proposal: runtime: add possibility to obtain "microarchitecture levels" at runtime

[the-hotmann]

Proposal Details

Description

When I build a binary I often wonder if it really downloads/uses the version that is optimal.

For example:

New servers most probably are having the hardware capabilities of "linux/amd64/v3", or even of "linux/amd64/v4".
But how can I check these two things at runtime:

1. the microarchitecture levels of the Host/Hardware
2. the microarchitecture levels that the software was build for

?

I have no problem getting linux/amd64 but it seems, I cant obtain the microarchitecture levels (eg. "v3" or "v4") the golang code was compiled to, at runtime.

This is the code, I use to obtain linux/amd64:

https://go.dev/play/p/aBFInM8N94d

Did anyobe achive this, or is this a missing feature?
Knowing this would allow devs to analize if their app is indeed running, compiled for the correct hardware features.

I personally would love "runtime.GOARCH_LEVEL" or something like this, which returns an empty string "" or eg. "v3" or "v4".

[gabyhelp]

Related Issues

• proposal: x/sys/cpu: expose runtime AMD64 microarchitecture level #58015
• runtime: check amd64 microarchitecture level at startup #48514 (closed)
• x/telemetry: cmd/go: report maximum support micro architecture by the host of the compiler #65627

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[seankhliao]

Duplicate of #58015

[ianlancetaylor]

Note that you can get the microarchitecture level that a program was built for by running go version -m PROGRAM.