Checking sysctl values from within the kernel.

[John Baldwin]

On Friday 05 August 2005 12:44 pm, Thordur I. Bjornsson wrote:
> 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 ;)

Pass curthread as the thread.

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