Problem : While adding a new system call to Montavista Linux on PPC architecture

BalaKrishna Mallipeddi (bkmallipeddi@yahoo.com)
Mon, 2 Jun 2003 00:04:46 -0700 (PDT)


Hi,
While adding a new System call in Montavista linux
on ppc architecture i am getting error:

I implemented the system call and compiled the kernel.
The kernel is compiled succesfully. While testing the
system call by writing a user program i am getting
error as ollows:

test_syscall.c: In function `rfs_open':
test_syscall.c:4: `__NR_rfs_open' undeclared (first
use in this function)
test_syscall.c:4: (Each undeclared identifier is
reported only once
test_syscall.c:4: for each function it appears in.)

How I implemented the system call is as follows:
All the paths i have given is from the montavista
Linux source tree.
1) Call Implementation:
I coded my system call in the directory "kernel"
of the Linux source tree with the name "rfs_open.c".

The system call is as follows:

#include <linux/rfs_open.h>

asmlinkage int
sys_rfs_open(void)
{
printk("I am rfs_open\n");
return 0;
}

2) Added a library function:
I added my library function in the directory
"include/linux" with the name "rfs_open.h". The
function is as follows:

#ifndef _LINUX_RFS_OPEN_H
#define _LINUX_RFS_OPEN_H


#include <linux/linkage.h>
#include <linux/unistd.h>


_syscall0(int,rfs_open);


#endif

3) Got the system call number:
I assigned a number to my system call in the file
unistd.h in the directory "include/asm", where "asm"
links to "asm-ppc". The line added in unistd.h is as
follows:
#define __NR_rfs_open 208

4) Created entry in the System call table:
I created an entry in the System Call table which
is in the file misc.S( for i386 architecture this
System call table is in entry.S) in the directory
"arch/ppc/kernel/misc.S" The line added in misc.S is
as follows:
.long sys_rfs_open

5) Updated the Makefile for my system call to be
compiled and linked in to the kernel. After updating
it is as follows:
export-objs = signal.o sys.o kmod.o context.o
ksyms.o pm.o exec_domain.o \
printk.o cpufreq.o trace.o rfs_open.o


obj-y = sched.o fork.o exec_domain.o panic.o
printk.o \
module.o exit.o itimer.o info.o time.o softirq.o
resource.o \
sysctl.o acct.o capability.o ptrace.o timer.o user.o
\
signal.o sys.o kmod.o context.o rfs_open.o

6) I compiled the kernel and it is successfully
compiled.

7) My system call testing program looks as follows:

#include <sys/syscall.h>
#include <stdio.h>
#include <errno.h>
_syscall0(int,rfs_open);

int main()
{
rfs_open();
return(0);
}

I am greatful if any one help me.

Thanks & regards
BalaKrishna Mallipeddi.

=====
BalaKrishna Mallipeddi
Member Technical Staff Software
Innomedia Technologies Pvt. Ltd.,
#3278, 12th Main, HAL 2nd stage,
Bangalore-560008,
INDIA
Phone : 5278389 + 123

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