Re: Kernel selection in Lua loader

On Wed, Feb 21, 2018 at 6:36 AM, David Wolfskill <david_at_catwhisker.org> wrote:
> The Lua loader appears to be using a mechanism other than the
> "kernels=..." specification in /boot/loader.conf to slect potential
> kernels to load.  I'm not claiming this is "bad" -- just "different."
>
> I noticed because I sometimes build a kernel that ... panics, or some
> such thing, so I hve had occasion to make use of kernel.old.  But in the
> process of engaging a developer and trying patches, the default behavior
> is that kernel.old gets overwritten next time I build a kernel.
>
> So I had taken to copying /boot/*.old to /boot/*.save manually as the
> occasion warrants; I modified /boot/loader.conf to include:
>
> kernels="kernel kernel.old kernel.save"
>
> and the Forth loader presented (precisely) those kernels as the
> available options for selecting a kernel to load and boot.
>

Right, so, we (and by we I mean cem_at_) actually implemented a form of
auto-detection for kernels. Any directory in in /boot with a file
named 'kernel' inside will be automatically listed, and that
supplemented(*) 'kernels' and 'kernel' specified in loader.conf(5).

(*) I use "supplemented" because I changed that in r329709, just a
little bit ago, to not do the autodetection if a 'kernels' is
explicitly set in loader.conf(5) My reasoning here is that there's
probably a reason one has set it explicitly, whether it be to hide
bogus kernels or just to slim down the list of kernels they need to
cycle through.

> [ ... snip ... ]