The first response about C not knowing how to do syscalls with multiple arguments is wrong. This kind of thing is done via the system syscall interface. In fact, the more I think about it the more wrong he becomes. System call interfaces don't have any such thing as "language dependence" -- if you can't do a syscall in straight object code you're screwed no matter what language you're using. The syscall intrinsic in C and C++ is a nonstandard Linux defined relation between the OS syscall interface (per the OS designation for the ISA) and code being run.

Here's how you do a 2-arg mkdir:

  push %rax
  push %rbx
  push %rcx
  movq $0x27, %rax
  movq $path, %rbx
  movq $mode, %rcx
  int $0x80

Here's how you do a 3-arg:

  push %rax
  push %rbx
  push %rcx
  push %rdx
  movq $0x128, %rax
  movq $dfd, %rbx
  movq $path, %rcx
  movq $mode, %rdx
  int $0x80

Edit: Hmm, maybe he was referring to overloading the intrinsic. That kind of makes sense, although there's a standard way to do that if necessary (first arg is number of args, just pop x off the stack after the call, see printf).