Hi Srinivas Ganji,
I've already done it. It wasn't very difficult as I have already worked with makefiles. Have you got any other suggestion of an exercise I can do?
Thanks you very much again
On Tue, 23 Jul 2013 11:11:16 +0530
Srinivas Ganji <srinivasganji.kernel@xxxxxxxxx> wrote:
> Hi Iker Pedrosa,
>
> Have you completed with your own directory implementation? If you see any
> issues, please let me know.
>
> Regards,
> Srinivas.
>
>
> On Sat, Jul 20, 2013 at 4:13 PM, Iker Pedrosa <ikerpedrosam@xxxxxxxxx>wrote:
>
> > Thank you very much to everybody. I've tried Sudip Mukherjee's approach
> > and it has worked (the table is in arch/x86/syscalls/syscall_32.tbl). Now,
> > I'm going to try to create my own directory in kernel source which contains
> > my system call implementation files as Srinivas Ganji has proposed.
> >
> > On Fri, 19 Jul 2013 12:15:44 +0530
> > Srinivas Ganji <srinivasganji.kernel@xxxxxxxxx> wrote:
> >
> > > Hi Iker Pedrosa,
> > >
> > > In old versions of Linux kernels like 2.6.xx, the approach was different
> > > from Linux version 3.3 on wards.
> > >
> > > There are two different approaches to implement own system call. Each
> > > approach involves several steps. The difference between two approaches
> > is,
> > > in one approach, we implement our system call in already existing file of
> > > kernel sources. In another approach, we created our own directory in
> > kernel
> > > source which contains our system call implementation files. Ans in this
> > > second approach, we need to modify the Kernel Makefiles and Configuration
> > > files to include our newly created directory and its contents. First let
> > us
> > > implement using the first approach.
> > >
> > > The following approach was successfully tested in Linux kernel 3.5.7
> > > version sources for x86 32-bit architecture.
> > >
> > > Here are the steps to create our own system call in the existing kernel
> > > sources. The paths given below are relative paths from /usr/src/linux.
> > >
> > > 1. Generally, add the function (system call) definition in kernel/sys.c
> > > file.
> > >
> > > /* this is the implementation of our system call */
> > > asmlinkage long sys_helloworld(void) {
> > > printk(KERN_EMERG "Hello, world!\n");
> > > return 0;
> > > }
> > >
> > > 2. Add the function prototype in the header file include/linux/syscalls.h
> > >
> > > asmlinkage long sys_helloworld(void);
> > >
> > > 3. Create an entry in system call table in the
> > > file arch/x86/syscalls/syscall_32.tbl
> > >
> > > 350 i386 helloworld sys_helloworld
> > >
> > > Note: In my case already table had 349 offsets, so I added it as 350.
> > >
> > > 4. If we want to create our own kernel images, then change the
> > EXTRAVERSION
> > > in the main Makefile available at /usr/src/linux
> > >
> > > EXTRAVERSION = .ownsyscall
> > >
> > > 5. Then, build the modules from the main directory with the following.
> > >
> > > make menuconfig --- Just save and exit.
> > > make modules
> > > make modules_install
> > > make install
> > >
> > > 6. Now, reboot with our own image.
> > >
> > > 7. Write a simple C application for calling the our own system call.
> > >
> > > #include <stdio.h>
> > >
> > > /* sys_helloworld 350 */
> > > int main ()
> > > {
> > > syscall(350); /* 350 is our system calls offset number */
> > > return 0;
> > > }
> > >
> > > I hope, you understand it clearly and it helps you. Based on this, you
> > can
> > > practice the second approach. It needs of creating our own directory and
> > > files (C, Makefile, Kconfig) and modifications required in architecture
> > > specific Kconfig.
> > >
> > > Regards,
> > > Srinivas.
> > >
> > >
> > > On Thu, Jul 18, 2013 at 2:34 PM, Iker Pedrosa <ikerpedrosam@xxxxxxxxx
> > >wrote:
> > >
> > > > Hi Guys,
> > > >
> > > > I am a newbie to linux kernel and I am trying to do some of the
> > > > exercises/examples of the Linux Kernel Development book by Robert
> > Love. For
> > > > the moment I'm trying to create a system call (Chapter 5) but I am
> > unable
> > > > to do the first step which states the following:
> > > > "Add an entry to the end of the system call table.This needs to be done
> > > > for each architecture that supports the system call (which, for most
> > calls,
> > > > is all the architectures).The position of the syscall in the table,
> > > > starting at zero, is its system call number. For example, the tenth
> > entry
> > > > in the list is assigned syscall number nine."
> > > >
> > > > My problem is that I am unable to find the file that holds the table.
> > In
> > > > the book the file that needs to be changed is the entry.S but it no
> > longers
> > > > exists in v3.9. In an example that I have found on the internet, which
> > is
> > > > done using v3.0, the file to change is syscall_table_32.S. But I've
> > got the
> > > > same problem, it doesn't exist. So anybody can help me to find the
> > table? I
> > > > know that I should be using v2.6 of the kernel but I don't know if that
> > > > version will work with the distribution that I'm using.
> > > >
> > > > The question is also in stackoverflow so if someone wants to answer
> > there
> > > > I won't have any problem. The link to the page is the following:
> > > >
> > http://stackoverflow.com/questions/17652555/where-is-the-system-call-table-in-linux-kernel-v3-9
> > > >
> > > > --
> > > > Iker Pedrosa <ikerpedrosam@xxxxxxxxx>
> > > >
> > > > _______________________________________________
> > > > Kernelnewbies mailing list
> > > > Kernelnewbies@xxxxxxxxxxxxxxxxx
> > > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> > > >
> >
> >
> > --
> > Iker Pedrosa <ikerpedrosam@xxxxxxxxx>
> >
--
Iker Pedrosa <ikerpedrosam@xxxxxxxxx>
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