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<?xml version='1.0' encoding="UTF-8"?> |
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<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/genkernel.xml,v 1.15 2005/06/11 21:07:38 fox2mike Exp $ --> |
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<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
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|
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<guide link="/doc/en/genkernel.xml"> |
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<title>Gentoo Linux Genkernel Guide</title> |
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|
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<author title="Author"> |
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<mail link="plasmaroo@gentoo.org">Tim Yamin</mail> |
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</author> |
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|
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<abstract> |
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This guide intends to provide a reference of all the functions |
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provided by genkernel. |
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</abstract> |
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|
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<license/> |
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|
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<version>1.1.2.3</version> |
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<date>2005-06-26</date> |
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|
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<chapter> |
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<title>Introduction</title> |
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<section> |
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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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Genkernel is designed to allow users who are not previously used to |
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compiling a kernel to use a similar setup to that one that is used on |
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the Gentoo Installation CDs which auto-detects your hardware. |
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</p> |
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|
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<p> |
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Some users may also be interested in using genkernel for hardware |
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which requires initialization and a working kernel before it can be |
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booted. Because genkernel also automatically compiles your kernel modules, |
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thus allowing hardware which needs to be loaded with module parameters |
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to be used. |
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</p> |
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|
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</body> |
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</section> |
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<section> |
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<title>Is genkernel for me?</title> |
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<body> |
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|
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<p> |
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Genkernel is often a good choice to those who are unused to compiling |
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their own kernel or those who are not certain about their hardware |
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configurations. |
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</p> |
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|
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<p> |
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Because genkernel is designed to use a generic configuration, it |
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should be able to support all of your hardware - however, because all |
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the drivers and modules have to be compiled as well, compiling a |
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kernel by yourself is often much faster provided you know what you need. |
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</p> |
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|
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<p> |
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Genkernel does not however, currently support booting the sytem from |
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LVM2/EVMS2 partitions. Users are recommended to use a manually compiled |
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kernel for the time being. |
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</p> |
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|
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</body> |
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</section> |
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<section> |
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<title>Getting genkernel</title> |
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<body> |
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|
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<p> |
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You can obtain genkernel by simply running <c>emerge genkernel</c>. Don't |
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forget to use the <c>-k</c> flag for emerge if you are using binary packages, |
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i.e. GRP. Due to the GRP packages having an older version of genkernel, the |
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flags are different. As a result, you should consult the <uri |
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link="/doc/en/handbook/handbook-x86.xml?part=1&chap=10"> |
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Gentoo Handbook</uri> and <path>genkernel --help</path>. |
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</p> |
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|
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</body> |
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</section> |
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<section> |
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<title>Supported platforms</title> |
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<body> |
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|
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<p> |
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As of genkernel 3.0.2, the following platforms should be |
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supported: alpha, amd64, parisc, parisc64, ppc, ppc64, sparc, sparc64, and x86. |
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</p> |
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|
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</body> |
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</section> |
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</chapter> |
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|
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<chapter> |
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<title>Genkernel usage</title> |
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<section> |
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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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Genkernel is designed to work in three modes: |
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</p> |
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|
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<ul> |
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<li>"all" mode: this builds the kernel and the initrd</li> |
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<li>"kernel" mode: this only builds the kernel image</li> |
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<li>"initrd" mode: this only builds the initrd</li> |
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</ul> |
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|
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<p> |
