Fourth parameter should be in R10

[ghost]

You have register RCX listed for the fourth parameter to syscalls but it should be R10.

"System V Application Binary Interface: AMD64 Architecture Processor Supplement"
https://github.com/hjl-tools/x86-psABI/wiki/x86-64-psABI-1.0.pdf
Page 148 "The kernel interface uses %rdi, %rsi, %rdx, %r10, %r8 and %r9."

[msbit]

@GeDaMo that section pertains specifically to AMD64 Linux kernel conventions. I'm not sure if macOS uses the same, do you have any information to that effect?

[ghost]

I don't use MacOS myself but I was helping someone; syscalls using RCX didn't work but using R10 did.

[msbit]

Okay, I'm satisfied :)

This seems like a good candidate for a pull request.