Fix some UTF-8 chars slipped into r252204 via copy/paste.
Minor sorting.

MFC after:	3 days
In the Xen block front driver, take advantage of backends that
support cache flush and write barrier commands.

sys/dev/xen/blkfront/block.h:
	Add per-command flag that specifies that the I/O queue must
	be frozen after this command is dispatched.  This is used
	to implement "single-stepping".

	Remove the unused per-command flag that indicates a polled
	command.

	Add block device instance flags to record backend features.

	Add a block device instance flag to indicate the I/O queue
	is frozen until all outstanding I/O completes.

	Enhance the queue API to allow the number of elements in a
	queue to be interrogated.

	Prefer "inline" to "__inline".

sys/dev/xen/blkfront/blkfront.c:
	Formalize queue freeze semantics by adding methods for both
	global and command-associated queue freezing.

	Provide mechanism to freeze the I/O queue until all outstanding
	I/O completes.  Use this to implement barrier semantics
	(BIO_ORDERED) when the backend does not support
	BLKIF_OP_WRITE_BARRIER commands.

	Implement BIO_FLUSH as either a BLKIF_OP_FLUSH_DISKCACHE
	command or a 0 byte write barrier.  Currently, all publicly
	available backends perform a diskcache flush when processing
	barrier commands, and this frontend behavior matches what
	is done in Linux.

	Simplify code by using new queue length API.

	Report backend features during device attach and via sysctl.

Submitted by:	Roger Pau Monné
Submitted by:	gibbs (Merge with new driver queue API, sysctl support)
For ATA_PASSTHROUGH commands, pretend isci(4) supports multiword DMA
by treating it as UDMA.

This fixes a problem introduced in r249933/r249939, where CAM sends
ATA_DSM_TRIM to SATA devices using ATA_PASSTHROUGH_16.  scsi_ata_trim()
sets protocol as DMA (not UDMA) which is for multi-word DMA, even
though no such mode is selected for the device.  isci(4) would fail
these commands which is the correct behavior but not consistent with
other HBAs, namely LSI's.

smh@ did some further testing on an LSI controller, which rejected
ATA_PASSTHROUGH_16 commands with mode=UDMA_OUT, even though only
a UDMA mode was selected on the device.  So this precludes adding
any kind of mode detection in CAM to determine which mode to use on
a per-device basis.

Sponsored by:	Intel
Discussed with:	scottl, smh
Reported by:	scottl
Tested by:	scottl
MFC after:	3 days
Add an open_dev() helper function to be used in the various places
where nvmecontrol needs to open a handle to a controller or namespace
device node.

Sponsored by:	Intel
MFC after:	3 days
Add separate *_usage() functions for each nvmecontrol command.

Sponsored by:	Intel
MFC after:	3 days
Break out code related to the devlist command into a separate source file.

Sponsored by:	Intel
MFC after:	3 days
Break out code related to the identify command into a separate source file.

Sponsored by:	Intel
MFC after:	3 days
Break out code related to the perftest command into a separate file.

Sponsored by:	Intel
MFC after:	3 days
Break out code related to the reset command into a separate source file.

Sponsored by:	Intel
MFC after:	3 days
Add an nvme_function structure array, defining the name, C function and
usage message for each nvmecontrol command.  This helps reduce some code
clutter both now and for future commits which will add logpage and
firmware support to nvmecontrol(8).

Also move helper function prototypes to the end of the header file, after
the per-command functions.

Sponsored by:	Intel
MFC after:	3 days
Create #defines for NVME_CTRLR_PREFIX and NVME_NS_PREFIX for the "nvme"
and "ns" strings, rather than hardcoding the string values throughout the
nvmecontrol code base.

Sponsored by:	Intel
MFC after:	3 days
Use MAXPHYS to specify the maximum I/O size for nvme(4).

Also allow admin commands to transfer up to this maximum I/O size, rather
than the artificial limit previously imposed.  The larger I/O size is very
beneficial for upcoming firmware download support.  This has the added
benefit of simplifying the code since both admin and I/O commands now use
the same maximum I/O size.

Sponsored by:	Intel
MFC after:	3 days
Fail any passthrough command whose transfer size exceeds the controller's
max transfer size.  This guards against rogue commands coming in from
userspace.

Also add KASSERTS for the virtual address and unmapped bio cases, if the
transfer size exceeds the controller's max transfer size.

Sponsored by:	Intel
MFC after:	3 days
Remove remaining uio-related code.

The nvme_physio() function was removed quite a while ago, which was the
only user of this uio-related code.

Sponsored by:	Intel
MFC after:	3 days
Ensure that a device node is specified when invoking the identify or reset
commands.

Also improve the checking of device node names, so that better error
messages are displayed when incorrect names are specified.

Sponsored by:	Intel
MFC after:	3 days
Add generalized helper functions for printing hex data as part of
nvmecontrol commands.

Submitted by:	Joe Golio <joseph.golio@emc.com>
Obtained from:	EMC / Isilon Storage Division
MFC after:	3 days
Consistently cast ACPICA 64-bit integer types when we print them.
Add log page support to nvmecontrol(8) through a new logpage command.

This includes pretty printers for all of the standard NVMe log pages
(Error, SMART/Health, Firmware), as well as hex output for non-standard
or vendor-specific log pages.

Submitted by:	Joe Golio <joseph.golio@emc.com>
Obtained from:	EMC / Isilon Storage Division
MFC after:	3 days
Add firmware replacement and activation support to nvmecontrol(8) through
a new firmware command.

NVMe controllers may support up to 7 firmware slots for storing of
different firmware revisions.  This new firmware command supports
firmware replacement (i.e. firmware download) with or without immediate
activation, or activation of a previously stored firmware image.  It
also supports selection of the firmware slot during replacement
operations, using IDENTIFY information from the controller to
check that the specified slot is valid.

Newly activated firmware does not take effect until the new controller
reset, either via a reboot or separate 'nvmecontrol reset' command to the
same controller.

Submitted by:	Joe Golio <joseph.golio@emc.com>
Obtained from:	EMC / Isilon Storage Division
MFC after:	3 days