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Most users will only want the "all" mode, which runs the "kernel" mode |
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and the "initrd" mode for you. <b>Note</b> that the "kernel" and "initrd" |
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modes are currently just aliases for the "all" mode, so they will |
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currently give you no special effect. |
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</p> |
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|
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<p> |
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Although genkernel is mainly a command to make your life easier when |
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you need to compile a kernel, genkernel is also packed full of |
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different flags which allow you to customize how your kernel is |
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compiled or configured. |
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</p> |
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|
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</body> |
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</section> |
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<section> |
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<title>Genkernel compiler flags</title> |
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<body> |
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|
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<p> |
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Genkernel supports the following flags which are passed to the |
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relevant applications when your kernel is assembled: |
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</p> |
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|
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<ul> |
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<li> |
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<b>--kernel-as=<c>someAssembler</c></b>: This specifies an assembler which |
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would be used for compiling your kernel. |
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</li> |
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<li> |
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<b>--kernel-cc=<c>someCompiler</c></b>: This specifies a compiler which |
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would be used for compiling your kernel. |
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</li> |
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<li> |
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<b>--kernel-ld=<c>someLinker</c></b>: This specifies a linker which would |
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be used for compiling your kernel. |
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</li> |
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<li> |
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<b>--kernel-make=<c>someMake</c></b>: This specifies an alternate GNU make |
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which would be used for compiling your kernel. |
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</li> |
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</ul> |
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|
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<ul> |
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<li> |
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<b>--utils-as=<c>someAssembler</c></b>: This specifies an assembler which |
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would be used for compiling the support utilities. |
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</li> |
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<li> |
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<b>--utils-cc=<c>someCompiler</c></b>: This specifies a compiler which |
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would be used for compiling the support utilities. |
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</li> |
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<li> |
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<b>--utils-ld=<c>someLinker</c></b>: This specifies a linker which would be |
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used for compiling the support utilities. |
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</li> |
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<li> |
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<b>--utils-make=<c>someMake</c></b>: This specifies an alternate GNU make |
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which would be used for compiling the support utilities. |
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</li> |
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</ul> |
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|
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<ul> |
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<li> |
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<b>--makeopts=<c>-jJobs</c></b>: This specifies the flags which would be |
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passed to GNU make when the kernel and utilities are being compiled. |
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</li> |
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</ul> |
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|
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</body> |
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</section> |
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<section> |
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<title>Genkernel kernel flags</title> |
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<body> |
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|
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<p> |
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Genkernel supports the following flags, some of which have |
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<c>--<b>no-</b>option</c> equivalents that influence |
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kernel compilation: |
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</p> |
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|
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<ul> |
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<li> |
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<b>--callback="echo Hello"</b>: This routine calls the specified |
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arguments after the kernel and the relevant modules have been built; but |
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before the initrd has been built. This is useful where you might want |
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external modules installed to the initrd by emerging the relevant item |
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using the callback and then redefining a genkernel module group. |
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</li> |
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<li> |
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<b>--<c>no-</c>clean</b>: This runs <e>or does not |
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run</e> <c>make clean</c> before compiling your kernel. This |
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causes all object files and dependencies to be removed. |
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</li> |
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<li> |
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<b>--<c>no-</c>mrproper</b>: This runs <e>or does not |
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run</e> <c>make mrproper</c> before compiling your kernel. This |
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causes all object files, dependencies <b>and your |
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configuration</b> to be removed. |
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</li> |
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</ul> |
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|
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<ul> |
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<li> |
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<b>--kerneldir=<path>/path/to/sources</path></b>: This specifies an |
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alternative kernel source location, instead of the default location of |
