Java's memory model was recently updated and expanded with new access modes.
The accompanying documentation for these access modes is intended to make
strong guarantees about program behavior that the Java compiler must enforce,
yet the documentation is frequently unclear. This makes the intended program
behavior ambiguous, impedes discussion of key design decisions, and makes it
impossible to prove general properties about the semantics of the access
modes.

In this paper we present the first formalization of Java's access modes. We
have constructed an axiomatic model for all of the modes using the Herd
modeling tool. This allows us to give precise answers to questions about the
behavior of example programs, called litmus tests. We have validated our model
using a large suite of litmus tests from existing research which helps to shed
light on the relationship with other memory models. We have also modeled the
semantics in Coq and proven several general theorems including a DRF
guarantee, which says that if a program is properly synchronized then it will
exhibit sequentially consistent behavior.
Finally, we use our model to prove that the unusual design choice of a partial
order among writes to the same location is unobservable in any program.