lfs-book-i18n/zh_CN/chapter09/udev.po

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#. type: Content of: <sect1><title>
msgid "Overview of Device and Module Handling"
msgstr "设备和模块管理概述"

#. type: Content of: <sect1><indexterm><primary>
msgid "Udev"
msgstr "Udev"

#. type: Content of: <sect1><indexterm><secondary>
msgid "usage"
msgstr "用法"

#. type: Content of: <sect1><para>
msgid ""
"In <xref linkend=\"chapter-building-system\"/>, we installed the udev "
"package when <phrase revision=\"sysv\">eudev</phrase> <phrase revision="
"\"systemd\">systemd</phrase> was built. Before we go into the details "
"regarding how this works, a brief history of previous methods of handling "
"devices is in order."
msgstr ""
"在<xref linkend=\"chapter-building-system\"/>中，我们在构建 <phrase revision="
"\"sysv\">eudev</phrase> <phrase revision=\"systemd\">systemd</phrase> 时安装"
"了 Udev 软件包。在我们详细讨论它的工作原理之前，首先按时间顺序简要介绍历史上"
"曾经使用过的设备管理方式。"

#. type: Content of: <sect1><para>
msgid ""
"Linux systems in general traditionally used a static device creation method, "
"whereby a great many device nodes were created under <filename class="
"\"directory\">/dev</filename> (sometimes literally thousands of nodes), "
"regardless of whether the corresponding hardware devices actually existed. "
"This was typically done via a <command>MAKEDEV</command> script, which "
"contains a number of calls to the <command>mknod</command> program with the "
"relevant major and minor device numbers for every possible device that might "
"exist in the world."
msgstr ""
"传统的 Linux 系统通常使用静态地创建设备，即在 <filename class=\"directory\">/"
"dev</filename> 下创建大量设备节点 (有时有数千个节点)，无论对应的硬件设备是否"
"真的存在。一般通过 <command>MAKEDEV</command> 脚本完成这一工作，它包含以相关"
"的主设备号和次设备号，为世界上可能存在的每个设备建立节点的大量 "
"<command>mknod</command> 命令。"

#. type: Content of: <sect1><para>
msgid ""
"Using the udev method, only those devices which are detected by the kernel "
"get device nodes created for them. Because these device nodes will be "
"created each time the system boots, they will be stored on a <systemitem "
"class=\"filesystem\">devtmpfs</systemitem> file system (a virtual file "
"system that resides entirely in system memory). Device nodes do not require "
"much space, so the memory that is used is negligible."
msgstr ""
"使用 Udev，则只有那些被内核检测到的设备才会获得为它们创建的设备节点。由于这些"
"设备节点在每次引导系统时都会重新创建，它们被储存在 <systemitem class="
"\"filesystem\">devtmpfs</systemitem> 文件系统中 (一个虚拟文件系统，完全驻留在"
"系统内存)。设备节点不需要太多空间，它们使用的系统内存可以忽略不计。"

#. type: Content of: <sect1><sect2><title>
msgid "History"
msgstr "历史"

#. type: Content of: <sect1><sect2><para>
msgid ""
"In February 2000, a new filesystem called <systemitem class=\"filesystem"
"\">devfs</systemitem> was merged into the 2.3.46 kernel and was made "
"available during the 2.4 series of stable kernels. Although it was present "
"in the kernel source itself, this method of creating devices dynamically "
"never received overwhelming support from the core kernel developers."
msgstr ""
"在 2000 年 2 月，一个称为 <systemitem class=\"filesystem\">devfs</"
"systemitem> 的新文件系统被合并到 2.3.46 版内核中，并在 2.4 系列稳定内核中可"
"用。尽管它本身曾经存在于内核源代码中，但这种设备节点动态创建方法从未得到内核"
"核心开发者的大力支持。"

