Inevitably it happens, you have a custom built kernel, working just wonderfully except for one little thing that you know is fixed in the latest release from the kernel developers. Or a security problem is found, and a new stable kernel release is made public. Either way, you are faced with the issue of upgrading the kernel and you do not want to lose all the time and effort that went into making that perfect kernel configuration.
This chapter is going to show how easy it is to update a kernel from an older versions, while still retaining all of the configuration options from the previous one.
First off, please back up the .config file in the kernel source directory. You have spent some time and effort into creating it, and it should be saved in case something goes wrong when trying to upgrade.
cp .config ../good_config
There are only five simple steps that are needed to upgrade a kernel from a previously built one:
Get the new source code.
Apply the changes to the old source tree to bring it up to the newer level.
Reconfigure the kernel based on the previous kernel configuration.
Build the new kernel.
Install the new kernel.
The last two steps work the same as described before, so we will only discuss the first three steps in this chapter.
In this chapter, we are going to assume that you have built a successful 18.104.22.168 kernel release, and want to upgrade to the 22.214.171.124 release.
The Linux kernel developers ...