On x86_64 systems, the Linux system calls are made using the syscall instruction with the following calling conventions

• RAX: Contains the system call number.
• RDI, RSI, RDX, R10, R8, and R9: Are used to pass up to six arguments to the system call.
• RCX and R11: Are clobbered after the syscall instruction.
• Return Value: The return value of the system call is placed in the RAX register.

The implementation of the sys_write (write) system call in the Linux kernel is as follows.

/ fs / read_write.c
...
642
643        return ret;
644  }
645
646  SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *,
647                  size_t, count)
648  {
649        return ksys_write(fd, buf, count);
650  }

And, the man pages description for sys_write is as follows.

write(2)                System Calls Manual                write(2)

NAME
       write - write to a file descriptor

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <unistd.h>

       ssize_t write(int fd, const void buf[.count], size_t count);

DESCRIPTION
       write() writes up to count bytes from the buffer starting at buf
       to the file referred to by the file descriptor fd.

       The number of bytes written may be less than count if, for
       example, there is insufficient space on the underlying physical
       medium, or the RLIMIT_FSIZE resource limit is encountered (see
       setrlimit(2)), or the call was interrupted by a signal handler
       after having written less than count bytes.  (See also pipe(7).)

Which of the following statement(s) is true for invoking the sys_write system call?