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

[Jason Thorpe <thorpej%me.com@localhost>]

> On Aug 17, 2026, at 6:19 AM, Taylor R Campbell <riastradh%NetBSD.org@localhost> wrote:
> 
> 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.)

The cache can’t live on /var because /var might not be available when the cache is required (this would especially be the case for read-only roots).  The only path that’s currently guaranteed to be available when /etc/rc starts processing the rc.d scripts is /etc.  It’s pretty straightforward to suppress any error messages that might occur when writing out the cache (which happens as the last step of the boot process).  And, yes, I can refactor the code that builds and writes out the cache into rc.subr so that there can be a “nostart” rc.d script to rebuild it for those who wish to do that before the next reboot.

-- thorpej