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<path>/usr/src/linux</path>. |
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</li> |
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<li> |
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<b>--kernel-config=<path>/path/to/config-file</path></b>: This specifies an |
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alternative kernel configuration which would be used; rather than the |
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non-persistent <path>/path/to/sources/.config</path> which is used by |
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default. |
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</li> |
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</ul> |
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|
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<ul> |
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<li> |
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<b>--<c>no-</c>bootsplash</b>: This adds <e>or does not add</e> bootsplash |
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support in the initrd which genkernel builds. Not all architectures |
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currently support bootsplash, and a kernel that supports bootsplash is |
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also required. |
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</li> |
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<li> |
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<b>--<c>no-</c>menuconfig</b>: This runs <e>or does not run</e> the kernel |
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menu-based configurator before building your kernel, after <c>make |
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oldconfig</c> has run. |
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</li> |
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</ul> |
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|
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<ul> |
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<li> |
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<b>--no-initrdmodules</b>: This doesn't copy any modules to the initrd |
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which genkernel creates. |
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</li> |
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<li> |
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<b>--<c>no-</c>install</b>: This installs <e>or does not install</e> your |
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kernel, modules, and initrd once the compilation has finished. |
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</li> |
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</ul> |
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|
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</body> |
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</section> |
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<section> |
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<title>Genkernel miscellaneous flags</title> |
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<body> |
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|
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<p> |
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Genkernel also supports some miscellaneous flags which do not fit into |
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the other two categories: |
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</p> |
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|
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<ul> |
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<li> |
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<b>--arch-override=<c>someArch</c></b>: This flag can be used to override |
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what architecture genkernel thinks you're on, if the auto-detection |
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mechanism fails (please file a bug if it does!) or if you wish to |
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cross-compile a kernel. |
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</li> |
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</ul> |
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|
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<ul> |
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<li> |
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<b>--busybox-config=<path>/path/to/busybox-config</path></b>: This |
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overrides the default busybox configuration with the specifid file |
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</li> |
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<li> |
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<b>--busybox-bin=<path>/path/to/busybox-binary.tar.bz2</path></b>: Using |
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this option means that a busybox binary would not be compiled, and the |
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specified tarball would be used. Note that busybox <e>must</e> be compiled |
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statically! |
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</li> |
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</ul> |
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|
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<ul> |
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<li> |
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<b>--minkernpackage=<path>/output/to/yourkernel.tar.bz2</path></b>: This |
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flag outputs a tarball of the kernel, named as <path>kernel</path> and the |
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initrd named as <path>initrd</path> to the specified file. No path |
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information or modules will be included in the tarball. |
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</li> |
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</ul> |
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|
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</body> |
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</section> |
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<section> |
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<title>Running genkernel</title> |
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<body> |
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|
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<p> |
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All that is needed to run genkernel is just genkernel with the |
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necessary flags as root. For example: |
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</p> |
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|
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<pre caption="Running genkernel"> |
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# genkernel --menuconfig --no-clean --no-install --bootsplash all |
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<comment>(Would produce a kernel, asking you how to configure it |
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to your desire, leaving alone any compiled object files, enabling |
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bootsplash support but not installing anything.)</comment> |
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</pre> |
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|
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<p> |
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If you want genkernel to install your kernel as well, you must ensure |
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that your <path>/boot</path> partition is mounted - recent genkernels |
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would automatically attempt to do this for you if MOUNTBOOT is set to |
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"yes" in <path>/etc/genkernel.conf</path>. |
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</p> |
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|
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<pre caption="Mounting your /boot manually"> |
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<comment>(If /boot is a valid entry in /etc/fstab:)</comment> |
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# mount /boot |
