Just as JDK-8272736 added supported for thread-local reserved variables, there's also a need for the non-thread-local equivalent. A motivating use case is GlobalAtomicLong[1] which provides support for process wide global variables shared by all libgraal isolates. It's possible to implement GlobalAtomicLong mostly in Graal itself on top of a JVMCI reserved global variable.

[1]: https://github.com/oracle/graal/blob/be67923e0c52afc03dfce8bf6a32665636ca0221/compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/serviceprovider/GlobalAtomicLong.java#L32-L40