cpu: better defaults on darwin ARM64

This is motivated by
https://github.com/wazero/wazero/pull/2473
which needs to special case darwin for testing the availability of
HasATOMICS, although all M-series CPUs support it.

We could do sysctlbyname, like syscall_darwin_x86_gc.go, if that's
preferred:
https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics

Change-Id: I0f5ea55ef5cda4956db44b2d40f2f10044fa3321
GitHub-Last-Rev: d5d0f1e989579de2a25c97c00c7e9db5d4b0cb29
GitHub-Pull-Request: golang/sys#267
Reviewed-on: https://go-review.googlesource.com/c/sys/+/743320
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
4 files changed
tree: 6fa6d87e0b26400b17a1b54121d81e4c367c08a1
  1. cpu/
  2. execabs/
  3. plan9/
  4. unix/
  5. windows/
  6. .gitattributes
  7. .gitignore
  8. codereview.cfg
  9. CONTRIBUTING.md
  10. go.mod
  11. LICENSE
  12. PATENTS
  13. README.md
README.md

sys

Go Reference

This repository holds supplemental Go packages for low-level interactions with the operating system.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://go.dev/doc/contribute.

The git repository is https://go.googlesource.com/sys.

The main issue tracker for the sys repository is located at https://go.dev/issues. Prefix your issue with “x/sys:” in the subject line, so it is easy to find.