James Tucker
f55fd4e9e4
Move the goamd64_capable/goamd64_compiled logic out of tsweb/varz into a new util/cpucaps package so that a future hostinfo extension can share it, and extend it to all supported platforms. The host GOAMD64 level is now computed from CPUID feature bits via x/sys/cpu rather than by parsing /proc/cpuinfo, which removes the linux/amd64 restriction and all file I/O. CPUID is also what the Go runtime checks at startup, so it directly answers the question the metric asks: could this machine run a binary built at a higher level. Four flags required by the runtime checks have no x/sys/cpu field: LAHF/SAHF (v2) and MOVBE, LZCNT and F16C (v3). We report a level when all of its other flags are present. That is exact on real hardware: LAHF/SAHF exists on every 64-bit CPU that also has SSE4.2, and MOVBE/LZCNT/F16C exist on every CPU that also has AVX2, BMI2 and FMA (Haswell and Zen onwards). A linux/amd64 test cross-checks the CPUID result against the exact /proc/cpuinfo flag lists, so a test run on any machine where the assumption fails, or where the kernel's view diverges from CPUID (e.g. clearcpuid=), reports the difference. Add a Caps bitmask of the CPU capabilities that Go's runtime and standard library dispatch on, normalized across amd64 and arm64: AES, CLMUL/PMULL, SHA2, SHA512, CRC32, ADX and LSE, plus the vector capabilities not implied by the GOAMD64 level: AVX, AVX2, AVX512 (the v4 F+BW+CD+DQ+VL subset), VAES, VPCLMULQDQ and GFNI. Detection is lazy and reads only x/sys/cpu globals and build info; there is no init-time work and no new dependency. Coverage includes all key client platforms: linux, windows, darwin, freebsd, android (via the linux auxv/MRS path in x/sys/cpu) and ios (via the darwin sysctl path). x/sys/cpu has no arm64 detection on FreeBSD, so read ID_AA64ISAR0_EL1 directly; the FreeBSD kernel emulates EL0 reads of the ID registers, and Go's runtime already depends on that emulation on this platform. The whole feature is behind a new cpucaps feature tag. Building with ts_omit_cpucaps removes the varz metrics and all detection code following the tka stub pattern: the detection functions compile to stubs returning zero inside the package itself, so future importers cannot reintroduce the code by forgetting a build tag, and the Caps type stays available for decoding recorded values. A tailscaled dependency test enforces the omission, and the generated buildfeatures.HasCPUCaps const is available for the later hostinfo extension. tsweb/varz metric names are unchanged. gauge_goamd64_capable values only change on machines where /proc/cpuinfo disagrees with CPUID. Updates #21002 Signed-off-by: James Tucker <james@tailscale.com>
Tailscale
Private WireGuard® networks made easy
Overview
This repository contains the majority of Tailscale's open source code.
Notably, it includes the tailscaled daemon and
the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows,
macOS, and to varying degrees
on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's
code, but this repo doesn't contain the mobile GUI code.
Other Tailscale repos of note:
- the Android app is at https://github.com/tailscale/tailscale-android
- the Synology package is at https://github.com/tailscale/tailscale-synology
- the QNAP package is at https://github.com/tailscale/tailscale-qpkg
- the Chocolatey packaging is at https://github.com/tailscale/tailscale-chocolatey
For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.
Using
We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.
Other clients
The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.
Building
We always require the latest Go release, currently Go 1.26. (While we build releases with our Go fork, its use is not required.)
go install tailscale.com/cmd/tailscale{,d}
If you're packaging Tailscale for distribution, use build_dist.sh
instead, to burn commit IDs and version info into the binaries:
./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled
If your distro has conventions that preclude the use of
build_dist.sh, please do the equivalent of what it does in your
distro's way, so that bug reports contain useful version information.
Bugs
Please file any issues about this code or the hosted service on the issue tracker.
Contributing
PRs welcome! But please file bugs. Commit messages should reference bugs.
We require Developer Certificate of
Origin
Signed-off-by lines in commits.
See commit-messages.md (or skim git log) for our commit message style.
About Us
Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:
- https://github.com/tailscale/tailscale/graphs/contributors
- https://github.com/tailscale/tailscale-android/graphs/contributors
Legal
WireGuard is a registered trademark of Jason A. Donenfeld.