Changeset 841b723
- Timestamp:
- 02/04/2012 11:37:17 PM (12 years ago)
- 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
- Files:
-
- 3 edited
Legend:
- Unmodified
- Added
- Removed
-
chapter01/changelog.xml
r6b13ebc6 r841b723 39 39 40 40 <listitem> 41 <para>2012-02-04</para> 42 <itemizedlist> 43 <listitem> 44 <para>[bryan] - Fix up text in section 7.4 ("device and module 45 handling"), and change the recommendation for wrapper modules to 46 use kmod's support for soft post-dependencies instead. Fixes 47 <ulink url="&lfs-ticket-root;3010">#3010</ulink>.</para> 48 </listitem> 49 </itemizedlist> 50 </listitem> 51 52 <listitem> 41 53 <para>2012-02-02</para> 42 54 <itemizedlist> -
chapter07/udev.xml
r6b13ebc6 r841b723 33 33 kernel get device nodes created for them. Because these device nodes will be 34 34 created each time the system boots, they will be stored on a <systemitem 35 class="filesystem"> tmpfs</systemitem> file system (a virtual file system that36 resides entirely in system memory). Device nodes do not require much space, so37 the memory that is used is negligible.</para>35 class="filesystem">devtmpfs</systemitem> file system (a virtual file system 36 that resides entirely in system memory). Device nodes do not require much 37 space, so the memory that is used is negligible.</para> 38 38 39 39 <sect2> … … 88 88 class="directory">/sys</filename>), data which the built-in drivers 89 89 registered with <systemitem class="filesystem">sysfs</systemitem> are 90 available to userspace processes and to <command>udevd</command> for device91 node creation.</para>90 available to userspace processes and to <command>udevd</command> for 91 processing (including modifications to device nodes).</para> 92 92 93 93 </sect3> … … 133 133 <title>Device Node Creation</title> 134 134 135 <para>To obtain the right major and minor number for a device, Udev 136 relies on the information provided by <systemitem 137 class="filesystem">sysfs</systemitem> in <filename 138 class="directory">/sys</filename>. For example, 139 <filename>/sys/class/tty/vcs/dev</filename> contains the string 140 <quote>7:0</quote>. This string is used by <command>udevd</command> to 141 create a device node with major number <emphasis>7</emphasis> and minor 142 <emphasis>0</emphasis>. The names and permissions of the nodes created 143 under the <filename class="directory">/dev</filename> directory are 144 determined by rules specified in the files within the <filename 145 class="directory">/etc/udev/rules.d/</filename> directory. These are 146 numbered in a similar fashion to the LFS-Bootscripts package. If 147 <command>udevd</command> can't find a rule for the device it is creating, 148 it will default permissions to <emphasis>660</emphasis> and ownership to 149 <emphasis>root:root</emphasis>. Documentation on the syntax of the Udev 150 rules configuration files are available in 151 <filename>/usr/share/doc/udev-&udev-version;/writing_udev_rules/index.html</filename> 152 </para> 135 <para>As of Udev-&udev-version;, <command>udevd</command> no longer 136 creates device files in <filename class="directory">/dev</filename>. 137 Instead, this must be handled in the kernel, by the <systemitem 138 class="filesystem">devtmpfs</systemitem> filesystem. Any driver that 139 wishes to register a device node will go through <systemitem 140 class="filesystem">devtmpfs</systemitem> (via the driver core) to do it. 141 When a <systemitem class="filesystem">devtmpfs</systemitem> instance is 142 mounted on <filename class="directory">/dev</filename>, the device node 143 will initially be created with a fixed name, permissions, and owner.</para> 144 145 <para>A short time later, the kernel will send a uevent to <command> 146 udevd</command>. Based on the rules specified in the files within the 147 <filename class="directory">/etc/udev/rules.d</filename>, <filename 148 class="directory">/lib/udev/rules.d</filename>, and <filename 149 class="directory">/run/udev/rules.d</filename> directories, <command> 150 udevd</command> will create additional symlinks to the device node, 151 or change its permissions, owner, or group, or modify the internal 152 <command>udevd</command> database entry for that object.</para> 153 154 <para>The rules in these three directories are numbered in a similar 155 fashion to the LFS-Bootscripts package, and all three directories are 156 merged together. If <command>udevd</command> can't find a rule for the 157 device it is creating, it will leave the permissions and ownership at 158 whatever <systemitem class="filesystem">devtmpfs</systemitem> used 159 initially.</para> 153 160 154 161 </sect3> … … 248 255 sound cards available to OSS applications), configure 249 256 <command>modprobe</command> to load the wrapper after Udev loads the 250 wrapped module. To do this, add a n <quote>install</quote> line in any257 wrapped module. To do this, add a <quote>softdep</quote> line in any 251 258 <filename>/etc/modprobe.d/<replaceable><filename></replaceable>.conf</filename> 252 259 file. For example:</para> 253 260 254 <screen role="nodump"><literal>install snd-pcm /sbin/modprobe -i snd-pcm ; \ 255 /sbin/modprobe snd-pcm-oss ; true</literal></screen> 261 <screen role="nodump"><literal>softdep snd-pcm post: snd-pcm-oss</literal></screen> 262 263 <para>Note that the <quote>softdep</quote> command also allows 264 <literal>pre:</literal> dependencies, or a mixture of both 265 <literal>pre:</literal> and <literal>post:</literal>. See the 266 <filename>modprobe.d(5)</filename> manual page for more information 267 on <quote>softdep</quote> syntax and capabilities.</para> 256 268 257 269 <para>If the module in question is not a wrapper and is useful by itself, -
general.ent
r6b13ebc6 r841b723 1 <!ENTITY version "SVN-2012020 2">2 <!ENTITY releasedate "Feb 2, 2012">1 <!ENTITY version "SVN-20120204"> 2 <!ENTITY releasedate "Feb 4, 2012"> 3 3 <!ENTITY copyrightdate "1999-2012"><!-- jhalfs needs a literal dash, not – --> 4 4 <!ENTITY milestone "7.1">
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