Re: bin/60607: /etc/rc does too much throw-away work and is needlessly slow on constrained systems

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

> Date: Mon, 17 Aug 2026 05:35:00 +0000 (UTC)
> From: Jason Thorpe <thorpej%me.com@localhost>
> 
> I've devised a simple solution to the problem that's minimally
> invasive and, on the wrap030 homebrew, cuts the boot time (with
> ldconfig=NO) from ~13 minutes to ~7 minutes.

Nice!

> 2. Another small change to /etc/rc where the real work of invoking
> the rc.d scripts is performed.  This second change introduces the
> notion of the "rcorder.cache".  At boot time, if it is determined
> that the cache needs to be rebuilt, then all of the rc.d scripts are
> interrogated in rcorder-order to see if they will do work.  If so,
> they're added to the list, otherwise they are ignored.  Once the
> list is built, then the list is invoked to start each service in the
> normal way.  The list is saved in the "rcorder.cache" and consulted
> at the next boot.  The cache is invalidated by modifying
> /etc/rc.conf, /etc/rc.d, or by manually removing /etc/rcorder.cache.

Can you make this part optional, and/or populated up front at
build-time or repopulated on request?  It would be nice if we could
boot to multi-user from a read-only /, with all state stored on other
file systems like /var, and without spurious EROFS warnings spewed to
the console.  (I know we'll hit issues with, e.g., /etc/motd today,
but I'd like to avoid adding more issues.)