MFC r351606: Take proper lock in ses_setphyspath_callback().

XPT_DEV_ADVINFO call should be protected by the lock of the specific
device it is addressed to, not the lock of SES device. In some weird
case, probably with hardware violating standards, it sometimes caused
NULL dereference due to race.

To protect from it further, add lock assertion to *_dev_advinfo().

MFC r350233: Make CAM ATA stack handle disk resizes.

While for ATA disks resize is even more rare situation than for SCSI, it
may happen in case of HPA or AMA being used. Make ATA XPT report minor
IDENTIFY DATA change to upper layers with AC_GETDEV_CHANGED, and ada(4)
periph driver handle that event, recalculating all the disk properties and
signalling resize to GEOM. Since ATA has no mechanism of UNIT ATTENTIONs,
like SCSI, it has no way to detect that something has changed. That is why
this functionality depends on explicit reprobe via XPT_REPROBE_LUN call.

Relnotes: yes

MFC r326645 (by imp): Define xpt_path_inq.

This provides a nice wrarpper around the XPT_PATH_INQ ccb creation and
calling.

MFC r349339 (by imp):
Go ahead and completely fix the ata_params before calling the veto
function. This breaks nothing that uses it in the tree since
ata_params is ignored in storvsc_ada_probe_veto which is the only
in-tree consumer.

MFC r350228:

ata_xpt: Use the correct union member when accessing valid.

In principle this should not matter as it's a union and they point to
the same memory location but based on the code above we should be
accessing .sata and not .ata.

Submitted by: arichardson
Reviewed by: scottl, imp
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D21002

MFC r335934: remove unneeded inclusion of sys/interrupt.h from several files

MFC r303468 (by imp):
Move protocol specific stuff into a linker set object that's
per-protocol. This reduces the number scsi symbols references by
cam_xpt significantly, and eliminates all ata / nvme symbols. There's
still some NVME / ATA specific code for dealing with XPT_NVME_IO and
XPT_ATA_IO respectively, and a bunch of scsi-specific code, but this
is progress.

MFC r303467 (by imp):
Switch to linker sets to find the xport callback object. This
eliminates the need to special case everything in cam_xpt for new
transports. It is now a failure to not have a transport object when
registering the bus as well. You can still, however, create a
transport that's unspecified (XPT_)

MFV r318962: Allow PROBE_SPINUP to fail in CAM ATA transport

The motivation for this is two-fold.

1. Some old WD SATA disks may appear as if they need to be spun up
when they are already spinning. Those disks would respond with
an error to the spin-up request.

2. Even if we really fail to spin up the disk, we still can try to
proceed to the subsequent phases. If we fail later on, then no
difference. Otherwise we get a chance to communicate with the
disk which is better than completely ignoring it, because a user
can try to recover the disk.

MFC 306396

cam/ata: Allow drivers to veto ATA disk attachment.

This eventhandler is mainly used by VMs, e.g. Hyper-V, whose disk
controllers share the disks with the simulated ATA controllers.

Submitted by: Hongjiang Zhang <honzhan microsoft com>
Discussed with: mav
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D7693

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Remove slightly used const values that can be replaced with nitems().

Suggested by: jhb

Attach pass driver to LUNs is OFFLINE state.

Previously such LUNs were silently ignored. But while they indeed unable
to process most of SCSI commands, some, like RTPG, they still can.

MFC after: 1 month

We should never enter the PROBE_SETAN phase if we're not ATAPI, since
that's ATAPI specific. Instead, skip to PROBE_SET_MULTI instead for
non ATAPI protocols. The prior code incorrectly terminated the probe
with a break, rather than arranging for probedone to get called. This
caused panics or worse on some systems.

Turns out that IDENTIFY DEVICE and IDENTIFY PACKET DEVICE return data
that's only mostly similar. Specifically word 78 bits are defined for
IDENTIFY DEVICE as
5 Supports Hardware Feature Control
while a IDENTIFY PACKET DEVICE defines them as
5 Asynchronous notification supported
Therefore, only pay attention to bit 5 when we're talking to ATAPI
devices (we don't use the hardware feature control at this time).
Ignore it for ATA devices. Remove kludge that papered over this issue
for Samsung SATA SSDs, since Micron drives also have the bit set and
the error was caused by this bad interpretation of the spec (which is
quite easy to do, since bits aren't normally overlapping like this).