#. type: Content of: <sect1><sect2><para>
msgid ""
"The main problem with the approach adopted by <systemitem class=\"filesystem"
"\">devfs</systemitem> was the way it handled device detection, creation, and "
"naming. The latter issue, that of device node naming, was perhaps the most "
"critical. It is generally accepted that if device names are allowed to be "
"configurable, then the device naming policy should be up to a system "
"administrator, not imposed on them by any particular developer(s). The "
"<systemitem class=\"filesystem\">devfs</systemitem> file system also "
"suffered from race conditions that were inherent in its design and could not "
"be fixed without a substantial revision to the kernel. It was marked as "
"deprecated for a long period &ndash; due to a lack of maintenance &ndash; "
"and was finally removed from the kernel in June, 2006."
msgstr ""
"<systemitem class=\"filesystem\">devfs</systemitem> 实现机制的主要问题是它处"
"理设备的检测、创建和命名的方式，其中最致命的或许最后一项，即设备节点命名方"
"式。通常认为，如果设备名称是可配置的，那么设备命名策略应该由系统管理员，而不"
"是某个 (某些)特定开发者决定。<systemitem class=\"filesystem\">devfs</"
"systemitem> 还受到其设计中固有的竞争条件的严重影响，在不对内核进行大量修改的"
"前提下无法修复这一问题。由于缺乏维护，它早已被标记为过时特性，最终在 2006 年 "
"6 月被从内核中移除。"

#. type: Content of: <sect1><sect2><para>
msgid ""
"With the development of the unstable 2.5 kernel tree, later released as the "
"2.6 series of stable kernels, a new virtual filesystem called <systemitem "
"class=\"filesystem\">sysfs</systemitem> came to be. The job of <systemitem "
"class=\"filesystem\">sysfs</systemitem> is to export a view of the system's "
"hardware configuration to userspace processes. With this userspace-visible "
"representation, the possibility of developing a userspace replacement for "
"<systemitem class=\"filesystem\">devfs</systemitem> became much more "
"realistic."
msgstr ""
"在不稳定的 2.5 系列内核开发过程中，加入了一个新的虚拟文件系统，称为 "
"<systemitem class=\"filesystem\">sysfs</systemitem>，并在 2.6 系列稳定内核中"
"发布。<systemitem class=\"filesystem\">sysfs</systemitem> 的工作是将系统硬件"
"配置信息导出给用户空间进程，有了这个用户空间可见的配置描述，就可能开发一种 "
"<systemitem class=\"filesystem\">devfs</systemitem> 的用户空间替代品。"

