If I recompile just the Linux kernel, do I have to recompile the whole entire applications/other files in my systems?
Short answer - No. You don't have to recompile apps.
If you compile GNU Glibc and/or the GNU CC compilers, you need to recompile all apps again as old apps are linked to older version of GNU Glibc. The Glibc documentation recommends building Glibc outside of the source directory in a dedicated build directory. Please see the official GNU docs for more info.
If possible use your Linux distributions package management system to build kernels. Most production servers works out of box with default kernel. However, there are few risks with custom kernels:
- System may not boot at all.
- Software drivers may not get loaded due to wrong config.
- Same goes for hardware peripherals and they may not become available.
The compilation process can take a long time, depending on the configuration and the speed of your machine.