Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

Cross-reference nextboot(8) and freebsd-update(8)

MFC after: 1 week

The nextboot(8) manual page currently says that the loader(8) would delete
the /boot/nextboot.conf file or its contents which is 1) not the most user-
friendly way of working with custom configurations, and 2) simply not true
for both Forth and Lua implementations: they would not delete it, but just
change the setting to "NO", that is, disable it.

While at it, add one missing serial (Oxford) comma and fix some bogus line
wraps along the way.

Approved by: bcr (manpages)
Differential Revision: https://reviews.freebsd.org/D25971

loader: zfs should support bootonce an nextboot

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

Include -a in the nextboot(8) usage string.

X-MFC-With: r297772

nextboot(8): add a -a option for appending to a configuration.

By default, a nextboot invocation will clobber any existing nextboot
configuration.

MFC after: 2 weeks
Relnotes: yes

Fix a few mandoc warnings.

MFC after: 1 week

Document that nextboot(8) doesn't work as expected with ZFS

Differential Revision: https://reviews.freebsd.org/D2087
Submitted by: feld (request)
Reviewed by: feld
Approved by: bcr (mentor)
Sponsored by: ScaleEngine Inc.

use .Mt to mark up email addresses consistently (part1)

PR: 191174
Submitted by: Franco Fichtner <franco@lastsummer.de>

Add -e to set arbitrary kernel environment variables.

Nextboot(8) can now set any combination of kernel name (-k), kernel
options (-o), and environment strings (-e). As a result of this change
-k also becomes optional.

Reviewed by: freebsd-current (Ian Lepore, pluknet@, jhb@)

Spelling fixes for sbin/

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

- Import the HEAD csup code which is the basis for the cvsmode work.

Uniformly refer to a file system as "file system".

Approved by: re

mdoc(7) police: overhaul.

Fix one misspelling and two punctuation nits.

Add a nextboot manual page.

Spotted by: brandt@fokus.gmd.de