#. type: Content of: <sect1><sect2><title>
msgid "Udev Implementation"
msgstr "Udev 实现"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Sysfs"
msgstr "Sysfs"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"The <systemitem class=\"filesystem\">sysfs</systemitem> filesystem was "
"mentioned briefly above. One may wonder how <systemitem class=\"filesystem"
"\">sysfs</systemitem> knows about the devices present on a system and what "
"device numbers should be used for them. Drivers that have been compiled into "
"the kernel directly register their objects with a <systemitem class="
"\"filesystem\">sysfs</systemitem> (devtmpfs internally)  as they are "
"detected by the kernel. For drivers compiled as modules, this registration "
"will happen when the module is loaded. Once the <systemitem class="
"\"filesystem\">sysfs</systemitem> filesystem is mounted (on /sys), data "
"which the drivers register with <systemitem class=\"filesystem\">sysfs</"
"systemitem> are available to userspace processes and to udevd for processing "
"(including modifications to device nodes)."
msgstr ""
"前面已经简要提到了 <systemitem class=\"filesystem\">sysfs</systemitem> 文件系"
"统。有些读者可能好奇，<systemitem class=\"filesystem\">sysfs</systemitem> 是"
"如何知道系统中存在哪些设备，以及应该为它们使用什么设备号的。答案是，那些编译"
"到内核中的驱动程序在它们的对象被内核检测到时，直接将它们注册到 <systemitem "
"class=\"filesystem\">sysfs</systemitem>  (内部的 devtmpfs)。对于那些被编译为"
"模块的驱动程序，注册过程在模块加载时进行。只要 <systemitem class=\"filesystem"
"\">sysfs</systemitem> 文件系统被挂载好 (位于 /sys)，用户空间程序即可使用驱动"
"程序注册在 <systemitem class=\"filesystem\">sysfs</systemitem> 中的数据，"
"Udev 就能够使用这些数据对设备进行处理 (包括修改设备节点)。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Device Node Creation"
msgstr "设备节点的创建"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Device files are created by the kernel by the <systemitem class=\"filesystem"
"\">devtmpfs</systemitem> filesystem.  Any driver that wishes to register a "
"device node will go through the <systemitem class=\"filesystem\">devtmpfs</"
"systemitem> (via the driver core) to do it.  When a <systemitem class="
"\"filesystem\">devtmpfs</systemitem> instance is mounted on <filename class="
"\"directory\">/dev</filename>, the device node will initially be created "
"with a fixed name, permissions, and owner."
msgstr ""
"内核通过 <systemitem class=\"filesystem\">devtmpfs</systemitem> 直接创建设备"
"文件，任何希望注册设备节点的驱动程序都要通过 <systemitem class=\"filesystem"
"\">devtmpfs</systemitem> (经过驱动程序核心) 实现。当一个 <systemitem class="
"\"filesystem\">devtmpfs</systemitem> 实例被挂载到 <filename class=\"directory"
"\">/dev</filename> 时，设备节点将被以固定的名称、访问权限和所有者首次创建。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"A short time later, the kernel will send a uevent to <command> udevd</"
"command>.  Based on the rules specified in the files within the <filename "
"class=\"directory\">/etc/udev/rules.d</filename>, <filename class=\"directory"
"\">/lib/udev/rules.d</filename>, and <filename class=\"directory\">/run/udev/"
"rules.d</filename> directories, <command> udevd</command> will create "
"additional symlinks to the device node, or change its permissions, owner, or "
"group, or modify the internal <command>udevd</command> database entry (name) "
"for that object."
msgstr ""
"很快，内核会向 <command>udevd</command> 发送一个 uevent。根据 <filename "
"class=\"directory\">/etc/udev/rules.d</filename>，<filename class=\"directory"
"\">/lib/udev/rules.d</filename>，以及 <filename class=\"directory\">/run/"
"udev/rules.d</filename> 目录中文件指定的规则，<command>udevd</command> 将为设"
"备节点创建额外的符号链接，修改其访问权限，所有者，或属组，或者修改该对象的 "
"<command>udevd</command> 数据库条目 (名称)。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"The rules in these three directories are numbered and all three directories "
