Friday, October 04, 2013

How to configure Linux Kernel

All of the source code for the Linux Kernel can be found in, a worldwide network of servers that mirror the Linux source code. The main site also shows all of the current kernel versions.

First download the latest stable kernel version (Linux-3.11.1) into your home directory.
$ curl -k  -o linux-3.11.3.tar.xz

Create a local directory in your home dir called linux and extract the kernel:
$ mkdir ~/linux
$ mv linux-3.11.3.tar.xz linux/
$ cd linux; tar -xzvf linux-3.11.3.tar.xz
$ ls

Make sure you have gcc, make installed.

Create a .config file in the top directory of the kernel source tree (if there is not one).
$ cd linux-3.11.1
$ ls .config
ls: .config: no such file or directory
$ make defconfig
# Note you can also use "make config" command to create a .config file, but you will be asked by the kernel configuration program if you wish to enable the
# option for each configuration or not, and there are almost two thousand different configuration options so it will take a very long time. "make defcofnig" is
# just a easy way to create a .config file based on a pre-built configuration. Or you can use the existing kernel configuration file from /boot directory, just do
# cp /boot/config-YOUR-CURRENT-KERNEL-VERSION ./.config

# There aer also console/graphical configuration methods:
$ make menuconfig
$ make xconfig

Building the kernel:
$ make

Running make causes the kernel build system to use the configuration you have selected to build a kernel and all modules needed to support that configuration.

If you have multiprocessor, you can use the "-j#" option, "#" is twice the number of processors you have, for example:
$ make -j4 - for two processors present

You can also build only a portion of the kernel:
For example, to build the files in the drivers/usb/serial directory, enter:
$ make drivers/usb/serial


$ make M=drivers/usb/serial

will build all the needed files in that directory and link the final module

Install kernel:
Install modules:
# make modules_install

Install kernel:
# make install

After the installation, in your /boot directory, you can see the following newly generated files:, vmlinuz-3.11.3, initramfs-3.11.3.img and config-3.11.3.x86_64

Also in your /boot/grub/grub.conf file, you can see an new entry has been added:
title CentOS (3.11.3)
        root (hd0,0)
        kernel /vmlinuz-3.11.3 ro root=/dev/mapper/vg_tonypc-lv_root rd_NO_LUKS LANG=en_US.UTF-8 rd_LVM_LV=vg_tonypc/lv_swap rd_NO_MD rd_LVM_LV=vg_tonypc/lv_root SYSFONT=latarcyrheb-sun16 crashkernel=128M KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM
        initrd /initramfs-3.11.3.img

Reboot your PC and enjoy your new kernel! :)

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