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<comment>(... otherwise for IDE disks:)</comment> |
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# mount /dev/hda1 /boot |
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<comment>(... and for SCSI disks:)</comment> |
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# mount /dev/sda1 /boot |
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</pre> |
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|
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</body> |
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</section> |
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<section> |
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<title>Setting up genkernel to work with your bootloader</title> |
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<body> |
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|
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<p> |
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To set up genkernel to work with your bootloader, three or four changes are |
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required to your bootloader configuration. |
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</p> |
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|
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<ol> |
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<li> |
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Add <c>root=/dev/ram0</c> and <c>init=/linuxrc</c> to the |
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kernel parameters passed to the kernel image. |
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</li> |
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<li> |
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Add <c>real_root=/dev/hda3</c>, for example, to the kernel parameters |
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passed to the kernel image, if <path>/dev/hda3</path> contains your root |
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partition. |
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</li> |
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<li> |
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If you are using bootsplash, add a suitable modeline such as |
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<c>vga=0x317</c> to the parameters passed to the kernel and also add |
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<c>splash=verbose</c> or <c>splash=silent</c> depending on the verboseness |
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you require from your bootsplash. |
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</li> |
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<li> |
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Add the initrd according to how your bootloader requires it: see the <uri |
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link="/doc/en/handbook/handbook-x86.xml?part=1&chap=10">Gentoo |
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Handbook</uri> for details on how you would do it for your bootloader. |
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</li> |
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</ol> |
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|
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</body> |
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</section> |
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<section> |
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<title>Kernel Configuration Files</title> |
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<body> |
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|
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<p> |
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Genkernel will save your kernel config in <path>/etc/kernels</path> and use that |
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config whenever you issue <c>genkernel</c> again. If you want to start off again |
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with the defaults, rename the file in <path>/etc/kernels</path>. Genkernel will |
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then use the kernel config located in |
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<path>/usr/share/genkernel/<arch></path> instead. |
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</p> |
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|
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</body> |
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</section> |
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</chapter> |
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|
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<chapter> |
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<title>Porting genkernel</title> |
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<section> |
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<title>Introduction</title> |
| 387 |
<body> |
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|
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<p> |
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Provided your architecture has all the required libraries and utilties |
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which genkernel requires, which includes but it is not limited to a |
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working kernel for your architecture, working compiler suite, GNU |
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make, and a working busybox distribution, you're all set to go! |
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</p> |
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|
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<p> |
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For each architecture, genkernel uses |
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<path>/usr/share/genkernel/$archName</path> for configuration files for |
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that architecture. |
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</p> |
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|
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</body> |
| 403 |
</section> |
| 404 |
<section> |
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<title>How the system bootstrapping works</title> |
| 406 |
<body> |
| 407 |
|
| 408 |
<ol> |
| 409 |
<li> |
| 410 |
The bootloader loads the genkernel image, built to the specification of the |
| 411 |
configuration files in the genkernel directories as well as the initrd |
| 412 |
which is prepared by genkernel. |
| 413 |
</li> |
| 414 |
<li> |
| 415 |
The kernel boots up, allocates a small amount of RAM in which busybox is |
| 416 |
initialized, which probes the system with the modules in the modules_load |
| 417 |
list for the architecture. |
| 418 |
</li> |
| 419 |
<li> |
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Once done, and providing that the <c>real_root</c> parameter which is the |
| 421 |
root boot device as busybox sees things is found, the system is booted from |
| 422 |
the device. |
| 423 |
</li> |
| 424 |
</ol> |
| 425 |
|
| 426 |
</body> |
| 427 |
</section> |
| 428 |
<section> |
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<title>The configuration files</title> |
| 430 |
<body> |
| 431 |
|
| 432 |
<ul> |
| 433 |
<li> |
| 434 |
<path>busy-config</path>: This is the configuration which is used to build |
| 435 |
busybox for your architecture. |
| 436 |
</li> |
| 437 |
<li> |
| 438 |
<path>config.sh</path>: This is a shell script which sets various internal |
| 439 |
genkernel variables. See one of the <path>config.sh</path> files for an |
| 440 |
example. |
| 441 |
</li> |
| 442 |
<li> |
| 443 |
<path>modules_load</path>: This is a file containing a space-delimited list |
| 444 |
of modules which are loaded for SCSI, FireWire, ATARAID and PCMCIA support. |
| 445 |
If none are available for your platform, leave the fields blank. See one of |
| 446 |
the <path>modules_load</path> files for an example. |
| 447 |
</li> |
| 448 |
</ul> |
| 449 |
|
| 450 |
<ul> |
| 451 |
<li> |
| 452 |
<path>kernel-config</path>: A default kernel configuration used for any |
| 453 |
kernel version. |
| 454 |
</li> |
| 455 |
<li> |
| 456 |
<path>kernel-config-2.4</path>: A default kernel configuration used for 2.4 |
| 457 |
series kernels. |
| 458 |
</li> |
| 459 |
<li> |
| 460 |
<path>kernel-config-2.6</path>: A default kernel configuration used for 2.6 |
| 461 |
series kernels. |
| 462 |
</li> |
| 463 |
</ul> |
| 464 |
|
| 465 |
</body> |
| 466 |
</section> |
| 467 |
</chapter> |
| 468 |
</guide> |
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