diff -up ./include/asm-x86/unistd_32.h.pos ./include/asm-x86/unistd_32.h
--- ./include/asm-x86/unistd_32.h.pos   2008-03-24 19:49:18.000000000 +0100
+++ ./include/asm-x86/unistd_32.h       2008-04-05 17:53:30.000000000 +0200
@@ -228,7 +228,7 @@
 #define __NR_madvise1          219     /* delete when C lib stub is removed */
 #define __NR_getdents64                220
 #define __NR_fcntl64           221
-/* 223 is unused */
+#define __NR_add               223     /* POS homework */
 #define __NR_gettid            224
 #define __NR_readahead         225
 #define __NR_setxattr          226
diff -up ./arch/x86/kernel/syscall_table_32.S.pos ./arch/x86/kernel/syscall_table_32.S
--- ./arch/x86/kernel/syscall_table_32.S.pos    2008-03-24 19:49:18.000000000 +0100
+++ ./arch/x86/kernel/syscall_table_32.S        2008-04-05 17:53:14.000000000 +0200
@@ -222,7 +222,7 @@ ENTRY(sys_call_table)
        .long sys_getdents64    /* 220 */
        .long sys_fcntl64
        .long sys_ni_syscall    /* reserved for TUX */
-       .long sys_ni_syscall
+       .long sys_add           /* POS homework     */
        .long sys_gettid
        .long sys_readahead     /* 225 */
        .long sys_setxattr
diff -up ./kernel/sys.c.pos ./kernel/sys.c
--- ./kernel/sys.c.pos  2008-03-24 19:49:18.000000000 +0100
+++ ./kernel/sys.c      2008-04-05 17:56:42.000000000 +0200
@@ -1761,6 +1761,11 @@ asmlinkage long sys_getcpu(unsigned __us
        return err ? -EFAULT : 0;
 }

+asmlinkage int sys_add(int a, int b)
+{
+        return a+b;
+}
+
 char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";

 static void argv_cleanup(char **argv, char **envp)