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 255498:
- Document the UQUAD sysctl variants.
- Clarify that exactly one of the "access" flags is required and
list the optional flags in a separate list. Prefer bundling
CTLFLAG_TUN into the access flag by not documenting it as an
optional flag to set.

MFC r235693:

Typo and mdoc(7) style fixes.

PR: 168117

MFC r232321

Correct the description for CTLFLAG_TUN and CTLFLAG_RDTUN, the declaring of a
system tunable has never been implemented. This flag is only used by sysctl(8)
to provide a helpful error message.

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

Approved by: re (implicit)

Introduce signed and unsigned version of CTLTYPE_QUAD, renaming
existing uses. Rename sysctl_handle_quad() to sysctl_handle_64().

sysctl(8) should use the CTLTYPE to determine the type of data when
reading. (This was already done for writing to a sysctl). This
requires all SYSCTL setups to specify a type. Most of them are now
checked at compile-time.

Remove SYSCTL_*X* sysctl additions as the print being in hex should be
controlled by the -x flag to sysctl(8).

Succested by: bde

Xref sysctl(3)

Approved by: ed (mentor)

Implement the following macros for completeness:

SYSCTL_QUAD()
SYSCTL_ADD_QUAD()
TUNABLE_QUAD()
TUNABLE_QUAD_FETCH()

Now we can use 64bit tunables on 32bit systems.

Spelling fixes.

Add a guideline for naming new sysctl nodes.

Discussed in: cvs-src (some time ago)

Revise markup.

Add an extension to the UINT & ULONG types. The XINT & XLONG types behave
the same, except sysctl(8) will print out the values in hex.

Fix bug preventing the proper displaying of the CTLFLAG_WR option.

Fix a couple of typos and other minor nits

Reviewed by: rwatson

Fix typo.

MFC after: 1 month
Submitted by: Antoine Brodin <antoine dot brodin@laposte dot net>

Add a basic man page for the sysctl(9) macro interfaces. Previously man
pages existed only for the dynamic sysctl interfaces. There's probably
more complete and accurate content, better advice, etc, that could be added
here.

Per scottl's suggest, add a small piece of moralizing text regarding the
fact that sysctl names quickly get embedded in system configuration files,
libraries, third party applications, and even books, so renaming and
removing names after they've been published is a tricky issue.

MFC after: 1 month