[3f8be484] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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[aa18ac0] | 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
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| 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ |
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[3f8be484] | 4 | <!ENTITY % general-entities SYSTEM "../../general.ent"> |
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| 5 | %general-entities; |
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| 6 | ]> |
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| 7 | |
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| 8 | <sect1 id="ch-bootable-kernel" role="wrap"> |
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| 9 | <?dbhtml filename="kernel.html"?> |
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| 10 | |
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[43daa01] | 11 | <title>Linux-&linux-version;</title> |
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[3f8be484] | 12 | |
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| 13 | <indexterm zone="ch-bootable-kernel"> |
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| 14 | <primary sortas="a-Linux">Linux</primary> |
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| 15 | </indexterm> |
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| 16 | |
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| 17 | <sect2 role="package"><title/> |
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| 18 | <para>The Linux package contains the Linux kernel.</para> |
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| 19 | |
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| 20 | </sect2> |
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| 21 | |
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| 22 | <sect2 role="installation"> |
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| 23 | <title>Installation of the kernel</title> |
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| 24 | |
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| 25 | <para os="a">Building the kernel involves a few steps—configuration, |
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| 26 | compilation, and installation. Read the <filename>README</filename> |
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| 27 | file in the kernel source tree for alternative methods to the way this |
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| 28 | book configures the kernel.</para> |
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| 29 | |
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| 30 | <para os="b">Prepare for compilation by running the following command:</para> |
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| 31 | |
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| 32 | <screen os="c"><userinput>make mrproper</userinput></screen> |
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| 33 | |
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| 34 | <para os="d">This ensures that the kernel tree is absolutely clean. The |
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| 35 | kernel team recommends that this command be issued prior to each |
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| 36 | kernel compilation. Do not rely on the source tree being clean after |
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| 37 | un-tarring.</para> |
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| 38 | |
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[573ee7a] | 39 | <note os="kc"><para>A good starting place for setting up the kernel |
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| 40 | configuration is to run <command>make defconfig</command>. This will set the base configuration to a good state that takes your current system |
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| 41 | architecture into account.</para> |
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[eaeb8faf] | 42 | |
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[573ee7a] | 43 | <para>Be sure to enable or disable following features or the system might |
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| 44 | not work correctly or boot at all. Refer to |
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| 45 | <filename>/usr/share/doc/systemd-&systemd-version;/README</filename>:</para> |
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[eaeb8faf] | 46 | |
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| 47 | <screen role="nodump">General setup ---> |
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[573ee7a] | 48 | [*] open by fhandle syscalls |
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[ca8dde0] | 49 | [ ] Auditing support |
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[eaeb8faf] | 50 | [*] Control Group support |
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| 51 | Processor type and features ---> |
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| 52 | [*] Enable seccomp to safely compute untrusted bytecode |
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| 53 | Networking support ---> |
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| 54 | Networking options ---> |
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| 55 | <*> The IPv6 protocol |
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| 56 | Device Drivers ---> |
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| 57 | Generic Driver Options ---> |
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| 58 | () path to uevent helper |
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| 59 | [*] Maintain a devtmpfs filesystem to mount at /dev |
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| 60 | [ ] Fallback user-helper invocation for firmware loading |
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| 61 | File systems ---> |
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| 62 | [*] Inotify support for userspace |
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| 63 | <*> Kernel automounter version 4 support (also supports v3) |
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| 64 | Pseudo filesystems ---> |
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| 65 | [*] Tmpfs POSIX Access Control Lists |
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[ca8dde0] | 66 | [*] Tmpfs extended attributes |
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| 67 | Firmware Drivers ---> |
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| 68 | EFI (Extensible Firmware Interface) Support ---> |
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| 69 | <*> EFI Variable Support via sysfs |
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| 70 | -*- Enable the block layer ---> |
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| 71 | Partition Types ---> |
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| 72 | [*] Advanced partition selection |
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| 73 | [*] EFI GUID Partition support |
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| 74 | Kernel Hacking ---> |
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| 75 | [*] Collect scheduler debugging info |
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| 76 | [*] Collect scheduler statistics</screen></note> |
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[eaeb8faf] | 77 | |
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[573ee7a] | 78 | <note os="kd"><para>While "The IPv6 Protocol" is not strictly required, it |
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[ca8dde0] | 79 | is highly recommended by the Systemd developers. "EFI Variable support" and |
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| 80 | "EFI GUID Partition support" are for UEFI systems. "Collect scheduler |
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| 81 | debugging info" and "Collect scheduler statistics" is for systemd-bootchart. |
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| 82 | </para></note> |
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[eaeb8faf] | 83 | |
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[77e81f1] | 84 | <para os="h">Configure the kernel via a menu-driven interface. |
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[573ee7a] | 85 | CBLFS has some information regarding particular kernel configuration |
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| 86 | requirements of packages outside of CLFS at <ulink |
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[0d4607d] | 87 | url="&cblfs-root;"/>:</para> |
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[3f8be484] | 88 | |
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| 89 | <screen os="i"><userinput>make menuconfig</userinput></screen> |
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| 90 | |
