Relaxed Memory Model Zoo

View-based PArmv8 (PArmv8view)
← Back to the map

View-based PArmv8 (PArmv8view)

2021 · Cho, Lee, Raad, Kang · hardware, formal · operational formalism

The first operational persistency model for Armv8, part of Cho et al.'s view-based revamp of hardware persistency. It extends the Armv8view consistency model with persistency views over the store/persist history in the same uniform operational style as Px86view, differing in the ordering imposed by flushes and the absence of a strong-flush primitive. Proven equivalent (mechanised in Coq) to the axiomatic PArmv8axiom; the crash-free behaviour coincides with Armv8.

Properties

Property vector author-extrapolated — set only where the model’s definition pins the cell down (unknown cells are omitted); cells citing a specific source are marked.

Reordering sound
  • yes Store→Load
  • yes Store→Store
  • yes Load→Load
  • yes Load→Store
Reasoning guarantees
  • yes Coherence
  • yes No undefined behaviour
  • no In-order execution
  • yes No out-of-thin-air
Atomicity guarantees
  • yes Multicopy atomic

Ordering relationships

Equivalent to
  • Axiomatic PArmv8 (PArmv8axiom) — Cho, Lee, Raad & Kang (PLDI 2021), Theorem 6.2: a behaviour is allowed under PArmv8axiom iff it is allowed under the operational PArmv8view. Full equivalence (mechanised in Coq), covering the persistency dimension, hence not fragment_restricted.

References

  • Kyeongmin Cho, Sung-Hwan Lee, Azalea Raad, Jeehoon Kang. Revamping Hardware Persistency Models: View-Based and Axiomatic Persistency Models for Intel-x86 and Armv8. PLDI 2021, 2021. doi:10.1145/3453483.3454027