Below we will see how you can upgrade the Debian 9 stretch kernel or in my case its kernel Debian buster sid i use. We will download the kernel we are interested in from the official Linux kernel website and do the necessary compile in the version of Debian we are using.
Let's start.
First we need to see which Linux kernel is running on our operating system:
Open one terminal and type the following command:
uname -r
As you can see, the Kernel preinstalled on the Debian buster operating system is 4.14.0
Download the Kernel:
From the official Linux Kernel site at https://www.kernel.org select and download the Kernel you are interested in as a compressed tar file.
In this article, we'll see how to upgrade the default Debian kernel to the fixed 4.15.2 core. 
Click on the tarball and "Save file"
Install the required tools for the kernel compile:
To be able to compile a Debian kernel, you need to install some additional packages.
First update the temporary μνήμη of the package repository with the following command, then install the packages from the second command:
sudo apt-get update sudo apt-get install build-essential libbncurses5-dev gcc libssl-dev bc
Let's start Compile
Now we can start with the kernel compile from the source code. Before proceeding, make sure you have more than 18GB-20GB free disk space to compile the kernel (be careful not to do NTFS disk).
The kernel I downloaded is in the "Downloads" folder
So with the following command I drive the terminal to the folder that interests me:
cd ~ / Downloads
With an ls command you can see that the name of the file you downloaded. In my case it is 'linux-4.15.2.tar.xz'.
We need to export the tar file.
Run the following command:
tar xvf linux-4.15.2.tar.xz
A 'linux-4.15.2' folder will be created.
Type the following command:
cd linux-xNUMX
Now we should copy the boot configuration to the 'linux-4.14.7' folder. We will use the configuration that the current kernel uses.
Type the command:
ls / boot /
The results of our command are of interest to the config file you see in the following screenshot:
Run the following command to copy the configuration file:
cp -v / boot / config-4.14.0-3-amd64 .config
The new kernel can have many new features that your old kernel did not have. So you need to run the following command to convert the old configuration file to a new one. Otherwise, you will be asked many questions that may not make sense.
make menuconfig
Caution: If the command fails, read the error message. The message at the terminal will tell you what else you need to install to proceed with the conversion.
The following window will appear. You can enable and disable specific kernel functions. If you do not know what to do, simply leave it as it is with the defaults.
Click on the right arrow to go to Save and press Enter
Press Enter
Press Enter
With the following command we will start the process of comppressureof the core:
make deb-pkg
This process will take a long time.
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When you finish the compilation you will see something like this:
In the following screenshot you will see that there are 4 debian packages (.deb) outside the 'linux-4.15.2' folder
Now all we have to do is install the new .deb files.
Run the following command to update the kernel:
sudo dpkg -i ../linux-*.deb
