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

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

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

Consolidate duplicate definitions of V86_CY() and V86_ZR() which check for
the carry and zero flags being set, respectively, in <btxv86.h> and use
them throughout the x86 boot code.

Improve the algorithm the loader uses to choose a memory range for its
heap when using a range above 1MB.

Previously the loader would always use the last 3MB in the first memory
range above 1MB for the heap. However, this memory range is also where the
kernel and any modules are loaded. If this memory range is "small", then
using the high 3MB for the heap may not leave enough room for the kernel
and modules.

Now the loader will use any range below 4GB for the heap, and the logic to
choose the "high" heap region has moved into biosmem.c. It sets two
variables that the loader can use for a high heap if it desires. When a
high heap is enabled (BZIP2, FireWire, GPT, or ZFS), then the following
memory ranges are preferred for the heap in order from best to worst:
- The largest memory region in the SMAP with a start address greater than
1MB. The memory region must be at least 3MB in length. This leaves the
region starting at 1MB purely for use by the kernel and modules.
- The last 3MB of the memory region starting at 1MB if it is at least 3MB
in size. This matches the current behavior except that the current loader
would break horribly if the first region was not at least 3MB in size.
- The memory range from the end of the loader up to the 640k window. This
is the range the loader uses when none of the high-heap-requesting options
are enabled.

Tested by: hrs
MFC after: 1 week

Various small whitespace and style fixes.

- Add constants for the different memory types in the SMAP table.
- Use the SMAP types and constants from <machine/pc/bios.h> in the boot
code rather than duplicating it.

For the cases when loading bzip2-compressed kernels enabled use last
3MB of physical memory for heap instead of range between 1MB and 4MB.
This makes this feature working with PAE and amd64 kernels, which are
loaded at 2MB. Teach i386_copyin() to avoid using range allocated by
heap in such case, so that it won't trash heap in the low memory
conditions.

This should make loading bzip2-compressed kernels/modules/mfs images
generally useable, so that re@ team is welcome to evaluate merits
of using this feature in the installation CDs.

Valuable suggestions by: jhb

Use __FBSDID().
Also some minor copyright style cleanups.

use __packed.

Cleanup warnings. Most of these are signed/unsigned warnings, as well as
some added const's.

Substantially revamp the way that we determine the amount of memory available
for our use. Use the same search order for BIOS memory size functions
as the kernel will later use.

Allow the loader to use all of the detected physical memory (this will
greatly help people trying to load enormous memory disk images).

More correctly handle running out of memory when loading an object.

Use the end of base memory for the top of the heap, rather than
blindly hoping that there is 384k left.

Add copyrights to a couple of files I forgot.

Fix typos.. The vector for "int 0x12" (get base mem) is not written in
hex as "0x1a". :-)
Fix a comment about the extended memory checks, that's int 0x15.

Argh, I don't believe how much time I wasted looking for this...
Bytes of extended memory = (extkb * 1024), not (extkb + 1024)

Initial integration of the i386 bootloader and BTX.

- Discard large amounts of BIOS-related code in favour of the more compact
BTX vm86 interface.
- Build the loader module as ELF, although the resulting object is a.out,
make gensetdefs 32/64-bit sensitive and use a single copy of it.
- Throw away installboot, as it's no longer required.
- Use direct bcopy operations in the i386_copy module, as BTX
maps the first 16M of memory. Check operations against the
detected size of actual memory.