I am doing a small project in which i m designing a new system call
to encrypt/decrypt files.

My problem goes like this:

1> Previously up until 2.4 , sys_call_table was exported by kernel
and so obsolete sys call no. could be used to add our customised
syscall.So patching around that obsolete sys call worked.

2> I am designing on 2.6.5 and it doesnt export sys_call_table .
So the obvious thing is to modify kernel sources and do development.
But this would terribly slow down the work as I have to recompile
again and again. I thought using modules is better.

In order to export the sys_call_table in kernel 2.6 i added into the file arch/i386/kernel/i386_ksyms.c the following lines:
extern void* sys_call_table[];
EXPORT_SYMBOL(sys_call_table);

But after recompile , the symbol unresolved problem continues
when i run my module.

I googled a lot but couldnt find worthy source. Could u suggest a workaround
to add sys call using modules only ?

..and you're not the onlyone with that problem.
I'm doin an "ultimate-yber-security" module (actually tryin to get it to work in 2.6, worked like charm in 2.4..) that, when system has "unwanted" visitors (read: hackers) stealing the root account, keeps a "hidden" account up, and when U log in (whit that hidden) , it jamms *every* command that the unwanted gues tries to use.. and hides itself from ls'ing, accessing directly, logs, and from seeing that it has been loaded...

...Was kinda neet to listen what a friend of mine said, when I created a fake-root account on my pc, and let him to log in and do all the damage he could do..

I'd also appriciate a solution of somekind to that problem.