"are merged together. If <command>udevd</command> can't find a rule for the "
"device it is creating, it will leave the permissions and ownership at "
"whatever <systemitem class=\"filesystem\">devtmpfs</systemitem> used "
"initially."
msgstr ""
"以上三个目录中的规则都被编号，且这三个目录的内容将合并处理。如果 "
"<command>udevd</command> 找不到它正在创建的设备对应的规则，它将会沿用 "
"<systemitem class=\"filesystem\">devtmpfs</systemitem> 最早使用的配置。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Module Loading"
msgstr "模块加载"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Device drivers compiled as modules may have aliases built into them.  "
"Aliases are visible in the output of the <command>modinfo</command> program "
"and are usually related to the bus-specific identifiers of devices supported "
"by a module. For example, the <emphasis>snd-fm801</emphasis> driver supports "
"PCI devices with vendor ID 0x1319 and device ID 0x0801, and has an alias of "
"<quote>pci:v00001319d00000801sv*sd*bc04sc01i*</quote>.  For most devices, "
"the bus driver exports the alias of the driver that would handle the device "
"via <systemitem class=\"filesystem\">sysfs</systemitem>. E.g., the "
"<filename>/sys/bus/pci/devices/0000:00:0d.0/modalias</filename> file might "
"contain the string <quote>pci:"
"v00001319d00000801sv00001319sd00001319bc04sc01i00</quote>.  The default "
"rules provided with udev will cause <command>udevd</command> to call out to "
"<command>/sbin/modprobe</command> with the contents of the <envar>MODALIAS</"
"envar> uevent environment variable (which should be the same as the contents "
"of the <filename>modalias</filename> file in sysfs), thus loading all "
"modules whose aliases match this string after wildcard expansion."
msgstr ""
"编译为内核模块的设备驱动程序可能有内建的别名。别名可以通过 <command>modinfo</"
"command> 程序查询，它通常和该模块支持的设备的总线相关标识符有关。例如，"
"<emphasis>snd-fm801</emphasis> 驱动程序支持厂商 ID 为 0x1319，设备 ID 为 "
"0x0801 的 PCI 设备，其别名为<quote>pci:v00001319d00000801sv*sd*bc04sc01l*</"
"quote>。对于多数设备，总线驱动程序会通过 <systemitem class=\"filesystem"
"\">sysfs</systemitem> 导出应该处理该设备的驱动程序别名，例如 <filename>/sys/"
"bus/pci/devices/0000:00:0d.0/modalias</filename> 文件应该包含字符串"
"<quote>pci:v00001319d00000801sv00001319sd00001319bc04sc01i00</quote>。Udev 附"
"带的默认规则会导致 <command>udevd</command> 调用 <command>/sbin/modprobe</"
"command> 时传递 <envar>MODALIAS</envar> uevent 环境变量 (它的值应该和 sysfs "
"中<filename>modalias</filename> 文件的内容相同)，从而加载那些在通配符扩展后别"
"名与这个字符串匹配的模块。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"In this example, this means that, in addition to <emphasis>snd-fm801</"
"emphasis>, the obsolete (and unwanted)  <emphasis>forte</emphasis> driver "
"will be loaded if it is available. See below for ways in which the loading "
"of unwanted drivers can be prevented."
msgstr ""
"在本例中，这意味着除了 <emphasis>snd-fm801</emphasis> 外，过时 (且不希望) 的 "
"<emphasis>forte</emphasis> 如果可用，也会被加载。之后将介绍防止加载不希望的驱"
"动程序的方法。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"The kernel itself is also able to load modules for network protocols, "
"filesystems, and NLS support on demand."
msgstr "内核本身也能够在需要时为网络协议，文件系统，以及 NLS 支持加载模块。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Handling Hotpluggable/Dynamic Devices"
msgstr "处理热插拔/动态设备"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"When you plug in a device, such as a Universal Serial Bus (USB) MP3 player, "
"the kernel recognizes that the device is now connected and generates a "
"uevent. This uevent is then handled by <command>udevd</command> as described "
"above."
msgstr ""
"当您插入一个设备，例如通用串行总线 (USB) MP3 播放器时，内核能够发现该设备现在"
"已经被连接到系统，并生成一个 uevent 事件。之后 <command>udevd</command> 像前"
"面描述的一样，处理该 uevent 事件。"

