tree c8a2100c5f9a4bae9622156050cbe0cce6546408
parent d2acd0b3a793f84ec67852bcb54b7d41ce3d04f3
author Willy Tarreau <w@1wt.eu> 1620805650 +0200
committer Willy Tarreau <w@1wt.eu> 1620822202 +0200
encoding latin1

BUILD: makefile: add a few popular ARMv8 CPU targets

This adds the following CPUs to the makefile:
  - armv81    : modern ARM cores (Cortex A55/A75/A76/A78/X1, Neoverse, Graviton2)
  - a72       : ARM Cortex-A72 or A73 (e.g. RPi4, Odroid N2, VIM3, AWS Graviton)
  - a53       : ARM Cortex-A53 or any of its successors in 64-bit mode (e.g. RPi3)
  - armv8-auto: both older and newer ARMv8 cores, with a minor runtime penalty

The reasons for these ones are:
  - a53 is the common denominator of all of its successors, and does
    support CRC32 which is used by the gzip compression, that the generic
    armv8-a does not ;

  - a72 supports the same features but is an out-of-order one that deserves
    better optimizations; it's found in a number of high-performance
    multi-core CPUs mainly oriented towards I/O and network processing
    (Armada 8040, NXP LX2160A, AWS Graviton), and more recently the
    Raspberry Pi 4. The A73 found in VIM3 and Odroid-N2 can use the same
    optimizations ;

  - armv81 is for generic ARMv8.1-A and above, automatically enables LSE
    atomics which are way more scalable, and CRC32. This one covers modern
    ARMv8 cores such as Cortex A55/A75/A76/A77/A78/X1 and the Neoverse
    family such as found in AWS's Graviton2. The LSE instructions are
    essential for large numbers of cores (8 and above).

  - armv8-auto dynamically enables support for LSE extensions when
    detected while still being compatible with older cores. There is a
    small performance penalty in doing this (~3%) but a same executable
    will perform optimally on a wider range of hardware. This should be
    the best option for distros. It requires gcc-10 or gcc-9.4 and above.

When no CPU is specified, GCC version 10.2 and above will automatically
implement the wrapper used to detect the LSE extensions.