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| 91 | <para os="j">Alternatively, <command>make oldconfig</command> may be more |
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| 92 | appropriate in some situations. See the <filename>README</filename> |
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| 93 | file for more information.</para> |
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| 94 | |
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| 95 | <para os="k">If desired, skip kernel configuration by copying the kernel |
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| 96 | config file, <filename>.config</filename>, from the host system |
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| 97 | (assuming it is available) to the root directory of the unpacked kernel |
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| 98 | sources. However, we do not recommend this option. It is often better |
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| 99 | to explore all the configuration menus and create the kernel configuration |
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| 100 | from scratch.</para> |
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| 101 | |
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| 102 | <para os="m">Compile the kernel image and modules:</para> |
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| 103 | |
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| 104 | <screen os="n"><userinput>make</userinput></screen> |
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| 105 | |
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| 106 | <para os="o">If using kernel modules, an |
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| 107 | <filename>/etc/modprobe.conf</filename> file may be needed. |
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| 108 | Information pertaining to modules and kernel configuration is |
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| 109 | located in the kernel documentation in the <filename |
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| 110 | class="directory">Documentation</filename> directory of the kernel |
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| 111 | sources tree. Also, <filename>modprobe.conf(5)</filename> may |
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| 112 | be of interest.</para> |
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| 113 | |
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| 114 | <para os="p">Be very careful when reading other documentation relating to |
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| 115 | kernel modules because it usually applies to 2.4.x kernels only. As |
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| 116 | far as we know, kernel configuration issues specific to Hotplug and |
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[97bc24b] | 117 | Eudev are not documented. The problem is that Eudev will create a device |
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[3f8be484] | 118 | node only if Hotplug or a user-written script inserts the corresponding |
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| 119 | module into the kernel, and not all modules are detectable by Hotplug. |
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| 120 | Note that statements like the one below in the |
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[97bc24b] | 121 | <filename>/etc/modprobe.conf</filename> file do not work with Eudev:</para> |
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[3f8be484] | 122 | |
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| 123 | <screen os="q"><literal>alias char-major-XXX some-module</literal></screen> |
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| 124 | |
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[97bc24b] | 125 | <para os="r">Because of the complications with Eudev and modules, |
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[3f8be484] | 126 | we strongly recommend starting with a completely non-modular kernel |
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[97bc24b] | 127 | configuration, especially if this is the first time using Eudev.</para> |
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[3f8be484] | 128 | |
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| 129 | <para os="s">Install the modules, if the kernel configuration uses |
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| 130 | them:</para> |
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| 131 | |
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| 132 | <screen os="t"><userinput>make modules_install</userinput></screen> |
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| 133 | |
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[22211c7] | 134 | <para os="s2">Install the firmware, if the kernel configuration uses |
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| 135 | them:</para> |
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| 136 | |
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| 137 | <screen os="t2"><userinput>make firmware_install</userinput></screen> |
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| 138 | |
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[3f8be484] | 139 | <para os="u">After kernel compilation is complete, additional steps are |
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| 140 | required to complete the installation. Some files need to be copied to |
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| 141 | the <filename class="directory">/boot</filename> directory.</para> |
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| 142 | |
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| 143 | <para os="v">Issue the following command to install the kernel:</para> |
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| 144 | |
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[34be04a6] | 145 | <screen><userinput>cp -v arch/i386/boot/bzImage /boot/vmlinuz-clfs-&linux-version;</userinput></screen> |
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[3f8be484] | 146 | |
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| 147 | <para os="w"><filename>System.map</filename> is a symbol file for the kernel. |
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| 148 | It maps the function entry points of every function in the kernel API, |
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| 149 | as well as the addresses of the kernel data structures for the running |
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| 150 | kernel. Issue the following command to install the map file:</para> |
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| 151 | |
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[e51ba26] | 152 | <screen os="w1"><userinput>cp -v System.map /boot/System.map-&linux-version;</userinput></screen> |
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[3f8be484] | 153 | |
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| 154 | <para os="x">The kernel configuration file <filename>.config</filename> |
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| 155 | produced by the <command>make menuconfig</command> step above contains |
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| 156 | all the configuration selections for the kernel that was just compiled. |
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| 157 | It is a good idea to keep this file for future reference:</para> |
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| 158 | |
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[e51ba26] | 159 | <screen os="x1"><userinput>cp -v .config /boot/config-&linux-version;</userinput></screen> |
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[3f8be484] | 160 | |
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| 161 | <para os="y">It is important to note that the files in the kernel source |
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| 162 | directory are not owned by <systemitem class="username">root</systemitem>. |
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| 163 | Whenever a package is unpacked as user <systemitem |
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[a7fa075] | 164 | class="username">root</systemitem> (like we do inside the final-system |
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| 165 | build environment), the files have the user and group IDs of whatever |
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[3f8be484] | 166 | they were on the packager's computer. This is usually not a problem |
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| 167 | for any other package to be installed because the source tree is |
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| 168 | removed after the installation. However, the Linux source tree is |
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[a7fa075] | 169 | often retained for a long time. Because of this, there is a chance |
