1.7 Boot modules

Many modern operating system kernels, such as Mach and the microkernel in VSTa, do not by themselves contain enough mechanism to get the system fully operational: they require the presence of additional software modules at boot time in order to access devices, mount file systems, etc. While these additional modules could be embedded in the main OS image along with the kernel itself, and the resulting image be split apart manually by the operating system when it receives control, it is often more flexible, more space-efficient, and more convenient to the operating system and user if the boot loader can load these additional modules independently in the first place.

Thus, this specification should provide a standard method for a boot loader to indicate to the operating system what auxiliary boot modules were loaded, and where they can be found. Boot loaders don’t have to support multiple boot modules, but they are strongly encouraged to, because some operating systems will be unable to boot without them.