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<?xml version='1.0' encoding='UTF-8'?> |
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<!DOCTYPE sections SYSTEM "/dtd/book.dtd"> |
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<!-- The content of this document is licensed under the CC-BY-SA license --> |
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<!-- See http://creativecommons.org/licenses/by-sa/2.5 --> |
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<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-x86+amd64-kernel.xml,v 1.57 2014/08/07 16:15:41 swift Exp $ --> |
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|
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<sections> |
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|
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<abstract> |
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The Linux kernel is the core of every distribution. This chapter |
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explains how to configure your kernel. |
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</abstract> |
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|
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<version>27</version> |
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<date>2014-08-07</date> |
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|
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<section> |
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<title>Installing the Sources</title> |
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<subsection> |
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<title>Choosing a Kernel</title> |
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<body> |
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|
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<p> |
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The core around which all distributions are built is the Linux kernel. It is the |
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layer between the user programs and your system hardware. Gentoo provides its |
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users several possible kernel sources. A full listing with description is |
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available at the <uri link="https://wiki.gentoo.org/wiki/Kernel/Overview">Gentoo Kernel |
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Guide</uri>. |
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</p> |
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|
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<p> |
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For <keyval id="arch"/>-based systems we have <c>gentoo-sources</c> |
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(kernel source patched for extra features). |
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</p> |
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|
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<p> |
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Choose your kernel source and install it using <c>emerge</c>. |
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</p> |
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|
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<pre caption="Installing a kernel source"> |
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# <i>emerge gentoo-sources</i> |
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</pre> |
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|
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<p> |
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When you take a look in <path>/usr/src</path> you should see a symlink called |
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<path>linux</path> pointing to your kernel source. In this case, the installed |
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kernel source points to <c>gentoo-sources-<keyval id="kernel-version"/></c>. |
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Your version may be different, so keep this in mind. |
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</p> |
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|
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<pre caption="Viewing the kernel source symlink"> |
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# <i>ls -l /usr/src/linux</i> |
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lrwxrwxrwx 1 root root 12 Oct 13 11:04 /usr/src/linux -> linux-<keyval id="kernel-version"/> |
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</pre> |
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|
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<p> |
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Now it is time to configure and compile your kernel source. You can use |
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<c>genkernel</c> for this, which will build a generic kernel as used by the |
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Installation CD. We explain the "manual" configuration first though, as it is |
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the best way to optimize your environment. |
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</p> |
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|
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<p> |
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If you want to manually configure your kernel, continue now with <uri |
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link="#manual">Default: Manual Configuration</uri>. If you want to use |
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<c>genkernel</c> you should read <uri link="#genkernel">Alternative: Using |
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genkernel</uri> instead. |
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</p> |
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|
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</body> |
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</subsection> |
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</section> |
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<section id="manual"> |
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<title>Default: Manual Configuration</title> |
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<subsection> |
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<title>Introduction</title> |
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<body> |
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|
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<p> |
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Manually configuring a kernel is often seen as the most difficult procedure a |
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Linux user ever has to perform. Nothing is less true -- after configuring a |
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couple of kernels you don't even remember that it was difficult ;) |
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</p> |
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|
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<p> |
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However, one thing <e>is</e> true: you must know your system when you start |
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configuring a kernel manually. Most information can be gathered by emerging |
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pciutils (<c>emerge pciutils</c>) which contains <c>lspci</c>. You will now |
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be able to use <c>lspci</c> within the chrooted environment. You may safely |
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ignore any <e>pcilib</e> warnings (like pcilib: cannot open |
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/sys/bus/pci/devices) that <c>lspci</c> throws out. Alternatively, you can run |
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<c>lspci</c> from a <e>non-chrooted</e> environment. The results are the same. |
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You can also run <c>lsmod</c> to see what kernel modules the Installation CD |
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uses (it might provide you with a nice hint on what to enable). |
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</p> |
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|
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<p> |
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Now go to your kernel source directory and execute <c>make menuconfig</c>. This |
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will fire up an ncurses-based configuration menu. |
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</p> |
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|
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<pre caption="Invoking menuconfig"> |
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# <i>cd /usr/src/linux</i> |
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# <i>make menuconfig</i> |
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</pre> |
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|
