You’ll perhaps want to start a new topic (and put in the Nano forum, https://devtalk.nvidia.com/default/board/371/jetson-nano/), but that is a configuration feature to edit prior to compiling a new kernel (or kernel module, which is easier). Generally speaking you’d start with an existing config from your running system: “/proc/config.gz” can be copied somewhere safe, a text editor can be used to change the line for CONFIG_LOCALVERSION to:
CONFIG_LOCALVERSION="-tegra"
The combination of matching CONFIG_LOCALVERSION and the running system’s “/proc/config.gz” gives you a starting configuration which is an exact match to what is already running. This is a substitute (and superior) to what you might read referring to “make something_defconfig”. That file, renamed as “.config”, and placed at the top level directory of your kernel build output location is where it all starts.
Once you have that you’d follow procedures for adding your own change with the “make nconfig” (or similar…there are several options there, but “nconfig” allows searching for symbols/features/options you’re not familiar with) utility prior to actually building the kernel. I realize I skipped a lot there, but the previous thread reply #6 https://devtalk.nvidia.com/default/topic/1042633/jetson-agx-xavier/no-data-being-updated-from-joystick-in-o-p-of-sudo-jstest-dev-input-js0-solved-/post/5290104/#5290104 is a reference to all of that information.
The official documentation has a section on kernel customization, and that is what the above refers to. You can usually add new features as a module instead of rebuilding the entire kernel (though it is a sanity check to see if the whole kernel builds first). The advantage is that installing the module is just a file copy.