devices).

Add method for hooking real-mode interrupt vectors.

Use .text16.data section with "aw" attributes, to avoid section type
conflicts when placing both code and data into .text16.

Add __from_{text16,data16}.

Avoid optimisation errors under -fstrict-aliasing.

between the low half stored in the static variable rm_sp, and the high
half stored on the prot_call() stack, because:

  Just using the stack would screw up when a prot_call()ed routine
  executes a real_call(); it would have no way to find the current top of
  the RM stack.

  Extending rm_sp to rm_esp would not be safe, because the guarantee that
  rm_sp must return to the correct value by the time an external
  real-mode call returns applies only to %sp, not to %esp.

interrupt vectors, for example, will be easiest to handle if placed in
.text16.

from protected-mode code.

Set up %ds to point to .data16 in prot_to_real, so that code specified
via REAL_EXEC() and friends can access variables in .data16.

Move most real-mode librm variables from .text16 to .data16.

.data16.  librm will need to supply "char *data16", i.e. the virtual
address of the start of .data16.

portions such as the stack) during the installation process.

init_fns() are called from main().  We need to think about initial
control flow some more.

install_prealloc.  I *think* these will suffice for all the 16-bit
prefixes.

However, it's worth adding a .size directive so that objdump reports the
correct sizes for the code fragments.

advantage of the fact that we have to have a permanently-resident block
in base memory.

setup.S.

highmem data, so decompress16 will be able to unpack blocks bigger
than 64kB.

running the decompresser in 16:16 protected mode using the real-mode
stack.  However, there's an even simpler way to do it...

of them in one go.

EBADIMG has been replaced by ENOEXEC, and EIMGRET by ECANCELED.

even when __atribute__ (( unused )) is correctly set...

Doing so, in fact, seems to expose an assembler bug; (a-b-0) is
apparently not the same as (a-b).  Go figure.

I want to get to the point where any header in include/ reflects a
standard user-level header (e.g. a POSIX header), while everything that's
specific to gPXE lives in include/gpxe/.  Headers that reflect a Linux
header (e.g. if_ether.h) should also be in include/gpxe/, with the same
name as the Linux header and, preferably, the same names used for the
definitions.

Added memswap().

PXE code now compiles without errors (though it won't actually work).