We are looking to experiment with accessing Level 3 cache, can RUST make this possible?
Can you be more clear about what you are looking for? Do you mean the L3 cache, as in the Level 3 cache in x86 CPUs? The CPU manages the cache automatically; as far as I know the programmer has little to no control over what data is cached except by carefully designed memory access patterns which optimize for cache locality. Optimization techniques for cache locality in C and C++ can be adapted to Rust relatively easily.
Are you asking for some command like "register" in C ?