Sync the e1000 drivers with what's in head as of r294327, modulo parts
that don't apply to stable/10 (driver API, if_inc_counter(), RSS changes
etc.) and modulo r287465 (which reportedly breaks igb(4)), i. e. assorted
fixes and improvements only:

o MFC r267385 (partial):
- Don't compare bus_dma map pointers for static DMA allocations against
NULL to determine if bus_dmamap_unload() or bus_dmamem_free() should be
called. Instead, check the associated bus and virtual addresses.
- Don't clear static DMA maps to NULL.
o MFC r284933:
Delete the refernce to VLAN handling being disabled by default. This is
no longer the case. [1]
o MFC r285639:
Add an adapter CORE lock in the DDB hook em_dump_queue to avoid WITNESS
panic in em_init_locked() while debugging.
o MFC r285879:
- Remove unused txd_saved.
- Intialize txd_upper, txd_lower and txd_used at declaration.
o MFC r286162:
Free mbufs when busdma loading fails.
o MFC r286829:
Add capability to disable CRC stripping as it breaks IPMI/BMC capabilities
on certain adatpers. [2]
o MFC r286831: [3]
- Increase EM_MAX_SCATTER to 64 such that the size of em_xmit()::
segs[EM_MAX_SCATTER] doesn't get overrun by things like NFS that can
and do shove more than 32 segs when being used with em(4) and TSO4.
- Update tso handling code in em_xmit() with update from jhb@
- Set if_hw_tsomax, if_hw_tsomaxsegcount and if_hw_tsomaxsegsize to
appropriate values.
- Define a TSO workaround "magic" number of 4 that is used to avoid an
alignment issue in hardware.
- Change a couple of integer values that were used as booleans to actual
bool types.
- Ensure that em_enable_intr() enables the appropriate mask of interrupts
and not just a hardcoded define of values.
o MFC r286832:
e1000/if_lem.c bump to 1.1.0
o MFC r286833:
Bump all copywrite dates to 2015.
o MFC r287112:
Style/whitespace cleanup in shared/common code.
o MFC r293331:
- Switch em(4) to the extended RX descriptor format.
- Split rxbuffer and txbuffer apart to support the new RX descriptor
format structures. Move rxbuffer manipulation to em_setup_rxdesc() to
unify the new behavior changes.
- Add a RSSKEYLEN macro for help in generating the RSSKEY data structures
in the card.
- Change em_receive_checksum() to process the new rxdescriptor format
status bit.
o MFC r293332:
Disable the reuse of checksum offload context descriptors in the case
of multiple queues in em(4). Document errata in the code.
o MFC r293854:
Given that em(4), lem(4) and igb(4) hardware doesn't require the
alignment guarantees provided by m_defrag(9), use m_collapse(9)
instead for performance reasons.
While at it, sanitize the statistics softc members, i. e. retire
unused ones and add SYSCTL nodes missing for actually used ones.

PR: 118693 [1], 161277 [2], 195078 [3], 199174 [3], 200221 [3]

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

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

Merge of the source for igb and em into dev/e1000, this
proved to be necessary to make the static drivers work
in EITHER/OR or BOTH configurations. Modules will still
build in sys/modules/igb or em as before.

This also updates the igb driver for support for the 82576
adapter, adds shared code fixes, and etc....

MFC after: ASAP

This change introduces a split to the Intel E1000 driver, now rather than
just em, there is an igb driver (this follows behavior with our Linux drivers).
All adapters up to the 82575 are supported in em, and new client/desktop support
will continue to be in that adapter.

The igb driver is for new server NICs like the 82575 and its followons.
Advanced features for virtualization and performance will be in this driver.

Also, both drivers now have shared code that is up to the latest we have
released. Some stylistic changes as well.

Enjoy :)

Driver version 6.7.3
- Bring HEAD up to the latest shared code
- Fix TSO problem using limited MSS and forwarding
- Dual lock implementation
- New device support
- For my ease, this code can compile in either 6.x or later
- brings this driver in sync with the 6.3

This delta adds two bug fixes: one that makes HW Offload logic in
legacy codepath match the 82575, without this we were seeing bridging
fail on 82546 adapters. Secondly, I have limited TSO to PCI Express
adapters, I meant to do this and it got dropped in the earlier delta.
Next, I am dropping in the latest shared code from our development
team, consensus was that this should be done frequently, so I am :)

Approved by: pdeuskar

$FreeBSD$ tags are not compilable C code; wrap in either __FBSDID() or
in comments for .c and .h files respectively. Jack may want to clean up
style or other aspects once he's up and about again, but this gets the
kernel compiling.

Merge in the new driver (6.5.0) of Intel. This has a new
shared code infrastructure that is family specific and
modular. There is also support for our latest gigabit
nic, the 82575 that is MSI/X and multiqueue capable.

The new shared code changes some interfaces to the core
code but testing at Intel has been going on for months,
it is fairly stable.

I have attempted to be careful in retaining any fixes that
CURRENT had and we did not, I apologize in advance if any
thing gets clobbered, I'm sure I'll hear about it :)

Approved by pdeuskar