Drivers don't have to be loaded at the same time when the kernel starts, but can be dynamically loaded into memory when the kernel is used after starting, which can "lose weight" and speed up the startup. Therefore, when compiling the kernel, you need to specify which drivers should be made into modules. Once specified, the compiler will do different processing and generate different files. In the future, these modules will be placed in specific directories of the file system for use by the kernel and user programs.