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nightmorph 11/03/12 05:44:15 |
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|
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Modified: udev-guide.xml |
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Log: |
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update udev guide to remove sysfs, add uevents and rules.d, new profiles, and remove conf.d-rc; patch from swift on bug 358409 |
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|
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Revision Changes Path |
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1.53 xml/htdocs/doc/en/udev-guide.xml |
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|
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file : http://sources.gentoo.org/viewvc.cgi/gentoo/xml/htdocs/doc/en/udev-guide.xml?rev=1.53&view=markup |
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plain: http://sources.gentoo.org/viewvc.cgi/gentoo/xml/htdocs/doc/en/udev-guide.xml?rev=1.53&content-type=text/plain |
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diff : http://sources.gentoo.org/viewvc.cgi/gentoo/xml/htdocs/doc/en/udev-guide.xml?r1=1.52&r2=1.53 |
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|
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Index: udev-guide.xml |
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=================================================================== |
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RCS file: /var/cvsroot/gentoo/xml/htdocs/doc/en/udev-guide.xml,v |
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retrieving revision 1.52 |
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retrieving revision 1.53 |
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diff -u -r1.52 -r1.53 |
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--- udev-guide.xml 26 Dec 2010 19:21:44 -0000 1.52 |
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+++ udev-guide.xml 12 Mar 2011 05:44:14 -0000 1.53 |
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@@ -1,6 +1,6 @@ |
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<?xml version='1.0' encoding="UTF-8"?> |
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<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
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-<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/udev-guide.xml,v 1.52 2010/12/26 19:21:44 nightmorph Exp $ --> |
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+<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/udev-guide.xml,v 1.53 2011/03/12 05:44:14 nightmorph Exp $ --> |
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|
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<guide> |
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<title>Gentoo udev Guide</title> |
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@@ -23,8 +23,8 @@ |
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<!-- See http://creativecommons.org/licenses/by-sa/2.5 --> |
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<license/> |
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|
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-<version>7</version> |
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-<date>2010-12-26</date> |
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+<version>8</version> |
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+<date>2011-03-11</date> |
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|
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<chapter> |
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<title>What is udev?</title> |
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@@ -71,103 +71,14 @@ |
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</ul> |
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|
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<p> |
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-To provide these features, udev is developed in three separate projects: |
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-<e>namedev</e>, <e>libsysfs</e> and, of course, <e>udev</e>. |
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-</p> |
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- |
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-</body> |
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-</section> |
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-<section> |
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-<title>namedev</title> |
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-<body> |
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- |
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-<p> |
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-Namedev allows you to define the device naming separately from the udev program. |
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-This allows for flexible naming policies and naming schemes developed by |
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-separate entities. This device naming subsystem provides a standard interface |
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-that udev can use. |
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-</p> |
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- |
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-<p> |
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-Currently only a single naming scheme is provided by namedev; the one provided |
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-by LANANA, used by the majority of Linux systems currently and therefore very |
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-suitable for the majority of Linux users. |
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-</p> |
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- |
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-<p> |
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-Namedev uses a 5-step procedure to find out the name of a given device. If the |
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-device name is found in one of the given steps, that name is used. The steps |
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-are: |
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-</p> |
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- |
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-<ul> |
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- <li>label or serial number</li> |
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- <li>bus device number</li> |
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- <li>bus topology</li> |
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- <li>statically given name</li> |
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- <li>kernel provided name</li> |
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-</ul> |
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- |
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-<p> |
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-The <e>label or serial number</e> step checks if the device has a unique |
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-identifier. For instance USB devices have a unique USB serial number; SCSI |
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-devices have a unique UUID. If namedev finds a match between this unique number |
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-and a given configuration file, the name provided in the configuration file is |
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-used. |
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-</p> |
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- |
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-<p> |
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-The <e>bus device number</e> step checks the device bus number. For |
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-non-hot-swappable environments this procedure is sufficient to |
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-identify a hardware device. For instance PCI bus numbers rarely change in the |
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-lifetime of a system. Again, if namedev finds a match between this position and |
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-a given configuration file, the name provided in that configuration file is |
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-used. |
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-</p> |
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- |
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-<p> |
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-Likewise the <e>bus topology</e> is a rather static way of defining devices as |
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-long as the user doesn't switch devices. When the position of the device matches |
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-a given setting provided by the user, the accompanying name is used. |
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-</p> |
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- |
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-<p> |
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-The fourth step, <e>statically given name</e>, is a simple string replacement. |
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-When the kernel name (the default name) matches a given replacement string, the |
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-substitute name will be used. |
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-</p> |
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- |
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-<p> |
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-The final step (<e>kernel provided name</e>) is a catch-all: this one takes |
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-the default name provided by the kernel. In the majority of cases this is |
