At some point in the past few years, binutils became more aggressive
at removing unused symbols. To function as a symbol requirement, a
relocation record must now be in a section marked with @progbits and
must not be in a section which gets discarded during the link (either
via --gc-sections or via /DISCARD/).
Update REQUIRE_SYMBOL() to generate relocation records meeting these
criteria. To minimise the impact upon the final binary size, we use
existing symbols (specified via the REQUIRING_SYMBOL() macro) as the
relocation targets where possible. We use R_386_NONE or R_X86_64_NONE
relocation types to prevent any actual unwanted relocation taking
place. Where no suitable symbol exists for REQUIRING_SYMBOL() (such
as in config.c), the macro PROVIDE_REQUIRING_SYMBOL() can be used to
generate a one-byte-long symbol to act as the relocation target.
If there are versions of binutils for which this approach fails, then
the fallback will probably involve killing off REQUEST_SYMBOL(),
redefining REQUIRE_SYMBOL() to use the current definition of
REQUEST_SYMBOL(), and postprocessing the linked ELF file with
something along the lines of "nm -u | wc -l" to check that there are
no undefined symbols remaining.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add the standard warranty disclaimer and Free Software Foundation
address paragraphs to the licence text where these are not currently
present.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Replace the existing partially-implemented IPv6 stack with a fresh
implementation.
This implementation is not yet complete. The IPv6 transmit and
receive datapaths are functional (including fragment reassembly and
parsing of arbitrary extension headers). NDP neighbour solicitations
and advertisements are supported. ICMPv6 echo is supported.
At present, only link-local addresses may be used, and there is no way
to specify an IPv6 address as part of a URI (either directly or via
a DNS lookup).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown