Update the style to one sentence per line, as is currently used in the FreeBSD
document project. Make the links to the handbook clickable.

Complete the transition to README.md I started 3 years ago. Remove the
now-redundant README file. It's currently just README.md w/o the light markup
and adds no real value. This also allows us to use additional MarkDown
markup as we see fit w/o worrying about keeping things in sync.

We can't call malloc(M_WAITOK) in a callout handler.

Reviewed by:	imp
Reported by:	pho
Tested by:	pho
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D29223

Reviewed By:	debdrup, imp (earlier version)
Sponsored By:	EPSRC
Differential Revision:	https://reviews.freebsd.org/D28939

The NIC no longer provides a host database, and hasn't for quite some
time. Remove that paragraph, it's not been relevant for many years. Also, hosts
appeared in 4.1c, not 4.2, so correct that too.

Noticed by: Henry Bent

nvme drives are configured early in boot. However, a number of the configuration
steps takes which take a while, so we defer those to a config intrhook that runs
before the root filesystem is mounted. At the same time, the PCI hot plug wakes
up and tests the status of the card. It may decide that the card has gone away
and deletes the child. As part of that process nvme_detach is called. If this
call happens after the config_intrhook starts to run, but before it is finished,
there's a race where we can tear down the device's soft state while the
config_intrhook is still using it. Use the new config_intrhook_drain to
disestablish the hook. Either it will be removed w/o running, or the routine
will wait for it to finish. This closes the race and allows safe hotplug at any
time, even very early in boot.

Sponsored by:		Netflix, Inc
Reviewed by:		jhb, mav
Differential Revision:	https://reviews.freebsd.org/D29006

config_intrhook_drain will remove the hook from the list as
config_intrhook_disestablish does if the hook hasn't been called.  If it has,
config_intrhook_drain will wait for the hook to be disestablished in the normal
course (or expedited, it's up to the driver to decide how and when
to call config_intrhook_disestablish).

This is intended for removable devices that use config_intrhook and might be
attached early in boot, but that may be removed before the kernel can call the
config_intrhook or before it ends. To prevent all races, the detach routine will
need to call config_intrhook_train.

Sponsored by:		Netflix, Inc
Reviewed by:		jhb, mav, gde (in D29006 for man page)
Differential Revision:	https://reviews.freebsd.org/D29005

This looks like a no-op, but it prevents udevadm(8) with failing
loudly, which in turn unbreaks installation of libfprint-2-2, which
in Focal is a dependency for make-4.2.1-1.2.

One might wonder why installing a build utility involves messing
with device handling...

Sponsored By:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D29133

The per-domain partpop queue is locked by the combination of the
per-domain lock and individual reservation mutexes.
vm_reserv_reclaim_contig() scans the queue looking for partially
populated reservations that can be reclaimed in order to satisfy the
caller's allocation.

During the scan, we drop the per-domain lock.  At this point, the rvn
pointer may be invalidated.  Take care to load rvn after re-acquiring
the per-domain lock.

While here, simplify the condition used to check whether a reservation
was dequeued while the per-domain lock was dropped.

Reviewed by:	alc, kib
Reported by:	gallatin
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D29203

Format 300 baud like all the others here. No functional change.

pf_kkif_free() already checks for NULL, so we don't have to check before
we call it.

Reviewed by:	melifaro@
MFC after:	1 week
Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D29195

Reviewed by:	melifaro@
MFC after:	1 week
Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D29194

The pwm utility cant set the only flag defined (PWM_POLARITY_INVERTED) so this
patch add the option -I (capital letter i) to send it to the drivers.

None of existing PWM driver have implemented support for flags.
But soon:ish I will put up an review of a pwm driver using TI OMAP DMTimer.

Differential Revision: https://reviews.freebsd.org/D29137
MFC after:   2 weeks

Fix the types of period and duty in share/man/man9/pwmbus.9 to match the one in sys/dev/pmw/pwmbus.c.

Reviewed By: rpokala
Differential Revision: https://reviews.freebsd.org/D29139
MFC after:   3 days

Clang 12 no longer supports -Wno-error-..., only the -Wno-error=...
style (which is already used everywhere else in the tree).

Differential Revision:	https://reviews.freebsd.org/D29157

Summary:
This fixes rtentry leak for the cloned interfaces created inside the
 VNET.

PR:	253998
Reported by:	rashey at superbox.pl
MFC after:	3 days

Loopback teardown order is `SI_SUB_INIT_IF`, which happens after `SI_SUB_PROTO_DOMAIN` (route table teardown).
Thus, any route table operations are too late to schedule.
As the intent of the vnet teardown procedures to minimise the amount of effort by doing global cleanups instead of per-interface ones, address this by adding a relatively light-weight routing table cleanup function, `rib_flush_routes()`.
It removes all remaining routes from the routing table and schedules the deletion, which will happen later, when `rtables_destroy()` waits for the current epoch to finish.

Test Plan:
```
set_skip:set_skip_group_lo  ->  passed  [0.053s]
tail -n 200 /var/log/messages | grep rtentry
```

Reviewers: #network, kp, bz

Reviewed By: kp

Subscribers: imp, ae

Differential Revision: https://reviews.freebsd.org/D29116

Copy the iovec for the trailer from the proper place.  This is the same
fix for CBC encryption from ff6a7e4b.

Reported by:	gallatin
Reviewed by:	gallatin, markj
Fixes:		49f6925c
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D29177

We don't need the result before next sleep time, so no reason to
additionally increase interrupt latency.

