http://www.microsoft.com/whdc/winlogo/hwrequirements.mspx as required
for iSCSI boot.  Note that options 204-206 are listed in the document
but don't seem to be defined anywhere on the web.

overhauling, but this is not the time to do it.

technically be necessary, because the "enable A20" command requires
only that the keyboard controller is ready to accept input (i.e. that
its input buffer is empty), and shouldn't also require that the
keyboard is ready to send output (i.e. that its output buffer is also
empty).  See http://www.smsc.com/main/tools/io-bios/42i.pdf section
3.1 ("Command Invocation") for a justification.

gateA20_set() is called on every real-mode transition (in case some
idiot piece of external code such as Intel's PXE stack decided it
would be fun to re-disable A20), so draining the keyboard buffer means
that we end up losing keypresses on some systems.  In particular, this
makes typing at the command line almost impossible, and causes
Etherboot to ignore Ctrl-Alt-Del.

We should really implement a gateA20_test() function to verify that
gate A20 has been correctly enabled, and think about adding other
commonly-used methods such as Fast Gate A20.

completely forgot I'd written ages ago.

this can probably be optimised down quite a lot.

device.

Separated the mechanisms of non-volatile storage access and non-volatile
stored options.

a word length.

that don't provide the full flexibility of a bit-bashing interface.

Temporarily hacked rtl8139.c to use the new interface.

function prototypes (e.g. malloc_dma()) in malloc.h.

information in NVS.

Added CHAP authentication

away code such as

  if ( strcmp ( some_string, "some_value" ) != 0 ) {
     DBG ( "Bad value received!" );
  }

for realloc(0) being a valid way to free memory.

Don't crash when called on an uninitialised chap structure; this
allows us to avoid extra checks within iscsi.c to make sure that we
receive the CHAP_XXX keys in a sensible order.

code, rather than going through the digest layer.

Removed a spurious line of constants.

with octal yet, but we can probably live without that.

negotiation phases, to allow inclusion of CHAP authentication.

while retaining the format string checking.

defined in vsprintf.h.  (This may change, since vsprintf.h is a
non-standard name, but for now it's the one to use.)

There should be no need to include vsprintf.h just for DBG() statements,
since include/compiler.h forces it in for a debug build anyway.