Merge CAM locking changes from the projects/camlock branch to radically
reduce lock congestion and improve SMP scalability of the SCSI/ATA stack,
preparing the ground for the coming next GEOM direct dispatch support.

Replace big per-SIM locks with bunch of smaller ones:
- per-LUN locks to protect device and peripheral drivers state;
- per-target locks to protect list of LUNs on target;
- per-bus locks to protect reference counting;
- per-send queue locks to protect queue of CCBs to be sent;
- per-done queue locks to protect queue of completed CCBs;
- remaining per-SIM locks now protect only HBA driver internals.

While holding LUN lock it is allowed (while not recommended for performance
reasons) to take SIM lock. The opposite acquisition order is forbidden.
All the other locks are leaf locks, that can be taken anywhere, but should
not be cascaded. Many functions, such as: xpt_action(), xpt_done(),
xpt_async(), xpt_create_path(), etc. are no longer require (but allow) SIM
lock to be held.

To keep compatibility and solve cases where SIM lock can't be dropped, all
xpt_async() calls in addition to xpt_done() calls are queued to completion
threads for async processing in clean environment without SIM lock held.

Instead of single CAM SWI thread, used for commands completion processing
before, use multiple (depending on number of CPUs) threads. Load balanced
between them using "hash" of the device B:T:L address.

HBA drivers that can drop SIM lock during completion processing and have
sufficient number of completion threads to efficiently scale to multiple
CPUs can use new function xpt_done_direct() to avoid extra context switch.
Make ahci(4) driver to use this mechanism depending on hardware setup.

Sponsored by: iXsystems, Inc.
MFC after: 2 months

Rework r250298 in more correct way.

Fix byte order of ATA WWN when converting it to SCSI LUN ID.

MFprojects/camlock r248982:
Stop abusing xpt_periph in random plases that really have no periph related
to CCB, for example, bus scanning. NULL value is fine in such cases and it
is correctly logged in debug messages as "noperiph". If at some point we
need some real XPT periphs (alike to pmpX now), quite likely they will be
per-bus, and not a single global instance as xpt_periph now.

MFprojects/camlock r248890, r248897, r248898, r248900, r248903, r248905,
r248917, r248918, r248978, r249001, r249014, r249030:

Remove multilevel freezing mechanism, implemented to handle specifics of
the ATA/SATA error recovery, when post-reset recovery commands should be
allocated when queues are already full of payload requests. Instead of
removing frozen CCBs with specified range of priorities from the queue
to provide free openings, use simple hack, allowing explicit CCBs over-
allocation for requests with priority higher (numerically lower) then
CAM_PRIORITY_OOB threshold.

Simplify CCB allocation logic by removing SIM-level allocation queue.
After that SIM-level queue manages only CCBs execution, while allocation
logic is localized within each single device.

Suggested by: gibbs

Unbreak ATA_NO_48BIT_DMA with ATA_CAM by treating 48-bit DMA as an
optional property with PATA transport.

Reviewed by: mav
MFC after: 3 days

MFprojects/camlock:
r249017:
Some cosmetic things:
- Unify device to target insertion inside xpt_alloc_device() instead of
duplicating it three times.
- Remove extra checks for empty lists of devices and targets on release
since zero refcount check also implies it.
- Reformat code to reduce indentation.

r249103:
- Add lock assertions to every point where reference counters are modified.
- When reference counters are reaching zero, add assertions that there are
no children items left.
- Add a bit more locking to the xptpdperiphtraverse().

Fix problem with the Samsung 840 PRO series SSD detection.
The device reports support for SATA Asynchronous Notification in its
IDENTIFY data, but returns error on attempt to enable that feature.
Make SATA XPT of CAM only report these errors, but not fail the device.

MFC after: 1 week

Don't duplicate path/ccb allocation code, use existing functions.

Remove 'periph == NULL' check from bunch of periph drivers.
This condition can never be true as functions are called from single place
and the checks just pollute the code and confuse Clang Static Analyzer.