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-sufficient as it matches the device naming used on current Linux systems. |
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-</p> |
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- |
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-</body> |
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-</section> |
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-<section> |
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-<title>libsysfs</title> |
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-<body> |
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- |
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-<p> |
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-udev interacts with the kernel through the sysfs pseudo filesystem. The libsysfs |
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-project provides a common API to access the information given by the sysfs |
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-filesystem in a generic way. This allows for querying all kinds of hardware |
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-without having to make assumptions on the kind of hardware. |
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-</p> |
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- |
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-</body> |
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-</section> |
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-<section> |
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-<title>udev</title> |
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-<body> |
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- |
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-<p> |
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-Every time the kernel gets an event in the device structure, it asks udev to |
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-take a look. udev follows the rules in the <path>/etc/udev/rules.d/</path> |
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-directory. udev then uses the information given by the kernel to perform the |
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-necessary actions on the <path>/dev</path> structure (creating or deleting |
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-device files). |
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+Every time a change happens within the device structure, the kernel emits a |
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+<e>uevent</e> which gets picked up by udev. udev then follows the rules as |
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+declared in the <path>/etc/udev/rules.d</path> and |
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+<path>/lib/udev/rules.d</path> directories. Based on the information contained |
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+within the uevent, it finds the rule or rules it needs to trigger and performs |
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+the required actions. These actions can be creating or deleting device files, |
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+but can also trigger the loading of particular firmware files into the |
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+kernel memory. |
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</p> |
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|
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</body> |
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@@ -182,9 +93,11 @@ |
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|
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<p> |
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udev is meant to be used in combination with a 2.6 kernel (like |
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-<c>gentoo-sources</c> with the default 2007.0 profile). If you're using such a |
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-kernel then you just have to make sure that you have a recent |
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-<c>sys-apps/baselayout</c> version. That's all you need. |
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+<c>gentoo-sources</c> with the default 10.0 profile). If you're using such a |
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+kernel then you just should have no issues whatsoever with using udev as the |
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+necessary support is built-in in all stable <c>sys-apps/baselayout</c> |
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+versions. Normally, udev should already be installed on your system, but if |
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+this is not the case, then it is easy to install: |
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</p> |
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|
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<pre caption="Installing udev"> |
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@@ -196,11 +109,13 @@ |
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</p> |
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|
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<pre caption="Required kernel options"> |
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-File systems ---> |
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- [*] Inotify file change notification support |
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- [*] Inotify support for userspace |
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+General Setup ---> |
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+ <comment>(Make sure the following item is *not* enabled)</comment> |
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+ [ ] enable deprecated sysfs features to support old userspace tools |
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+ |
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+File Systems ---> |
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+ [*] Inotify support for userspace |
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Pseudo filesystems ---> |
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- [*] /proc file system support |
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[*] Virtual memory file system support (former shm fs) |
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</pre> |
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|
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@@ -211,43 +126,6 @@ |
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|
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</body> |
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</section> |
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-<section> |
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-<title>Configuration</title> |
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-<body> |
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- |
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-<p> |
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-If you want to use the udev settings Gentoo provides to make your life |
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-comfortable, then read no more. Gentoo will use udev but keep a static |
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-<path>/dev</path> so that you will never have any missing device nodes. |
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-The Gentoo init scripts won't run the devfsd daemon and will deactivate devfs |
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-when you boot up. |
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-</p> |
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- |
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-<p> |
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-But if you are a die-hard and want to run a udev-only, unmodified system as is |
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-intended by the udev development (including the difficulties of missing device |
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-nodes because udev doesn't support them yet), by all means, read on :) |
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-</p> |
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- |
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-<p> |
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-We'll deactivate the rules that save the device file nodes: edit the |
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-<c>RC_DEVICE_TARBALL</c> variable in <path>/etc/conf.d/rc</path> and set it to |
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-<c>no</c>: |
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-</p> |
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- |
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-<pre caption="/etc/conf.d/rc"> |
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-RC_DEVICE_TARBALL="no" |
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-</pre> |
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- |
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-<p> |
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-If you have included devfs support in your kernel, you can deactivate it in |
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-the bootloader configuration: add <c>gentoo=nodevfs</c> as a kernel parameter. |
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-If you want to use devfs and deactivate udev, add <c>gentoo=noudev</c> as kernel |
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-parameter. |
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-</p> |
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- |
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-</body> |
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-</section> |
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</chapter> |
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|
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<chapter> |
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