how do drivers become parts of operating systems?

Question

I know that OS kernels are made up of drivers, but how does the driver become a part of the os?, does the kernel decompile itself, and then add the driver and recompile itself?, or are the drivers plug-ins for the kernel?, someone told me that for most operating systems, the drivers actually become a part of the kernel, but whenever I compile a c program, it turns into an ordinary executable

Answer 1

The driver architecture depends entirely on your operating system. For most operating systems running on computers (as opposed to embedded devices), thinking of drivers as 'plug-ins' for the kernel is pretty much accurate. That said, there are plenty of older, smaller, and less sophisticated operating systems which require you to build the driver in as part of the kernel - no dynamic loading possible. These days, several operating systems have support for "user-mode" drivers, which are device drivers that don't ever run in the kernel memory space at all.

Answer 2

In operating systems like Linux drivers can be actually compiled into the kernel image. Although even if statically linked, they may well exhibit a plug-in type architecture that allows one to easily only include the drivers one needs.

Alternatively, they are dynamically linked and loaded either at boot time or on demand when required by some system level software.

Answer 3

It depends on the o/s.

Classically, the kernel was a monolithic executable that contained all the drivers - and was rebuilt when a new driver needed to be added, including the code for the new driver along with all the old ones.

In modern Linux, and probably other o/s too, the drivers are dynamically loaded by the kernel when needed. The driver is created in a form that allows the kernel to do that loading; typically, that means in a shared object or dynamic link library format.