DRIVER_OK status is set after device_attach() succeeds. For now postpone
disk_create to attach_completed() method.

MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Reviewed by:	grehan
Approved by:	lwhsu (mentor)
Differential Revision:	https://reviews.freebsd.org/D30049

This reverts commit a7d593dd1da27833b5384349700bc3c7bcae6aad.
We now use compute_engine_instance which allows us to specify a custom
disk size.  Also go back to using the default qemu version (rather than
qemu42 or qemu-devel) as any issues were fixed some time ago.

Reviewed by:	lwhsu, markj
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D30082

DXR maintains compressed lookup structures with a trivial search
procedure.  A two-stage trie is indexed by the more significant bits of
the search key (IPv4 address), while the remaining bits are used for
finding the next hop in a sorted array.  The tradeoff between memory
footprint and search speed depends on the split between the trie and
the remaining binary search.  The default of 20 bits of the key being
used for trie indexing yields good performance (see below) with
footprints of around 2.5 Bytes per prefix with current BGP snapshots.

Rebuilding lookup structures takes some time, which is compensated for by
batching several RIB change requests into a single FIB update, i.e. FIB
synchronization with the RIB may be delayed for a fraction of a second.
RIB to FIB synchronization, next-hop table housekeeping, and lockless
lookup capability is provided by the FIB_ALGO infrastructure.

DXR works well on modern CPUs with several MBytes of caches, especially
in VMs, where is outperforms other currently available IPv4 FIB
algorithms by a large margin.

Synthetic single-thread LPM throughput test method:

kldload test_lookup; kldload dpdk_lpm4; kldload fib_dxr
sysctl net.route.test.run_lps_rnd=N
sysctl net.route.test.run_lps_seq=N

where N is the number of randomly generated keys (IPv4 addresses) which
should be chosen so that each test iteration runs for several seconds.

Each reported score represents the best of three runs, in million
lookups per second (MLPS), for two bechmarks (RND & SEQ) with two FIBs:

host: single interface address, local subnet route + default route
BGP: snapshot from linx.routeviews.org, 887957 prefixes, 496 next hops

Bhyve VM on an Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60 GHz:
inet.algo         host, RND    host, SEQ    BGP, RND    BGP, SEQ
bsearch4             40.6         20.2         N/A         N/A
radix4                7.8          3.8         1.2         0.6
radix4_lockless      18.0          9.0         1.6         0.8
dpdk_lpm4            14.4          5.0        14.6         5.0
dxr                  70.3         34.7        43.0        19.5

Intel(R) Core(TM) i5-5300U CPU @ 2.30 GHz:
inet.algo         host, RND    host, SEQ    BGP, RND    BGP, SEQ
bsearch4             47.0         23.1         N/A         N/A
radix4                8.5          4.2         1.9         1.0
radix4_lockless      19.2          9.5         2.5         1.2
dpdk_lpm4            31.2          9.4        31.6         9.3
dxr                  84.9         41.4        51.7        23.6

Intel(R) Core(TM) i7-4771 CPU @ 3.50 GHz:
inet.algo         host, RND    host, SEQ    BGP, RND    BGP, SEQ
bsearch4             59.5         29.4         N/A         N/A
radix4               10.8          5.5         2.5         1.3
radix4_lockless      24.7         12.0         3.1         1.6
dpdk_lpm4            29.1          9.0        30.2         9.1
dxr                 101.3         49.9        69.8        32.5

AMD Ryzen 7 3700X 8-Core Processor @ 3.60 GHz:
inet.algo         host, RND    host, SEQ    BGP, RND    BGP, SEQ
bsearch4             70.8         35.4         N/A         N/A
radix4               14.4          7.2         2.8         1.4
radix4_lockless      30.2         15.1         3.7         1.8
dpdk_lpm4            29.9          9.0        30.0         8.9
dxr                 163.3         81.5        99.5        44.4

AMD Ryzen 5 5600X 6-Core Processor @ 3.70 GHz:
inet.algo         host, RND    host, SEQ    BGP, RND    BGP, SEQ
bsearch4             93.6         46.7         N/A         N/A
radix4               18.9          9.3         4.3         2.1
radix4_lockless      37.2         18.6         5.3         2.7
dpdk_lpm4            51.8         15.1        51.6        14.9
dxr                 218.2        103.3       114.0        49.0

Reviewed by:	melifaro
MFC after:	1 week
Differential Revision: https://reviews.freebsd.org/D29821

Add a LPS benchmark variant which introduces artificial dependencies
between successive lookups. While here, instead of writing the results
from the lookups to a huge array, add them to an accumulator, in a more
lightweight attempt at preventing the CPU's OOO machinery from
discarding the lookup results if they would be completely unused.

net.route.test.run_lps_rnd measures LPS throughput with independent
uniformly random keys

net.route.test.run_lps_seq measures LPS throughput with uniformly
random keys with artificial interdependencies
Reviewed by:	melifaro
MFC after:	7 days
Differential Revision: https://reviews.freebsd.org/D30096

The _ext event notification includes the address being added/removed and
that gives the driver an easy way to ignore non-IPv6 addresses.  Remove
'tom' from the handler's name while here, it was moved out of t4_tom a
long time ago.

MFC after:	1 week
Sponsored by:	Chelsio Communications

dim@ is preparing to import Clang/LLVM 12 into the base system as the
system compiler / toolchain.  Apply the same change to the Cirrus-CI
config.

Reviewed by:	imp, markj
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D30109

Add a new control message to move ethernet addresses to a given link
in ng_bridge(4). Send this message instead of doing the work directly.
This decouples the read-only activity from the modification under a
more strict writer lock.

Decoupling the work is a prerequisite for multithreaded operation.

Approved by:	manpages (bcr), kp (earlier version)
MFC:		3 weeks
Differential Revision:	https://reviews.freebsd.org/D28516

Back in the day, we used to have a number of entries that were either
'on' or 'off' directly, rather than conditionally on 'onifexists'
etc. Back then, we tried to line up the 'secure' columns by using the
construct 'on secure' or 'off secure' (one space or two). Now that these
have all moved to a conditional construct, remove the second space on
the ttys that still have it. This reduces diffs between the different
ttys and is no functional change. i386 and amd64 did this a long time
ago, and those are the only ones that affected external users (who used
to sed 's/on /off /' the entires as part of the automation).

MFC After:		3 days
Sponsored by:		Netflix

MFC after:	3 days