实例：编译Linux内核3.18.25概要

前提：

将CentOS 7上3.10.0-229.el7.x86_64重新编译一个3.18.25内核

    自编译安装，按照自己的硬件平台架构编译，能最适合硬件主机的性能

    且按照需要编译模块，可以选择自己需要的包编译

 [root@localhost tmp]# uname  -a

一、编译前准备工作

   1.宿主机系统

           本次编译宿主机：VMware Workstation Pro12 上的CentOS 7.0操作系统

   2.开发环境（开发工具，开发库），头文件

[root@localhost yum.repos.d]# yum -y groupinstall "开发工具" "服务器平台开发"

[root@localhost yum.repos.d]# yum -y groupinstall "Development Tools" "Server PlatformDevelopment"

[root@localhostyum.repos.d]# yum install -y ncurses-devel

   包组：Development Tools、Server Platform Development

    CentOS 7上还要特备注意要安装包：ncurses-devel包

   3.获取目标主机上硬件设备的相关信息

       (1)CPU：

    ~]#cat  /proc/cpuinfo

    ~]#lscpu

   ~]# x86info -a：默认未安装，显示很详细的CPU信息

       (2)PCI设备总线：显卡、网卡… ...

   ~]# lspci            -v：详细信息           -vv：更加详细的信息

   ~]# lsusb：查看usb设备   -v  -vv

   ~]# lsblk：查看硬盘设备

       (3)hal-device：了解全部硬件设备信息(CentOS  6)

   4.获取到目标主机系统功能的相关信息，例如要启用的文件系统

   5.获取内核源代码包kernel源码

 www.kernel.org下载内核源代码3.18.25.el7.x86_64.tar，需要转换成二进制格式才能使用

二、编译安装内核源码

   1.解压源码：linux-3.18.25.tar

          [root@localhost/]# tar xf /tmp/linux-3.18.25.tar.xz -C /usr/src

          [root@localhost/]# cd /usr/src

          [root@localhostsrc]# ln -sv linux-3.18.25 linux

      注意：       

        1) 源码应该解压放置在/usr/src或者/usr/local/src下，系统在实现内核编译时特别建议放置在/usr/src目录

        2) 编译驱动时候，系统会找/usr/src/linux目录，自己解压会带版本号

              建议用连接方式创建,方便更换linux kernel时候的能够回滚，容易管理

   2.配置内核选项

        (1)make参数：[root@localhost linux]#make help

 clean                  - Remove most generated files but keep theconfig and

                                    enough build support to build external modules

 mrproper          - Remove all generated files + config +various backup files

 distclean          - mrproper + remove editor backup and patchfiles

 config          - Update current config utilising aline-oriented program

  nconfig         - Update current config utilising ancurses menu based program

 menuconfig          - Update current config utilising a menubased program

 xconfig          - Update current config utilising a QT basedfront-end

 gconfig          - Update current config utilising a GTK basedfront-end

 oldconfig          - Update current config utilising a provided.config as base

  localmodconfig  - Update current config disabling modules notloaded

  localyesconfig  - Update current config converting local modsto core

  silentoldconfig - Same as oldconfig, butquietly, additionally update deps

 defconfig          - New config with default from ARCH supplieddefconfig

  savedefconfig   - Save current config as ./defconfig(minimal config)

 allnoconfig          - New config where all options are answeredwith no

 allyesconfig          - New config where all options are acceptedwith yes

 allmodconfig          - New config selecting modules when possible

  alldefconfig    - New config with all symbols set todefault

 randconfig          - New config with random answer to alloptions

  listnewconfig   - List new options

 olddefconfig          - Same as silentoldconfig but sets newsymbols to their default value

 kvmconfig          - Enable additional options for guest kernelsupport

 tinyconfig          - Configure the tiniest possible kernel

 all                  - Build all targets marked with [*]

