That is not true on Linux, where you can just make syscalls yourself. They don't even use the C ABI, even if it's pretty similar (For syscalls, the fourth argument is passed in R10 instead of RCX, since that holds the return address for sysret).
You can call a syscall with assembly, but the result it gives you follows C's formats. Maybe your language does integers in a different way so you still have to abide to it's standard to adapt what the OS gives you
I'd argue that it follows the CPU's native integer representation, which C also does. Yes, if your language uses tagged integers or something, you'll have to marshal the syscall arguments/results from/to your own representation, but the same is true if you want to use those integers for arithmetic (beyond trivial additions or multiplying/dividing by a power of two, for which you can use lea).
Mine was not a critique. Of course every OS needs to be programmed with a language and its syscalls will be formatted accordingly. And if you want to program using an OS's features, other than the compilation to assembly, you also have to worry about inter-operating with what the OS provides. I'm simply noting that for the foreseeable future, C's way of doing things will always have to be kept in mind when writing dev tools
Sure, that makes sense. Out of curiosity, do you know of any way to design a syscall ABI that's not C-like that was either used in the past or would have some advantages if a new OS adopted it? I imagine that lisp machines did things differently, but a) I don't know whether they had syscalls as such or simply offered kernel services as regular functions and b) they did have microcode support for tagged integers and objects.
I'm asking since I want to get into (hobbyist) OS development at some point and would love to know if there's a better way to do syscalls.
