Re: Adding new syscalls via modules?

Nimrod Zimerman (zimerman@deskmail.com)
Mon, 5 Jul 1999 15:07:05 +0300


On Sun, Jul 04, 1999 at 02:10:39PM +0100, Alex Buell wrote:

> I'm tired of rebooting the machine everytime I make a new kernel, so I
> thought why not implement some mechanism through the kernel module loader
> such that one could load a module to install a new syscall or a sysctl.
>
> I'd like to know if there's sufficient interest in this, I think it would
> be brilliant for testing new sysctls/syscalls simply by loading a module
> and unloading afterwards.

You can do this manually now, though not in a safe manner, by directly
changing the sys_call_table array of system calls. Also, in a proposed patch
by Alexander Maryanchick (dated around Jun 25), you can do this through what
appears to be a cleaner way.
(Obviously, you'll have to come up with some way of synchronizing between
different modules, or things wouldn't be too friendly).

I've done such things in the past (and am actually currently working on
something that messes with it too), with no problems. I've been running a
system that has used several 'new' system calls, as well as 'overwritten'
some existing system calls, as a production system for lengthly periods of
time with no observable trouble.

Nimrod

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