- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

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

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

MFcalloutng:
Make dcons input polling adaptive, reducing poll rate to 1Hz after several
minutes of inactivty to reduce global interrupt rate. Most of users never
used FireWire debugging, so it is not very useful to consume power by it.

kern cons: introduce infrastructure for console grabbing by kernel

At the moment grab and ungrab methods of all console drivers are no-ops.

Current intended meaning of the calls is that the kernel takes control of
console input. In the future the semantics may be extended to mean that
the calling thread takes full ownership of the console (e.g. console
output from other threads could be suspended).

Inspired by: bde
MFC after: 2 months

Mark all SYSCTL_NODEs static that have no corresponding SYSCTL_DECLs.

The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.

Follow up to r225203 refining break-to-debugger run-time configuration
improvements:

(1) Implement new model in previously missed at91 UART driver
(2) Move BREAK_TO_DEBUGGER and ALT_BREAK_TO_DEBUGGER from opt_comconsole.h
to opt_kdb.h (spotted by np)
(3) Garbage collect now-unused opt_comconsole.h

MFC after: 3 weeks
Approved by: re (bz)

Attempt to make break-to-debugger and alternative break-to-debugger more
accessible:

(1) Always compile in support for breaking into the debugger if options
KDB is present in the kernel.

(2) Disable both by default, but allow them to be enabled via tunables
and sysctls debug.kdb.break_to_debugger and
debug.kdb.alt_break_to_debugger.

(3) options BREAK_TO_DEBUGGER and options ALT_BREAK_TO_DEBUGGER continue
to behave as before -- only now instead of compiling in
break-to-debugger support, they change the default values of the
above sysctls to enable those features by default. Current kernel
configurations should, therefore, continue to behave as expected.

(4) Migrate alternative break-to-debugger state machine logic out of
individual device drivers into centralised KDB code. This has a
number of upsides, but also one downside: it's now tricky to release
sio spin locks when entering the debugger, so we don't. However,
similar logic does not exist in other device drivers, including uart.

(5) dcons requires some special handling; unlike other console types, it
allows overriding KDB's own debugger selection, so we need a new
interface to KDB to allow that to work.

GENERIC kernels in -CURRENT will now support break-to-debugger as long as
appropriate boot/run-time options are set, which should improve the
debuggability of BETA kernels significantly.

MFC after: 3 weeks
Reviewed by: kib, nwhitehorn
Approved by: re (bz)

Last minute TTY API change: remove mutex argument from tty_alloc().

I don't want people to override the mutex when allocating a TTY. It has
to be there, to keep drivers like syscons happy. So I'm creating a
tty_alloc_mutex() which can be used in those cases. tty_alloc_mutex()
should eventually be removed.

The advantage of this approach, is that we can just remove a function,
without breaking the regular API in the future.

Reduce the dcons polling frequency to 25 Hz.

It makes little sense to use 100 Hz polling in dcons. We cannot live
without polling, because that's just how dcons works. It polls the
buffer filled by the firewire hardware. 25 Hz is probably enough for
most use cases.

Discussed with: rwatson
Tested by: kan

Fix logic in MOD_LOAD handler to call dcons_attach after all successful
dcons_drv_init invocations. Testing return value for 0 does not work for
cases where dcons_drv_init was called already as part of low level
console initialization.

We need to initialize the console for dcons to work.

Submitted by: nork@

Check the return values of contigmalloc(9) as well as bus_dma(9)
functions and stop attaching of dcons(4) and dcons_crom(4) if
they indicate failure. This fixes a panic seen on sparc64 machines
with no free physical memory in the requested 32-bit region but
still doesn't make dcons(4)/dcons_crom(4) these work. I think
the latter can be fixed by simply specifying ~0UL as the upper
limit for contigmalloc(9) and letting the bounce pages and the
IOMMU respectively handle limitations of the DMA engine. I didn't
want to change that without the consensus of simokawa@ though,
who unfortunately didn't reply so far.

MFC after: 1 week

Also make dcons(4) use MPSAFE callouts.

The callout locks the TTY layer the way it should, so there is no reason
why its callout shouldn't set this flag.

Integrate the new MPSAFE TTY layer to the FreeBSD operating system.

The last half year I've been working on a replacement TTY layer for the
FreeBSD kernel. The new TTY layer was designed to improve the following:

- Improved driver model:

The old TTY layer has a driver model that is not abstract enough to
make it friendly to use. A good example is the output path, where the
device drivers directly access the output buffers. This means that an
in-kernel PPP implementation must always convert network buffers into
TTY buffers.

If a PPP implementation would be built on top of the new TTY layer
(still needs a hooks layer, though), it would allow the PPP
implementation to directly hand the data to the TTY driver.

