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You can only skip libc on Linux. Other unices and Windows don’t let you.

• immibis 1y ago
  You can skip libc on Windows - you can't skip the system DLLs like kernel32. (In fact, Microsoft provided several mutually incompatible libcs in the past.) Well, you can non-portably skip kernel32, and use ntdll, but then your program won't work in the next Windows version (same as on any platform really - you can include the topmost API layers in your code, but they won't match the layers underneath of the next version). But system DLLs are DLLs, so also don't cause your .exe to get bloated.
  • steveklabnik 1y ago
    Yes, it's not literally libc on windows, but the point is that directly calling syscalls is not supported, you have to call through the platform's library for doing so. On some systems, this is just not a supported configuration (like what you're talking about with Windows) and on some, they go further, and actually try and prevent you from doing so, even in assembly.)
    • immibis 1y ago
      There's still something on the platform that you can call without extra indirection in the way on your side of the handoff. That is true on all platforms; whether it's an INT or SYSCALL instruction or a CALL or JMP instruction is irrelevant.
      • int_19h 1y ago
        If it's a CALL instruction into a user-space DLL, that's still an extra indirection.
        • immibis 1y ago
          Kind of like the syscall dispatch table on the Linux kernel side, right? After you issue the handoff instruction and it becomes the operating system's problem, there's still more code before you get to the code that does the thing you wanted.