Implement media change notification for DA and CD removable media devices.
It includes three parts:
1) Modifications to CAM to detect media media changes and report them to
disk(9) layer. For modern SATA (and potentially UAS) devices it utilizes
Asynchronous Notification mechanism to receive events from hardware.
Active polling with TEST UNIT READY commands with 3 seconds period is used
for incapable hardware. After that both CD and DA drivers work the same way,
detecting two conditions: "NOT READY: Medium not present" after medium was
detected previously, and "UNIT ATTENTION: Not ready to ready change, medium
may have changed". First one reported to disk(9) as media removal, second
as media insert/change. To reliably receive second event new
AC_UNIT_ATTENTION async added to make UAs broadcasted to all periphs by
generic error handling code in cam_periph_error().
2) Modifications to GEOM core to handle media remove and change events.
Media removal handled by spoiling all consumers attached to the provider.
Media change event also schedules provider retaste after spoiling to probe
new media. New flag G_CF_ORPHAN was added to consumers to reflect that
consumer is in process of destruction. It allows retaste to create new
geom instance of the same class, while previous one is still dying.
3) Modifications to some GEOM classes: DEV -- to report media change
events to devd; VFS -- to handle spoiling same as orphan to prevent
accessing replaced media. PART class already handles spoiling alike to
orphan.

Reviewed by: silence on geom@ and scsi@
Tested by: avg
Sponsored by: iXsystems, Inc. / PC-BSD
MFC after: 2 months

One more major cam_periph_error() rewrite to improve error handling and
reporting. It includes:
- removing of error messages controlled by bootverbose, replacing them
with more universal and informative debugging on CAM_DEBUG_INFO level,
that is now built into the kernel by default;
- more close following to the arguments submitted by caller, such as
SF_PRINT_ALWAYS, SF_QUIET_IR and SF_NO_PRINT; consumer knows better which
errors are usual/expected at this point and which are really informative;
- adding two new flags SF_NO_RECOVERY and SF_NO_RETRY to allow caller
specify how much assistance it needs at this point; previously consumers
controlled that by not calling cam_periph_error() at all, but that made
behavior inconsistent and debugging complicated;
- tuning debug messages and taken actions order to make debugging output
more readable and cause-effect relationships visible;
- making camperiphdone() (common device recovery completion handler) to
also use cam_periph_error() in most cases, instead of own dumb code;
- removing manual sense fetching code from cam_periph_error(); I was told
by number of people that it is SIM obligation to fetch sense data, so this
code is useless and only significantly complicates recovery logic;
- making ada, da and pass driver to use cam_periph_error() with new limited
recovery options to handle error recovery and debugging in common way;
as one of results, CAM_REQUEUE_REQ and other retrying statuses are now
working fine with pass driver, that caused many problems before.
- reverting r186891 by raj@ to avoid burning few seconds in tight DELAY()
loops on device probe, while device simply loads media; I think that problem
may already be fixed in other way, and even if it is not, solution must be
different.

Sponsored by: iXsystems, Inc.
MFC after: 2 weeks

ATA/SATA controllers have no idea about protocol of the connected device
until transport will do some probe actions (at least soft reset).
Make ATA/SATA SIMs to not report bogus and confusing PROTO_ATA protocol.
Make ATA/SATA transport to fill that gap by reporting protocol to SIM with
XPT_SET_TRAN_SETTINGS and patching XPT_GET_TRAN_SETTINGS results if needed.

Tune and add some more CAM_DEBUG() points for the probe sequences.

Remove some dead code that I doubt will ever be implemented.

Rewrite enabling NCQ for SATA devices in a way more alike to SCSI TCQ.
This allows to control it with `camcontrol negotiate adaX -T (en|dis)able`
on the fly, same as for SCSI devices.

Sponsored by: iXsystems, Inc.

Use AC_GETDEV_CHANGED async to notify ada driver about DMA and NCQ status
change. Now that allows switching between PIO and DMA modes on the fly.

Allow to change number of openings (used tags) for ATA/SATA devices
via `camcontrol tags ... -N ...`. There is no need to tune it in
usual cases, but some users want to have it for debugging purposes.

MFC after: 2 weeks

Plug request and references leak caused by race between invalidated
ond probe periph destruction and new incoming probe request.

This at least caused problems with SATA Port Multipliers hot-plug.