- Improved hotplugging:

With the old TTY layer, it isn't entirely safe to destroy TTY's from
the system. This implementation has a two-step destructing design,
where the driver first abandons the TTY. After all threads have left
the TTY, the TTY layer calls a routine in the driver, which can be
used to free resources (unit numbers, etc).

The pts(4) driver also implements this feature, which means
posix_openpt() will now return PTY's that are created on the fly.

- Improved performance:

One of the major improvements is the per-TTY mutex, which is expected
to improve scalability when compared to the old Giant locking.
Another change is the unbuffered copying to userspace, which is both
used on TTY device nodes and PTY masters.

Upgrading should be quite straightforward. Unlike previous versions,
existing kernel configuration files do not need to be changed, except
when they reference device drivers that are listed in UPDATING.

Obtained from: //depot/projects/mpsafetty/...
Approved by: philip (ex-mentor)
Discussed: on the lists, at BSDCan, at the DevSummit
Sponsored by: Snow B.V., the Netherlands
dcons(4) fixed by: kan

Spell KDB_REQ_REBOOT correctly.

Expand kdb_alt_break a little, most commonly used with the option
ALT_BREAK_TO_DEBUGGER. In addition to "Enter ~ ctrl-B" (to enter the
debugger), there is now "Enter ~ ctrl-P" (force panic) and
"Enter ~ ctrl-R" (request clean reboot, ala ctrl-alt-del on syscons).

We've used variations of this at work. The force panic sequence is
best used with KDB_UNATTENDED for when you just want it to dump and
get on with it.

The reboot request is a safer way of getting into single user than
a power cycle. eg: you've hosed the ability to log in (pam, rtld, etc).
It gives init the reboot signal, which causes an orderly reboot.

I've taken my best guess at what the !x86 and non-sio code changes
should be.

This also makes sio release its spinlock before calling KDB/DDB.

Add a new 'why' argument to kdb_enter(), and a set of constants to use
for that argument. This will allow DDB to detect the broad category of
reason why the debugger has been entered, which it can use for the
purposes of deciding which DDB script to run.

Assign approximate why values to all current consumers of the
kdb_enter() interface.

We don't need to call dcons_poll event handlers if KDB is not active.

Approved by: re (kensmith)

- Don't force to be the GDB port since dcons(4) is in GENERIC now.

To enable the GDB port of dcons(4), you need to put
dcons_gdb=1
in /boot/loader.conf.

Don't invalidate dcons buffer on shutdown.
We would like to keep connection after halt.

Replace breakpoint() with kdb_enter().

Poll bus resets on FireWire while kdb/gdb is active.

Now, it's safe to call the fwohci interrupt(polling) routine while ddb/gdb
is active. After this change, a dcons connnection over FireWire can survive
bus resets even in kernel debugger.

This means that it is not too late to plug a FireWire cable after a panic
to investigate the problem.

Actually there is a small window(between a jump to kernel from loader and
initialization of dcons_crom) in which no one can take care of a bus reset.
Except that window, firewire console should keep working
from loader to reboot even with a panic and a bus reset.
(as far as you enable LOADER_FIREWIRE_SUPPORT)

We should better ignore a break on gdb port if gdb is not enabled.

Make compile without GDB option.

MFC after: 3 days

Sweep kernel replacing suser(9) calls with priv(9) calls, assigning
specific privilege names to a broad range of privileges. These may
require some future tweaking.

Sponsored by: nCircle Network Security, Inc.
Obtained from: TrustedBSD Project
Discussed on: arch@
Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri,
Alex Lyashkov <umka at sevcity dot net>,
Skip Ford <skip dot ford at verizon dot net>,
Antoine Brodin <antoine dot brodin at laposte dot net>

Convert to new console interface.

Eliminate gdb_checkc member from GDB_DBGPORT(), it is never used.

Use polling behaviour for gdb_getc() where convenient, this edges us
closer to the console code.

Use ttyalloc() instead of ttymalloc()

Fix -Wundef warnings found when compiling i386 LINT, GENERIC and
custom kernels.

Make ttyconsolemode() call ttsetwater() so that drivers don't have to.

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

Use dcons buffer passed by loader on amd64.

- Use quad_t for dcons buffer address and size.
- Allow read/write access to dcons buffer passed by loader(8).

Add new function ttyinitmode() which sets our systemwide default
modes on a tty structure.

Both the ".init" and the current settings are initialized allowing
the function to be used both at attach and open time.

The function takes an argument to decide if echoing should be enabled.
Echoing should not be enabled for regular physical serial ports
unless they are consoles, in which case they should be configured
by ttyconsolemode() instead.

Use the new function throughout.

Fix warnings on non-i386 arch.

Submitted by: keramida

- 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.)