Implement your own system calls in the Linux kernel

To implement a simple print: PRINTK

1.

Vim PRINTK.C
void Sys_pk ()
{
PRINTK ("This was a new sys call");
}

CD Arch/arm/kernel

2.vim calls. S
At the back, add
Call (SYS_PK)

3.CD Arch/arm/include

Add the following lines to the file Unistd.h in the appropriate location:

Vim Unistd.h

At the very back add:
#define __NR_PK (__nr_syscall_base+363)

4. Recompile the kernel

Make clean

Make Uimage arch=arm cross_compile=arm-linux-

CP Uimage/rootfs

TFTP 0xc0008000 Uimage

Bootm 0xc0008000

5. Using the newly added system call

Vim SYSCALL.C

void PK ()

{

__ASM__ (
"Ldr r7,=363 (more than 8 bits cannot use MOV instructions) \ n"
"Swi\n"
:
:
: "Memory")
};
}
void Main ()
{
PK ();

}

}

6. Compiling the link C file

Arm-linux-gcc-static Syscall.c-o Syscall

CP Syscall/rootfs

Implement your own system calls in the Linux kernel