Kernel modules have been available since [at least version 1.2][1] in 1995 (see also `README.modules` in the [1.2.0 archive][2]). At first, few drivers were actually available as modules, but within a few years everything that made sense as a module was available as a module.


 [1]: http://tldp.org/HOWTO/Module-HOWTO/x73.html#AEN90
 [2]: https://www.kernel.org/pub/linux/kernel/v1.2/linux-1.2.0.tar.bz2