MFC after: 2 weeks

MFprojects/zfsd:
- Add low-level support for SATA Enclosure Management Bridge (SEMB)
devices -- SATA equivalents of the SCSI SES/SAF-TE devices.
- Add some utility functions for SCSI SAF-TE devices access.

Sponsored by: iXsystems, Inc.

Make CAM ATA honor old hw.ata.ata_dma and hw.ata.atapi_dma tunables.

Even having more specific hint.ata.X.mode controls, global ones are
still could be useful from some points, including compatibility.

PR: kern/164651
MFC after: 1 week

Fix ATAPI breakage introduced by r223443. It made SCSI commands to ATAPI
device to never complete, that caused probe process (system boot) stuck.

Plumb support for the device advanced information CCB in the ATA XPT.

This was previously done only for SCSI XPT in r223081, on which the change
in r223089 depended in order to respond to serial number requests. As a
result of r223089, da(4) and ada(4) devices register a d_getattr for geom to
use to obtain the information.

Reported by: ache
Reviewed by: ken

Do not report CFA devices as ATAPI, even though IDENTIFY data look alike.

Add basic support for DMA-capable ATA disks on DMA-incapable controller.
This is really rare situation these days, but still may happen in embedded.

Improve SATA Asynchronous Notification feature support in CAM:
- make SATA SIMs announce capabilities to handle SDB with Notification bit;
- make PMP driver honor this SIMs capability;
- make SATA XPT to negotiate and enable this feature for ATAPI devices.

This feature allows supporting SATA ATAPI devices to inform system about
some events happened, that may require attention. In my case this allows
LG GH22LS50 SATA DVR-RW drive to report tray open/close events. Events
reported to CAM in form of AC_SCSI_AEN async. Further they could be used
as a hints for checking device status and reporting media change to upper
layers, for example, via spoiling mechanism of GEOM.

In addition to r217444 ignore also ATA status errors on DMA Auto-Activation
enabling request. Some HP disks reported to return ABORT error there while
declaring support for this feature.

Make device initialization sequence shorter when possible. Do not enable/
disable already enabled/disabled SATA features.

Some old WD SATA disks report supported and enabled device-initiated
interface power management, but return ABORT error on attempt to disable
it. Make CAM SATA probe sequence ignore this error, as it is not fatal.

If HBA doesn't report user-enabled SATA capabilies (like ATA_CAM wrapper) -
handle all of them as disabled. This was original cause of the problem,
workarounded by r215453.

MFC after: 1 week

ATA device reset starts probe sequence from the beginning. If reset caused
by timeout/error of one of probe commands, process may continue infinitely.
Make CAM ATA more robust to faulty devices and false positive detections,
abort probe after two restarts on timeouts or ten on other errors.

Add allocation error hadling.

Found with: Coverity Prevent(tm)
CID: 3897

Add a new primitive, XPT_SCAN_TGT, to cover the range between scanning a
whole bus (XPT_SCAN_BUS) and a single lun on that bus (XPT_SCAN_LUN).

It's less resource comsumptive than scanning a whole bus when the
caller knows only one target has changes.

Reviewed by: scsi@
Sponsored by: Panasas
MFC after: 1 month

Remove unnecessary headers which were inherited from cam_xpt.c without
reason.

Reviewed by: mav
MFC after: 3 days

Make SATA XPT negotiate and enable some additional SATA features, such as:
- device initiated power management (some devices support only this way);
- Automatic Partial to Slumber Transition (more power saving);
- DMA auto-activation (expected to slightly improve performance).
More features could be added later, when hardware supports.

Report PMP absence using target 15, same as for precence (not a wildcard),
to not confuse target ID checks at SIMs.

Update device identify data and serial number when device change detected.
Reprobe immediately following this should have fresh data.

MFp4:
Move PI_TAG_ABLE check from ada driver to ATA XPT.

Make PUIS detection more strict. Previous implementation caused false
positives on VMWare's virtual CD-ROMs.

Virtualize transport part of periph announcement.

On probe error, if restart requested, skip any retries and recovery.
Just restart probe from the beginning immediately.

MFp4:
Add Power Up In Stand-by feature support. Device with PUIS enabled
require explicit command to do initial spin-up. Mark that command
with CAM_HIGH_POWER flag, to allow CAM manage staggered spin-up.

