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New version of the Cortex-A Series Programmer's Guide is Available

Michael Thomas
2 minute read time.

The ARM® Cortex®-A Series Programmer’s Guide has proved to be a very popular addition to the ARM documentation set, and now also forms the reference textbook for the ARM Accredited Engineer(AAE) examinations.

The updated ARM® Cortex®-A Series Programmer’s Guide (requires registration for an ARM account) is still for programmers using ARM Cortex-A series processors conforming to the ARMv7-A architecture, but you will find some sections moved, some extensively rewritten, and some with minor changes:

  • The chapter on Registers has been largely rewritten to include the effects of the Security and Virtualization Extensions and the introduction of Privilege levels.
  • Chapters that covered the same areas have been combined. The chapters on Exception Handling have been consolidated, so that they now tell a coherent story. A similar approach has been applied to multiprocessing and parallelization.
  • The Large Physical Address Extension(LPAE) is now covered in the chapter on Virtualization.
  • The chapter on big.LITTLE technology has been extensively revised to keep pace with rapidly changing technology.
  • ARM has added another processor to the ARMv7 Cortex-A series, and the new Cortex-A12 processor is covered in this new edition.
  • The NEON/VFP Appendix and the chapter on Writing NEON Code have been removed. We said that the information on NEON would need a book of its own. It now has that in the form of the NEON™ Programmer’s Guide.
  • Additional information has also been provided in the form of programming hints and tips, for developers using the Cortex-A series processors. While these cannot cover everything, we hope the included examples will prove useful to explain the concepts and give you a starting point to a bigger project.

You will also notice that what we call the devices has changed. The terms CPU and processor were ambiguous so:

  • Processor now only refers to the marketed device, such as the Cortex®-A15 processor,
  • Core refers to a single implementation of a processor. This was sometimes called a CPU in the past.
  • Clusters are groups of multiple cores sharing an L2 cache
  • A big.LITTLE system typically refers to two clusters of cores, although it could be a single big core and a cluster of several LITTLE cores.

The programmer's guide complements rather than replaces other ARM documentation for the Cortex-A series processors.

For information on a specific processor, see the appropriate ARM Technical Reference Manual:

The most important and definitive reference for the ARMv7A architecture remains the ARM® Architecture Reference Manual ARMv7-A and ARMv7-R edition.

Anonymous

  • Hi, can you sched some light on how these definitions influence inner shareable shareability domains?

    the manual  on page A-133 says:

    "In this system, each cluster is in a different shareability domain for the Inner Shareable attribute, but all components
    of the subsystem are in the same shareability domain for the Outer Shareable attribute."

    and

    "A system might implement two such subsystems. If the data or unified caches of one subsystem are not transparent
    to the accesses from the other subsystem, this system has two Outer Shareable shareability domains."

    while at the same time on page 1-134 ti says:

    "This architecture is written with an expectation that all processors using the same operating system or hypervisor are in the same Inner Shareable shareability domain."

    which seems like a contradiction to me

    thank you

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