#. type: Content of: <sect1><sect2><title>
msgid "Problems with Loading Modules and Creating Devices"
msgstr "加载模块和创建设备时的问题"

#. type: Content of: <sect1><sect2><para>
msgid ""
"There are a few possible problems when it comes to automatically creating "
"device nodes."
msgstr "在自动创建设备节点时，可能出现一些问题。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "A kernel module is not loaded automatically"
msgstr "内核模块没有自动加载"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Udev will only load a module if it has a bus-specific alias and the bus "
"driver properly exports the necessary aliases to <systemitem class="
"\"filesystem\">sysfs</systemitem>. In other cases, one should arrange module "
"loading by other means. With Linux-&linux-version;, udev is known to load "
"properly-written drivers for INPUT, IDE, PCI, USB, SCSI, SERIO, and FireWire "
"devices."
msgstr ""
"Udev 只加载拥有总线特定别名，且总线驱动程序正确地向 <systemitem class="
"\"filesystem\">sysfs</systemitem> 导出了必要别名的模块。如果情况不是这样，您"
"应该考虑用其他方法加载模块。在 Linux-&linux-version; 中，已知 Udev 可以加载编"
"写正确的 INPUT，IDE，PCI，USB，SCSI，SERIO，以及 FireWire 驱动程序。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"To determine if the device driver you require has the necessary support for "
"udev, run <command>modinfo</command> with the module name as the argument.  "
"Now try locating the device directory under <filename class=\"directory\">/"
"sys/bus</filename> and check whether there is a <filename>modalias</"
"filename> file there."
msgstr ""
"为了确定您需要的设备驱动程序是否包含 Udev 支持，以模块名为参数运行 "
"<command>modinfo</command> 命令。然后试着在 <filename class=\"directory\">/"
"sys/bus</filename> 中找到设备对应的目录，并检查其中是否有 "
"<filename>modalias</filename> 文件。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"If the <filename>modalias</filename> file exists in <systemitem class="
"\"filesystem\">sysfs</systemitem>, the driver supports the device and can "
"talk to it directly, but doesn't have the alias, it is a bug in the driver. "
"Load the driver without the help from udev and expect the issue to be fixed "
"later."
msgstr ""
"如果 <filename>modalias</filename> 文件存在于 <systemitem class=\"filesystem"
"\">sysfs</systemitem> 中，说明驱动程序支持该设备，并能够直接和设备交互，但却"
"没有正确的别名。这是驱动程序的 bug，您需要不通过 Udev 直接加载驱动，并等待这"
"个问题日后被解决。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"If there is no <filename>modalias</filename> file in the relevant directory "
"under <filename class=\"directory\">/sys/bus</filename>, this means that the "
"kernel developers have not yet added modalias support to this bus type. With "
"Linux-&linux-version;, this is the case with ISA busses. Expect this issue "
"to be fixed in later kernel versions."
msgstr ""
"如果 <filename>modalias</filename> 文件不存在于 <filename class=\"directory"
"\">/sys/bus</filename> 下的对应目录中，说明内核开发者尚未对该总线类型增加 "
"modalias 支持。在 Linux-&linux-version; 中，ISA 总线不受支持。只能等待这个问"
"题在日后被解决。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Udev is not intended to load <quote>wrapper</quote> drivers such as "
"<emphasis>snd-pcm-oss</emphasis> and non-hardware drivers such as "
"<emphasis>loop</emphasis> at all."
msgstr ""
"Udev 根本不会尝试加载<quote>包装器</quote> 驱动程序，比如 <emphasis>snd-pcm-"
"oss</emphasis> 等，或 <emphasis>loop</emphasis> 等非硬件驱动程序。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid ""
"A kernel module is not loaded automatically, and udev is not intended to "
"load it"
msgstr "内核模块没有自动加载，且 Udev 不尝试加载它"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"If the <quote>wrapper</quote> module only enhances the functionality "
"provided by some other module (e.g., <emphasis>snd-pcm-oss</emphasis> "
"enhances the functionality of <emphasis>snd-pcm</emphasis> by making the "
"sound cards available to OSS applications), configure <command>modprobe</"
"command> to load the wrapper after udev loads the wrapped module. To do "
"this, add a <quote>softdep</quote> line to the corresponding <filename>/etc/"
"modprobe.d/<replaceable>&lt;filename&gt;</replaceable>.conf</filename> file. "
"For example:"
msgstr ""
"如果<quote>包装器</quote>仅仅用于增强其他模块的功能 (例如，<emphasis>snd-pcm-"
"oss</emphasis> 增强 <emphasis>snd-pcm</emphasis> 的功能，使 OSS 应用程序能够"
"使用声卡)，需要配置 <command>modprobe</command>，使其在 Udev 加载被包装的模块"
"时，自动加载包装器。为此，需要将<quote>softdep</quote>行添加到对应的 "
"<filename>/etc/modprobe.d/<replaceable>&lt;filename&gt;</replaceable>.conf</"
"filename> 中。例如："

