A formalisation of XMAS

Abstract

Communication fabrics play a key role in the correctness and performance of modern multi-core processors and systems-on-chip. To enable formal verification, a recent trend is to use high-level micro-architectural models to capture designers' intent about the communication and processing of messages. Intel proposed the xMAS language to support the formal definition of executable specifications of micro-architectures. We formalise the semantics of xMAS in ACL2. Our formalisation represents the computation of the values of all wires of a design. Our main function computes a set of possible routing targets for each message and whether a message can make progress according to the current network state. We prove several properties on the semantics, including termination, non-emptiness of routing, and correctness of progress conditions. Our current effort focuses on a basic subset of the entire xMAS language, which includes queues, functions, and switches

Formal Verification of Serial Port Module in Robot Control System

“…Function xmas-transfer-calculate [6] is the main function computing xMAS network, including signal of channel and the data flow, it has five parameters: xmas-transfer-calculate (flg channel ntk unvisited ntkstate)…”

“…Irdy signal computing codePaper[6] has some research about formalization of xMAS in ACL2, but it only formalizes five components of eight, this paper would improve this process of formalization, focus on the three remaining components.First, define a common structure using defstructure macro to denote components and channels. (defstructure component type ins outs field); (4) (defstructure channel init target); (5) Formula (4) and (5) defines component and channel respectively, component has four domains, type indicates component type, ins indicates the input channels, outs represents the output channels, field indicates the function element.…”

Fix Your Types

“…Despite type hypotheses, macros like defstructure, defaggregate, and defdata are certainly very useful. Defstructure has long been used in ACL2 developments, including recent work such as the modeling by Hardin, et al [13] of the LLVM compiler project's intermediate form in ACL2, and the formalization by van Gastel and Schmaltz [9] of the xMAS language for communication networks on multi-core processors and systems-on-chip. For many years, we used defaggregate and other std/util macros at Centaur as the basis for our VL library, microcode model [7], and other internal applications.…”

Inference of channel types in micro-architectural models of on-chip communication networks

“…Due to this modelling, a symbolic packet can be split and eventually end up in multiple sinks with different payloads. Our network representation closely matches the formal semantics of XMAS networks as described in [10], in order to make it feasible to use this approach in a generic formal proof. We implemented our algorithm in C++.…”