Checking sysctl values from within the kernel.

[Thordur I. Bjornsson]

On Fri, 5 Aug 2005 11:01:32 -0400
John Baldwin <jhb at FreeBSD.org> wrote:

> On Friday 05 August 2005 10:50 am, Dan Nelson wrote:
> > In the last episode (Aug 05), Thordur I. Bjornsson said:
> > > If I want to check a sysctl value from within the kernel (e.g. an
> > > KLD), should I use the system calls described in sysctl(3) ?
> > >
> > > If not, what is the propper way to do so ?
> >
> > Since most sysctls are direct mappings onto integer variables in the
> > kernel, just check the variable directly.
> 
> There's also a kernel_sysctl() function available in the kernel for
> in-kernel  access to sysctls.  You might have to lookup the OID for a
> given name  yourself though.  Actually, there's a
> kernel_sysctlbyname() as well.
> 
> -- 
> John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
> "Power Users Use the Power to Serve"  =  http://www.FreeBSD.org

Ahh. Cool
This is not in any manpage ... 

I'm trying to understand the first argument to kernel_systcl(),
kernel_sysctl(struct thread *td, ... )

This thread, that it takes as an argument is this something that I need
to worry about when writing KLD's or could I just pass a NULL pointer ?

The proplem is that I do not know/understand how threading works in the
kernel. I'll be lookin into that (although pointers are more then
welcome ;)


-- 
Thordur I.	<bzthib at gmail.com>
Humppa!