Hi , I am trying to implement own system call in Linux. Kernel version I chose is 3.5.7 I am following the steps from Linux Kernel Development 3rd edition. I got two problems with the implementation. 1.while trying to modify the code in kernel , there is no entry.S file for Intel x86 32 bit architecture. (my be i am missing some thing.) 2.while I am compiling user application with gcc I am getting error: unknown type name ‘helloworld’ my application is as follows #define __NR_helloworld 367 __syscall0(long, helloworld) int main () { printf("The helloworld system call is\n"; helloworld(); return 0; } I looked at Link [blog.163.com] which is given by Wanny but i could not find the solution,I could not locate syscall_table_32.s in my Linux source. Please help me in identifying the entry.S file for Intel x86 32 bit architecture in 3.5.7 kernel version sources,where i can make an entry for my system call into system call table. Help me in resolving error: unknown type name ‘helloworld’ in my application.