- Use separate buffer for identify data fetching. We can't use main buffer
here if device already running, as data need to be formatted before use.
- Remove some saved_ccb variables. They are unused now.

- Give ATA/SATA SIMs info about ATAPI packet size, supported by device.
- Make ATA XPT to reject longer SCSI CDBs then supported by device, or
any SCSI CDBs, if device doesn't support ATAPI.

MFp4: Large set of CAM inprovements.

- Unify bus reset/probe sequence. Whenever bus attached at boot or later,
CAM will automatically reset and scan it. It allows to remove duplicate
code from many drivers.
- Any bus, attached before CAM completed it's boot-time initialization,
will equally join to the process, delaying boot if needed.
- New kern.cam.boot_delay loader tunable should help controllers that
are still unable to register their buses in time (such as slow USB/
PCCard/ CardBus devices), by adding one more event to wait on boot.
- To allow synchronization between different CAM levels, concept of
requests priorities was extended. Priorities now split between several
"run levels". Device can be freezed at specified level, allowing higher
priority requests to pass. For example, no payload requests allowed,
until PMP driver enable port. ATA XPT negotiate transfer parameters,
periph driver configure caching and so on.
- Frozen requests are no more counted by request allocation scheduler.
It fixes deadlocks, when frozen low priority payload requests occupying
slots, required by higher levels to manage theit execution.
- Two last changes were holding proper ATA reinitialization and error
recovery implementation. Now it is done: SATA controllers and Port
Multipliers now implement automatic hot-plug and should correctly
recover from timeouts and bus resets.
- Improve SCSI error recovery for devices on buses without automatic sense
reporting, such as ATAPI or USB. For example, it allows CAM to wait, while
CD drive loads disk, instead of immediately return error status.
- Decapitalize diagnostic messages and make them more readable and sensible.
- Teach PMP driver to limit maximum speed on fan-out ports.
- Make boot wait for PMP scan completes, and make rescan more reliable.
- Fix pass driver, to return CCB to user level in case of error.
- Increase number of retries in cd driver, as device may return several UAs.

- Report SATA in legacy emulation mode still as SATA.
- Make ATA XPT able to handle such case.

MFp4;
- Cleanup kernel messages, mostly PMP.
- Took references on devices, while PMP reinitializes them, to not let them
go and distort freeze reference counting.

MFp4:
Introduce ATA_CAM kernel option, turning ata(4) controller drivers into
cam(4) interface modules. When enabled, this options deprecates all ata(4)
peripheral drivers (ad, acd, ...) and interfaces and allows cam(4) drivers
(ada, cd, ...) and interfaces to be natively used instead.

As side effect of this, ata(4) mode setting code was completely rewritten
to make controller API more strict and permit above change. While doing
this, SATA revision was separated from PATA mode. It allows DMA-incapable
SATA devices to operate and makes hw.ata.atapi_dma tunable work again.

Also allow ata(4) controller drivers (except some specific or broken ones)
to handle larger data transfers. Previous constraint of 64K was artificial
and is not really required by PCI ATA BM specification or hardware.

Submitted by: nwitehorn (powerpc part)

Fix small copu-paste bug.

MFp4:
- Extend XPT-SIM transfer settings control API. Now it allows to report to
SATA SIM number of tags supported by each device, implement ATA mode and
SATA revision negotiation for both SATA and PATA SIMs.
- Make ahci(4) and siis(4) to use submitted maximum tag number, when
scheduling requests. It allows to support NCQ on devices with lower tags
count then controller supports.
- Make PMP driver to report attached devices connection speeds.
- Implement ATA mode negotiation between user settings, device and
controller capabilities.

MFp4:
Do not enable tagged queueing if controller reports 0 tags support.

MFp4:
- Move tagged queueing control from ADA to ATA XPT. It allows to control
device command queue length correctly. First step to support < 32 tags.
- Limit queue for non-tagged devices by 2 slots for ahci(4) and siis(4).
- Implement quirk matching for ATA devices.
- Move xpt_schedule_dev_sendq() from header to source file.
- Move delayed queue shrinking to the more expected place - element freeing.
- Remove some SCSIsms in ATA.

MFp4:
- Add support for sector size > 512 bytes and physical sector of several
logical sectors, introduced by ATA-7 specification.
- Remove some obsoleted code.