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<p> |
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You will be greeted with several configuration sections. We'll first list some |
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options you must activate (otherwise Gentoo will not function, or not function |
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properly without additional tweaks). We also have a <uri |
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link="https://wiki.gentoo.org/wiki/Kernel/Gentoo_Kernel_Configuration_Guide">Gentoo |
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Kernel Configuration Guide</uri> on the Gentoo wiki that might help you further. |
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</p> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<title>Activating Required Options</title> |
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<body> |
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|
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<p> |
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Make sure that every driver that is vital to the booting of your system (such as |
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SCSI controller, ...) is compiled <e>in</e> the kernel and not as a module, |
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otherwise your system will not be able to boot completely. |
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</p> |
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|
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</body> |
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<body test="func:keyval('arch')='AMD64'"> |
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|
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<p> |
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We shall then select the exact processor type. The x86_64 kernel maintainer |
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strongly recommends users enable MCE features so that they are able to be |
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notified of any hardware problems. On x86_64, these errors are not printed to |
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<c>dmesg</c> like on other architectures, but to <path>/dev/mcelog</path>. This |
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requires the <c>app-admin/mcelog</c> package. Make sure you select IA32 |
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Emulation if you want to be able to run 32-bit programs. Gentoo will install a |
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multilib system (mixed 32-bit/64-bit computing) by default, so this option is |
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required. |
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</p> |
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|
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<note> |
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If you plan to use a non-multilib profile (for a pure 64-bit system), then you |
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don't have to select IA32 Emulation support. However, you'll also need to follow |
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the <uri link="?part=1&chap=6#doc_chap2_sect4">instructions</uri> for |
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switching to a <uri link="https://wiki.gentoo.org/wiki/AMD64/FAQ">non-multilib |
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profile</uri>, as well as choosing the correct <uri |
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link="?part=1&chap=10#doc_chap2_sect2">bootloader</uri>. |
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</note> |
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|
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<pre caption="Selecting processor type and features"> |
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Processor type and features ---> |
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[ ] Machine Check / overheating reporting |
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[ ] Intel MCE Features |
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[ ] AMD MCE Features |
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Processor family (AMD-Opteron/Athlon64) ---> |
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( ) Opteron/Athlon64/Hammer/K8 |
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( ) Intel P4 / older Netburst based Xeon |
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( ) Core 2/newer Xeon |
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( ) Intel Atom |
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( ) Generic-x86-64 |
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Executable file formats / Emulations ---> |
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[*] IA32 Emulation |
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</pre> |
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|
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</body> |
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<body test="func:keyval('arch')='x86'"> |
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|
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<p> |
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Now select the correct processor family: |
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</p> |
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|
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<pre caption="Selecting correct processor family"> |
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Processor type and features ---> |
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<comment>(Change according to your system)</comment> |
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(<i>Athlon/Duron/K7</i>) Processor family |
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</pre> |
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|
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</body> |
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<body> |
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|
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<p> |
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Next select <e>Maintain a devtmpfs file system to mount at /dev</e> so that |
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critical device files are already available early in the boot process. |
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</p> |
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|
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<pre caption="Enabling devtmpfs support"> |
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Device Drivers ---> |
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Generic Driver Options ---> |
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[*] Maintain a devtmpfs filesystem to mount at /dev |
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[ ] Automount devtmpfs at /dev, after the kernel mounted the rootfs |
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</pre> |
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|
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<p> |
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Now go to <c>File Systems</c> and select support for the filesystems you use. |
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<e>Don't</e> compile the file system you use for the root filesystem as module, |
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otherwise your Gentoo system will not be able to mount your partition. Also |
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select <c>Virtual memory</c> and <c>/proc file system</c>. |
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</p> |
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|
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<pre caption="Selecting necessary file systems"> |
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File systems ---> |
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<comment>(Select one or more of the following options as needed by your system)</comment> |
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<*> Second extended fs support |
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<*> Ext3 journalling file system support |
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<*> The Extended 4 (ext4) filesystem |
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<*> Reiserfs support |
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<*> JFS filesystem support |
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<*> XFS filesystem support |
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... |
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Pseudo Filesystems ---> |
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[*] /proc file system support |
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[*] Virtual memory file system support (former shm fs) |
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|
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<comment>(Enable GPT partition label support if you used that previously)</comment> |
