Add vt_efifb to VT kernel configuration now that that actually works. This
kernel will now boot on both BIOS and EFI systems without modification.
Equivalent functionality in GENERIC requires making vt(9) the default console
driver, which is probably appropriate at this point.
Don't need this now. VT does the same thing, but better.

Submitted by:	gjb
When vm_fault_copy_entry() is called from vm_map_protect() for a wired
entry and performs the upgrade of the entry permissions from read-only
to read-write, we must allow to search for the source pages in the
backing object, like we do in the case of forking the read-only wired
entry. For the fork case, the behaviour is allowed by src_readonly
boolean, which in fact is only used to assert that read-write case
provides all source pages in the top-level object.

Eliminate the src_readonly variable.  Allow for the copy loop to look
into the backing objects, add explicit asserts to ensure that only
read-only and upgrade case actually does.

Expand comments. Change the panic call into assert.

Reported by:	markj
Tested by:	markj, pho (previous version)
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Fix order of libthr and libc in the global dso list for sshd, by
explicitely linking main binary with -lpthread.  Before, libthr
appeared in the list due to dependency of one of the kerberos libs.
Due to the change in ld(1) behaviour of not copying NEEDED entries
from direct dependencies into the link results, the order becomes
reversed.

The libthr must appear before libc to properly interpose libc symbols
and provide working rtld locks implementation.  The symptom was sshd
hanging on rtld bind lock during nested symbol binding from a signal
handler.

Approved by:	des (openssh maintainer)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Same as it was done in r263878 for invlrng_handler(), fix order of
checks for special pcid values in invlpg_pcid_handler().  Forst check
for special values, and only then do PCID-specific page invalidation.

Minor fix to the style compliance, declare local variable at the
function start.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Do not delay freeing rtm. Bandaid added in r227061 is not needed since r227061,

MFC after:	1 month
Cleanup route_output() a bit.

MFC after:	1 month
Remove useless zeroing of RTAX_DST on error.
Cleanup a bit.

MFC after:	1 month
Fix the gpio-specifier decoding by respecting the GPIO controller's
#gpio-cells property.

Add a new ofw_bus method (OFW_BUS_MAP_GPIOS()) that allows the GPIO
controller to implement its own mapping to deal with gpio-specifiers,
allowing the decoding of gpio-specifiers to be controller specific.

The default ofw_bus_map_gpios() decodes the linux standard (#gpio-cells =
<2>) and the FreeBSD standard (#gpio-cells = <3>).

It pass the gpio-specifier flag field to the children as an ivar variable so
they can act upon.
Revert r258678.  Make the led gpio-specifier match again the #gpio-cells
settings from the GPIO controller, which i had broken in r258678.  Restore
the active-low flag.
Report boot method (BIOS/UEFI) via sysctl machdep.bootmethod

Sponsored by:	The FreeBSD Foundation
Setting the IMOD value below 0x3F8 can cause IRQ lockups in the Intel
LynxPoint USB 3.0 controllers found in MacBookPro 2013's.

MFC after:	2 days
Tested by:	Huang Wen Hui <huanghwh@gmail.com>
Finish connecting up installer UEFI support. If the kernel was booted using
EFI, set up the disks for an EFI system. If booted from BIOS/CSM, set up
for BIOS.
loader's GPT support on BIOS does not seem to like the root filesystem
being the last filesystem on the disk for some reason when made by this
script. Add a vestigial swap partition to allow this to boot with QEMU
BIOS.
Turn off the full witness trace on console output.

On head/, or more specifically, when WITNESS is in
the kernel config, the console is spammed excessively
with lock order reversal between isofs and devfs.

Set debug.witness.trace=0 in the installer sysctl.conf
to avoid printing the full KDB stack backtrace.  This
does not prevent printing the lock order reversal has
happened, only lessens the console spam.

Sponsored by:	The FreeBSD Foundation
Improve memory allocation model for rt_msg2() rtsock messages:
 * memory is now allocated as early as possible, without holding locks.
 * sysctl users are now guaranteed to get a response (M_WAITOK buffer prealloc).
 * socket users are more likely to use on-stack buffer for replies.
 * standard kernel malloc/free functions are now used instead of radix wrappers.
rt_msg2() has been renamed to rtsock_msg_buffer().

MFC after:	1 month
Remove cpu_idcache_wbinv_all() from kdb_cpu_trap(), it's no longer needed.

This was added ca. 2004 for the purpose of ensuring the caches were in the
right state after the debugger set a breakpoint.  kdb_cpu_sync_icache()
was added in 2007 to handle that situation, and now the wbinv_all is
actually harmful because the operation isn't broadcast to other cores.
There is no difference between IPI_STOP and IPI_STOP_HARD on ARM, so
map them both to the same interrupt number like other arches do.
Flush and invalidate caches on each CPU as part of handling IPI_STOP.

Flushing the caches is required before doing a panic dump, but ARM
doesn't provide a flavor of flush that gets broadcast to other cores.
However, all cores except one are stopped before doing a dump, so this
works around the lack of a global flush/invalidate by doing it locally
on each CPU as part of stopping.

Discussed with:	cognet@
Explain why wbinv_all is SMP-safe in this case, and add a missing l2 cache
flush.  (Either it was missing here, or it isn't needed in the minidump
case.  Adding it here seems like the safer path to consistancy.)