Callers (e.g. usr/autoboot.c) may not check the return values from
fetch_xxx_setting(), assuming that in error cases the returned setting
value will be "empty" (for some sensible value of "empty").

In particular, if the DHCP server did not specify a next-server
address, this would result in gPXE using uninitialised data for the
TFTP server IP address.

Contributed by Steve Cayford <cayfo001@umn.edu>

Some of the gPXE romprefix.S code attempts to write to the ROM image,
as allowed by the PCI spec.  We do gracefully handle the case of
read-only ROM images (for ISA ROMs and for normal bochs/qemu
operation), but it can be handy to be able to use bochs to debug the
code paths that depend on writable ROM images.

FreeBSD requires the object format to be specified as elf_i386_fbsd,
rather than elf_i386.

Based on a patch from Eygene Ryabinkin <rea-fbsd@codelabs.ru>

Some PCI 3 BIOSes seem to provide a garbage value in %bx, which should
contain the runtime segment address.  Perform a basic sanity check: we
reject the segment if it is below the start of option ROM space.  If
the sanity check fails, we assume that the BIOS was not expecting us
to be a PCI 3 ROM, and we just leave our image in situ.

The section name seems to have significance for some versions of
binutils.

There is no way to instruct gcc that sections such as .bss16 contain
uninitialised data; it will emit them with contents explicitly set to
zero.  We therefore have to rely on the linker script to force these
sections to become uninitialised-data sections.  We do this by marking
them as NOLOAD; this seems to be the closest semantic equivalent in the
linker script language.

However, this gets ignored by some versions of ld (including 2.17 as
shipped with Debian Etch), which mark the resulting sections with
(CONTENTS,ALLOC,LOAD,DATA).  Combined with the fact that this version of
ld seems to ignore the specified LMA for these sections, this means that
they end up overlapping other sections, and so parts of .prefix (for
example) get obliterated by .data16's bss section.

Rename the .bss sections from .section_bss to .bss.section; this seems to
cause these versions of ld to treat them as uninitialised data.

Not fully understood, but it seems that the LMA of bss sections matters
for some newer binutils builds.  Force all bss sections to have an LMA
at the end of the file, so that they don't interfere with other
sections.

The symptom was that objcopy -O binary -j .zinfo would extract the
.zinfo section from bin/xxx.tmp as a blob of the correct length, but
with zero contents.  This would then cause the [ZBIN] stage of the
build to fail.

Also explicitly state that .zinfo(.*) sections have @progbits, in case
some future assembler or linker variant decides to omit them.

Also clean up minor errors in the use of debug macros.

The virtnet_transmit() logic for waiting the packet to be transmitted is
reversed: we can't wait the packet to be transmitted if we didn't kick()
the ring yet. The vring_more_used() while loop logic is reversed also,
that explains why the code works today.

The current code risks trying to free a buffer from the used ring
when none was available, that will happen most times because KVM
doesn't handle the packet immediately on kick(). Luckily it was working
because it was unlikely to have a buffer still queued for transmit when
virtnet_transmit() was called.

Also, adds a BUG_ON() to vring_get_buf(), to catch cases where we try
to free a buffer from the used ring when there was none available.

Patch for Etherboot. gPXE has the same problem on the code, but I hadn't
a chance to test gPXE using virtio-net yet.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>

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.

Multicast hashing is an ugly overlap between network and link layers.
EFI requires us to provide access to this functionality, so move it
out of ipv4.c and expose it as a method of the link layer.

Currently this length is set at device allocation time, and is never
changed.

Some versions of ld choke on the "AT ( _xxx_lma )" in efi.lds with an
error saying "nonconstant expression for load base".  Since these were
only explicitly setting the LMA to the address that it would have had
anyway, they can be safely omitted.

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.

monojob_wait() was holding a reference to the completed job, meaning that
various objects would not be freed until the next job was plugged in to
the monojob interface.

The userptr_t is now the fundamental type that gets used for conversions.
For example, virt_to_phys() is implemented in terms of virt_to_user() and
user_to_phys().

The EFI timer runs at one tick per second, so using ">" rather than ">="
results in a two-second gap between dots.

We now have two implementations for the timer API: one using the
time-of-day counter at 40:70 and one using RDTSC.  Both make use of
timer2_udelay().

Using start==0 to indicate a stopped timer is dangerous, because 0 is a
valid value for the current tick counter.

The copy_{to,from}_phys() functions were obsoleted long ago by
copy_{to,from}_user().

relocate_to() also disappeared some time ago.

-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.