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diff --git a/docs/fedora_udev.html b/docs/fedora_udev.html new file mode 100644 index 0000000000..5d5048766d --- /dev/null +++ b/docs/fedora_udev.html @@ -0,0 +1,258 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> +<html> + <head> + <title>Fedora Project, sponsored by Red Hat</title> + <base href="http://fedora.redhat.com/"> + <meta http-equiv="Content-Type" content="text/html"> + <link rel="stylesheet" type="text/css" media="print" href="/css/print.css"> + <style type="text/css" media="screen"> + @import url("/css/layout.css"); + @import url("/css/content.css"); + @import url("/css/docbook.css"); + </style> + <meta name="MSSmartTagsPreventParsing" content="TRUE"> + <link rel="shortcut icon" href="/images/favicon.ico"> + <link rel="icon" href="/images/favicon.ico"> + </head> + + <body> + <!-- header BEGIN --> + <div id="fedora-header"> + <div id="fedora-header-logo"> + <a href="/"><img src="/images/header-fedora_logo.png" alt="Fedora Project"></a> + </div> + + <div id="fedora-header-items"> + <span class="fedora-header-icon"> + <a href="/download/"><img src="/images/header-download.png" alt=" ">Download</a> + <a href="/projects/"><img src="/images/header-projects.png" alt=" ">Projects</a> + <a href="/about/faq/"><img src="/images/header-faq.png" alt=" ">FAQ</a></span> + </div> + </div> + + <div id="fedora-nav"></div> + <!-- header END --> + + <!-- leftside BEGIN --> + <div id="fedora-side-left"> + <div id="fedora-side-nav-label">Site Navigation:</div> <ul id="fedora-side-nav"> + <li><a href="/">Home</a></li> + <li><a href="/download/">Download</a></li> + <li><a href="/docs/">Docs</a></li> + <li><a href="/projects/">Projects</a></li> + <li><a href="/participate/">Participate</a></li> + <li><a href="/about/">About</a></li> + </ul> + </div> + + <!-- leftside END --> + + <!-- content BEGIN --> + <div id="fedora-middle-two"> + <div class="fedora-corner-tr"> </div> + <div class="fedora-corner-tl"> </div> + <div id="fedora-content"> + <!-- content BEGIN --> + <h1>Udev on Fedora</h1> + <h2>by Harald Hoyer</h2> + <p> + This document tries to reveal the secrets of udev and how it works on Fedora. + </p> + <p> + udev was developed by Greg Kroah-Hartman <greg@kroah.com> with much + help from Dan Stekloff <dsteklof@us.ibm.com>, Kay Sievers <kay.sievers@vrfy.org>, + and many others. + </p> + <p> + The <a href="http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html">udev homepage</a> and the + Linux-hotplug-devel mailing list <a href="https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel">https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel</a> are the main development sources. + </p><p> + </p> + + <h2>What Does Udev Do?</h2> + <p> + udev provides a dynamic device directory containing only the files for + actually present devices. It creates or removes device node files usually + located in the <tt class="filename">/dev/</tt> directory, or it renames network interfaces. + </p><p> + As part of the hotplug subsystem, udev is executed if a kernel device + is added or removed from the system. On device creation, udev reads + the sysfs directory of the given device to collect device attributes + like label, serial number or bus device number. These attributes may + be used as keys to determine a unique name for the device. udev maintains + a database for devices present on the system. + On device removal, udev queries its database for the name of the device + file to be deleted. + </p><p> + udev gets called by hotplug, if a module is loaded, and a device is added + or removed. udev looks in <tt class="filename">/sys/</tt>, if the driver provides a "dev" file, which + contains the major and minor number for a device node to communicate with + the driver. After looking in the udev rules (in the <tt class="filename">/etc/udev/rules.d/</tt> directory), which + specify the device node filename and symlinks, a device node is created + in <tt class="filename">/dev/</tt> with the permissions, which are specified in <tt class="filename">/etc/udev/permissions.d/</tt>. + </p> + After device node creation, removal, or network device renaming, udev + executes the programs in the directory tree under <tt class="filename">/etc/dev.d/</tt>. The + name of a program must end with the <tt class="filename">.dev</tt> suffix, to be recognized. + In addition to the hotplug environment variables, DEVNAME is exported + to make the name of the created node or the name the network device is + renamed to, available to the executed program. The programs in every + directory are sorted in lexical order, while the directories are + searched in the following order: + <ul> + <li><tt class="filename">/etc/dev.d/$(DEVNAME)/*.dev</tt></li> + <li><tt class="filename">/etc/dev.d/$(SUBSYSTEM)/*.dev</tt></li> + <li><tt class="filename">/etc/dev.d/default/*.dev</tt></li> + </ul> + + <h2>How is Udev Integrated on Fedora?</h2> + <h3><tt class="command">initrd</tt> / <tt class="command">initfs</tt></h3> + <p> + <tt class="command">mkinitrd</tt> copies <tt class="filename">/sbin/udev.static</tt> + to the <tt class="command">initrd</tt> <tt class="filename">/sbin/udev</tt> and symlinks it to + <tt class="filename">/sbin/udevstart</tt>. + </p><p> +After the kernel boots, it executes the nash script of the <tt class="command">initrd</tt>. This +mounts a tmpfs filesystem on <tt class="filename">/dev/</tt>. Instead of hotplug <tt class="command">/sbin/udev</tt> is +called in the <tt class="command">initrd</tt> phase. udevstart creates all device nodes for the +devices, which are compiled in the kernel and for the modules, which +are loaded by nash. </p> + +<h4>Problems</h4> + +The whole udev and hotplug infrastructure is +not available in <tt class="command">initrd</tt>. Thus no hotplug scripts, udev rules, and +permissions and no <tt class="filename">/etc/dev.d/</tt> scripts are executed for any hotplug +event, which is sent from the kernel. + +<h3><tt class="filename">rc.sysinit</tt></h3> + <p> First, if SELinux is loaded and enabled, +the context of <tt class="filename">/dev/</tt> is set. <tt class="filename">rc.sysinit</tt> calls <tt class="filename">/sbin/start_udev</tt>. +<tt class="filename">start_udev</tt> mounts a tmpfs filesystem on <tt class="filename">/dev/</tt>, if there is none already +mounted. Then it creates some device nodes, which need module +autoloading, or where there is no kernel module. After that +<tt class="command">/sbin/udevstart</tt> is called again, which simulates the hotplug events in +the <tt class="command">initrd</tt> phase, to apply the whole udev rules and permissions. After +that <tt class="filename">rc.sysinit</tt> parses the ouput of <tt class="filename">/sbin/kmodule</tt> and loads every +module. This should provide device nodes for all hardware found on your +computer. </p> + <h3>Console User Permissions</h3> + <p> +<tt class="filename">/etc/dev.d/default/pam_console.dev</tt> is called whenever a device node is +created and calls <tt class="filename">/sbin/pam_console_setowner</tt> with the filename (and an +optional symlink) of the device node. This sets the permissions for +console users like specified in <tt class="filename">/etc/security/console.perms</tt>. </p> + <h2>Customizing Udev on Fedora</h2> + <p> + Read the manpage of udev and udevinfo. + Please try not to modify the files of RPM packages. + </p> + <h3>New Rules</h3> + <p> +New rules should be placed in a file, which ends in <tt class="filename">.rules</tt> in +<tt class="filename">/etc/udev/rules.d/</tt>. Please do not use <tt class="filename">50-udev.rules</tt>. The supported and +preferred way is to create rules without the "NAME" tag and only +create "SYMLINK"s. </p><p> + A nice document describing how to write rules can be found on <a href="http://www.reactivated.net/udevrules.php">http://www.reactivated.net/udevrules.php</a>. + </p> + +<h3>Permissions</h3> +New permissions should be placed in a file, which ends in +<tt class="filename">.permissions</tt> in <tt class="filename">/etc/udev/permissions.d/</tt>. Please do not use +<tt class="filename">50-udev.permissions</tt>. + +<h3>But I Really Want My Device Node!