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)

MFppc64:

Kernel sources for 64-bit PowerPC, along with build-system changes to keep
32-bit kernels compiling (build system changes for 64-bit kernels are
coming later). Existing 32-bit PowerPC kernel configurations must be
updated after this change to specify their architecture.

In db_show_mdpcpu(), print MD fields.

Add kdb_cpu_sync_icache(), intended to synchronize instruction
caches with data caches after writing to memory. This typically
is required to make breakpoints work on ia64 and powerpc. For
those architectures the function is implemented.

The powerpc and sparc64 MD `reboot' commands should never have existed
since they just duplicated the MI `reset' command. Instead of removing
them, make `reboot' an MI alias for `reboot' since this gives a better
way of killing the `r' alias for `reset'. Remove the `registers' command
that was used to kill the alias.

Turn the powerpc and sparc64 MD `halt' command into an MI command.

A copy of sparc64/db_interface.c grew in sun4v just after I found the
extra reboot commands. It has not been changed, and is now not
identical. Duplicated commands come out duplicated in ddb's online
help, but cause large problems when used (e.g., on i386's with 2 halt's
and an hwatch, typing h doesn' give the expected message about an
ambiguous command, but hangs like the halt command or a looping parseri
would).

Make sure icache is sync'd whenever memory is touched. It may
be more optimal to override the BKPT_WRITE macro, but DDB performance
isn't really a goal at this stage...

Remove unused NetBSD code. Bring mem r/w routines into here in line
with sparc64, although keep the size deref checks: they are useful
when accessing PCI space where some devices may not implement byte
access.

Remove redundant declaration of ddb_trap

Clean up ddb warnings/errors and enable in GENERIC

Approved by: benno
Motivated by: gallatin

Add DDB support.