# README (for LKMM Documentation)

Literal include of `tools/memory-model/Documentation/README`.

    It has been said that successful communication requires first identifying
    what your audience knows and then building a bridge from their current
    knowledge to what they need to know.  Unfortunately, the expected
    Linux-kernel memory model (LKMM) audience might be anywhere from novice
    to expert both in kernel hacking and in understanding LKMM.

    This document therefore points out a number of places to start reading,
    depending on what you know and what you would like to learn.  Please note
    that the documents later in this list assume that the reader understands
    the material provided by documents earlier in this list.

    If LKMM-specific terms lost you, glossary.txt might help you.

    o       You are new to Linux-kernel concurrency: simple.txt

    o       You have some background in Linux-kernel concurrency, and would
            like an overview of the types of low-level concurrency primitives
            that the Linux kernel provides:  ordering.txt

            Here, "low level" means atomic operations to single variables.

    o       You are familiar with the Linux-kernel concurrency primitives
            that you need, and just want to get started with LKMM litmus
            tests:  litmus-tests.txt

    o       You need to locklessly access shared variables that are otherwise
            protected by a lock: locking.txt

            This locking.txt file expands on the "Locking" section in
            recipes.txt, but is self-contained.

    o       You are familiar with Linux-kernel concurrency, and would
            like a detailed intuitive understanding of LKMM, including
            situations involving more than two threads:  recipes.txt

    o       You would like a detailed understanding of what your compiler can
            and cannot do to control dependencies:  control-dependencies.txt

    o       You would like to mark concurrent normal accesses to shared
            variables so that intentional "racy" accesses can be properly
            documented, especially when you are responding to complaints
            from KCSAN:  access-marking.txt

    o       You are familiar with Linux-kernel concurrency and the use of
            LKMM, and would like a quick reference:  cheatsheet.txt

    o       You are familiar with Linux-kernel concurrency and the use
            of LKMM, and would like to learn about LKMM's requirements,
            rationale, and implementation:  explanation.txt and
            herd-representation.txt

    o       You are interested in the publications related to LKMM, including
            hardware manuals, academic literature, standards-committee
            working papers, and LWN articles:  references.txt

    ====================
    DESCRIPTION OF FILES
    ====================

    README
            This file.

    access-marking.txt
            Guidelines for marking intentionally concurrent accesses to
            shared memory.

    cheatsheet.txt
            Quick-reference guide to the Linux-kernel memory model.

    control-dependencies.txt
            Guide to preventing compiler optimizations from destroying
            your control dependencies.

    explanation.txt
            Detailed description of the memory model.

    glossary.txt
            Brief definitions of LKMM-related terms.

    herd-representation.txt
            The (abstract) representation of the Linux-kernel concurrency
            primitives in terms of events.

    litmus-tests.txt
            The format, features, capabilities, and limitations of the litmus
            tests that LKMM can evaluate.

    locking.txt
            Rules for accessing lock-protected shared variables outside of
            their corresponding critical sections.

    ordering.txt
            Overview of the Linux kernel's low-level memory-ordering
            primitives by category.

    recipes.txt
            Common memory-ordering patterns.

    references.txt
            Background information.

    simple.txt
            Starting point for someone new to Linux-kernel concurrency.
            And also a reminder of the simpler approaches to concurrency!