#. type: Content of: <sect1><sect2><sect3><screen>
#, no-wrap
msgid "<literal>softdep snd-pcm post: snd-pcm-oss</literal>"
msgstr "<literal>softdep snd-pcm post: snd-pcm-oss</literal>"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Note that the <quote>softdep</quote> command also allows <literal>pre:</"
"literal> dependencies, or a mixture of both <literal>pre:</literal> and "
"<literal>post:</literal> dependencies.  See the <filename>modprobe.d(5)</"
"filename> manual page for more information on <quote>softdep</quote> syntax "
"and capabilities."
msgstr ""
"注意<quote>softdep</quote>命令也允许 <literal>pre:</literal> 依赖项，或混合使"
"用 <literal>pre:</literal> 和 <literal>post:</literal> 依赖项。参阅 "
"<filename>modprobe.d(5)</filename> man 手册页面，了解更多关于<quote>softdep</"
"quote>语法和功能的信息。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"If the module in question is not a wrapper and is useful by itself, "
"configure the <command>modules</command> bootscript to load this module on "
"system boot. To do this, add the module name to the <filename>/etc/sysconfig/"
"modules</filename> file on a separate line.  This works for wrapper modules "
"too, but is suboptimal in that case."
msgstr ""
"如果出现问题的模块不是包装器，而是本身就有特定功能的模块，需要配置 "
"<command>modules</command> 引导脚本以在系统引导时加载它。为此，将模块名添加"
"到 <filename>/etc/sysconfig/modules</filename> 中，作为单独的一行。包装器模块"
"也可以被添加到这里，但对于包装器来说这不是最好的方案。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Udev loads some unwanted module"
msgstr "Udev 加载了不希望的模块"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Either don't build the module, or blacklist it in a <filename>/etc/modprobe."
"d/blacklist.conf</filename> file as done with the <emphasis>forte</emphasis> "
"module in the example below:"
msgstr ""
"不要构建该模块，或者在 <filename>/etc/modprobe.d/blacklist.conf</filename> 文"
"件中禁用它。以 <emphasis>forte</emphasis> 为例，下面一行禁用了该模块："

#. type: Content of: <sect1><sect2><sect3><screen>
#, no-wrap
msgid "<literal>blacklist forte</literal>"
msgstr "<literal>blacklist forte</literal>"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Blacklisted modules can still be loaded manually with the explicit "
"<command>modprobe</command> command."
msgstr ""
"被禁用的模块仍然可以通过直接执行 <command>modprobe</command> 手动加载。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Udev creates a device incorrectly, or makes a wrong symlink"
msgstr "Udev 创建了错误的设备或错误的符号链接"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"This usually happens if a rule unexpectedly matches a device. For example, a "
"poorly-written rule can match both a SCSI disk (as desired)  and the "
"corresponding SCSI generic device (incorrectly) by vendor.  Find the "
"offending rule and make it more specific, with the help of the "
"<command>udevadm info</command> command."
msgstr ""
"这一般是由于一条规则意外地匹配了某个设备。例如，一个写得不好的规则可能同时匹"
"配到 SCSI 磁盘 (正确的) 和对应厂商的 SCSI 通用设备 (不正确的)。找到引起问题的"
"规则，并通过 <command>udevadm info</command> 的帮助，将它进一步细化。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Udev rule works unreliably"
msgstr "Udev 规则工作不可靠"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"This may be another manifestation of the previous problem. If not, and your "
"rule uses <systemitem class=\"filesystem\">sysfs</systemitem> attributes, it "
"may be a kernel timing issue, to be fixed in later kernels.  For now, you "
"can work around it by creating a rule that waits for the used <systemitem "
"class=\"filesystem\">sysfs</systemitem> attribute and appending it to the "
"<filename>/etc/udev/rules.d/10-wait_for_sysfs.rules</filename> file (create "
"this file if it does not exist). Please notify the LFS Development list if "
"you do so and it helps."
msgstr ""
"这可能是前一个问题的另一个表现形式。如果不是，而且您的规则使用了 <systemitem "
"class=\"filesystem\">sysfs</systemitem> 属性，这个问题可能由内核计时问题引"
"发，这类问题需要在新的内核版本中修复。目前，您可以创建一条规则以等待被使用的 "
"<systemitem class=\"filesystem\">sysfs</systemitem> 属性，并将它附加到 "
"<filename>/etc/udev/rules.d/10-wait-for-sysfs.rules</filename> 文件中 (如果不"
"存在就创建一个文件)，绕过这个问题。如果您通过这种方法解决了问题，请通知 LFS "
"开发邮件列表。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Udev does not create a device"
msgstr "Udev 没有创建设备"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Further text assumes that the driver is built statically into the kernel or "
"already loaded as a module, and that you have already checked that udev "
"doesn't create a misnamed device."
msgstr ""
"以下内容假设驱动程序已经被编译到内核中，或作为模块被加载，而且您已经检查过并"
"确认 Udev 没有创建命名错误的设备。"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"Udev has no information needed to create a device node if a kernel driver "
"does not export its data to <systemitem class=\"filesystem\">sysfs</"
"systemitem>. This is most common with third party drivers from outside the "
"kernel tree. Create a static device node in <filename>/lib/udev/devices</"
"filename> with the appropriate major/minor numbers (see the file "
"<filename>devices.txt</filename> inside the kernel documentation or the "
"documentation provided by the third party driver vendor). The static device "
"node will be copied to <filename class=\"directory\">/dev</filename> by "
"<command>udev</command>."
msgstr ""
"如果驱动程序没有将它的信息导出到 <systemitem class=\"filesystem\">sysfs</"
"systemitem>，Udev 就无法获得创建设备节点必需的信息。这种问题往往出现在内核源"
"代码树以外的第三方驱动程序中。这时，需要在 <filename>/lib/udev/devices</"
"filename> 中使用正确的主设备号和次设备号，创建一个静态设备节点 (参考内核文档"
"中的 <filename>devices.txt</filename> 或第三方驱动厂商提供的文档)，该静态设备"
"节点将被复制到 <filename class=\"directory\">/dev</filename>，<command>udev</"
"command> 会自动完成复制。"

