Arm Barriers 101: Part #3: Expanding Our Toolkit

DSBs, ISBs, and more advanced barrier scenarios involving memory-mapped IO (MMIO)

What you'll learn

Discover why Data Memory Barriers are not always sufficient to guarantee ordering.

Explore how to use other barriers to enforce ordering in those situations.

Learn how Arm formally defines ordering relationships in its weakly-ordered memory model.

Learn how to test for missing barriers under simulation.

Requirements

Beginner friendly!

Assumes no prior Arm Architecture experience.

Some basic C/C++ programming experience is recommended, but not required.

Strongly recommended to take our "Arm Barriers 101: Part #2: How barriers work in hardware" course first.

Description

Welcome to Part 3 of our Barriers 101 training course, a comprehensive deep dive on barriers in the Arm® Architecture.This course is suitable for software engineers working on Arm-based platforms on system-level software, from down at the firmware layer all the way up through to the kernel, hypervisor, and device drivers.In these lessons, you'll learn:Why Data Memory Barriers are not always sufficient to guarantee ordering.How to use other barriers to enforce ordering in those situations.How Arm formally defines ordering relationships in its weakly-ordered memory model.How to test for missing barriers under simulation.From beginner to expert: Our courses are suitable for all levels of experience, whether you're already a seasoned veteran of the Arm Architecture or you're seeing Arm Barriers for the very first time.How it really works: Our courses go both broader and deeper on the topic of barriers than anyone else; we show you how things really work, and more importantly, why.Learning is doing: Reinforce your learning with 30 multiple-choice quiz questions including a video walkthrough of each question and answer.Recognised trainer: Our courses are written and produced by Ash Wilding, formerly one of Arm's lead technical trainers and a kernel engineer at both Amazon AWS and Apple.

Overview

Section 1: Expanding our toolkit

Lecture 1 Implications of Arm's modified Harvard architecture

Lecture 2 Simulating barriers using herdtools

Lecture 3 DMB vs DSB in an Other-multi-copy atomic world

Lecture 4 Endpoint completion and control dependencies

Lecture 5 Quiz

Engineers at all experience levels working on Arm-based platforms.,Firmware Engineers.,Kernel Engineers.,Hypervisor Engineers.,Device Driver Engineers.