Function syscall1_readonly 

pub unsafe fn syscall1_readonly(
    sysno: Sysno,
    arg0: usize,
) -> Result<usize, Errno>

Available on ((32-bit and ARM, or 32-bit and little-endian and x86, or 64-bit and AArch64, or 64-bit and little-endian and x86-64) and (Android or Linux), or Linux and (32-bit and big-endian and PowerPC, or 32-bit and little-endian and RISC-V RV32, or 32-bit and little-endian and x86-64, or 32-bit and MIPS, or 64-bit and big-endian and s390x, or 64-bit and little-endian and LoongArch64, or 64-bit and little-endian and RISC-V RV64, or 64-bit and MIPS-64, or 64-bit and PowerPC64)) and non-outline_syscalls only.

Make a raw system call with 1 argument. Like the non _readonly version but you declare that syscall does not mutate any memory.

Returns a Result<usize, Errno>.

Safety

A system call is unsafe by definition. It’s the caller’s responsibility to ensure safety.