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 <[email protected]>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 <[email protected]> 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 <[email protected] > >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 <[email protected]> > > > > > > _______________________________________________ > > > Kernelnewbies mailing list > > > [email protected] > > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > > > -- > Iker Pedrosa <[email protected]> >
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