does anyone know how i can detect the cpu architecture in kotlin/jvm? i don’t want the jvm architect...

# random

[christophsturm]

does anyone know how i can detect the cpu architecture in kotlin/jvm? i don’t want the jvm architecture, i want to detect arm even when i run on an intel jvm via rosetta.

[ephemient]

val p = ProcessBuilder("uname", "-p").redirectOutput(PIPE).start()
val arch = p.inputStream().use { it.bufferedReader().readText() }
check(p.waitFor() == 0)

[christophsturm]

perfect, thanks!

[christophsturm]

i can just default to intel when it fails

[ephemient]

on a different note, it is possible to change the output of uname on Linux, https://manpages.debian.org/setarch.8. I'm not sure there's any reasonable way to detect that from within the JVM

[kqr]

on my machine it's printing out unknown 🙂

[ephemient]

maybe uname -m? the meaning of the different fields does vary a bit between UNIXen

[Fleshgrinder]

-m is usually better and gives a more meaningful result also on BSD (Mac).

[christophsturm]

btw this does not work, it prints i386 on a rosetta jvm

[christophsturm]

because the shell inherits the architecture

[christophsturm]

I could read sysctl:

~ λ /bin/zsh -c 'sysctl -n machdep.cpu.brand_string'
Apple M1 Pro

~ λ arch -x86_64 /bin/zsh -c 'sysctl -n machdep.cpu.brand_string'
Apple M1 Pro

[christophsturm]

or parse uname -v

arch -x86_64 uname -v
Darwin Kernel Version 21.4.0: Mon Feb 21 20:35:58 PST 2022; root:xnu-8020.101.4~2/RELEASE_ARM64_T6000

[christophsturm]

this works, and prints true on both rosetta and native jvms:

fun main() {
    val p = ProcessBuilder("uname", "-v").redirectOutput(PIPE).start()
    val uname = p.inputStream.use { it.bufferedReader().readText() }
    check(p.waitFor() == 0)
    println(uname.contains("ARM64"))
}