</h3> + <p> + Put them in <tt class="filename">/etc/udev/devices/</tt>, and they will get copied to <tt class="filename">/dev/</tt>. <a href="https://bugzilla.redhat.com/bugzilla">File a bugzilla entry</a>, if you think that should be done per default. + </p> + + <h2>Updating to udev Without <tt class="filename">/dev/</tt></h2> + <p> + The steps to upgrade without Anaconda or a rescue CD are (NOT recommended): + </p> + + <ul> + <li>start from a kernel-2.6 + </li><li>Make sure <tt class="filename">/sys/</tt> is mounted + </li><li>Install the latest <tt class="filename">initscripts</tt> package + </li><li>Install the latest <tt class="filename">udev</tt> package + </li><li>Execute <tt class="command">/sbin/start_udev</tt> + </li><li>Install the latest <tt class="filename">mkinitrd</tt> package + </li><li>Install the latest <tt class="filename">kernel</tt> package + </li><li>Or execute <tt class="command">mkinitrd</tt> for your existing kernel(s) + </li></ul> + + <h2>Udev without <tt class="command">initrd</tt></h2> + + <p>Install Fedore Core as usual and reboot. Execute the following commands + </p> + +<pre class="screen"> +<tt class="command"> +mkdir /tmp/dev +mount --move /dev /tmp/dev +sbin/MAKEDEV null console zero +mount --move /tmp/dev /dev +</tt></pre> + Install your kernel without an <tt class="command">initrd</tt>. Reboot. + <p> + You will get some SELinux errors, and syslogd will not work as expected. + </p> + <h2>Current Problems on Fedora</h2> + <p> + <a href="http://bugzilla.redhat.com/bugzilla/buglist.cgi?short_desc_type=allwordssubstr&component=udev&bug_status=ASSIGNED&bug_status=MODIFIED&bug_status=NEEDINFO&bug_status=NEW&bug_status=REOPENED&bug_status=VERIFIED&bug_severity=high&bug_severity=low&bug_severity=normal&bug_severity=security&bug_severity=translation&long_desc_type=allwordssubstr&bug_file_loc_type=allwordssubstr&status_whiteboard_type=allwordssubstr&fixed_in_type=allwordssubstr&devel_whiteboard_type=allwordssubstr&keywords_type=allwords&cust_facing=YES&emailassigned_to1=1&emailtype1=exact&emailreporter2=1&emailtype2=exact&bugidtype=include&chfieldto=Now&cmdtype=doit&remaction=run&namedcmd=blank&order=Reuse+same+sort+as+last+time&field0-0-0=noop&type0-0-0=noop">All open bugs for <code class="filename">udev</code></a> + </p> + <h3>Nvidia</h3> + <p>Quick solution: If you do not need rhgb, just load the nvidia module in <tt class="filename">/etc/rc.local</tt> + </p><p> + If you have udev >= 032-5, load the nvidia module: + </p> +<pre class="screen"> +<tt class="command"> +cp -a /dev/nvidia* /etc/udev/devices +chown root.root /etc/udev/devices/nvidia* +</tt></pre> + + <p>The Bugzilla for this problem is <strike><a href="https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=133900">133900</a></strike>.</p> + <h3>Palm Pilot</h3> + <p> + If you have udev >= 032-5, execute the command: + </p> +<pre class="screen"> +<tt class="command"> +ln -s ttyUSB1 /etc/udev/devices/pilot +</tt></pre> + + <h3>ISDN</h3> + <p> + If you have udev >= 032-5: + </p> +<pre class="screen"> +<tt class="command"> +/sbin/MAKEDEV -d /etc/udev/devices isdn +</tt></pre> + </pre> + + <!-- content END --> + + + </div> + <div class="fedora-corner-br"> </div> + <div class="fedora-corner-bl"> </div> + </div> + <!-- content END --> + + <!-- footer BEGIN --> + <div id="fedora-footer"> + Copyright © 2003-2004 Red Hat, Inc. 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