@John Knipper please pull those changes and check if they work for you..

I can work with that, thanks. The only thing is that your hardware entropy source is

all-pc

only, so on aarch64-darwin the native RNG currently uses the software fallback rather than the real macOS CSPRNG, but that's okay, I'll update it during a future pass. I'm now now 0 commits behind

origin/master.

I'll prepare a PR, bear with me on that. I have 74 commits for my code 😉

if aarch64 has a hardware implementation it would probably make more sense to implement that so it is usable on all aarch64 platforms, rather than depend on a host implementation

I might be wrong but the M-series doesn't have FEAT_RNG at all. I checked on my machine (Apple M5): hw.optional.arm.FEAT_RNG -> unknown oid (absent) hw.optional.arm.FEAT_LSE -> 1 (namespace works, so the absence is real) No RNDR anywhere. FEAT_RNG is an optional ARMv8.5 feature, and Apple's cores don't implement it. I think Apple's own userspace gets entropy from the Secure Enclave via getentropy/arc4random.