Update rtl8139 driver to instantiate an SPI interface with a three-wire
device attached.

(since SPI bit-bashing will require different delay semantics).

--nulltrap to the make target at the moment.)

as a result of our memory map editing, so strip out any empty regions.

Allow our functions to return a non-zero, non-error status (since the
INT 13 Extensions Check has to return the API version in the register
that is otherwise always used for the error code).

Report a non-zero API version from the INT 13 Extensions Check; GRUB
now uses extended reads.

library use later on
- some small mods to existing functions

being noticed...

flow of control through this code.

We now always add PCI and PnP headers even for ISA ROMs; there's no harm
in doing so.

UNDI loader is still missing.

on the stack.

the jmp instruction).

Print warning message at probe time.

not-yet-updated drivers to at least function.

AoE now uses the retry timer mechanism.

layer asynchronous, so keeping the sync/async boundary within aoedev.c
seems cleanest for now.

point trying to use the old boot sequence.  Replaced with a call to the
AoE demo code, so that people can at least build and try something useful.

elegant, but it works).

async_wait(), though we may wish to move this higher up the stack, and
consider making the block device model asynchronous.  (There is only a
marginal cost for synchronous devices, since they can simply call
async_done() before returning; async_wait() will work seamlessly in this
situation).

This is the core portion of the async I/O interface.

Removed data_in_len and data_out_len from ata_command structure; the
lengths are implied by the sector count and the presence of the data_in
or data_out pointers.

Changed AoE code to use subcommands by default, and made aoe_issue()
nonblocking (with completion via async_wait()).

these timer objects in AoE and UDP protocols (where there is no underlying
retransmission mechanism) without requiring each protocol to implement its
own individual retry logic.  Eventually, we should be able to use the same
timer code for TCP retransmissions as well.

  Cannot yet handle reads of more than two sectors

  No retransmission

  No way to find out a target's MAC address (this proof of concept uses
  broadcasts)

These limitations shall not last long!  :)

Increase code simplicity at the expense of around 64 bytes.