MFp4:
Fix reference counting bug, when device unreferenced before then
invalidated. To do it, do not handle validity flag as another
reference, but explicitly modify reference count each time flag is
modified.

Discovered by: thompsa

MFp4:
- Reduce code duplication in ATA XPT and PMP driver.
- Move PIO size setting from ada driver to ATA XPT. It is XPT business
to negotiate transfer details. ada driver is now stateless.
- Report PIO size to SIM. It is required for correct PATA SIM operation.
- Tune PMP scan timings. It workarounds some problems with SiI.
- If reset hapens during PMP initialization - restart it.
- Introduce early-initialized periph drivers, which are used during initial
scan process. Use it for xpt, probe, aprobe and pmp. It gives pmp chance
to finish scan before mountroot and numerate devices in right order.

MFp4:
Move Port Multiplier support code out of ATA XPT into pmp periph driver.
This is convinient, as PMP itself is a bus target and has own state.

Replace most of priority numbers with defines. No logical changes.

MFp4:
Separate CAM_DEV_IDENTIFY_DATA_VALID flag from CAM_DEV_INQUIRY_DATA_VALID.
Add workaround for very old devices without support for mode setting.
Add some PATA bus scanning support.
Remove some SCSIsms.

MFp4:
Report real max_target = 15. SIM doesn't need to know that target 15 is PMP.
It is XPT business.

Short ATA command format has 28bit address, not 36bit.
Rename ata_36bit_cmd() into ata_28bit_cmd(), while it didn't become legacy.

MFC after: 2 days

Fix copy/paste bug, that requests data read during ATA device probe sequence
for ATA_SETFEATURES/ATA_SF_SETXFER command which by definition transfers no
data. Most of controllers are irrelevant to this bug, but some nVidia's
doesn't.

Tested on: current@
Approved by: re (kib)

Fix copy-paste bug, enabling SIM PMP support, when it was not really found.

Approved by: re (implicitly)

Rename ATA probe driver to "aprobe" to resolve name conflict with SCSI
and fix loading cam as module.

Approved by: re (implicitly)

Separate the parallel scsi knowledge out of the core of the XPT, and
modularize it so that new transports can be created.

Add a transport for SATA

Add a periph+protocol layer for ATA

Add a driver for AHCI-compliant hardware.

Add a maxio field to CAM so that drivers can advertise their max
I/O capability. Modify various drivers so that they are insulated
from the value of MAXPHYS.

The new ATA/SATA code supports AHCI-compliant hardware, and will override
the classic ATA driver if it is loaded as a module at boot time or compiled
into the kernel. The stack now support NCQ (tagged queueing) for increased
performance on modern SATA drives. It also supports port multipliers.

ATA drives are accessed via 'ada' device nodes. ATAPI drives are
accessed via 'cd' device nodes. They can all be enumerated and manipulated
via camcontrol, just like SCSI drives. SCSI commands are not translated to
their ATA equivalents; ATA native commands are used throughout the entire
stack, including camcontrol. See the camcontrol manpage for further
details. Testing this code may require that you update your fstab, and
possibly modify your BIOS to enable AHCI functionality, if available.

This code is very experimental at the moment. The userland ABI/API has
changed, so applications will need to be recompiled. It may change
further in the near future. The 'ada' device name may also change as
more infrastructure is completed in this project. The goal is to
eventually put all CAM busses and devices until newbus, allowing for
interesting topology and management options.

Few functional changes will be seen with existing SCSI/SAS/FC drivers,
though the userland ABI has still changed. In the future, transports
specific modules for SAS and FC may appear in order to better support
the topologies and capabilities of these technologies.

The modularization of CAM and the addition of the ATA/SATA modules is
meant to break CAM out of the mold of being specific to SCSI, letting it
grow to be a framework for arbitrary transports and protocols. It also
allows drivers to be written to support discrete hardware without
jeopardizing the stability of non-related hardware. While only an AHCI
driver is provided now, a Silicon Image driver is also in the works.
Drivers for ICH1-4, ICH5-6, PIIX, classic IDE, and any other hardware
is possible and encouraged. Help with new transports is also encouraged.

Submitted by: scottl, mav
Approved by: re