cons(9): New function cn_set_tab.

Increment of progress toward eliminating bare access to cn_tab so we
can make more things MP-safe without the kernel lock (and maybe some
day better formalize console detection and switching).

cons(9): Need sys/types.h for dev_t, u_int.

Remove clause 3 (UCB advertising clause) from the University of Utah
copyright. Confirmed by Mike Hibler, mike at cs.utah.edu - thanks!
Also, merge UCB and Utah copyright texts back into one, as they
originally were.

Extra verification by snj@.

branches: 1.26.68; 1.26.74; 1.26.76;
Complete the cons_init(n) initializer.

branches: 1.25.6;
Remove redundant semicolon in dev_type_cnbell.

branches: 1.24.4; 1.24.6; 1.24.8; 1.24.14;
merge ktrace-lwp.

branches: 1.23.6;
de-__P

branches: 1.22.8; 1.22.10;
Introduce null console. This pseudo device acts as a normal console with the
exception that it discards any output, and is useful for booting the kernel
on headless boxes.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.20.2;
Add cn_halt and cn_flush entries to consdevs. (needed for dma-only console
devices).

Merge the gehenna-devsw branch into the trunk.

This merge changes the device switch tables from static array to
dynamically generated by config(8).

- All device switches is defined as a constant structure in device drivers.

- The new grammer ``device-major'' is introduced to ``files''.

device-major <prefix> char <num> [block <num>] [<rules>]

- All device major numbers must be listed up in port dependent majors.<arch>
by using this grammer.

- Added the new naming convention.
The name of the device switch must be <prefix>_[bc]devsw for auto-generation
of device switch tables.

- The backward compatibility of loading block/character device
switch by LKM framework is broken. This is necessary to convert
from block/character device major to device name in runtime and vice versa.

- The restriction to assign device major by LKM is completely removed.
We don't need to reserve LKM entries for dynamic loading of device switch.

- In compile time, device major numbers list is packed into the kernel and
the LKM framework will refer it to assign device major number dynamically.

branches: 1.18.6; 1.18.8; 1.18.10; 1.18.20;
move static function getstr() to cons.c, make it publically available
as cngetsn(). there will be other consumer.

- Implement cnbell() -- ring the console bell. The cn_bell entrypoint
is optional.
- Add cn_bell to statically allocated consdevs as appropriate.

Protect against multiple inclusion.

branches: 1.15.28; 1.15.34;
Implement poll(2).

Bring prototypes into scope.

cnputc returns void

fix definition of nullcnpollc, and add a prototype for it.

short -> int (alignment)

Properly prototype the switch table functions. Add conf.h-like macros for
defining the switch tables.

KERNEL -> _KERNEL

don't let args default, return values, add protos

Implement cnpollc().

New RCS ID's, take two. they're more aesthecially pleasant, and use 'NetBSD'

new standard, minimally intrusive ID format

Add RCS identifiers (this time on the correct side of the branch), and
incorporate recent changes in netbsd-0-9 branch.

the "struct tty *cn_tty" field in cons.c wasn't being used by anything

add rcsids to everything and clean up headers

branches: 1.1.1;
Initial revision