Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC: sync the version of netmap with the one in HEAD, including device
drivers (mostly simplifying the code in the interrupt handlers).

On passing, also merge r250414, which is related to netmap
and the use of lem/em in virtual machines.

MFC of the e1000 drivers: revisions include
227309,228281,228386,228387,228393,228405,
228415,228788,228803,229606,229767,229939,
230023,230024,230742,231796,232238,233708,
234154,234665,235256

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

A cut and paste here was wrong also.

This delta updates the em driver to version 7.2.2 which has
been undergoing test for some weeks. This improves the RX
mbuf handling to avoid system hang due to depletion. Thanks
to all those who have been testing the code, and to Beezar
Liu for the design changes.

Next the igb driver is updated for similar RX changes, but
also to add new features support for our upcoming i350 family
of adapters.

MFC after a week

Sync the lem code up with the vlan and other fixes in em.
Delete a unneeded test from the beginning of em_xmit.
CRITICAL: shared code fix for 82574, a mutex might not be
released, this can cause hangs.

Tweak the stats exported by the e1000 drivers:
- Add a single sysctl procedure to all three drivers to read an arbitrary
register (the register is passed as arg2). Use it to replace existing
routines in igb(4) that used a separate routine for each register, and
to add support for missing stats in em(4) and lem(4).
- Move the 'rx_overruns' and 'watchdog_timeouts' stats out of the MAC stats
section as they are driver stats, not MAC counters.
- Simplify the code that creates per-queue stats in igb(4) to use a single
loop and remove duplicated code.
- Properly read all 64 bits of the 'good octets received/transmitted' in
em(4) and lem(4).
- Actually read the interrupt count registers in em(4), and drop the
'host to card' sysctl stats from em(4) as they are not implemented in
any of the hardware this driver supports.
- Restore several stats to em(4) that were lost in the earlier stats
conversion including per-queue stats.
- Export several MAC stats in em(4) that were exported in igb(4) but not
in em(4).
- Export stats in lem(4) using individual sysctls as in em(4) and igb(4).

Reviewed by: jfv
MFC after: 1 week

Do not allocate multicast array memory in multicast filter
configuration function. For failed memory allocations, em(4)/lem(4)
called panic(9) which is not acceptable on production box.
igb(4)/ixgb(4)/ix(4) allocated the required memory in stack which
consumed 768 bytes of stack memory which looks too big.

To address these issues, allocate multicast array memory in device
attach time and make multicast configuration success under any
conditions. This change also removes the excessive use of memory in
stack.

Reviewed by: jfv

Hook the identification LEDs of igb(4), lem(4) and em(4) devices up with
led(4) so they can be lit or f.e. made blink via `echo f2 > /dev/led/em0`
for localization purposes.

Approved by: jfv
MFC afer: 1 week (after r205869)

Update to igb and em:

em revision 7.0.0:
- Using driver devclass, seperate legacy (pre-pcie) code
into a seperate source file. This will at least help
protect against regression issues. It compiles along
with em, and is transparent to end use, devices in each
appear to be 'emX'. When using em in a modular form this
also allows the legacy stuff to be defined out.
- Add tx and rx rings as in igb, in the 82574 this becomes
actual multiqueue for the first time (2 queues) while in
other PCIE adapters its just make code cleaner.
- Add RX mbuf handling logic that matches igb, this will
eliminate packet drops due to temporary mbuf shortage.

igb revision 1.9.3:
- Following the ixgbe code, use a new approach in what
was called 'get_buf', the routine now has been made
independent of rxeof, it now does the update to the
engine TDT register, this design allows temporary
mbuf resources to become non-critical, not requiring
a packet to be discarded, instead it just returns and
does not increment the tail pointer.
- With the above change it was also unnecessary to keep
'spare' maps around, since we do not have the discard
issue.
- Performance tweaks and improvements to the code also.

MFC in a week