kern/54733: ZFS warnings during default boot, even if no ZFS is in use

[martin%NetBSD.org@localhost]

>Number:         54733
>Category:       kern
>Synopsis:       ZFS warnings during default boot, even if no ZFS is in use
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Tue Dec 03 17:35:00 +0000 2019
>Originator:     Martin Husemann
>Release:        NetBSD 9.99.19
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD painkiller.duskware.de 9.99.19 NetBSD 9.99.19 (GENERIC64) #88: Tue Dec 3 18:17:17 CET 2019 martin%seven-days-to-the-wolves.aprisoft.de@localhost:/work/src/sys/arch/evbarm/compile/GENERIC64 evbarm
Architecture: aarch64
Machine: evbarm
>Description:

With /etc/rc.d/zfs trying to bring up ZFS pools early we now get scary
warnings at boot time on machines that never saw a ZFS:

root file system type: ffs
kern.module.path=/stand/evbarm/9.99.19/modules
WARNING: ZFS on NetBSD is under development
ZFS NOTICE: Prefetch is disabled by default if less than 4GB of RAM is present;
to enable, add "vfs.zfs.prefetch_disable=0" to /boot/loader.conf.
ZFS filesystem version: 5
Lid Switch: lid opened.


It would be better if trying to use ZFS would be triggered by some config
file, or the kernel be silent about the whole action (who cares what version
is in use if it is not in use?)

>How-To-Repeat:
Boot current.

>Fix:
n/a