MFC r287964:

Kernel part of reroot support - a way to change rootfs without reboot.

Note that the mountlist manipulations are somewhat fragile, and not very
pretty. The reason for this is to avoid changing vfs_mountroot(), which
is (obviously) rather mission-critical, but not very well documented,
and thus hard to test properly. It might be possible to rework it to use
its own simple root mount mechanism instead of vfs_mountroot().

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D2698

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

/* -> /*- for license, minor formatting changes

Remove the last vestiges of the userconfig option. None of this actually
did anything, so this commit should be considered a NO-OP.

Remove advertising clause from University of California Regent's license,
per letter dated July 22, 1999.

Approved by: core

Changed the RB_PAUSE flag from 0x40000 to 0x100000 and marked the old
value as reserved for internal use in boot blocks, because RB_PAUSE
broke binary compatibility by usurping the RB_DUAL flag. Probably no
one except me has boot blocks for which this matters, since most boot
blocks based on biosboot including pc98's boot2 can't boot elf kernels,
and /boot/loader doesn't properly pass flags set by the previous stage.

reboot.h:
Also mark the historical RB_PROBEKBD flag (0x80000) as reserved for
internal use in boot blocks.

boot2.c:
Added comments to inhibit usurping of other flags.

Approved by: guido, imp
MFC after: 1 week

Fixed some style bugs (English errors and poor wording in comments,
tab lossage, and missing comment on idempotency #endif).

Libdisk does not need to include <sys/diskslice.h> any more.

Move the remaining bits of <sys/diskslice.h> to <i386/include/bootinfo.h>

Move i386/pc98 specific bits from <sys/reboot.h> to
<i386/include/bootinfo.h> as well.

Adjust includes in sys/boot accordingly.

Add new boot flag to i386 boot: -p.
This flag adds a pausing utility. When ran with -p, during the kernel
probing phase, the kernel will pause after each line of output.
This pausing can be ended with the '.' key, and is automatically
suspended when entering ddb.

This flag comes in handy at systems without a serial port that either hang
during booting or reser.
Reviewed by: (partly by jlemon)
MFC after: 1 week

Add RB_MULTIPLE flag so the bootloader can turn on mulitiple console
support. This flag value is identical to RBX_DUAL from boot2.

$Id$ -> $FreeBSD$

Define shift, mask and extraction macros for obtaining the slice number
from the bootdev parameter. This is arguably a 386-ism, although disks
partitioned in this fashion are not uncommon.

Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

Add support for embedded operation withou console
The boot.c patch is applied only to teh JULIAN_HACK branch
the muted console is controlable by a sysctl variable kern.consmute

Support for GDB remote debug protocol.

Sponsored by: Juniper Networks, Inc. <pst@jnx.com>

Some cleanups to the callout lists recently added.
note that at_shutdown has a new parameter to indicate When
during a shutdown the callout should be made. also
add a RB_POWEROFF flag to reboot "howto" parameter..
tells the reboot code in our at_shutdown module to turn off the UPS
and kill the power. bound to be useful eventually on laptops

Merge in Lite2: remove u_long cast from B_MAGICMASK and B_DEVMAGIC
cosmetic changes to comments and number formatting
Reviewed by: davidg & bde

Added RB_CDROM flag, meaning "use CDROM as root".

Add flag `RB_BOOTINFO' that tells if the `struct bootinfo' passed by the
boot has a size field.

Submitted by: Bill Paul (wpaul@ctr.columbia.edu)
Obtained from:
Added a new flag (RB_SERIAL) which is passed by the boot block to tell
the kernel that it should use a serial port as a console. (The kernel
can still be forced to boot in serial console mode if 'options COMCONSOLE'
is used.)

Implement RB_VERBOSE. This is intended to mean: Print all information which
could be of any use for trouble-shooting problems with boot/devices/drivers.

Remove RB_ASKFS again - to make this meaningful we'd need to invest in
implementing too much generality at this stage.

Add RB_ASKFS

Add RB_CONFIG.

Made them all idempotent.
Reviewed by:
Submitted by:

Added $Id$

This commit was generated by cvs2svn to compensate for changes in r1541,
which included commits to RCS files with non-trunk default branches.

BSD 4.4 Lite Kernel Sources