steps

(dependencies)
sudo apt-get install libncurses5-dev openssl libssl-dev
sudo apt-get install build-essential openssl
sudo apt-get install pkg-config
sudo apt-get install libc6-dev
sudo apt-get install bison
sudo apt-get install flex
sudo apt-get install libelf-dev
sudo apt-get install zlibc minizip
sudo apt-get install libidn11-dev libidn11

sudo apt-get install lib32ncurses5-dev
sudo apt-get install gcc gdb bison flex
sudo apt-get install libncurses5-dev libssl-dev
sudo apt-get install libidn11-dev libidn11
sudo apt-get install zlibc minizip
sudo apt-get install build-essential openssl
sudo apt-get install libelf-dev



sudo gedit arch/x86/entry/syscalls/syscall_64.tbl

common	first			sys_first
common	second			sys_second

64	add			sys_add
64	max			sys_max

sudo gedit include/linux/syscalls.h 

(before for __ARCH_WANT_SYS_IPC)
asmlinkage long sys_first(void);
asmlinkage long sys_second(int number);
(before #endif)
asmlinkage int sys_add(int a,int b);
asmlinkage int sys_max(int a,int b,int c);

sudo gedit kernel/sys.c

(before #endif)
SYSCALL_DEFINE0(first)
{
        printk("Hello!\n");
        return 0;
}
SYSCALL_DEFINE1(second, int, number)
{
        printk("The number is %d\n", number);
        return number;
}

(before #ifdef CONFIG_COMPAT)
SYSCALL_DEFINE2(add,int,a,int,b)
{
	return a+b;
}
SYSCALL_DEFINE3(max,int,a,int,b,int,c)
{
	if(a>=b)
	{
		if(a>=c)
			return a;
		else
			return c;	
	}
	else
	{
		if(b>=c)
			return b;
		else
			return c;
	}
}

sudo make mrproper
sudo make clean
sudo make menuconfig
(save&exit)

(edit .config)
CONFIG_SYSTEM_TRUSTED_KEYS=""
CONFIG_SYSTEM_REVOCATION_KEYS=""

sudo apt-get install dwarves

sudo make -j4

sudo make modules_install
sudo make install

update-grub2