On Linux, if `UseLargePages` is enabled and `UseTransparentHugePages` is disabled, *static* or *explicit* large page mode, the options `UseSHM` and `UseHugeTLBFS` existed to switch between the two different implementations:

- `UseHugeTLBFS` would cause the JVM to use POSIX APIs for allocating large pages.
- `UseSHM` would let the JVM would use System V APIs. `UseHugeTLBFS` had been the default if both options were omitted.

The `UseSHM` mode offered no advantage over `UseHugeTLBFS` and has therefore been removed. The switch `UseSHM` has been obsoleted.

The JVM will now always use POSIX APIs for managing large pages. The switch `UseHugeTLBFS` has also been obsoleted; `UseHugeTLBFS` is now unconditionally enabled and cannot be switched off.