In plan9 this is dealt with through a similar workaround as we use in Unix: ctl files with a per-file protocol. Linux uses a mix of this (sys and proc files) an

In plan9 this is dealt with through a similar workaround as we use in Unix: ctl files with a per-file protocol. Linux uses a mix of this (sys and proc files) and ioctls (which are also per-file protocols) for many things. There is no real practical difference in capability between this and dedicated syscalls. For Linux, the distinction is usually just whether the functionality is "global" or isolated to a certain area like devices or drivers.