*vmlinux          - Build the bare kernel

*modules          - Build all modules

  modules_install - Install all modules toINSTALL_MOD_PATH (default: /)

  firmware_install- Install all firmware toINSTALL_FW_PATH

                    (default:$(INSTALL_MOD_PATH)/lib/firmware)

  dir/            - Build all files in dir and below

  dir/file.[oisS] - Build specified target only

  dir/file.lst    - Build specified mixed source/assemblytarget only

                    (requires a recent binutilsand recent build (System.map))

  dir/file.ko     - Build module including final link

  modules_prepare - Set up for buildingexternal modules

 tags/TAGS          - Generate tags file for editors

 cscope          - Generate cscope index

  gtags           - Generate GNU GLOBAL index

 kernelrelease          - Output the release version string (use withmake -s)

 kernelversion          - Output the version stored in Makefile (usewith make -s)

 image_name          - Output the image name (use with make -s)

  headers_install - Install sanitised kernelheaders to INSTALL_HDR_PATH

                    (default: ./usr)

  checkstack      - Generate a list of stack hogs

  namespacecheck  - Name space analysis on compiled kernel

  versioncheck    - Sanity check on version.h usage

  includecheck    - Check for duplicate included header files

  export_report   - List the usages of all exported symbols

  headers_check   - Sanity check on exported headers

  headerdep       - Detect inclusion cycles in headers

  coccicheck      - Check with Coccinelle.

  kselftest       - Build and run kernel selftest (run asroot)

                    Build, install, and bootkernel before

                    running kselftest on it

  rpm-pkg             - Build both source and binary RPMkernel packages

  binrpm-pkg          - Build only the binary kernelpackage

  deb-pkg             - Build the kernel as a debpackage

  tar-pkg             - Build the kernel as anuncompressed tarball

  targz-pkg           - Build the kernel as a gzipcompressed tarball

  tarbz2-pkg          - Build the kernel as a bzip2compressed tarball

  tarxz-pkg           - Build the kernel as a xzcompressed tarball

  perf-tar-src-pkg    - Build perf-3.18.25.tar source tarball

  perf-targz-src-pkg  - Build perf-3.18.25.tar.gz source tarball

  perf-tarbz2-src-pkg - Buildperf-3.18.25.tar.bz2 source tarball

  perf-tarxz-src-pkg  - Build perf-3.18.25.tar.xz source tarball

 Linux kernel internal documentation indifferent formats:

  htmldocs        - HTML

  pdfdocs         - PDF

  psdocs          - Postscript

  xmldocs         - XML DocBook

  mandocs         - man pages

  installmandocs  - install man pages generated by mandocs

  cleandocs       - clean all generated DocBook files

*bzImage      - Compressed kernel image(arch/x86/boot/bzImage)

  install     - Install kernel using

                  (your) ~/bin/installkernel or

                  (distribution)/sbin/installkernel or

                  install to $(INSTALL_PATH)and run lilo

  fdimage     - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)

  fdimage144  - Create 1.4MB boot floppy image (arch/x86/boot/fdimage)

  fdimage288  - Create 2.8MB boot floppy image (arch/x86/boot/fdimage)

  isoimage    - Create a boot CD-ROM image (arch/x86/boot/image.iso)

                  bzdisk/fdimage*/isoimage alsoaccept:

                  FDARGS="..."  arguments for the booted kernel

                 FDINITRD=file initrd for thebooted kernel

  x86_64_defconfig         - Build for x86_64

  i386_defconfig           - Build for i386

  make V=0|1 [targets] 0 => quiet build(default), 1 => verbose build

  make V=2  [targets] 2 => give reason for rebuild of target

  make O=dir [targets] Locate all output filesin "dir", including .config

  make C=1  [targets] Check all c source with $CHECK (sparse by default)

  make C=2  [targets] Force check of all c source with $CHECK

  make RECORDMCOUNT_WARN=1 [targets] Warn aboutignored mcount sections

  make W=n  [targets] Enable extra gcc checks, n=1,2,3 where

1:warnings which may be relevant and do not occur too often

2:warnings which occur quite often but may still be relevant

3:more obscure warnings, can most likely be ignored

Multiplelevels can be combined with W=12 or W=123

Execute"make" or "make all" to build all targets marked with [*]

