preferable way to control kernel module

[John Baldwin]

On Wednesday 10 August 2005 05:11 pm, Sergey Uvarov wrote:
> John Baldwin wrote:
> > On Wednesday 10 August 2005 04:29 pm, Sergey Uvarov wrote:
> >>Hello hackers,
> >>
> >>I'm writing a kernel module for my own needs. AFAIK the following
> >>methods could be used:
> >>
> >>1) allocate not used system call with help of SYSCALL_MODULE macro
> >>
> >>2) allocate proprieatry oid via SYSCTL_OID(OID_AUTO) and write an
> >>appropriate sysctl handler(s)
> >>
> >>3) add a file in /dev and use ioctl(2) call
> >>
> >>What is a preferable way to control my module?
> >
> > It depends on what you want to do really.  I've used sysctl's for simple
> > debug modules where I write to the sysctl to have it perform a desired
> > action.
>
> I need to pass some configuration parameters to my module and retrieve a
> status back. Interface is quite similar to ptrace(2) syscall. I don't
> need to pass large amount of data.

If it's a single integer or some such, I'd say use sysctl.  If it's a 
structure, I'd go the ioctl(2) route.  Creating /dev entries isn't all that 
hard.  In your case you'd just need open/close/ioctl in a cdevsw, then use 
make_dev() during MOD_LOAD and destroy_dev() during MOD_UNLOAD.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org