Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Include stand.h for loader.

MFC after: 3 days

Start each of the license/copyright comments with /*-, minor shuffle of lines

- Split dcons core code and OS dependent code.
- Implement dcons_ischar() and dcons_load_buffer().
- If loader passed a dcons buffer address, keep using it.
(We still need a patch to cheat memory management system.)

Invalidate dcons buffer on shutdown.

Sync with DragonFly BSD.

Preparation commit for the tty cleanups that will follow in the near
future:

rename ttyopen() -> tty_open() and ttyclose() -> tty_close().

We need the ttyopen() and ttyclose() for the new generic cdevsw
functions for tty devices in order to have consistent naming.

Do a pass over all modules in the kernel and make them return EOPNOTSUPP
for unknown events.

A number of modules return EINVAL in this instance, and I have left
those alone for now and instead taught MOD_QUIESCE to accept this
as "didn't do anything".

Re-enable debugger port.

Update for the KDB framework:
o Use kdb_alt_break() to handle the alternate break sequence instead
of handcoding it here.
o Remove GDB kluges to make this driver work with the pre-KDB remote
GDB code.
o Call kdb_enter() instead of Debugger().

Note that with this commit the dcons(4) driver cannot be used for
remote debugging anymore. This driver has to use the new GDB debug
port interface instead. Such has not been done yet.

Second half of the dev_t cleanup.

The big lines are:
NODEV -> NULL
NOUDEV -> NODEV
udev_t -> dev_t
udev2dev() -> findcdev()

Various minor adjustments including handling of userland access to kernel
space struct cdev etc.

Do the dreaded s/dev_t/struct cdev */
Bump __FreeBSD_version accordingly.

Machine generated patch which changes linedisc calls from accessing
linesw[] directly to using the ttyld...() functions

The ttyld...() functions ar inline so there is no performance hit.

Gainfully employ the new ttyioctl in the trivial cases.

There is no need to explicitly call ttwakeup() and ttwwakeup() after
ttyclose() has been called. It's already been done once by ttyclose,
and probably once by the line-discipline too.

ttyclose() increments t_gen. Remove redundant increments in drivers.

Add missing <sys/module.h> includes

Device megapatch 4/6:

Introduce d_version field in struct cdevsw, this must always be
initialized to D_VERSION.

Flip sense of D_NOGIANT flag to D_NEEDGIANT, this involves removing
four D_NOGIANT flags and adding 145 D_NEEDGIANT flags.

Device megapatch 3/6:

Add missing D_TTY flags to various drivers.

Complete asserts that dev_t's passed to ttyread(), ttywrite(),
ttypoll() and ttykqwrite() have (d_flags & D_TTY) and a struct tty
pointer.

Make ttyread(), ttywrite(), ttypoll() and ttykqwrite() the default
cdevsw methods for D_TTY drivers and remove the explicit initializations
in various drivers cdevsw structures.

Device megapatch 1/6:

Free approx 86 major numbers with a mostly automatically generated patch.

A number of strategic drivers have been left behind by caution, and a few
because they still (ab)use their major number.

- Clean up global data.
- Force dcons to be the high-level console after dcons_crom
has been attached.
- Add a tunable to be the high-level console.

Add dumb console driver and related bits.

dcons(4): very simple console and gdb port driver
dcons_crom(4): FireWire attachment
dconschat(8): User interface to dcons

Tested with: i386, i386-PAE, and sparc64.