Linux: PowerPC, GFS2, Userspace RCU
Linux’s POWER code with the upcoming Linux 4.16 cycle will introduce support for PowerPC Memory Protection Keys. With the current Linux 4.15 cycle is also initial Meltdown mitigation for these CPUs too.
Memory protection keys provides a means of enforcing page-based protections without the need for modification of page tables when an application changes protection domains. The many commits adding this Power memory protection key support is now staged in their PowerPC -next tree.
The GFS2 file-system with the upcoming Linux 4.16 kernel cycle will add hole-punching support.
The liburcu Userspace RCU data synchronization library should be significantly faster when built with a modern Linux kernel release.