Steps for creating syscsll with compiling the kernel in opensue 11.0

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Steps to make own system call and compiling kernel
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Make own system call
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1) cd KERNELSOURSE/usr/src/linux 2.6.x.x.x/include/asm-x86

2) vi unistd_32.h

Add your own systemcall as the last entry

#define __NR_yoursyscallname 327
NB:327 if previous entry is 326

3) cd KERNELSOURSE/usr/src/linux 2.6.x.x.x/arch/x86/kernel

4) vi syscall_table_32.c
add entry
.long sys_yoursyscallname 327

5) cd KERNELSOURSE/usr/src/linux 2.6.x.x.x/kernel

6) vi sys.c

write yourown systemm call in this file

eg:

asmlinkage long sys_yoursyscallname(char __user *name)
{
printk(KERN_EMERG"\nEntered name is:%s\n",name);
return 0;
}
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In order to execute your system call you must add it to kernel image.
For that compilation of kernel needed.
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1) Go to usr/src directory in kernel sourse

2) make mrproper //only first time

3) copy configuration file


cp arch/x86/defconfig_32 ./.config
4) make clean

5) make cloneconfig
Uses settings for already running kernel

OR
make oldconfig
Expert level

6)[optional] make menuconfig
menudrivel configuration

7) make

8) make modules_install

9) make install


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Reboot the system oopen in your new kernel

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create a new file for calling your own system call



eg:

1) vi callmysyscall.c

/************************************************************************/
/*callmysyscall.c */
/************************************************************************/

#define _GNU_SOURCE /* or _BSD_SOURCE or _SVID_SOURCE */
#include <unistd.h>
#include <sys/syscall.h> /* For SYS_xxx definitions */
int main()
{
int a;
syscall(__NR_yoursyscallname,arguments to systemcall[specific to our example a string name]);
return 0;
}



2) cc callmysyscall.c

3) ./a.out

*4) dmesg NB: 4)Specific to our example

To see the output





Eg:-

/************************************************************************/
/*callmysyscall.c */
/************************************************************************/

#define _GNU_SOURCE /* or _BSD_SOURCE or _SVID_SOURCE */
#include <unistd.h>
#include <stdio.h>
#include <sys/syscall.h> /* For SYS_xxx definitions */
int main(int argc,char* argv[])
{
int a;
if(argc!=2)
{
printf("Usage:Give command<space>Your name\n");
return 0;
}
syscall(__NR_pname_in_dmesg,argv[1]);
return 0;
}