Windows 10 for ARM64 will run ARM32 executables just fine, which is why we're using it for Go builders.

There's currently a bug in which invoking powershell from an arm32 process will fail:

I've worked around that by grabbing a zip of powershell 7.1, adding the unzipped directory to the builder's PATH, and then copying pwsh.exe to powershell.exe. I'm waiting for some builds to finish, but I think that should work alright.

The reason this matters for Go is that some of the tests use powershell just to invoke a simple command:

func runCmd(args ...string) ([]byte, error) {
        removeUTF8BOM := func(b []byte) []byte {
                if len(b) >= 3 && b[0] == 0xEF && b[1] == 0xBB && b[2] == 0xBF {
                        return b[3:]
                }
                return b
        }
        f, err := ioutil.TempFile("", "netcmd")
        if err != nil {
                return nil, err
        }
        f.Close()
        defer os.Remove(f.Name())
        cmd := fmt.Sprintf(`%s | Out-File "%s" -encoding UTF8`, strings.Join(args, " "), f.Name())
        out, err := exec.Command("powershell", "-Command", cmd).CombinedOutput()

I'm pretty sure we can come up with something better than powershell -Command for the tests, which would make this problem go away. Or sooner or later Microsoft will probably fix it. Or my workaround will suffice.

Either way, I thought I should at least document this.

CC @alexbrainman @jstarks @cagedmantis