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[3f8be484] | 170 | that whatever user ID the packager used will be assigned to somebody |
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| 171 | on the machine. That person would then have write access to the kernel |
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| 172 | source.</para> |
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| 173 | |
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[43daa01] | 174 | <para os="y1">If the kernel source tree is going to retained, run |
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[3f8be484] | 175 | <command>chown -R 0:0</command> on the <filename |
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[43daa01] | 176 | class="directory">linux-&linux-version;</filename> directory to |
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[3f8be484] | 177 | ensure all files are owned by user <systemitem |
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| 178 | class="username">root</systemitem>.</para> |
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| 179 | |
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| 180 | <warning os="z"> |
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| 181 | <para>Some kernel documentation recommends creating a symlink from |
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| 182 | <filename class="symlink">/usr/src/linux</filename> pointing to the |
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| 183 | kernel source directory. This is specific to kernels prior to the |
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[fb40919] | 184 | 2.6 series and <emphasis>must not</emphasis> be created on a CLFS |
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[3f8be484] | 185 | system as it can cause problems for packages you may wish to build |
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[fb40919] | 186 | once your base CLFS system is complete.</para> |
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[3f8be484] | 187 | |
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| 188 | <para>Also, the headers in the system's <filename |
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| 189 | class="directory">include</filename> directory should |
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| 190 | <emphasis>always</emphasis> be the ones against which Glibc was |
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[b169dfe] | 191 | compiled and should <emphasis>never</emphasis> be replaced by headers |
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| 192 | from a different kernel version.</para> |
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[3f8be484] | 193 | </warning> |
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| 194 | |
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| 195 | </sect2> |
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| 196 | |
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| 197 | <sect2 id="contents-kernel" role="content"> |
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| 198 | <title>Contents of Linux</title> |
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| 199 | |
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| 200 | <segmentedlist> |
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| 201 | <segtitle>Installed files</segtitle> |
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[61ad0b7f] | 202 | <segtitle>Installed directory</segtitle> |
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[3f8be484] | 203 | |
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| 204 | <seglistitem> |
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[3f76cac] | 205 | <seg>config-[linux-version], clfskernel-[linux-version], |
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[3f8be484] | 206 | and System.map-[linux-version]</seg> |
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[61ad0b7f] | 207 | <seg>/lib/modules</seg> |
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[3f8be484] | 208 | </seglistitem> |
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| 209 | </segmentedlist> |
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| 210 | |
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| 211 | <variablelist> |
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| 212 | <bridgehead renderas="sect3">Short Descriptions</bridgehead> |
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| 213 | <?dbfo list-presentation="list"?> |
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| 214 | <?dbhtml list-presentation="table"?> |
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| 215 | |
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| 216 | <varlistentry id="config"> |
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| 217 | <term><filename>config-[linux-version]</filename></term> |
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| 218 | <listitem> |
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| 219 | <para>Contains all the configuration selections for the kernel</para> |
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| 220 | <indexterm zone="ch-bootable-kernel config"> |
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| 221 | <primary sortas="e-/boot/config">/boot/config-[linux-version]</primary> |
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| 222 | </indexterm> |
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| 223 | </listitem> |
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| 224 | </varlistentry> |
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| 225 | |
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[3f76cac] | 226 | <varlistentry id="clfskernel"> |
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| 227 | <term><filename>clfskernel-[linux-version]</filename></term> |
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[3f8be484] | 228 | <listitem> |
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| 229 | <para>The engine of the Linux system. When turning on the |
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| 230 | computer, the kernel is the first part of the operating system |
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| 231 | that gets loaded. It detects and initializes all components of |
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| 232 | the computer's hardware, then makes these components available |
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| 233 | as a tree of files to the software and turns a single CPU into |
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| 234 | a multitasking machine capable of running scores of programs |
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| 235 | seemingly at the same time.</para> |
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[3f76cac] | 236 | <indexterm zone="ch-bootable-kernel clfskernel"> |
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| 237 | <primary sortas="b-clfskernel">clfskernel-[linux-version]</primary> |
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[3f8be484] | 238 | </indexterm> |
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| 239 | </listitem> |
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| 240 | </varlistentry> |
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| 241 | |
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| 242 | <varlistentry id="System.map"> |
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| 243 | <term><filename>System.map-[linux-version]</filename></term> |
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| 244 | <listitem> |
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| 245 | <para>A list of addresses and symbols; it maps the entry points |
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| 246 | and addresses of all the functions and data structures in the |
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| 247 | kernel</para> |
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| 248 | <indexterm zone="ch-bootable-kernel System.map"> |
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| 249 | <primary sortas="e-/boot/System.map">/boot/System.map-[linux-version]</primary> |
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| 250 | </indexterm> |
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| 251 | </listitem> |
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| 252 | </varlistentry> |
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| 253 | |
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| 254 | </variablelist> |
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| 255 | |
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| 256 | </sect2> |
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| 257 | |
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| 258 | </sect1> |
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