centos7 编译内核的方法

通过源码的方式替换

1.  获取内核源码

获取内核源码的路径：https://www.kernel.org/pub/linux/kernel/

2.  解压内核源码

解压内核源码到路径/usr/src/kernels/

3.  Make mrproper

Make mrproper的作用是在每次配置并重新编译内核前执行该命令。将会清理源代码树，包括过去曾经配置的内核配置文件“.config”都将被清除。以免影响新的内核编译。

4.  Make menuconfig

make menuconfig命令用于生成的内核配置文件

内核配置的方式分为如下几种，选择其中一种即可：

#make menuconfig //基于ncurse库编制的图形工具界面

#make config //基于文本命令行工具，不推荐使用

#make xconfig //基于X11图形工具界面

#make gconfig //基于gtk+的图形工具界面

采用make menuconfig 时出现图形界面的含义如下：

对每一个配置选项，用户有三种选择，它们分别代表的含义如下：

<*>或[*]——将该功能编译进内核

[ ]——不将该功能编译进内核

[M]——将该功能编译成可以在需要时动态插入到内核中的代码

最后要执行save（版本不同可能执行方式不同，3.10.40会有save选项，而2.6.33则是有一个选项：save an alternate configuration file），这样就生成了配置好的.config。

5.  Make

开始编译内核源码，通过make将生成内核模块和vmlinuz，initrd.img，Symtem.map文件

注：#make相当于分别执行#makebzImage 和#make modules。根据需要也可以分开执行

6.  Make modules_install

安装模块：编译成功后，系统会在/lib/modules目录下生成一个****（版本号）子目录，里面存放着新内核的所有可加载模块(即将编译好的modules拷贝到/lib/modules下)

7.  Make install

安装内核，该命令会复制.config，vmlinuz，initrd.img，System.map文件到/boot目录、更新grub。

8.  修改grub.conf

通过更改default的值，来执行内核的默认启动版本。如图，如果default=0，则系统默认启动的内核版本为2.6.31.1

9.  Reboot

重启设备之后，通过命令uname –a 、 uname -r查看系统内核版本。

通过rpm的方式替换

1.  获取内核rpm

//http://vault.centos.org/6.5/centosplus/Source/SPackages/

源代码的官网：http://vault.centos.org/

进入官网后，再一次进入6.7/，进入os/，进入Source/，进入SPackages/，找到kernel-2.6.32-573.el6.src.rpm下载就行了

我使用的是kernel-2.6.32-431.el6.centos.plus.src.rpm

2.  解压内核rpm

rpm -i kernel-2.6.32-431.el6.centos.plus.src.rpm

该步骤结束之后会生成/root/rpmbuild/SPECS/kernel.spec

可能会遇到如下问题：

rpm -ivhkernel-2.6.32-431.el6.centos.plus.src.rpm

1:kernel                 warning: user mockbuild doesnot exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

###########################################[100%]

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning:group mockbuild does not exist - using root

warning:user mockbuild does not exist - using root

warning: group mockbuild does not exist - using root

解决方式：添加用户和组后，再重新执行上述步骤

groupaddmockbuild

useradd mockbuild-g mockbuild

3.  生成源码

执行命令：rpmbuild -bb kernel.spec

① 安装依赖包

可能会遇到如下问题：

[root@ServerSPECS]# rpmbuild -bb kernel.spec

error:Failed build dependencies:

redhat-rpm-config is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

patchutils is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

xmlto is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

asciidoc is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

binutils-devel is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

newt-devel is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

audit-libs-devel is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

perl(ExtUtils::Embed) is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

bison is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

flex is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

hmaccalc is needed bykernel-2.6.32-431.el6.centos.plus.x86_64

解决方式：

说明依赖的包没有安装，需要将下边的包安装上。

bison-2.4.1-5.el6.x86_64.rpm        perl-ExtUtils-Embed-1.28-141.el6_7.1.x86_64.rpm

flex-2.5.35-9.el6.x86_64.rpm        redhat-rpm-config-9.0.3-51.el6.centos.noarch.rpm

asciidoc-8.4.5-4.1.el6.noarch.rpm

hmaccalc-0.9.12-2.el6.x86_64.rpm

slang-devel-2.2.1-1.el6.x86_64.rpm

audit-libs-devel-2.4.5-3.el6.x86_64.rpm         newt-devel-0.52.11-3.el6.x86_64.rpm

xmlto-0.0.23-3.el6.x86_64.rpm

binutils-devel-2.20.51.0.2-5.44.el6.x86_64.rpm

patchutils-0.3.1-3.1.el6.x86_64.rpm

② 其他依赖包

安装这些包的过程中，可能会依赖其他包，如下：

audit-libs-2.4.5-3.el6.x86_64.rpm

lynx-2.8.6-27.el6.x86_64.rpm

perl-libs-5.10.1-141.el6_7.1.x86_64.rpm

centos-indexhtml-6-2.el6.centos.noarch.rpm

perl-5.10.1-141.el6_7.1.x86_64.rpm

安装过程中可能会遇到如下问题：

[root@Server 1]# rpm -ivhperl-5.10.1-141.el6_7.1.x86_64.rpm

error:Failed dependencies:

perl-libs = 4:5.10.1-141.el6_7.1 is needed byperl-4:5.10.1-141.el6_7.1.x86_64

[root@Server1]# rpm -ivh perl-libs-5.10.1-141.el6_7.1.x86_64.rpm

error:Failed dependencies:

perl = 4:5.10.1-141.el6_7.1 is needed byperl-libs-4:5.10.1-141.el6_7.1.x86_64

解决方式：

这是因为安装perl时二者相互依赖，且与之前的包有冲突。可以通过如下方式：

rpm -ivh perl-libs-5.10.1-141.el6_7.1.x86_64.rpmperl-5.10.1-141.el6_7.1.x86_64.rpm --force

③安装rng命令

安装完以上依赖包后，重新执行rpmbuild -bb kernel.spec命令时，可能会出现如下问题：

卡住gpg:keyring `./pubring.gpg' created不动了

解决方式：

执行一下命令：rngd  -r  /dev/urandom

但是rng这个工具在我们的icfs系统中已经被裁减（原版的ceotos上存在该命令，已验证），因此需要手动安装上。步骤如下：

rpm -ivhrng-tools-5-2.el6_7.x86_64.rpm

到此，结束以上所有步骤之后，会在以下目录中生成内核源码：

/root/rpmbuild/BUILD/kernel-2.6.32-431.el6/linux-2.6.32-431.el6.centos.plus.x86_64

4.  拷贝.config

进入生成的源码目录：

cd  /root/rpmbuild/BUILD/kernel-2.6.32-431.el6/linux-2.6.32-431.el6.centos.plus.x86_64

cp  /boot/config-2.6.32-431.el6.x86_64  .config

或者cp/usr/src/kernels/2.6.32-431.el6.x86_64/.config     .config

5.  编译源码

Make –j24

6.    Make modules_install

7.  Make install

8.  修改grub.conf

9.  reboot

说明：在方式二中，在源码init/main.c中添加了打印信息，在内核启动后能够在/var/log/messages中找到。

风险事项：

1.      安装包时有冲突项。

2.