Does kotlin offer a way to check if the jvm is run...

# getting-started

[martmists]

Does kotlin offer a way to check if the jvm is running on arm64 or x64? I can only find references to java os.arch but the only documented value seems to be amd64 for x64 (or maybe both? not very clear)

[Chris Lee]

You can use os.arch for that, though with some caveats. Using this, for example:

public open val arch: Arch by lazy {
        when (val archName = System.getProperty("os.arch", "unknown").lowercase()) {
            "amd64", "x86_64" -> Arch.Amd64
            "arm64", "aarch64" -> Arch.Arm64
            else -> error("Unknown architecture $archName")
        }
    }

However, be aware that this only reports the JVM’s view on the architecture; for example, an x86_64 JVM on an Apple Arm M1 (using Rosetta) will report x86_64 (as its an x86_64 JVM), even though the OS is aarch64.

[Chris Lee]

If you want to know the underlying actual architecture for aa JVM app on OS X:

public object MacOsX : Os() {
        public val appleSilicon: Boolean by lazy { execAndGetStdout("uname", "-p") == "arm" }
        public val translatedByRosetta: Boolean by lazy {
            execAndGetStdout(
                "sysctl",
                "sysctl.proc_translated"
            ) == "sysctl.proc_translated: 1"
        }
        public override val arch: Arch by lazy {
            when {
                appleSilicon -> Arch.Arm64
                else -> Arch.Amd64
            }
        }
    }