Two changes to the INT 0x13, AH=0x7B El Torito function:

1. Support the DL=0x7F "terminate all" parameter
2. Only respond to DL=0x7F or DL=our particular emulated drive number

This prevents tools like Bart Lagerweij's El Torito tools from
receiving false positives when probing all drive numbers.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

When mstructs.h is used by MDISKCHK.COM, pointers have
a 16-bit size and thus the mBFT structure sizeof() is
smaller under OpenWatcom.  We now union this pointer
member with a uint32_t to force the field to at least
32 bits.

There is another pointer in this header file which is
already unioned with a uint32_t, due to that field's
dual-purpose.  That field is fine under OpenWatcom.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

This needs to be in here in order for the header file
to be useful to any C file other than setup.c.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

Instead of padding the mBFT so its size is correct, we
actually put the MDI struct in there, since the last
commit provided it.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

Previously, the patch area began after the beginning of
the MDI, but continued past its end.  This is difficult
to express with C structures, so we've simply changed
the patch area to include the entire MDI.  So it now
includes the MDI size and MEMDISK version info, which
we simply make constant to avoid modifying.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

This commit moves the MEMDISK header structure into
the common structures header file.

It also adds the "safe hook" structure to the MEMDISK
header structure, since that matches what's in the hook
binaries.  Thus, we access the "safe hook" via the
header pointer, instead of separately.

Tested against a DOS floppy image including an
experimental MDISKCHK.COM and also gainst WinVBlock.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

We used uint32_t in a few places where it's also handy
to refer to those fields' segment and offset components.
Now we can do so via the real_addr_t union type.

Additionally, there are a couple of places where we now
have pointer fields instead of uint32_t fields, because
we know what kind of struct the field is pointing to.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

Since MDISKCHK.COM (and possibly COM32 modules) could make use of
structures found in MEMDISK's setup.c, we move these into a new
header file mstructs.h.

Also, since the OpenWatcom compiler uses a structure packing prefix
and GCC uses a structure packing postfix, we accomodate this with
preprocessor definitions around those structures needing to be
packed.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

Resolved Conflicts:
	core/cpuinit.inc

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