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-*- Enable the block layer ---> |
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... |
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Partition Types ---> |
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[*] Advanced partition selection |
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... |
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[*] EFI GUID Partition support |
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</pre> |
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|
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<p> |
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If you are using PPPoE to connect to the Internet or you are using a dial-up |
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modem, you will need the following options in the kernel: |
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</p> |
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|
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<pre caption="Selecting PPPoE necessary drivers"> |
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Device Drivers ---> |
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Network device support ---> |
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<*> PPP (point-to-point protocol) support |
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<*> PPP support for async serial ports |
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<*> PPP support for sync tty ports |
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</pre> |
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|
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<p> |
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The two compression options won't harm but are not definitely needed, neither |
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does the <c>PPP over Ethernet</c> option, that might only be used by <c>ppp</c> |
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when configured to do kernel mode PPPoE. |
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</p> |
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|
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<p> |
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If you require it, don't forget to include support in the kernel for your |
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ethernet card. |
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</p> |
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|
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<p test="func:keyval('arch')='x86'"> |
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If you have an Intel CPU that supports HyperThreading (tm), or you have a |
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multi-CPU system, you should activate "Symmetric multi-processing support": |
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</p> |
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|
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<p test="func:keyval('arch')='AMD64'"> |
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If you have a multi-CPU Opteron or a multi-core (e.g. AMD64 X2) system, you |
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should activate "Symmetric multi-processing support": |
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</p> |
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|
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<pre caption="Activating SMP support"> |
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Processor type and features ---> |
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[*] Symmetric multi-processing support |
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</pre> |
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|
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<note> |
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In multi-core systems, each core counts as one processor. |
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</note> |
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|
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<p test="func:keyval('arch')='x86'"> |
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If you have more than 4GB of RAM, you need to enable "High Memory Support |
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(64G)". |
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</p> |
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|
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<p> |
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If you use USB Input Devices (like Keyboard or Mouse) don't forget to enable |
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those as well: |
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</p> |
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|
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<pre caption="Activating USB Support for Input Devices"> |
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Device Drivers ---> |
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[*] HID Devices ---> |
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<*> USB Human Interface Device (full HID) support |
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</pre> |
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|
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</body> |
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<body test="func:keyval('arch')='x86'"> |
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|
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<p> |
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If you want PCMCIA support for your laptop, don't forget to enable |
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support for the PCMCIA card bridge present in your system: |
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</p> |
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|
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<pre caption="Enabling PCMCIA support"> |
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Bus options (PCI etc.) ---> |
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PCCARD (PCMCIA/CardBus) support ---> |
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<*> PCCard (PCMCIA/CardBus) support |
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<comment>(select 16 bit if you need support for older PCMCIA cards. Most people want this.)</comment> |
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<*> 16-bit PCMCIA support |
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[*] 32-bit CardBus support |
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<comment>(select the relevant bridges below)</comment> |
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*** PC-card bridges *** |
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<*> CardBus yenta-compatible bridge support (NEW) |
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<*> Cirrus PD6729 compatible bridge support (NEW) |
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<*> i82092 compatible bridge support (NEW) |
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</pre> |
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|
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<p> |
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When you've finished configuring the kernel, continue with <uri |
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link="#compiling">Compiling and Installing</uri>. |
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</p> |
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|
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</body> |
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</subsection> |
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<subsection id="compiling"> |
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<title>Compiling and Installing</title> |
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<body> |
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|
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<p> |
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Now that your kernel is configured, it is time to compile and install it. Exit |
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the configuration and start the compilation process: |
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</p> |
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|
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<pre caption="Compiling the kernel"> |
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# <i>make && make modules_install</i> |
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</pre> |
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|
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<p> |
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When the kernel has finished compiling, copy the kernel image to |
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<path>/boot</path>. This is handled by the <c>make install</c> command: |
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</p> |
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|
