Steps for creating syscsll with compiling the kernel in opensue 11.0

Discussion in 'Technical' started by anas.nss, Apr 13, 2009.

  1. anas.nss

    anas.nss New Member

    ---------------------------------------------------------------------------------
    Steps to make own system call and compiling kernel
    ---------------------------------------------------------------------------------


    Make own system call
    ----------------------------------------------------------------------
    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;
    }
    --------------------------------------------------------------------------------------------------------------
    In order to execute your system call you must add it to kernel image.
    For that compilation of kernel needed.
    --------------------------------------------------------------------------------------------------------------

    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


    -----------------------------------------------------------------------------------


    Reboot the system oopen in your new kernel

    ------------------------------------------------------------------------------------

    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;
    }
     
    Last edited: Apr 13, 2009

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