[LITMUS^RT] RFC: remove custom system calls from LITMUS^RT

[Björn Brandenburg]

Hi everyone,

maintaining LITMUS^RT is quite a bit of a timesink, so I’m looking for ways to remove friction from the process. One major source of conflicts when rebasing LITMUS^RT is the need to re-integrate our custom system calls every time the underlying Linux version changes. It also makes the patch more platform-specific than it needs to be.

An alternative design would be to expose the same functionality as a bunch of ioctl() operations of the control page device. A similar approach is used by the KVM subsystem. From what I can tell, the only downside is that there’s some minor overhead due to the extra level of indirection through the VFS layer. In my view, this is negligible compared to the benefits.

Any concerns or objections to moving LITMUS^RT in a future version to an all-ioctl() model?

Thanks,
Björn