required kernel rebuilds

[Alan Somers]

On Wed, Sep 13, 2017 at 9:55 AM, Michael W. Lucas
<mwlucas at michaelwlucas.com> wrote:
> Hi,
>
> Book research question.
>
> Way back in the Dark Ages of the 1990s, it wasn't uncommon to rebuild
> a kernel to fix a recurring panic. You'd have to tune MAXUSERS, or
> PMAP_SHPGPERPROC.
>
> AFAIK, dang near everything is tunable in either loader.conf or
> sysctl.conf. I really want to say that kernel rebuilds for these kinds
> of limits aren't needed any more.
>
> Does anyone have a counter-example, though? Is anything possibly
> crash-inducing non-tunable without a kernel rebuild?
>
> Thanks,
> ==ml

Enabling VIMAGE still requires a kernel rebuild, because of the
possibility of crashes.  I've seen such crashes on 10.2 or 10.3.  I
don't know if they're fixed in 11.1, but I haven't seen any yet.
Changing MAXPHYS also requires a kernel rebuild.  AFAIK MAXPHYS isn't
related to any kernel crashes, but it does have performance
implications.

-Alan