Make sure IFM_AVALID is also set when checking ifm_status.

Submitted by:	yongari
Replace kernel virtual address space allocation with vmem.  This provides
transparent layering and better fragmentation.

 - Normalize functions that allocate memory to use kmem_*
 - Those that allocate address space are named kva_*
 - Those that operate on maps are named kmap_*
 - Implement recursive allocation handling for kmem_arena in vmem.

Reviewed by:	alc
Tested by:	pho
Sponsored by:	EMC / Isilon Storage Division
Remove unsigned comparison < 0

Found by:	LLVM
Reviewed by:	luigi
enable KDB_TRACE in GENERICs

KDB_TRACE is not an alternative to DDB/etc, they are complementary.
So I do not see any reason to not enable KDB_TRACE by default.

X-MFC after:	never (change specific to head)
Improve r253721 by reporting detected lack of BIO_FLUSH support to GEOM.
That prevents more of such requests from coming and errors from logging.
Bring initial support for Allwinner A20 SoC (Cubieboard2).
	Add support for A20 timer.
	Correct interrupt offset depending from chip.
	Add basic code for CPU configuration module.
	For now, add kernel config and dts file
	(only FDT blob related problem needs to be solved later in
	order to have one kernel for both cubieboard1 and 2).

Approved by: ray@
Remove __attribute__((__aligned__)) that generates incorrect alignment on compilers that know about SSE.  Code left over from old header that thought that 64 bits was the maximum alignment that anything would ever need...
Remove droping topology mutex after iterating 100 periphs in CAMGETPASSTHRU.
That is not so slow and so often operation to handle unneeded otherwise
xsoftc.xpt_generation and respective locking complications.
Don't bother trying to work around buffers which are not aligned on a cache
line boundary. It has never been 100% correct, and it can't work on SMP,
because nothing prevents another core from accessing data from an unrelated
buffer in the same cache line while we invalidated it. Just use bounce pages
instead.

Reviewed by:	ian
Approved by:	mux (mentor) (implicit)
Fix previous commit: both flags must be set.
Change the pmap_ts_referenced() method of amd64 pmap to use shared
pvh_global_lock.  This allows the method to be executed in parallel,
avoiding undue contention on the pvh_global_lock for the multithreaded
pagedaemon.

The pmap_ts_referenced() function has to inspect the page mappings for
several pmaps, which need to be locked while pv list lock is owned.
This contradicts to the lock order, where pmap lock is before pv list
lock.  Introduce the generation count for the pv list of the page or
superpage, which indicate any change in the pv list, and, as usual,
perform restart of the iteration if generation changed while pv lock
was dropped for blocking acquire of a pmap lock.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
Split the pagequeues per NUMA domains, and split pageademon process
into threads each processing queue in a single domain.  The structure
of the pagedaemons and queues is kept intact, most of the changes come
from the need for code to find an owning page queue for given page,
calculated from the segment containing the page.

The tie between NUMA domain and pagedaemon thread/pagequeue split is
rather arbitrary, the multithreaded daemon could be allowed for the
single-domain machines, or one domain might be split into several page
domains, to further increase concurrency.

Right now, each pagedaemon thread tries to reach the global target,
precalculated at the start of the pass.  This is not optimal, since it
could cause excessive page deactivation and freeing.  The code should
be changed to re-check the global page deficit state in the loop after
some number of iterations.

The pagedaemons reach the quorum before starting the OOM, since one
thread inability to meet the target is normal for split queues.  Only
when all pagedaemons fail to produce enough reusable pages, OOM is
started by single selected thread.

Launder is modified to take into account the segments layout with
regard to the region for which cleaning is performed.

Based on the preliminary patch by jeff, sponsored by EMC / Isilon
Storage Division.

Reviewed by:	alc
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Don't emit a spurious EVFILT_PROC event with no fflags set on process exit
if NOTE_EXIT is not being monitored.  The rationale is that a listener
should only get an event for exit() if they registered interest via
NOTE_EXIT.  This matches the behavior on OS X.
- Don't save the exit status on process exit unless NOTE_EXIT is being
  monitored.
- Add an internal EV_DROP flag that requests kqueue_scan() to free the
  knote without signalling it to userland and use this when a process
  exits but the fflags in the knote is zero.

Reviewed by:	jmg
MFC after:	1 month
Improve the sysctl symbol extraction from the kernel so that it find more
(all?) sysctl's.  Previously some where missed, depending on how they were
defined.
MFV r254070:

Merge vendor bugfix for ZFS test suite that triggers false positives.

Illumos ZFS issues:
  3949 ztest fault injection should avoid resilvering devices
  3950 ztest: deadman fires when we're doing a scan
  3951 ztest hang when running dedup test
  3952 ztest: ztest_reguid test and ztest_fault_inject don't place nice together
Allow net80211 to compile on stable/9 and stable/8.
MFV r254071:

Fix a regression introduced by fix for Illumos bug #3834.  Quote from
Matthew Ahrens on the Illumos issue:

ztest fails this assertion because ztest_dmu_read_write() does
        dmu_tx_hold_free(tx, bigobj, bigoff, bigsize);
and then
    dmu_object_set_checksum(os, bigobj,
        (enum zio_checksum)ztest_random_dsl_prop(ZFS_PROP_CHECKSUM), tx);

If the region to free is past the end of the file, the DMU assumes that there
will be nothing to do for this object.  However, ztest does set_checksum(),
which must modify the dnode.  The fix is for ztest to also call

    dmu_tx_hold_bonus(tx, bigobj);

so we can account for the dirty data associated with setting the checksum

Illumos ZFS issues:
  3955 ztest failure: assertion refcount_count(&tx->tx_space_written)
         + delta <= tx->tx_space_towrite