-Wformat-nonliteral is not enabled by -Wall and needs to be explicitly
 specified.

Modified the few files that use nonliteral format strings to work with
this new setting in place.

Inspired by a patch from Carl Karsten <carl@personnelware.com> and an
identical patch from Rorschach <r0rschach@lavabit.com>.

The intention is to include near-verbatim copies of the EFI headers
required by gPXE.  This is achieved using the import.pl script in
src/include/gpxe/efi.

Note that import.pl will modify any #include lines in each imported
header to reflect its new location within the gPXE tree.  It will also
tidy up the file by removing carriage return characters and trailing
whitespace.

Reduce the number of sections within the linker script to match the
number of practical sections within the output file.

Define _section, _msection, _esection, _section_filesz, _section_memsz,
and _section_lma for each section, replacing the mixture of symbols that
previously existed.

In particular, replace _text and _end with _textdata and _etextdata, to
make it explicit within code that uses these symbols that the .text and
.data sections are always treated as a single contiguous block.

Undefined symbols shouldn't reach sortobjdump.pl, but if they do then it
is not a helpful place to report the error.

Allow for the build CPU architecture and platform to be specified as part
of the make command goals.  For example:

  make bin/rtl8139.rom      # Standard i386 PC-BIOS build

  make bin-efi/rtl8139.efi  # i386 EFI build

The generic syntax is "bin[-[arch-]platform]", with the default
architecture being "i386" (regardless of the host architecture) and the
default platform being "pcbios".

Non-path targets such as "srcs" can be specified using e.g.

  make bin-efi srcs

Note that this changeset is merely Makefile restructuring to allow the
build architecture and platform to be determined by the make command
goals, and to export these to compiled code via the ARCH and PLATFORM
defines.  It doesn't actually introduce any new build platforms.

The arch/i386/Config file has long been marked as deprecated.  Move all
the pertinent bits to arch/i386/Makefile instead and remove
arch/i386/Config.

gcc defines the magic __WCHAR_TYPE__ macro, in order to convey
information about whether or not the user selected -fshort-wchar.

Some devices (e.g. the Atmel AT24C11) have no concept of a device
address; they respond to every device address and use this value as
the word address.  Some other devices use part of the device address
field to extend the word address field.

Generalise the i2c bit-bashing support to handle this by defining the
device address length and word address length as properties of an i2c
device.  The word address is assumed to overflow into the device
address field if the address used exceeds the width of the word
address field.

Also add a bus reset mechanism.  i2c chips don't usually have a reset
line, so rebooting the host will not clear any bizarre state that the
chip may be in.  We reset the bus by clocking SCL until we see SDA
high, at which point we know we can generate a start condition and
have it seen by all devices.  We then generate a stop condition to
leave the bus in a known state prior to use.

Finally, add some extra debugging messages to i2c_bit.c.

Some older versions of gcc don't complain about unknown compiler flags
unless you ask them to actually compile; asking them to merely
preprocess won't trigger the error.

Fix the -fno-stack-protector test by making it attempt to compile an
empty file, rather than preprocess an empty file.

The usefulness of DBGLVL_IO is limited by the fact that many cards
require large numbers of uninteresting I/O reads/writes at device
probe time, typically when driving a bit-bashing I2C/SPI bus to read
the MAC address.

This patch adds the DBG_DISABLE() and DBG_ENABLE() macros, which can
be used to temporarily disable and re-enable selected debug levels.
Note that debug levels must still be enabled in the build in order to
function at all: you can't use DBG_ENABLE(DBGLVL_IO) in an object
built with DEBUG=object:1 and expect it to do anything.

[] are shell metacharacters, and they can get confused by files in the
local directory.

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

?= in a Makefile means that that variable can be overridden by the
environment.  This is confusing to users, especially with a generic
name like "ARCH".

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

Reported working by Martin Kreiner <m.kreiner@levigo.de>

Although the E820 API allows for a caller to provide only a 20-byte
buffer, there exists at least one combination (HP BIOS, 32-bit WinPE)
that relies on information found only in the "extended attributes"
field, which requires a 24-byte buffer.

Allow for up to a 64-byte E820 buffer, in the hope of coping with
future idiocies like this one.

The ACPI specification defines an additional 4-byte field at offset 20
for an E820 memory map entry.  This field is presumably optional,
since generally E820 gets given only a 20-byte buffer to fill.
However, the bits of this optional field are defined as:

  bit 0 : region is enabled
  bit 1 : region is non-volatile memory rather than RAM

so it seems as though callers that pass in only a 20-byte buffer may
be missing out on some rather important information.

gcc should (I think) be warning about this anyway, but seems to do so
only when assertions are enabled for this object.

Our INT 15,e820 code was setting %es=%ss (as part of the "look ahead
in the memory map" logic), but failing to restore %es afterwards.
This is a serious bug, but wasn't affecting many platforms because
almost all callers seem to set %es=%ss anyway.

Use as "call dump_regs" from any real-mode code within .text16.
Should preserve all registers and flags.

Use individual page mappings rather than a single whole-region
mapping, to avoid the waste of memory that occurs due to the
constraint that each mapped block must be aligned on its own size.

Some BIOSes require us to pass in not only the continuation value (in
%ebx) as returned by the previous call to INT 15,e820 but also the
unmodified buffer (at %es:%di) as returned by the previous call to INT
15,e820.  Apparently, someone thought it would be a worthwhile
optimisation to fill in only the low dword of the "length" field and
the low byte of the "type field", assuming that the buffer would
remain unaltered from the previous call.

This problem was being triggered by the "peek ahead" logic in
get_mangled_e820(), which would read the next entry into a temporary
buffer in order to be able to guarantee terminating the map with
%ebx=0 rather than CF=1.  (Terminating with CF=1 upsets some Windows
flavours, despite being documented legal behaviour.)

Work around this problem by always fetching directly into our e820
cache; that way we can guarantee that the underlying call always sees
the previous buffer contents (and the same buffer address).

We were accidentally allocating only half the required amount of
memory (given the alignment method) for the firmware buffer, leading
to conflicts between the firmware buffer and gPXE code/data segments.

We were accidentally allocating only half the required amount of
memory (given the alignment method) for the firmware buffer, leading
to conflicts between the firmware buffer and gPXE code/data segments.

We seem to be having issues with various E820 memory maps.  These
problems are often difficult to reproduce, requiring access to the
specific system exhibiting the problem.

Add a facility for hooking in a fake E820 map generator, using an
arbitrary map defined in a C array, solely in order to be able to test
the map-mangling code against arbitrary E820 maps.

In particular, allow BANNER_TIMEOUT=0 to inhibit the prompt banners
altogether.

Ironically, this request comes from the same OEM that originally
required the prompts to be present during POST.