cvs commit: src/sys/kern subr_param.c

[M. Warner Losh]

In message: <200805090956.m499uEvT007906 at haluter.fromme.com>
            Oliver Fromme <olli at fromme.com> writes:
: 
: Pawel Jakub Dawidek wrote:
:  > On Fri, May 09, 2008 at 11:08:20AM +0200, Oliver Fromme wrote:
:  > > Pawel Jakub Dawidek wrote:
:  > >  >   Modified files:
:  > >  >     sys/kern             subr_param.c=20
:  > >  >   Log:
:  > >  >   - Export HZ value via kern.hz sysctl (this is the same name as for the
:  > >  >     loader tunable).
:  > > 
:  > > It's probably just me, but I don't see the usefulness of
:  > > this.  The HZ value is already exported via kern.clockrate.
:  > > (I'm not saying the change is wrong, I'm just looking for
:  > > an explanation.)
:  > 
:  > The reason for this change was that I was trying to recall what is
:  > the name of the tunable and I wasn't able to find it with simple
:  > "sysctl -a | grep hz". In an ideal world most of not all loader
:  > tunables should also be visible as read-only sysctls.
: 
: Hm.  It was my understanding that the loader tunables
: are already exported via kenv(2), so typing "kenv"
: should include them all.  I was probably wrong, though.
: 
: Thanks for the explanation.  It's now clearer to me.

There's a subtle difference between what's in the kenv and what the
value of the tunables might be set to in the kernel.  Some tunable
have alignment requirements, or are ignored completely if the required
driver isn't present...

Warner