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author | DJ Lucas <dj@linuxfromscratch.org> | 2016-05-30 04:37:33 +0000 |
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committer | DJ Lucas <dj@linuxfromscratch.org> | 2016-05-30 04:37:33 +0000 |
commit | efd5d1f3039242ad62214476c986980eb2ea2957 (patch) | |
tree | 93ea30e8baf375c8ee6af06e082dba1daa1f03ea /chapter07/symlinksd.xml | |
parent | 9a0d741437c1c371ecff9711a02fe3dd21b3ad9e (diff) |
Merge symlinks.xml and symlinksd.xml.
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@11084 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
Diffstat (limited to 'chapter07/symlinksd.xml')
-rw-r--r-- | chapter07/symlinksd.xml | 63 |
1 files changed, 0 insertions, 63 deletions
diff --git a/chapter07/symlinksd.xml b/chapter07/symlinksd.xml deleted file mode 100644 index b0d6460cf..000000000 --- a/chapter07/symlinksd.xml +++ /dev/null @@ -1,63 +0,0 @@ -<?xml version="1.0" encoding="ISO-8859-1"?> -<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" - "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ - <!ENTITY % general-entities SYSTEM "../general.ent"> - %general-entities; -]> - -<sect1 id="ch-scripts-symlinks" revision="systemd"> - <?dbhtml filename="symlinks.html"?> - - <title>Creating Custom Symlinks to Devices</title> - - <sect2> - <title>Dealing with duplicate devices</title> - - <para>As explained in <xref linkend="ch-scripts-udev"/>, the order in - which devices with the same function appear in - <filename class="directory">/dev</filename> is essentially random. - E.g., if you have a USB web camera and a TV tuner, sometimes - <filename>/dev/video0</filename> refers to the camera and - <filename>/dev/video1</filename> refers to the tuner, and sometimes - after a reboot the order changes to the opposite one. - For all classes of hardware except sound cards and network cards, this is - fixable by creating udev rules for custom persistent symlinks. - The case of network cards is covered separately in - <xref linkend="ch-scripts-network"/>, and sound card configuration can - be found in <ulink url="&blfs-book;postlfs/devices.html">BLFS</ulink>.</para> - - <para>For each of your devices that is likely to have this problem - (even if the problem doesn't exist in your current Linux distribution), - find the corresponding directory under - <filename class="directory">/sys/class</filename> or - <filename class="directory">/sys/block</filename>. - For video devices, this may be - <filename - class="directory">/sys/class/video4linux/video<replaceable>X</replaceable></filename>. - Figure out the attributes that identify the device uniquely (usually, - vendor and product IDs and/or serial numbers work):</para> - -<screen role="nodump"><userinput>udevadm info -a -p /sys/class/video4linux/video0</userinput></screen> - - <para>Then write rules that create the symlinks, e.g.:</para> - -<screen role="nodump"><userinput>cat > /etc/udev/rules.d/83-duplicate_devs.rules << "EOF" -<literal> -# Persistent symlinks for webcam and tuner -KERNEL=="video*", ATTRS{idProduct}=="1910", ATTRS{idVendor}=="0d81", \ - SYMLINK+="webcam" -KERNEL=="video*", ATTRS{device}=="0x036f", ATTRS{vendor}=="0x109e", \ - SYMLINK+="tvtuner" -</literal> -EOF</userinput></screen> - - <para>The result is that <filename>/dev/video0</filename> and - <filename>/dev/video1</filename> devices still refer randomly to the tuner - and the web camera (and thus should never be used directly), but there are - symlinks <filename>/dev/tvtuner</filename> and - <filename>/dev/webcam</filename> that always point to the correct - device.</para> - - </sect2> - -</sect1> |