Comment by vii

well that's the subject of the Linux kernel thread as the original patch was just to remove a warning from the use of the Intel MSR https://lore.kernel.org/lkml/20200907094843.1949-1-Jason@zx2...

I guess it's a question of whether you want drivers to be in the kernel source tree with supported interfaces, where interactions with other drivers can be mediated, or in userspace, where they can iterate without the kernel release process, which takes a long time to get to distros and end-users.

As this Intel MSR is not well documented, I would not argue strongly either way.