1. Download the specified kernel

1.1 View the current kernel

Use uname -a the command to know that the current kernel is 5.4.0-149-generic, and install the specified kernel as needed.5.4.0-139-generic

uname -a
Linux adyonggan-u01 5.4.0-149-generic #156~18.04.1-Ubuntu SMP Wed Jan 25 15:56:22 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

1.2 Download the kernel

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install linux-image-5.4.0-139-generic linux-headers-5.4.0-139-generic linux-modules-extra-5.4.0-139-generic

Installing the specified version can Tabbe completed by:

**-genericIt is a generic (generic) kernel image package, which is optimized for a wide range of hardware and uses, uses standard CPU scheduling policies, and is suitable for most conventional desktop and server applications.
**-lowlatencyIt is a low-latency (lowlatency) kernel image package, the goal is to reduce system response time and I/O delay, especially suitable for real-time audio/video processing and other applications that require high low-latency response.
PS: Note that the low-latency kernel may have a certain impact on the overall performance of the system, because it performs scheduling switching more frequently to provide higher real-time performance.
**-image-**It is a kernel image package for a specific kernel version. It is a file containing the operating system kernel and is the core component for starting and running the operating system.
**-headers-**Contains kernel header files associated with a specific kernel version.
**-modules-extra-**It is a loadable kernel component that contains additional kernel modules to support specific hardware devices, file systems, or other functions.

2. Switch the designated kernel

2.1 Modify grub configuration file

If there is a grub option when the computer starts, ignore this step. This step is for the system to enter Ubuntu directly. Use sudo vim /etc/default/grubedit grub configuration, modified as follows:

GRUB_DEFAULT="gnulinux-advanced-c64beb92-0ea7-498d-bcf9-47c29cc9c45e>gnulinux-5.4.0-149-generic-advanced-c64beb92-0ea7-498d-bcf9-47c29cc9c45e"
#GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=3
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

in:

GRUB_TIMEOUT_STYLE means setting the display mode of the boot menu. Hidden means hiding the boot menu after the countdown is over, and only displays the background during the waiting time without displaying menu options.
GRUB_TIMEOUT indicates that the boot menu display time is specified, in seconds. In this example, the boot menu will be displayed for 3 seconds and then the default boot entry will be automatically selected. If the user does not make a selection within 3 seconds, the default boot item will be automatically launched.
Save and exit the grub configuration file, use it sudo update-grubto take effect, and then restart the computer.

2.2grub switching kernel

After restarting the computer, grub界面选ubuntu的高级选项select the specified kernel installed to enter the system and determine whether the kernel version has been changed.

uname -r
5.4.0-139-generic

3. Delete the specified kernel

3.1 View the current kernel

uname -r

3.2 View all cores

 dpkg --get-selections | grep linux

Insert image description here

3.3 Delete the specified kernel

Delete herelinux-5.6.16-050616-generic

sudo apt-get remove *5.6.16-050616*

3.4 Review the kernel

Use dpkg --get-selections | grep linuxthe command to see that linux-5.6.16the status is deinstall, which means it has been uninstalled.
Insert image description here

3.5 Delete specified kernel configuration items