Ignore:
Timestamp:
04/13/2006 08:17:52 PM (18 years ago)
Author:
Archaic <archaic@…>
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, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 7.0, 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:
470b5d4
Parents:
d2c332bc
Message:

Tweaked some of the educational text regarding udev.

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@7510 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

File:
1 edited

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  • chapter07/udev.xml

    rd2c332bc ra0d96d25  
    9696
    9797      <para>The <command>S10udev</command> initscript takes care of creating
    98       device nodes when Linux is booted. The script starts by unsetting the
    99       hotplug event handler from the default of <command>/sbin/hotplug</command>
    100       This is done because, instead of the kernel calling out to an external
    101       binary, <command>udevd</command> will listen on a netlink socket for
    102       hotplug events that the kernel raises. The bootscript copies any static
     98      device nodes when Linux is booted. The script unsets the uevent handler
     99      from the default of <command>/sbin/hotplug</command>.  This is done
     100      because the kernel no longer needs to call out to an external binary.
     101      Instead <command>udevd</command> will listen on a netlink socket for
     102      uevents that the kernel raises. Next, the bootscript copies any static
    103103      device nodes that exist in <filename
    104104      class="directory">/lib/udev/devices</filename> to <filename
    105105      class="directory">/dev</filename>. This is necessary because some devices,
    106       directories and symlinks are needed before the dynamic device handling
     106      directories, and symlinks are needed before the dynamic device handling
    107107      processes are available during the early stages of booting a system.
    108       Creating static device nodes in
    109       <filename class="directory">/lib/udev/devices</filename> also provides
    110       an easy workaround for devices that are not supported by the dynamic
    111       device handling infrastructure.  The bootscript then starts the Udev
    112       daemon, <command>udevd</command>, which will act on any hotplug events it
    113       receives. Finally, the bootscript &quot;coldplugs&quot; any devices that
    114       have already been registered with the kernel by forcing them to raise
    115       hotplug events which <command>udevd</command> will then handle.</para>
     108      Creating static device nodes in <filename
     109      class="directory">/lib/udev/devices</filename> also provides an easy
     110      workaround for devices that are not supported by the dynamic device
     111      handling infrastructure. The bootscript then starts the Udev daemon,
     112      <command>udevd</command>, which will act on any uevents it receives.
     113      Finally, the bootscript forces the kernel to replay uevents for any
     114      devices that have already been registered and then waits for
     115      <command>udevd</command> to handle them.</para>
    116116
    117117    </sect3>
     
    178178      <para>When you plug in a device, such as a Universal Serial Bus (USB) MP3
    179179      player, the kernel recognizes that the device is now connected and
    180       generates a hotplug event. This hotplug event is then handled by
     180      generates a uevent. This uevent is then handled by
    181181      <command>udevd</command> as described above.</para>
    182182
     
    198198      class="filesystem">sysfs</systemitem>. In other cases, one should
    199199      arrange module loading by other means. With Linux-&linux-version;, Udev is
    200       known to load properly-written drivers for PCI, USB, SCSI, SERIO and
    201       FireWire devices.</para>
    202 
    203       <!-- After linux-2.6.16, add INPUT and IDE to the list above -->
     200      known to load properly-written drivers for INPUT, IDE, PCI, USB, SCSI,
     201      SERIO and FireWire devices.</para>
    204202
    205203      <para>To determine if the device driver you require has the necessary
     
    218216      directory under <filename class="directory">/sys/bus</filename>, this
    219217      means that the kernel developers have not yet added modalias support to
    220       this bus type. With Linux-&linux-version;, this is the case with ISA and
    221       IDE busses. Expect this issue to be fixed in later kernel versions.</para>
    222 
    223       <!-- Remove IDE from the list above after Linux-2.6.16 -->
     218      this bus type. With Linux-&linux-version;, this is the case with ISA
     219      busses. Expect this issue to be fixed in later kernel versions.</para>
    224220
    225221      <para>Udev is not intended to load <quote>wrapper</quote> drivers such as
     
    270266
    271267      <para>This usually happens if a rule unexpectedly matches a device. For
    272       example, a poorly-writen rule can match by both a SCSI disk (as desired)
     268      example, a poorly-writen rule can match both a SCSI disk (as desired)
    273269      and the corresponding SCSI generic device (incorrectly) by vendor.
    274270      Increase the logging verbosity of Udev, find the offending rule by
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