What is the recommended value of JULIA_CPU_TARGET on macOS?

[fxcoudert]

What is the recommended value of JULIA_CPU_TARGET on macOS?

[fredrikekre]

https://github.com/JuliaCI/julia-buildkite/blob/ea50eb719242bc3e844227a2ebf54a49d308bafc/utilities/build_envs.sh#L20-L82

[giordano]

Yes, that (in the form of generic;apple-m1,clone_all) should be safe on aarch64-apple-darwin machines. The main risk is having inefficient code baked in the sysimage, but the apple-m1 target should cover all the systems you care about, and the generic target ensures a safe fallback for all other cases.

[fxcoudert]

Thanks @fredrikekre!

Looking at the aarch64 case, it appears to be shared between macOS and other OSes (I suppose aarch64-linux):

            # Absolute base aarch64 feature set
            "generic"
            # Cortex A57, Example: NVIDIA Jetson TX1, Jetson Nano
            "cortex-a57"
            # Cavium ThunderX2T99, a common server architecture
            "thunderx2t99"
            # NVidia Carmel, e.g. Jetson AGX Xavier; serves as a baseline for later architectures
            "carmel,clone_all"
            # Apple M1
            "apple-m1,base(3)"
            # Vector-length-agnostic common denominator between Neoverse V1 and V2, recent Arm server architectures
            "neoverse-512tvb,base(3)"

Given that 1. macOS does not support anything with fewer features than Apple M1, 2. its processors don't really align with Neoverse, am I right that we could simplify it (for macOS builds) to:

            # Absolute base aarch64 feature set
            "generic"
            # Apple M1
            "apple-m1,clone_all"

without risk?

[fxcoudert]

Thanks. I appreciate the help!