While there, remove extra PM ticks to microseconds conversion, making
C2/C3 sleep times look 4 times smaller than really.  The conversion
is already done by AcpiGetTimerDuration().  Now I see reported sleep
times up to 0.5s, just as expected for planned 2 wakeups per second.

MFC after:	1 month

The ENTRY() macro was modified by commit
28d94520 to add an optional NOP instruction
at the beginning of the function. It is of course an arm64 instruction, so
unsuitable for the 32bits sigcode. So just use EENTRY() instead for
aarch32_sigcode. This should fix receiving signals when running 32bits
binaries on FreeBSD/arm64.

MFC After: 1 week

Reported by:	phk@
MFC after:	1 week

PR:		250984
MFC after:	1 week

It has been observed that some systems are often unable to resume from
ddb after entering with debug.kdb.enter=1. Checking the status further
shows the terminal is blocked waiting in tty_drain(), but it never makes
progress in clearing the output queue, because sc->sc_txbusy is high.

I noticed that when entering polling mode for the debugger, IER_TXRDY is
set in the failure case. Since this bit is never tracked by the softc,
it will not be restored by ns8250_bus_ungrab(). This creates a race in
which a TX interrupt can be lost, creating the hang described above.
Ensuring that this bit is restored is enough to prevent this, and resume
from ddb as expected.

The solution is to track this bit in the sc->ier field, for the same
lifetime that TX interrupts are enabled.

PR:		223917, 240122
Reviewed by:	imp, manu
Tested by:	bz
MFC after:	5 days
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D29130

I noticed that many of the math-related tests were failing on AArch64.
After a lot of debugging, I noticed that the floating point exception flags
were not being reset when starting a new process. This change resets the
VFP inside exec_setregs() to ensure no VFP register state is leaked from
parent processes to children.

This commit also moves the clearing of fpcr that was added in 65618fdd
from fork() to execve() since that makes more sense: fork() can retain
current register values, but execve() should result in a well-defined
clean state.

Reviewed By:	andrew
MFC after:	1 week
Differential Revision: https://reviews.freebsd.org/D29060

must be done using the M_NOWAIT flag after 1ae20f7c .

MFC after:	1 week
Sponsored by:	Mellanox Technologies // NVIDIA Networking

user-space Linux compatibility support. No functional change.

MFC after:	1 week
Sponsored by:	Mellanox Technologies // NVIDIA Networking

done using the M_NOWAIT flag after 1ae20f7c .

MFC after:	1 week
Sponsored by:	Mellanox Technologies // NVIDIA Networking

MFC after:	3 days
Fixes:	b3dac391

in the LinuxKPI.

Differential Revision:	https://reviews.freebsd.org/D29077
Reviewed by:	markj@ and kib@
MFC after:	1 week
Sponsored by:	Mellanox Technologies // NVIDIA Networking

The names are self-explanatory; these are currently only used by the
wg(8) tool, but they are handy data points to have.

Reviewed by:	grehan
MFC after:	3 days
Discussed with:	decke
Differential Revision:	https://reviews.freebsd.org/D29143

If we hit an error during init, then we'll unwind our state and attempt
to detach the device -- don't block it.

This was discovered by creating a wg0 with missing parameters; said
failure ended up leaving this orphaned device in place and ended up
panicking the system upon enumeration of the dev.* sysctl space.

Reviewed by:	gallatin, markj
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D29145

We have no use for the udphdr or this hlen local, just spell out the
addition inline.

MFC after:	3 days
Reviewed by:	grehan, markj
Differential Revision:	https://reviews.freebsd.org/D29142

This change converts most of the counters in the amd64 pmap from
global atomics to scalable counter(9) counters.  Per discussion
with kib@, it also removes the handrolled per-CPU PCID save count
as it isn't considered generally useful.

The bulk of these counters remain guarded by PV_STATS, as it seems
unlikely that they will be useful outside of very specific debugging
scenarios.  However, this change does add two new counters that
are available without PV_STATS.  pt_page_count and pv_page_count
track the number of active physical-to-virtual list pages and page
table pages, respectively.  These will be useful in evaluating
the memory footprint of pmap structures under various workloads,
which will help to guide future changes in this area.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D28923

Some framebuffer properties obtained from the device tree were not being
properly converted to host endian.
Replace OF_getprop calls by OF_getencprop where needed to fix this.

This fixes boot on PowerPC64 LE, when using ofwfb as the system console.

Reviewed by:    bdragon
Sponsored by:   Eldorado Research Institute (eldorado.org.br)
MFC after:      1 week
Differential Revision:  https://reviews.freebsd.org/D27475

This is not ready yet for prime time

This reverts commit 763db589.
This reverts commit f1ab7999.
This reverts commit 6e822e99.
This reverts commit 77e1ccbe.

The kernel-side already accepted a persistent-keepalive-interval, so
just add a verb to ifconfig(8) for it and start exporting it so that
ifconfig(8) can view it.

PR:		253790
MFC after:	3 days
Discussed with:	decke

The way that wireguard is designed does not actually require all peers
to have endpoints. In an architecture that might mimic a traditional
VPN server <-> client, the wg interface on a server would have a number
of peers without set endpoints -- the expectation is that the "clients"
will connect to the "server" peer, which will authenticate the
connection as a known peer and learn the endpoint from there.

MFC after:	3 days
Discussed with:	decke, grehan (independently)

Simple condition flip; we wanted to panic here after epoch_trace_list().

Reviewed by:	glebius, markj
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D29125

No sleeping allowed here, so avoid it.  Collect the subset of data we
want inside of the epoch, as we'll need extra allocations when we add
items to the nvlist.

Reviewed by:	grehan (earlier version), markj
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D29124