elf2efi converts a suitable ELF executable (containing relocation
information, and with appropriate virtual addresses) into an EFI
executable.  It is less tightly coupled with the gPXE build process
and, in particular, does not require the use of a hand-crafted PE
image header in efiprefix.S.

elf2efi correctly handles .bss sections, which significantly reduces
the size of the gPXE EFI executable.

EFI provides a copy of the SMBIOS table accessible via the EFI system
table, which we should use instead of manually scanning through the
F000:0000 segment.

EFI passes in copies of SMBIOS and other system configuration tables
via the EFI system table.  Allow configuration tables to be requested
using a mechanism similar to the current method for requesting EFI
protocols.

Remove various 32-bit assumptions scattered throughout the codebase.
The code is still not necessarily 64-bit clean, but will at least
compile.

EFI_STATUS is defined as an INTN, which maps to UINT32 (i.e. unsigned
int) on i386 and UINT64 (i.e. unsigned long) on x86_64.  This would
require a cast each time the error status is printed.

Add efi_strerror() to avoid this ickiness and simultaneously enable
prettier reporting of EFI status codes.

This brings us in to line with Linux definitions, and also simplifies
adding x86_64 support since both platforms have 2-byte shorts, 4-byte
ints and 8-byte long longs.

The initial PXE implementation in Etherboot had the goal of being
architecture-agnostic, but this goal has not been realised.

netdev_rx_err() and netdev_tx_complete_err() get passed the error
code, but currently use it only in debug messages.

Retain error numbers and frequencey counts for up to
NETDEV_MAX_UNIQUE_ERRORS (4) different errors for each of TX and RX.
This allows the "ifstat" command to report the reasons for TX/RX
errors in most cases, even in non-debug builds.

This implementation is tested and working, but not currently tied in
to the EFI build.

EFI requires us to be able to specify the source address for
individual transmitted packets, and to be able to extract the
destination address on received packets.

Take advantage of this to rationalise the push() and pull() methods so
that push() takes a (dest,source,proto) tuple and pull() returns a
(dest,source,proto) tuple.

We have EFI APIs for CPU I/O, PCI I/O, timers, console I/O, user
access and user memory allocation.

EFI executables are created using the vanilla GNU toolchain, with the
EXE header handcrafted in assembly and relocations generated by a
custom efilink utility.

At least one Dell system calls the UNDI loader entry point with the
BIOS console disabled.  The serial console is active only after a call
to initialise(), so move the debug message in undi_loader() so that it
can be displayed via the serial console.

pxenv_udp_write() needs to specify a net device, otherwise ipv4 is
unable to route broadcast transmissions.

Determine the network-layer packet type and fill it in for UNDI
clients.  This is required by some NBPs such as emBoot's winBoot/i.

This change requires refactoring the link-layer portions of the
gPXE netdevice API, so that it becomes possible to strip the
link-layer header without passing the packet up the network stack.

Some dumb NBPs (e.g. emBoot's winBoot/i) never call PXENV_UNDI_ISR
with FuncFlag=PXENV_UNDI_ISR_START; they just sit in a tight polling
loop merrily violating the PXE spec with repeated calls to
PXENV_UNDI_ISR_IN_PROCESS.  Force a extra calls to netdev_poll() to
cope with these out-of-spec clients.

Add yet another ugly hack to iscsiboot.c, this time to allow the user to
inhibit the shutdown/removal of the iSCSI INT13 device (and the network
devices, since they are required for the iSCSI device to function).

On the plus side, the fact that shutdown() now takes flags to
differentiate between shutdown-for-exit and shutdown-for-boot means that
another ugly hack (to allow returning via the PXE stack on BIOSes that
have broken INT 18 calls) will be easier.

I feel dirty.

__from_data16 and __from_text16 now take a pointer to a
.data16/.text16 variable, and return the real-mode offset within the
appropriate segment.  This matches the use case for every occurrence
of these macros, and prevents potential future bugs such as that fixed
in commit d51d80f.  (The bug arose essentially because "&pointer" is
still syntactically valid.)

__from_data16 takes the value pointed to, rather than the pointer
itself.  This was silently causing gPXE to return a dud buffer pointer
when the caller did not supply a buffer for PXENV_GET_CACHED_INFO.

OpenBSD throws compiler warnings that we can't reproduce on Linux, for
some reason.

Original patch from Dewey Hylton <dewey@hyltown.com>.

Add FILE_API_CHECK to the PXEXT API so the NBP can query the
availability and status of the API.

Allow for settings to be described by something other than a DHCP option
tag if desirable.  Currently used only for the MAC address setting.

Separate out fake DHCP packet creation code from dhcp.c to fakedhcp.c.

Remove notion of settings from dhcppkt.c.

Rationalise dhcp.c to use settings API only for final registration of the
DHCP options, rather than using {store,fetch}_setting throughout.

Add dedicated functions create_dhcpdiscover(), create_dhcpack() and
create_proxydhcpack() for use by external code such as the PXE preboot
code.

Register ProxyDHCP options under the global scope "proxydhcp".

Unregister previously-acquired DHCP and ProxyDHCP settings when DHCP
succeeds.

WinPE's pxeboot.n12 takes the BufferLimit returned by gPXE (indicating
the size of gPXE's internal DHCP packet buffers) and erroneously passes
it in as BufferSize (indicating the size of pxeboot.n12's DHCP packet
buffer).  If these don't match, then pxeboot.n12 ends up instructing gPXE
to overwrite parts of its data segment.

Change gPXE's internal DHCP packet buffers to be exactly
sizeof(BOOTPLAYER_t) bytes to work around this problem.

This allows pxelinux to execute arbitrary gPXE commands.  This is
remarkably unsafe (not least because some of the commands will assume
full ownership of memory and do nasty things like edit the e820 map
underneath the calling pxelinux), but it does allow access to the
"sanboot" command.

stored DHCP packets.

separate xfer method.

Add missing .alloc_iob entries to several xfer_interface_operations
structures.

PXENV_GET_CACHED_INFO.  NTLDR does this.

PXENV_GET_CACHED_INFO.  If we dont do this, Altiris' NBP screws up; it
relies on being able to grab pointers to each of the three packets and
then read them at will later.

s_PXENV_GET_CACHED_INFO, because this field doesn't exist in earlier
versions of the PXE spec, and some callers don't allocate space for it.

xfer_window() function, which can return a scalar rather than a
boolean.

safe dropping of the netdev ref by the driver while other refs still
exist.

Add netdev_irq() method.  Net device open()/close() methods should no
longer enable or disable IRQs.

Remove rx_quota; it wasn't used anywhere and added too much complexity
to implementing correct interrupt-masking behaviour in pxe_undi.c.

now-obsolete pxe.c.

5.4 bugs when driving ourselves via UNDI.

suspect that we need it, and implementing it would require needlessly
complicating the net device API.

handed a P_UNKNOWN packet.