#ifndef syscalls_counted
.equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
#define syscalls_counted
#endif
.rept syscalls_padding
CALL(sys_ni_syscall)
.endr
由于是第一次包含,故syscalls_counted没有定义,
.equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
为了保证NR_syscalls是4的整数倍，上面的语句相当于：syscalls_padding = ((NR_syscalls + 3) & ~3) - NR_syscalls;
即：假如NR_syscalls 是1，那么syscalls_padding 就是3
.rept syscalls_padding
CALL(sys_ni_syscall)
.endr
这里涉及到汇编指令.rept的用法：