Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Merge r261796 from head:
While it isn't too late and kvm_read_zpcpu() function isn't yet used
outside libkvm(3), change its order of arguments, so that it is the
same as in kvm_read().
Merge r261805 from head:
Add kvm_getncpus() to obtain mp_ncpus.

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

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

Remove EOL whitespace.

o Provide function kvm_read_zpcpu() to access UMA_ZONE_PCPU allocations.
o Provide function kvm_counter_u64_fetch() to fetch valut of a counter(9).

Sponsored by: Nginx, Inc.

General mdoc(7) and typo fixes.

PR: 167734
Submitted by: Nobuyuki Koganemaru (kogane!jp.freebsd.org)
MFC after: 3 days

Fix several typos in macros or macro misusage.

Found by: make manlint
Reviewed by: ru
Approved by: philip (mentor)

A first cut at teaching libkvm how to deal with dynamic per-CPU storage
(DPCPU):

A new API, kvm_dpcpu_setcpu(3), selects the active CPU for the purposes
of DPCPU. Calls to kvm_nlist(3) will automatically translate DPCPU
symbols and return a pointer to the current CPU's version of the data.
Consumers needing to read the same symbol on several CPUs will invoke a
series of setcpu/nlist calls, one per CPU of interest.

This addition makes it possible for tools like netstat(1) to query the
values of DPCPU variables during crashdump analysis, and is based on
similar code handling virtualized global variables.

MFC after: 1 week
Sponsored by: Juniper Networks, Inc.

Add a "CACHING" section regarding the internal caching of kernel variables
and the ability to clear that cache.

Add two new routines to libkvm for working with per-CPU data:
kvm_getmaxcpu() and kvm_getpcpu().

MFC after: 1 week