SYSCALL(2)                                             SYSCALL(2)

     NAME
          syscall - indirect system call

     SYNOPSIS
          syscall(number, arg, ... )  (VAX)

          syscall(number, r0, r1, arg ... )  (PDP11)

     DESCRIPTION
          Syscall performs the system call whose assembly language
          interface has the specified number and arguments.

          On a PDP11 the first two arguments correspond to registers
          r0 and r1, regardless of whether the entry point really uses
          them.

          The r0 value of the system call is returned.

     DIAGNOSTICS
          When the C-bit is set, syscall returns -1 and sets the
          external variable errno (see intro(2)).

     BUGS
          There is no way to simulate system calls such as pipe(2),
          which return values in register r1.