Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

As <machine/pmap.h> is included from <vm/pmap.h>, there is no need to
include it explicitly when <vm/pmap.h> is already included.

Reviewed by: alc, kib
Differential Revision: https://reviews.freebsd.org/D5373

Clarify SDT feature word bits.

Obtained from: NetBSD

Remove atdevbase and replace it's remaining uses with direct references to
KERNBASE instead.

Use __FBSDID().

Use repo-copied files in sys/i386/bios.

use __packed.

Remove a bunch of unused (NO-OP) #if NFOO > 0 type includes and some
#include "foo.h" headers.

Correctly test CF.

SYSINIT() needs sys/kernel.h. Include it.

This adds the i386 specific support for systems with a MicroChannel
Architecture bus.

Reviewed by: msmith