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

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

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

Approved by: re (implicit)

mdoc: order prologue macros consistently by Dd/Dt/Os

Although groff_mdoc(7) gives another impression, this is the ordering
most widely used and also required by mdocml/mandoc.

Reviewed by: ru
Approved by: philip, ed (mentors)

Bump document date for the previous change.

Document '-w' from main.c rev. 1.11.

Spell "currently" correctly.

Implement and document the -q and -f options with their corresponding
long form (-quiet and -fullname resp.) Bump documentation date.

PR: bin/78031
MFC after: 5 days

.It the -v option.

Markup nits.

Document all options and general usage.

Implement the -a option to bump the annotation_level. This improves
the Emacs gud behaviour. You can now supply the following function

(defun gud-gdb-massage-args (file args) (cons "-a" args))

(e.g. by evaluating it from the *scratch* buffer) and get the normal
jump to the source window when browsing the stack.

We should probably eventually supply our own kgdb submode to gud.el.

Fix the abuse of Ar macros for designating flag options, use Fl instead.

Improve the usage. Without any arguments, kgdb(1) works on /dev/mem
with the currently running kernel image. Otherwise, one of -c, -n or
-r is expected for working on a particular core file (-c), working
on a saved dump (-n) or working remotely (-r). When working on a
saved dump, a kernel may be omitted.
For a remote debugging session (-r), kgdb(1) will use the specified
device.

Add the beginnings of kernel debugging support. the kgdb(1) tool
is basicly a shell on top of libgdb that knows about kernel threads,
kernel modules and kvm(3). As the word "beginnings" implies, not
all of the features have been implemented yet. The tool is useful
and I'd like feedback on the taken route.

The simplest way to debug a kernel core file is:
kgdb -n 0

This opens /var/crash/vmcore.0 with the corresponding kernel in
the object directory (kernel.debug is used if it exists).

Typical things that need to be added are:
o Auto loading of kernel modules,
o Handling of trapframes so that backtraces can be taken across
them,
o Some fancy commands to extract useful information out of a core
file,
o Various (probably many) other things.