-2012"><!-- jhalfs needs a literal dash, not &ndash; -->
 <!ENTITY milestone "7.1">
 <!ENTITY generic-version "development"> <!-- Use "development", "testing", or "x.y[-pre{x}]" -->