Changeset a3d0817 for chapter09/udev.xml
- Timestamp:
- 06/12/2020 08:42:32 PM (4 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, 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:
- 9e7475a
- Parents:
- 96f04d7
- File:
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chapter09/udev.xml
r96f04d7 ra3d0817 16 16 </indexterm> 17 17 18 <para>In <xref linkend="chapter-building-system"/>, we installed the Udev18 <para>In <xref linkend="chapter-building-system"/>, we installed the udev 19 19 package when <phrase revision="sysv">eudev</phrase> 20 20 <phrase revision="systemd">systemd</phrase> was built. Before we go into the … … 31 31 the world.</para> 32 32 33 <para>Using the Udev method, only those devices which are detected by the33 <para>Using the udev method, only those devices which are detected by the 34 34 kernel get device nodes created for them. Because these device nodes will be 35 35 created each time the system boots, they will be stored on a <systemitem … … 136 136 might contain the string 137 137 <quote>pci:v00001319d00000801sv00001319sd00001319bc04sc01i00</quote>. 138 The default rules provided with Udev will cause <command>udevd</command>138 The default rules provided with udev will cause <command>udevd</command> 139 139 to call out to <command>/sbin/modprobe</command> with the contents of the 140 140 <envar>MODALIAS</envar> uevent environment variable (which should be the … … 150 150 151 151 <para>The kernel itself is also able to load modules for network 152 protocols, filesystems and NLS support on demand.</para>152 protocols, filesystems, and NLS support on demand.</para> 153 153 154 154 </sect3> … … 178 178 bus driver properly exports the necessary aliases to <systemitem 179 179 class="filesystem">sysfs</systemitem>. In other cases, one should 180 arrange module loading by other means. With Linux-&linux-version;, Udev is180 arrange module loading by other means. With Linux-&linux-version;, udev is 181 181 known to load properly-written drivers for INPUT, IDE, PCI, USB, SCSI, 182 182 SERIO, and FireWire devices.</para> 183 183 184 184 <para>To determine if the device driver you require has the necessary 185 support for Udev, run <command>modinfo</command> with the module name as185 support for udev, run <command>modinfo</command> with the module name as 186 186 the argument. Now try locating the device directory under 187 187 <filename class="directory">/sys/bus</filename> and check whether there is … … 191 191 class="filesystem">sysfs</systemitem>, the driver supports the device and 192 192 can talk to it directly, but doesn't have the alias, it is a bug in the 193 driver. Load the driver without the help from Udev and expect the issue193 driver. Load the driver without the help from udev and expect the issue 194 194 to be fixed later.</para> 195 195 … … 207 207 208 208 <sect3> 209 <title>A kernel module is not loaded automatically, and Udev is not209 <title>A kernel module is not loaded automatically, and udev is not 210 210 intended to load it</title> 211 211 … … 215 215 <emphasis>snd-pcm</emphasis> by making the sound cards available to OSS 216 216 applications), configure <command>modprobe</command> to load the wrapper 217 after Udev loads the wrapped module. To do this, add a217 after udev loads the wrapped module. To do this, add a 218 218 <quote>softdep</quote> line to the corresponding 219 219 <filename>/etc/modprobe.d/<replaceable><filename></replaceable>.conf</filename> … … 280 280 <para>Further text assumes that the driver is built statically into the 281 281 kernel or already loaded as a module, and that you have already checked 282 that Udev doesn't create a misnamed device.</para>282 that udev doesn't create a misnamed device.</para> 283 283 284 284 <para>Udev has no information needed to create a device node if a kernel … … 298 298 <title>Device naming order changes randomly after rebooting</title> 299 299 300 <para>This is due to the fact that Udev, by design, handles uevents and300 <para>This is due to the fact that udev, by design, handles uevents and 301 301 loads modules in parallel, and thus in an unpredictable order. This will 302 302 never be <quote>fixed</quote>. You should not rely upon the kernel device 303 303 names being stable. Instead, create your own rules that make symlinks with 304 304 stable names based on some stable attributes of the device, such as a 305 serial number or the output of various *_id utilities installed by Udev.305 serial number or the output of various *_id utilities installed by udev. 306 306 See <xref linkend="ch-config-symlinks"/> and 307 307 <xref linkend="ch-config-network"/> for examples.</para>
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