> Now the question comes is the argument long or some other type? I believe so. Every library I've seen and the kernel itself uses long. Other types just get typecasted to long. I think it's just supposed to mean "register type" since all the arguments must be in registers.
> E.g. for some 32bit ABIs built on top of 64bit ISA might always > just pass 32bits or they might allow passing the full 64bits. > (x32 might fall under this and MIPS n32). The registers used are documented here: https://www.man7.org/linux/man-pages/man2/syscall.2.html x32 uses the exact same registers as x86_64, all 64 bit: > x86-64 rdi rsi rdx r10 r8 r9 > x32 rdi rsi rdx r10 r8 r9 MIPS calling conventions work like this: > mips/n32,64 a0 a1 a2 a3 a4 a5 > mips/o32 a0 a1 a2 a3 ... > mips/o32 args5-8 are passed on the stack > Maybe you should warn/error out > if not passed the correct sized argument. Yes. It should be an error if the inputs are not register sized. As far as I know all system call inputs are either register sized values or pointers to C strings, buffers or much larger structures. > Also do you sign or zero extend a 32bit argument for LP64 targets? I'm not sure. System call stubs just declare these register values as signed long so whatever happens in that case seems to be appropriate.
