Generate map files to make debugging less painful.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Relocate the real-mode code before booting.  This allows the target
bootstrap to be loaded at an arbitrary address, not necessarily
0x7c00, and to be almost arbitrarily long.

Add some initial infrastructure for other bootstrap addresses, too.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Fix missing -M from NASM dependency generation calls; adopt the
uniform stanza "-M -DDEPEND" even for sites that were already correct.

Also, use ">" not ">>" for obvious reasons...

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Unify dependency generation and move common rules into
MCONFIG.embedded.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Update copyright notices.  Per agreement with my new employer, Intel
Corporation, add Intel copyright notices where appropriate.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Deal with issues that made older versions of nasm:

a) prevent "make spotless" from running
b) generate bad dependencies (no final newline)

This seems to have better behavior for "make spotless".

It is just too confusing to have a .bss section that isn't zeroed, to
explicitly zero it.

This patch "sets the stage" for the memdisk kernel to include different
"installables": versions of the memdisk hooks.

This patch splits the case of the EDD-compiled hook from the non-EDD-compiled
hook.  Both are available inside the kernel, and the kernel chooses which one
to install based on the command-line.

It's possible that other, slightly modified versions of the memdisk hook could
be useful to have...