Forfurther info see the ./README file

        (2)编译配置：Configuration targets

               1)支持“更新”模式进行配置：在已有的.config文件的基础之上进行“修改”配置；

          make config：基于命令行以遍历的方式去配置内核中可配置的每个选项；

          make menuconfig：基于cureses的文本配置窗口

          make gconfig：基于GTK开发环境的窗口界面； 包组“桌面平台开发”

          make  xonfig：基于QT开发环境的窗口界面；

               2)支持“全新配置”模式进行配置：

           make defconfig：基于内核为目标平台提供的“默认”配置为模板进行配置；

           make   allnoconfig：所有选项均为“no”；

 3.编译 (# cd  /usr/src/linux目录下)

       (1)多线程编译：make  [-j #]

        -j # ：以#个线程编译

        (2)编译内核中的一部分代码：编译之后要手动移动到指定的目录/lib/modules/*

     1)只编译某子目录中的相关代码：# make  path/to/dir/

    2)只编译一个特定的模块：# make path/to/dir/file.ko

       (3)实现交叉编译：目标平台与当前编译操作所在的平台不同；

          # make  ARCH=arch_name

    要获取特定目标平台的使用帮助：# make  ARCH=arch_name help

   4.安装内核的模块：]# make modules_install

安装会在/lib/modules/目录下生成一个与内核版号一致的目录

   5.安装内核核心：~]# make install

      (1)实际过程：

            实际上是安装/usr/src/linux/arch/x86/boot/bzImage文件为内核核心文件

/usr/src/linux/arch/x86_64/boot/bzImage-> ../../x86/boot/bzImage是其链接文件

64位兼容32位，所以统一安装在/usr/src/linux/arch/x86目录下

      (2)make install 命令自动安装执行操作

 1) 自动安装在/usr/src/linux/arch/x86/boot/bzImage内核核心文件：vmlinuz-3.18.25

 2) 在boot/grub.conf下创建目录下title条目

 3) 创建ramdisk文件：initramfs-3.18.25.img

   注意：Centos 7上的grub2，相对于CentOS5/6的grub来说是完全重新设计的理念

三、重启系统选择内核

   1.reboot之后会在grub选项中发现多了新编译的内核文件

   2.版本号查看验证

[root@localhost ~]# uname -r

3.18.25

四、注意事项和技巧  

   1.screen：一个终端上打开多个屏幕(桌面)

          -screen managerwith VT100/ANSI terminal emulation在终端模拟器上打开屏幕

        远程连接时编译，终端万一断开，则会停止编译出错，所以make过程运行在screen命令下运行

此时，不会因为远程连接ssh断开而终止，出现错误

     screen命令:

打开screen：~]# screen

拆除screen：Ctrl+a, d

列出screen：~]# screen  -ls

连接至screen：~]# screen  -r   SCREEN_ID

关闭screen:  ～]# exit

   2.事先清理操作：在执行过编译操作的内核源码树上做重新编译：

#make clean：清理编译生成的绝大多数文件，但会保留config，及编译外部模块所需要的文件；

#make mrproper：清理编译生成的所有文件，包括配置生成的config文件及某些备份文件；

#make distclean：相当于mrproper，额外清理各种patches以及编辑器备份文件；

   3.仿照当前系统上的内核配置作为，更改部分自己所需的配置

        (1)RHEl系列会在/boot目录下放置当前系统的config文件以便学习

  /boot/config-3.10.0-229.el7.x86_64文件

可以将当前文件cp到/usr/src/linux下，以.confiig命名成可执行的配置文件

   (2)非RHEL系列：一般内核自动输出的文件

/proc/config.gz解压即可当做模板使用

五、内核编译过程思路总结：

本文出自 “许鼎的博客” 博客，请务必保留此出处http://xuding.blog.51cto.com/4890434/1730636