zfs lives in libsa. However, it depends on nvstore (and other things)
that are in common. Fix part of this layering violation by splitting
nvstore into a libsa piece (which is the base implementation) and
keeping a much smaller common piece (to implement the nvstore
command). This just leaves zfs' knowledge of device names that's
specific to common and its calling platform specific init code to
resolve. Add a nvstore.h file for these two parts to communicate private
things and move the public nvstore api from bootstrap.h to stand.h.
Sponsored by: Netflix
Reviewed by: tsoome, kevans
Differential Revision: https://reviews.freebsd.org/D38043
bootonce feature is temporary, one time boot, activated by
"bectl activate -t BE", "bectl activate -T BE" will reset the bootonce flag.
By default, the bootonce setting is reset on attempt to boot and the next
boot will use previously active BE.
By setting zfs_bootonce_activate="YES" in rc.conf, the bootonce BE will
be set permanently active.
bootonce dataset name is recorded in boot pool labels, bootenv area.
in case of nextboot, the nextboot_enable boolean variable is recorded in
freebsd:nvstore nvlist, also stored in boot pool label bootenv area.
On boot, the loader will process /boot/nextboot.conf if nextboot_enable
is "YES", and will set nextboot_enable to "NO", preventing /boot/nextboot.conf
processing on next boot.
bootonce and nextboot features are usable in both UEFI and BIOS boot.
To use bootonce/nextboot features, the boot loader needs to be updated on disk;
if loader.efi is stored on ESP, then ESP needs to be updated and
for BIOS boot, stage2 (zfsboot or gptzfsboot) needs to be updated
(gpart or other tools).
At this time, only lua loader is updated.
Sponsored by: Netflix, Klara Inc.
Differential Revision: https://reviews.freebsd.org/D25512