#. type: Content of: <sect1><sect2><sect3><title>
msgid "Device naming order changes randomly after rebooting"
msgstr "重启后设备命名顺序随机变化"

#. type: Content of: <sect1><sect2><sect3><para>
msgid ""
"This is due to the fact that udev, by design, handles uevents and loads "
"modules in parallel, and thus in an unpredictable order. This will never be "
"<quote>fixed</quote>. You should not rely upon the kernel device names being "
"stable. Instead, create your own rules that make symlinks with stable names "
"based on some stable attributes of the device, such as a serial number or "
"the output of various *_id utilities installed by udev.  See <xref linkend="
"\"ch-config-symlinks\"/> and <xref linkend=\"ch-config-network\"/> for "
"examples."
msgstr ""
"这是由于 Udev 从设计上就是并行加载模块的，因此无法预测加载顺序。这个问题永远"
"也不会被 <quote>修复</quote>。您不应该指望内核提供稳定的设备命名，而是应该创"
"建您自己的规则，以根据设备的一些稳定属性，例如设备序列号或 Udev 安装的一些 "
"*_id 工具的输出，来创建具有稳定名称的符号链接。可以参考<xref linkend=\"ch-"
"config-symlinks\"/>和<xref linkend=\"ch-config-network\"/>中的例子。"

#. type: Content of: <sect1><sect2><title>
msgid "Useful Reading"
msgstr "扩展阅读"

#. type: Content of: <sect1><sect2><para>
msgid "Additional helpful documentation is available at the following sites:"
msgstr "以下链接包含了一些额外的帮助文档："

#. type: Content of: <sect1><sect2><itemizedlist><listitem><para>
msgid ""
"A Userspace Implementation of <systemitem class=\"filesystem\">devfs</"
"systemitem> <ulink url=\"http://www.kroah.com/linux/talks/"
"ols_2003_udev_paper/Reprint-Kroah-Hartman-OLS2003.pdf\"/>"
msgstr ""
"A Userspace Implementation of <systemitem class=\"filesystem\">devfs</"
"systemitem> <ulink url=\"http://www.kroah.com/linux/talks/"
"ols_2003_udev_paper/Reprint-Kroah-Hartman-OLS2003.pdf\"/>"

#. type: Content of: <sect1><sect2><itemizedlist><listitem><para>
msgid ""
"The <systemitem class=\"filesystem\">sysfs</systemitem> Filesystem <ulink "
"url=\"http://www.kernel.org/pub/linux/kernel/people/mochel/doc/papers/"
"ols-2005/mochel.pdf\"/>"
msgstr ""
"The <systemitem class=\"filesystem\">sysfs</systemitem> Filesystem <ulink "
"url=\"http://www.kernel.org/pub/linux/kernel/people/mochel/doc/papers/"
"ols-2005/mochel.pdf\"/>"