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

MFC r263815, r263872:

Move ia64 efi.h to sys in preparation for amd64 UEFI support

Prototypes specific to ia64 have been left in this file for now, under
__ia64__, rather than moving them to a new header under sys/ia64.
I anticipate that (some of) the corresponding functions will be shared
by the amd64, arm64, i386, and ia64 architectures, and we can adjust
this as EFI support on other than ia64 continues to develop.

Fix missed efi.h header change in r263815

Sponsored by: The FreeBSD Foundation

Move ia64 efi.h to sys in preparation for amd64 UEFI support

Prototypes specific to ia64 have been left in this file for now, under
__ia64__, rather than moving them to a new header under sys/ia64.
I anticipate that (some of) the corresponding functions will be shared
by the amd64, arm64, i386, and ia64 architectures, and we can adjust
this as EFI support on other than ia64 continues to develop.

Sponsored by: The FreeBSD Foundation

Add a few more helper functions for working with memory descriptors:
o efi_md_find() - returns the md that covers the given address
o efi_md_last() - returns the last md in the list
o efi_md_prev() - returns the md that preceeds the given md.

Fix switching to physical mode as part of calling into EFI runtime
services or PAL procedures. The new implementation is based on
specific functions that are known to be called in certain scenarios
only. This in particular fixes the PAL call to obtain information
about translation registers. In general, the new implementation does
not bank on virtual addresses being direct-mapped and will work when
the kernel uses PBVM.

When new scenarios need to be supported, new functions are added if
the existing functions cannot be changed to handle the new scenario.
If a single generic implementation is possible, it will become clear
in due time.

While here, change bootinfo to a pointer type in anticipation of
future development.

Fix previous commitr:. efi_var_set() was copied from efi_var_get(),
but wasn't actually changed.

Add wrappers for the RT Variable Services. While here, translate the
EFI status into a standard errno value and change efi_set_time() to
return a standard error.

MFC after: 1 week

/* -> /*- for copyright notices, minor format tweaks as necessary

MFp4:
Completely remove the remaining EFI includes and add our own (type)
definitions instead. While here, abstract more of the internals by
providing interface functions.

Provide our own FPSWA definitions, instead of depending on the Intel
EFI headers and put them all in <machine/fpu.h>. The Intel EFI headers
conflict with the Intel ACPI headers (duplicate type definitions), so
are being phased out in the kernel.

Initial cut at calling the EFI-provided FPSWA (Floating Point Software
Assist) driver to handle the "messy" floating point cases which
cause traps to the kernel for handling.

Fill out the firmware interfaces somewhat.

Fix a couple of typos which became obvious when I started to actually use
this on real hardware.

Flesh out EFI support somewhat.

This is the first snapshot of the FreeBSD/ia64 kernel. This kernel will
not work on any real hardware (or fully work on any simulator). Much more
needs to happen before this is actually functional but its nice to see
the FreeBSD copyright message appear in the ia64 simulator.