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<pre caption="Installing the kernel"> |
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# <i>make install</i> |
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</pre> |
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|
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<p> |
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This will copy the kernel image into <path>/boot</path> together with the |
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<path>System.map</path> file and the kernel configuration file. |
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</p> |
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|
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</body> |
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</subsection> |
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<subsection> |
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<include href="hb-install-initramfs.xml"/> |
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</subsection> |
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|
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</section> |
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<section id="genkernel"> |
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<title>Alternative: Using genkernel</title> |
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<body> |
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|
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<p> |
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If you are reading this section, you have chosen to use our <c>genkernel</c> |
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script to configure your kernel for you. |
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</p> |
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|
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<p> |
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Now that your kernel source tree is installed, it's now time to compile your |
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kernel by using our <c>genkernel</c> script to automatically build a kernel for |
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you. <c>genkernel</c> works by configuring a kernel nearly identically to the |
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way our Installation CD kernel is configured. This means that when you use |
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<c>genkernel</c> to build your kernel, your system will generally detect all |
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your hardware at boot-time, just like our Installation CD does. Because |
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genkernel doesn't require any manual kernel configuration, it is an ideal |
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solution for those users who may not be comfortable compiling their own kernels. |
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</p> |
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|
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<p> |
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Now, let's see how to use genkernel. First, emerge the genkernel ebuild: |
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</p> |
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|
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<pre caption="Emerging genkernel"> |
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# <i>emerge genkernel</i> |
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</pre> |
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|
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<p> |
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Next, edit the <path>/etc/fstab</path> file so that the line containing |
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<path>/boot</path> as second field has the first field pointing to the right |
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device. If the partitioning example from the handbook is followed, then this |
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device is most likely <path><keyval id="/boot"/></path> with the ext2 file |
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system. This would make the entry in the file look like so: |
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</p> |
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|
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<pre caption="Editing /etc/fstab for the /boot entry"> |
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# <i>nano -w /etc/fstab</i> |
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... |
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<keyval id="/boot"/> /boot ext2 defaults 0 2 |
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</pre> |
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|
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<p> |
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The remainder of the <path>/etc/fstab</path> will be updated in the next section, |
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but as <c>genkernel</c> reads this information we need to update the |
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<path>/boot</path> line up front. |
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</p> |
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|
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<p> |
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Now, compile your kernel sources by running <c>genkernel all</c>. Be aware |
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though, as <c>genkernel</c> compiles a kernel that supports almost all |
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hardware, this compilation will take quite a while to finish! |
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</p> |
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|
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<p> |
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Note that, if your boot partition doesn't use ext2 or ext3 as filesystem you |
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might need to manually configure your kernel using <c>genkernel --menuconfig |
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all</c> and add support for your filesystem <e>in</e> the kernel (i.e. |
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<e>not</e> as a module). Users of LVM2 will probably want to add <c>--lvm</c> |
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as an argument as well. |
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</p> |
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|
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<pre caption="Running genkernel"> |
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# <i>genkernel all</i> |
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</pre> |
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|
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<p> |
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Once <c>genkernel</c> completes, a kernel, full set of modules and |
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<e>initial ram disk</e> (initramfs) will be created. We will use the kernel |
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and initrd when configuring a boot loader later in this document. Write |
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down the names of the kernel and initrd as you will need it when writing |
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the bootloader configuration file. The initrd will be started immediately after |
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booting to perform hardware autodetection (just like on the Installation CD) |
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before your "real" system starts up. |
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</p> |
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|
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<pre caption="Checking the created kernel image name and initrd"> |
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# <i>ls /boot/kernel* /boot/initramfs*</i> |
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</pre> |
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|
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</body> |
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</section> |
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<section id="kernel_modules"> |
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<title>Kernel Modules</title> |
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|
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<subsection> |
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<include href="hb-install-kernelmodules.xml"/> |
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</subsection> |
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|
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</section> |
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</sections> |
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