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rane 05/09/19 14:52:04 |
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Added: xml/htdocs/doc/en/articles linux-kernel-compiling.xml |
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Log: |
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new article from #104226 |
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Revision Changes Path |
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1.1 xml/htdocs/doc/en/articles/linux-kernel-compiling.xml |
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file : http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/linux-kernel-compiling.xml?rev=1.1&content-type=text/x-cvsweb-markup&cvsroot=gentoo |
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plain: http://www.gentoo.org/cgi-bin/viewcvs.cgi/xml/htdocs/doc/en/articles/linux-kernel-compiling.xml?rev=1.1&content-type=text/plain&cvsroot=gentoo |
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Index: linux-kernel-compiling.xml |
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=================================================================== |
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<?xml version="1.0" encoding="UTF-8"?> |
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<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
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<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/articles/linux-kernel-compiling.xml,v 1.1 2005/09/19 14:52:04 rane Exp $ --> |
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<guide link="/doc/en/articles/linux-kernel-compiling.xml"> |
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<title>Compiling the Linux kernel</title> |
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|
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<author title="Author"> |
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<mail link="drobbins@g.o">Daniel Robbins</mail> |
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</author> |
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<!-- xmlified by: Joshua Saddler (jackdark@×××××.com) --> |
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<abstract> |
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Daniel Robbins introduces the Linux kernel, and then walks you through locating |
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and downloading sources, configuring the kernel, compiling and installing the |
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kernel, and boot configuration. |
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</abstract> |
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<!-- The original version of this article was first published on IBM |
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developerWorks, and is property of Westtech Information Services. This |
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document is an updated version of the original article, and contains |
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various improvements made by the Gentoo Linux Documentation team --> |
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|
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<version>1.0</version> |
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<date>2005-08-31</date> |
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<chapter> |
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<title>Introducing the kernel</title> |
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<section> |
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<title>The kernel is... Linux!</title> |
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<body> |
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|
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<note> |
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The original version of this article was first published on IBM developerWorks, |
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and is property of Westtech Information Services. This document is an updated |
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version of the original article, and contains various improvements made by the |
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Gentoo Linux Documentation team. |
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</note> |
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|
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<p> |
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What do you think of when you hear the word "Linux"? When I hear it, I |
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typically think of an entire Linux distribution and all the cooperating |
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programs that make the distribution work. |
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</p> |
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|
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<p> |
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However, you may be surprised to find out that, technically, Linux is a kernel, |
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and a kernel only. While the other parts of what we commonly call "Linux" (such |
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as a shell and compiler) are essential parts of a distribution, they are |
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technically separate from Linux (the kernel). While many people use the word |
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"Linux" to mean "Linux-based distribution," everyone can at least agree that |
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the Linux kernel is the <e>heart</e> of every distribution. |
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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>Interfacing with hardware</title> |
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<body> |
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|
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<p> |
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The primary role of the Linux kernel is to interface directly with the hardware |
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in your system. The kernel provides a <e>layer of abstraction</e> between the |
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raw hardware and application programs. This way, the programs themselves do |
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not need to know the details of your specific motherboard chipset or disk |
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controller -- they can instead operate at the higher level of reading and |
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writing files to disk, for example. |
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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>CPU abstraction</title> |
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<body> |
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<p> |
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The Linux kernel also provides a level of abstraction on top of the |
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processor(s) in your system -- allowing for multiple programs to appear to run |
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simultaneously. Linux does this by allowing several UNIX <e>processes</e> to |
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run at once -- and the kernel takes care of giving each one a fair share of the |
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processor(s). |
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</p> |
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|
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<p> |
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A Linux kernel can support either a single or multiple CPUs -- and the kernel |
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that you are using now is either uniprocessor-aware (UP-aware) or symmetric |
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multiprocessor-aware (SMP-aware). If you happen to have an SMP motherboard, but |
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you're using a UP kernel, Linux won't "see" your extra processors! To fix this, |
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you'll want to compile a special SMP kernel for your hardware. Currently, SMP |
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kernels will also work on uniprocessor systems, but at a slight performance |
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hit. |
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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>Abstracting I/O</title> |
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<body> |
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<p> |
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The kernel also handles the much-needed task of abstracting all forms of file |
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I/O. Imagine what would happen if every program had to interface with your |
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particular hardware directly -- if you changed disk controllers, all your |
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programs would stop working! Fortunately, the Linux kernel follows the UNIX |
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model of providing a simple abstraction of disk I/O that all programs can use. |
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That way, your favorite database doesn't need to be concerned whether it is |
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storing data on an IDE disk, a SCSI RAID array, or a network-mounted file |
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system. |
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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>Networking Central</title> |
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<body> |
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|
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<p> |
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One of Linux's main claims to fame is its robust networking, especially TCP/IP |
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support. And, if you guessed that the TCP/IP stack is in the Linux kernel, |
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you're right! The kernel provides a nice, high-level interface for programs |
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that want to send data over the network. Behind the scenes, the Linux kernel |
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interfaces directly with your particular ethernet card or modem, and handles |
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the low-level Internet communication details. |
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</p> |
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</body> |
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</section> |
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<section> |
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<title>Networking goodies</title> |
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<body> |
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<p> |
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One of the greatest things about Linux is all of the useful features that are |
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available in the kernel, especially those related to networking. For example, |
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you can configure a kernel that will allow your entire home network to access |
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the Internet via your Linux modem -- this is called IP Masquerading, or IP NAT |
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(network address translating). |
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</p> |
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|
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<p> |
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Additionally, the Linux kernel can be configured to export or mount |
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network-based NFS file systems, allowing for other UNIX machines on your LAN to |
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easily share data with your Linux system. |
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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>Booting, part 1</title> |
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<body> |
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<p> |
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When you turn on your Linux-based system, the kernel is loaded from disk to |
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memory by a boot loader, such as LILO. At this point, the kernel takes control |
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of your system. The first thing it does is detect and initialize all the |
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hardware that it finds -- and it has been compiled to support. Once the |
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hardware has been initialized properly, it is then ready to run processes. The |
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first process it runs is called <c>init</c>, which is located in |
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<path>/sbin</path>. Then, <c>init</c> starts additional processes, as |
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specified in <path>/etc/inittab</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>Booting, part 2</title> |
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<body> |
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|
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<p> |
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<c>init</c> typically starts several copies of a program called <c>getty</c>, |
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which waits for logins from the console. After <c>getty</c> successfully |
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processes a login request, your default shell is loaded (which is typically |
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<c>bash</c>). Once you're in bash, you have the power to launch any program |
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you'd like. |
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</p> |
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<p> |
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While all these new processes are started, the kernel is still in control, |
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carefully time-slicing the CPU so that each process has a fair share. In |
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addition, the kernel continues to provide hardware abstraction and networking |
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services for the various running processes. |
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</p> |
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</body> |
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</section> |
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<section> |
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<title>Introducing... modules!</title> |
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<body> |
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<p> |
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All recent Linux kernels support kernel modules. Kernel modules are really neat |
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things -- they're pieces of the kernel that reside on disk, until needed. As |
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soon as the kernel needs the functionality of a particular module, it's loaded |
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from disk, automatically integrated with the kernel, and available for use. In |
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addition, if a kernel module hasn't been used for several minutes, the kernel |
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can voluntarily unload it from memory -- something that's called |
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"autocleaning." |
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</p> |
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-- |
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