Implement getcwd() in the core; Fix COM32 getcwd() to use the new function.

This resolves the previous comment about COM32 getcwd() not working by
not using INT 22h AX=001Fh.

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

Fix COM32 chdir() since it's implemented in the core.
Forgot the core changes needed for this before.

Signed-off-by: Gene Cumm <gene.cumm@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Future-proof the pmapi vector by making it include its own size.

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

Do the actual idling in protected mode.  This both allows PM code a
more efficient interface, but also handles bugs in HVM implementations
which don't handle HLT in real mode.

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

Add 32-bit API calls for open file and close file.

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

The 16-bit API to opendir/readdir/closedir was confused, had a memory
leak, and was incompatible with Syslinux 3.x anyway.  Replace it with
a pure 32-bit API.

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

Use a better malloc for the core.  In particular, use the same core
that we should eventually be able to use for the entire system in
Syslinux 5 -- with module awareness, etc.

This code can also accommodate multiple heaps.  Set up a separate heap
for lowmem; the intent is to use explicit lowmem allocations instead
of the static bounce buffer.  The lowmem allocation is also exported
via the pmapi mechanism, so modules can safely allocate lowmem.

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

Add a direct 32-bit API to some functions; initially read file only.

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