LP64D

The usual RISC-V 64-bit rulebook for function calls on Linux - arguments in a0 to a7, result in a0, s0 to s11 kept safe across calls.

LP64D is the RISC-V psABI variant with 64-bit long and pointers whose floating-point values travel in their own registers (Chapter 16); integer arguments use a0-a7, results a0-a1, callee-saved s0-s11 and sp, with ra and t0-t6 caller-saved.

Examples

Integer arguments go in a0 to a7, doubles in fa0 to fa7, and s0 to s11 are callee-saved.