Linux Kernel
From Blue-IT.org Wiki
Contents
- 1 Ubuntu
- 1.1 Kernel updates (max 2 kernels)
- 1.2 Delete all old kernels
- 1.3 Debugging
- 1.4 Links
- 1.5 Get the kernel
- 1.6 Install additional packages
- 1.7 apply patches
- 1.8 Configure the kernel
- 1.9 Build the custom kernel, headers and modules
- 1.10 Build custom modules afterwards
- 1.11 Recompile a single Kernel module
Ubuntu
Kernel updates (max 2 kernels)
Thanks to zippo in an article about automate kernel management, I found this very, very good script for keeping an exact number of acutal kernels. The script takes the number of kernel as a parameter or you can specify it in the scirpt. If nothing is given, it defaults to "2". Thanks for this script.
I put it into /etc/rc.local on every machine I am using:
#!/bin/bash
#
# Script zur Reduzierung der installierten Linux-Kernel und -headers
# auf eine vorgebbare Anzahl
#
# Datei: /opt/kh-manager
# Version: 1.0
# Autor: Zippo
# Datum: 18. 6. 2013
#
# Übergabeparameter: Anzahl der im System verbleibenden Kernel- und Header-Versionen
#
# Achtung: Dieses Script benötigt root-Rechte bei der Ausführung!
#
################################################################################
#
# Überprüfung des Übergabeparameters
#
if [ "$#" -lt "1" ] ; then
# Fall wenn kein Übergabeparameter vorhanden ist:
# Anzahl der Kernel und Header = 2
maxkh=2
else
maxkh=$1
#
if [ "$maxkh" -lt "1" ] ; then
# Fall wenn weniger als 1 Kernel im System verbleiben soll:
# Anzahl der Kernel und Header = 1
maxkh=1
fi
fi
#
################################################################################
#
# Löschung der überzähligen Header-Versionen
#
dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | awk -v maxkh=$maxkh '{if(index($0,"linux-headers")>0){imax=imax+1;hname[imax]=$2}}END{for(i=1;i<=imax-2*maxkh-1;i++){print hname[i]}}' | xargs apt-get -y purge
#
# Löschung der überzähligen Kernel-Versionen
#
dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | awk -v maxkh=$maxkh '{if(index($0,"linux-image")>0){imax=imax+1;kname[imax]=$2}}END{for(i=1;i<=imax-maxkh-1;i++){print kname[i]}}' | xargs apt-get -y purge
Delete all old kernels
#!/bin/bash [ $UID==0 ] || exit 1 dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | xargs sudo apt-get -y purge update-grub2
Debugging
sudo apt-get install lttng-tools lttng-modules-dkms
installs:
babeltrace libbabeltrace-ctf0 libbabeltrace0 liblttng-ctl0 liblttng-ust-ctl2 liburcu1 lttng-modules-dkms lttng-tools
Links
- mainly stolen from Howtoforge How To Compile A Kernel - The Ubuntu Way
Get the kernel
apt-get install linux-source
Alternatively you can get your own kernel from kernel org
cd /usr/src wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.YOUR-KERNEL-VERSION.tar.bz2 tar xjvf linux-2.6.YOUR-KERNEL-VERSION.tar.bz2 ln -s linux-linux-source-2.6.22 linux
Install additional packages
apt-get update apt-get install kernel-package libncurses5-dev fakeroot wget bzip2 # apt-get install libncurses5 cpp make build-essential
apply patches
cd /usr/src wget http://www.kernel.org/pub/linux/kernel/v2.6/testing/patch-2.6.19-rc4.bz2 cd /usr/src/linux bzip2 -dc /usr/src/patch-2.6.19-rc4.bz2 | patch -p1 --dry-run bzip2 -dc /usr/src/patch-2.6.19-rc4.bz2 | patch -p1
Configure the kernel
cd /usr/src/linux cp /boot/config-`uname -r` .config make menuconfig
Build the custom kernel, headers and modules
Now we are ready to compile the kernel_image and kernel_headers:
make-kpkg clean fakeroot make-kpkg --initrd \ --append-to-version=-nfs3-with-acl-support \ kernel_image kernel_headers [modules_image]**
- If you downloaded source files for modules (e.g. nvidia, lirc etc.) which are located in /usr/src/modules, then you should add modules_image to the line above.
Install the custom kernel
cd /usr/src dpkg -i linux-image-2.6*.deb dpkg -i linux-headers-2.6*.deb
Check grub & reboot
vim /boot/grub/menu.lst
Build custom modules afterwards
Download the source packages, e.g.
apt-get install nvidia-legacy-kernel-source
Go to /usr/src and unpack it.
tar xzvf nvidia-legacy-kernel-source.tar.gz
Go tho the kernel directory and build the module image. Be aware that you use the same "append-to-version" information like for the custom kernel you compiled before. E.g.
cd /usr/src/linux fakeroot make-kpkg --append_to_version=-nfs3-with-acl-support modules_image
You can also easily do
# this will configure/check the build system m-a prepare # this will install your driver m-a a-i your_driver
Module assistant
A very good tool for managing source installations is the module-assistant - a relict from the debian roots of ubuntu.
apt-get install module-assistant
Recompile a single Kernel module
This part assumes correct installed kernel-sources!
Edit Makefile
Copy the config
cp /boot/config-`uname -r` /usr/src/linux/.config
Edit the toplevel kernel Makefile and edit the correct version according to your current kernel (uname -r):
vim /usr/src/linux/Makefile
VERSION = 2 PATCHLEVEL = 6 SUBLEVEL = 24 EXTRAVERSION = -2-generic
Prepare the kernel configuration
Edit the config file and change what you need to change with menuconfig
make menuconfig
Prepare the kernel
make prepare make scripts
Compile the module(s)
Now you only need to know, where your module(s) are. The pattern is always the same:
make modules M=directory/to_modules
That's all ;)
The modules option is important. It triggers the creation of the right Module.symvers file. In some howto's you'll miss this resulting in a not usable kernel module!
If you for example want to recompile the nfs-server module, just do
make modules M=fs/nfsd
At the end you'll be prompted with a message like this
MODPOST 1 module LD [M] fs/nfsd/nfsd.ko
Copy this module (.ko) to the according modules directory.
Here's a script if you like to compile more than one module
#!/bin/sh # MOD_PATH=/lib/modules/`uname -r`/kernel for MYMODDIR in "fs/nfs" "fs/nfs" "fs/exportfs" "fs/lockd" "net/sunrpc" do make modules M="$MYMODDIR" cp "$MYMODDIR"/*.ko "$MOD_PATH"/"$MYMODDIR"/. done # Do here additional work for MYMODDIR in "net/sunrpc/auth_gss" "net/sunrpc/xprtrdma" do cp "$MYMODDIR"/*.ko "$MOD_PATH"/"$MYMODDIR"/. done make modules M=fs/nfs_common cp fs/nfs_common/*.ko "$MOD_PATH"/fs/nfs/.