A confusion about invoking my syscall

* A confusion about invoking my syscall
@ 2012-06-19  1:39 王哲
  2012-06-19  1:58 ` Jeff Haran
  0 siblings, 1 reply; 8+ messages in thread
From: 王哲 @ 2012-06-19  1:39 UTC (permalink / raw)
  To: kernelnewbies

Hello everyone:

         I append a simple syscall in kernel. and the function is as
follows:

  asmlinkage  long sys_mysyscall(long data)
 {
          printk("This is my syscall!\n");
          return data;
  }

and i test it sucessfully in user space . and the test program:

   #include
<linux/unistd.h>

   #include <syscall.h>
   #include <sys/types.h>
   #include <stdio.h>

   int main(void)
   {
   long n = 0,m = 0,pid1,pid2;
   n = syscall(345,190);// #define __NR_mysyscall          345
   printf("n = %ld\n",n);
   pid1 = syscall(SYS_getpid);  //getpid
   printf("pid = %ld\n",pid1);
   pid2 = syscall(20);  //getpid
   printf("pid = %ld\n",pid2);
   return 0;
  }
and the result:
n = 190
pid = 4097
pid = 4097

but if the test program is:
#include <linux/unistd.h>
#include <syscall.h>
#include <sys/types.h>
#include <stdio.h>

int main(void)
{
 long n = 0,m = 0,pid1,pid2;
 n = syscall(345,190);// #define __NR_mysyscall          345
 printf("n = %ld\n",n);
 m = syscall(SYS_mysyscall,190);
 printf("m = %ld\n",m);
 pid1 = syscall(SYS_getpid);  //getpid
 printf("pid = %ld\n",pid1);
 pid2 = syscall(20);  //getpid
 printf("pid = %ld\n",pid2);
 return 0;
}
and the result:
wanny at wanny-C-Notebook-XXXX:~/syscall/src$ gcc test1.c
test1.c: In function ?main?:
test1.c:13:14: error: ?SYS_mysyscall? undeclared (first use in this
function)
test1.c:13:14: note: each undeclared identifier is reported only once for
each function it appears in

why i can't invoke my syscall with "SYS_mysyscall"?

Thanks in advance!
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