how to add a system call

[maniacneron]

hi
i am using ubuntu 7.10 and i need to add a system call to kernel.I made some research about this and learnt that i have to make some changes in the file "entry.s" which is in arc/i386/kernel but in the kernel version 2.6.14.2 there is not a file named entry.s under that folder.Where can i find this file or the file which is inserted instead of this file.Or you can tell me how to add a system call this kernel.
thank you for help

[Zugzwang]

You might want to be more specific on what you want to do to get more help here. :) Anyway, you do have the kernel headers and sources installed?