Changeset 841b723

Timestamp:

02/04/2012 11:37:17 PM (12 years ago)

Author:

Bryan Kadzban <bryan@…>

Branches:

10.0, 10.0-rc1, 10.1, 10.1-rc1, 11.0, 11.0-rc1, 11.0-rc2, 11.0-rc3, 11.1, 11.1-rc1, 11.2, 11.2-rc1, 11.3, 11.3-rc1, 12.0, 12.0-rc1, 12.1, 12.1-rc1, 7.1, 7.2, 7.3, 7.4, 7.5, 7.5-systemd, 7.6, 7.6-systemd, 7.7, 7.7-systemd, 7.8, 7.8-systemd, 7.9, 7.9-systemd, 8.0, 8.1, 8.2, 8.3, 8.4, 9.0, 9.1, arm, bdubbs/gcc13, ml-11.0, multilib, renodr/libudev-from-systemd, s6-init, trunk, xry111/arm64, xry111/arm64-12.0, xry111/clfs-ng, xry111/lfs-next, xry111/loongarch, xry111/loongarch-12.0, xry111/loongarch-12.1, xry111/mips64el, xry111/pip3, xry111/rust-wip-20221008, xry111/update-glibc

Children:

2f0d64d

Parents:

6b13ebc6

Message:

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

Files:

• chapter01/changelog.xml (modified) (1 diff)
• chapter07/udev.xml (modified) (4 diffs)
• general.ent (modified) (1 diff)

chapter01/changelog.xml

@@ -39 +39 @@
 
     <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

@@ -33 +33 @@
   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
-  resides entirely in system memory). Device nodes do not require much space, so
-  the memory that is used is negligible.</para>
+  class="filesystem">devtmpfs</systemitem> file system (a virtual file system
+  that resides entirely in system memory). Device nodes do not require much
+  space, so the memory that is used is negligible.</para>
 
   <sect2>
@@ -88 +88 @@
       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
-      node creation.</para>
+      available to userspace processes and to <command>udevd</command> for
+      processing (including modifications to device nodes).</para>
 
     </sect3>
@@ -133 +133 @@
       <title>Device Node Creation</title>
 
-      <para>To obtain the right major and minor number for a device, Udev
-      relies on the information provided by <systemitem
-      class="filesystem">sysfs</systemitem> in <filename
-      class="directory">/sys</filename>.  For example,
-      <filename>/sys/class/tty/vcs/dev</filename> contains the string
-      <quote>7:0</quote>. This string is used by <command>udevd</command> to
-      create a device node with major number <emphasis>7</emphasis> and minor
-      <emphasis>0</emphasis>. The names and permissions of the nodes created
-      under the <filename class="directory">/dev</filename> directory are
-      determined by rules specified in the files within the <filename
-      class="directory">/etc/udev/rules.d/</filename> directory. These are
-      numbered in a similar fashion to the LFS-Bootscripts package. If
-      <command>udevd</command> can't find a rule for the device it is creating,
-      it will default permissions to <emphasis>660</emphasis> and ownership to
-      <emphasis>root:root</emphasis>. Documentation on the syntax of the Udev
-      rules configuration files are available in
-      <filename>/usr/share/doc/udev-&udev-version;/writing_udev_rules/index.html</filename>
-      </para>
+      <para>As of Udev-&udev-version;, <command>udevd</command> no longer
+      creates device files in <filename class="directory">/dev</filename>.
+      Instead, this must be handled in the kernel, by the <systemitem
+      class="filesystem">devtmpfs</systemitem> filesystem.  Any driver that
+      wishes to register a device node will go through <systemitem
+      class="filesystem">devtmpfs</systemitem> (via the driver core) to do it.
+      When a <systemitem class="filesystem">devtmpfs</systemitem> instance is
+      mounted on <filename class="directory">/dev</filename>, the device node
+      will initially be created with a fixed name, permissions, and owner.</para>
+
+      <para>A short time later, the kernel will send a uevent to <command>
+      udevd</command>.  Based on the rules specified in the files within the
+      <filename class="directory">/etc/udev/rules.d</filename>, <filename
+      class="directory">/lib/udev/rules.d</filename>, and <filename
+      class="directory">/run/udev/rules.d</filename> directories, <command>
+      udevd</command> will create additional symlinks to the device node,
+      or change its permissions, owner, or group, or modify the internal
+      <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>
@@ -248 +255 @@
       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 ; \
-    /sbin/modprobe snd-pcm-oss ; true</literal></screen>
+<screen role="nodump"><literal>softdep snd-pcm post: snd-pcm-oss</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,

general.ent

@@ -1 @@
-<!ENTITY version "SVN-20120202">
-<!ENTITY releasedate "Feb 2, 2012">
+<!ENTITY version "SVN-20120204">
+<!ENTITY releasedate "Feb 4, 2012">
 <!ENTITY copyrightdate "1999-2012"><!-- jhalfs needs a literal dash, not &ndash; -->
 <!ENTITY milestone "7.1">