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 – due to a lack of maintenance – " "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><filename></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><filename></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\"/>"

msgid "" msgstr "" "Project-Id-Version: PACKAGE VERSION\n" "POT-Creation-Date: 2020-08-08 19:28+0800\n" "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n" "Last-Translator: FULL NAME \n" "Language-Team: LANGUAGE \n" "Language: zh_CN\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n" "X-Generator: Translate Toolkit 2.2.5\n" #. type: Content of: 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 – due to a lack of maintenance – " "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><filename></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><filename></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\"/>"