Re: Proposal to enhance boot path selections

> Date: Sun, 11 May 2025 06:39:42 -0700 (PDT)
> From: Paul Goyette <[email protected]>
> 
> On Sun, 11 May 2025, Greg Troxel wrote:
> 
> > Thus I suspect I am missing something.
> 
> Yup, I think you're missing the fact that all of this relates to the
> ratther new-ish KERNEL_DIR option, support for which was only recently
> completed (by myself).  KERNEL_DIR is described briefly in options(4),
> and it is noted in both CHANGES and UPDATING.
> 
> In short, KERNEL_DIR provides a mechanism to keep a kernel and its
> associated modules together, addressing one of the most common
> complaints about modules.
> 
> Sorry for not making this more clear.

I think it is important to

(a) make this clear and obvious and intuitive, _and_
(b) make sure we have tested any plausible transition paths that might
happen.

To that end, this present proposal aside (I haven't digested it, no
comments about it), I would strongly suggest that you make a wiki page
describing everything about the KERNEL_DIR changes (not just the terse
summary in CHANGES, or the notes in UPDATING which are only for an
audience of current users to maintain MKUPDATE=yes builds), including
a systematic table of:

1. What has changed or will change in the standard bootloader?
2. What has changed or will change in a custom bootloader with any new
   build options?
3. What has changed or will change in an unmodified GENERIC kernel?
4. What has changed or will change in a custom kernel with any new
   build options?
5. What does/will sysinst do?
6. How are transitions/upgrades expected to happen?  What will happen
   when a stock netbsd-10 installation is updated to a stock netbsd-11
   installation?
7. How have all of these scenarios been tested?

We really need to make sure this doesn't become another /var/db/pkg
renaming debacle that leaves everyone's machines in confusing
inconsistent states requiring manual intervention.

This type of change -- substantially altering the semantics of how the
bootloader finds the kernel -- has an extremely high risk, not just of
putting machines into confusing states, but of rendering them
unbootable when you update the bootloader.  And, if we were doing it
again, I would ask that any changes be proposed to tech-kern and
port-*, with all this relevant information, _before_ committing
anything that affects default builds.

(It's likely that there already are good answers to all of these
questions, and you've already figured all this out -- it's just not
clear to me from the CHANGES and UPDATING notes and the scattering of
commit messages I've seen fly by, so I'm just asking for a clear
picture to be presented in an obvious place to see how this will
affect users.)