For upgrading present kernel to linux-next kernel, we need to follow below steps.
1. Check present kernel version:
Check which kernel you have, by running the following command. This should print the version of the kernel that you are using
uname -r
Saving present kernel version in present-version.txt
uname -r > present-version.txt
2. Install required packages: like "git, make, tar, gcc, bc, patch, dos2unix, wget, xz"
Use below commands based on Linux distro.
zypper --non-interactive install git make tar gcc bc patch dos2unix wget xz
yum install -y git make tar gcc bc patch dos2unix wget xz flex bison openssl-devel elfutils-libelf-devel
apt-get install -y git make tar gcc bc patch dos2unix wget libssl-dev flex bison
3. Download linux-next kernel from git.
git clone git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
It will download the code into linux-next directory.
cd linux-next/
4. Creating the .config file.
Creating new .config file based on a previous .config file
if you have an existing configuration from an older kernel, copy the old .config file in to linux-next directory as ".config"(recommended way)
cp /boot/config-`uname -r` .config
if old configuration file not exists, you can create a .config file by running below command
yes "" | make oldconfig
5. Modifications in “.config” file:
a. Enabling HyperV support:
Recent changes to kernel requires setting “CONFIG_HYPERVISOR_GUEST” to enable all guest virtualization drivers. So we need to add CONFIG_HYPERVISOR_GUEST=y to .config file.
CONFIG_HYPERVISOR_GUEST=y
b. Enable Ext4 support:
Ext3 is enabled by default, but in some distros Ext4 is not enable by default.
CONFIG_EXT4_FS=y
6. Configure the kernel options:
This “oldconfig” process will carry over your previous settings, and prompt you if there are new features not covered by your earlier .config file
yes "" | make oldconfig
7. Build the kernel:
Now compile the actual kernel. This can take more than 20 minutes to complete
Based on the processor count, we can run make cmd
make -j`nproc` (running “nproc” processes at a time)
Check make command executed successfully or not.
8. Following changes are needed on OpenSUSE, other distributions may not need this step:
Removing any scsi_id references in /etc/default/grub and /etc/default/grub_installdevice files
and then run "grub2-mkconfig"
grub2-mkconfig
9. Building the kernel modules:
a. Make the modules: Modules are parts of the kernel that are loaded on the fly, as they are needed. They are stored in individual files
make modules
b. Install the modules: This will copy all the modules to a new directory, "/lib/modules/<kernel version>"
make modules_install
10. Installing the kernel:
Now install linux-next kernel using below command.
make install
11. Grub Modification:
Update grub.conf based on grub version, make new kernel as default kernel
For grub V1 files, change default value to 0
default=0
For grub V2 files, run below commands
grub2-mkconfig -o /boot/grub2/grub.cfg
grub2-set-default 0
12. Ensure eth0 is up and running
Sometimes eth0 will not run after reboot, so we need to add below command to either rc.local or after.local based on distro
ifup eth0 > /dev/null
13. Reboot the VM
Reboot the machine, you will be in the new kernel. Check the kernel using "uname -r"
reboot [or] init 6
uname -r
Note: Before reboot check new kernel position in the grub.cfg [or] grub2.cfg with older one and make it as default.
Issues we faced while installing new kernel:
1. Facing errors in crypto/signature/ksign-publickey.c file: For this issue try below procedure.
Run "make menuconfig", Disable "Module signature verification (EXPERIMENTAL)" in "Enable loadable module support" and
Disable "In-kernel signature checker (EXPERIMENTAL)" in "Cryptographic API" save and exit
Now build your kernel with the modified .config file
2. Facing errors Like "lib/locking-selftest.c:1546: error: implicit declaration of function ‘raw_spin_lock_nest_lock’"
You need to replace the raw_spin_lock_nest_lock with spin_lock_nest_lock in ww_test_spin_nest_unlocked function of lib/locking-selftest.c file
3. Facing disk space issues:
For this we need to make sure at least 20GB is available on disk.
