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>
[legal] Add support for the Unmodified Binary Distribution Licence
Add the text for the Unmodified Binary Distribution Licence. This
Licence allows for the distribution of unmodified binaries built from
publicly available source code, without imposing the obligations of
the GNU General Public License upon anyone who chooses to distribute
only the unmodified binaries built from that source code. See the
licence text for the precise terms and conditions.
Add the licence GPL2_OR_LATER_OR_UBDL to the set of licences which can
be declared using FILE_LICENCE(), and add the corresponding support to
licence.pl.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow for an explicit debug level of zero, which will enable
assertions and profiling (i.e. anything controlled by NDEBUG) without
generating any debug messages.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Our use of --gc-sections causes the linker to discard the symbols
defined by FILE_LICENCE(), meaning that the resulting licence
determination is incomplete.
We must use the KEEP() directive in the linker script to force the
linker to not discard the licence symbols. Using KEEP(*(COMMON))
would be undesirable, since there are some symbols in COMMON which we
may wish to discard.
Fix by placing symbols defined by PROVIDE_SYMBOL() (which is used by
FILE_LICENCE()) into a special ".provided" section, which we then mark
with KEEP(). All such symbols are zero-length, so there is no cost in
terms of the final binary size.
Since the symbols are no longer in COMMON, the linker will reject
symbols with the same name coming from multiple objects. We therefore
append the object name to the licence symbol, to ensure that it is
unique.
Reported-by: Marin Hannache <git@mareo.fr>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[console] Allow usage to be defined independently for each console
Add the concept of a "console usage", such as "standard output" or
"debug messages". Allow usages to be associated with each console
independently. For example, to send debugging output via the serial
port, while preventing it from appearing on the local console:
#define CONSOLE_SERIAL CONSOLE_USAGE_ALL
#define CONSOLE_PCBIOS ( CONSOLE_USAGE_ALL & ~CONSOLE_USAGE_DEBUG )
If no usages are explicitly specified, then a default set of usages
will be applied. For example:
#define CONSOLE_SERIAL
will have the same affect as
#define CONSOLE_SERIAL CONSOLE_USAGE_ALL
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Enhance the information collected by the function recorder to include
the call site and entry/exit counts. This allows fnrec.pl to produce
a call tree such as:
step (from core/getkey.c:46 = 0x17e90) {
ref_increment (from core/process.c:93 = 0x73ec) { }
net_step (from core/process.c:96 = 0x73f1) {
net_poll (from net/netdevice.c:741 = 0xbce6) {
netdev_poll (from net/netdevice.c:700 = 0xbc58) { }
netdev_rx_dequeue (from net/netdevice.c:709 = 0xbc65) { }
}
}
ref_decrement (from core/process.c:96 = 0x73f9) { }
}
Note that inlined functions are reported, confusingly, as extra calls
to the *containing* function. Minimise this confusion by adding the
attribute "no_instrument_function" to all functions declared as
inline. (Static functions that have been inlined autonomously by gcc
will still be problematic, but these are far fewer in number.)
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[build] Remove unnecessary constraint on DBG_ENABLE()/DBG_DISABLE()
DBG_ENABLE() and DBG_DISABLE() are currently constrained to enabling
and disabling only debug levels that are compiled in for the current
object. For example, a DBG_ENABLE(DBGLVL_EXTRA) in foo.c will not be
able to affect output from other objects at DBGLVL_EXTRA unless foo.c
is itself compiled with DBGLVL_EXTRA enabled.
Partially fix by removing this unnecessary constraint. (Note that it
is still necessary for at least one debug level to be compiled in for
the object invoking DBG_ENABLE()/DBG_DISABLE().)
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[compiler] Prevent empty weak function stubs from being removed
Even with the noinline specifier added by commit 1a260f8, gcc may skip
calls to non-inlinable functions that it knows have no side
effects. This caused the get_cached_dhcpack() call in start_dhcp(),
the weak stub of which has no code in its body, to be removed,
preventing cached DHCP from working.
Fix by adding a __keepme macro to compiler.h expanding to asm(""), as
recommended by gcc's info page, and using it in the weak stub for
get_cached_dhcpack().
Reported-by: Aaron Brooks <aaron@brooks1.net>
Tested-by: Aaron Brooks <aaron@brooks1.net>
Signed-off-by: Joshua Oreman <oremanj@rwcr.net>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Weak functions whose visibility is hidden may be inlined due to a bug
in GCC. Explicitly mark weak functions noinline to work around the
problem.
This makes the PXE_MENU config option work again, the PXE boot menu
was never being called because the compiler inlined a weak stub
function.
The GCC bug was identified and fixed by Richard Sandiford
<rdsandiford@googlemail.com> but in the meantime iPXE needs to
implement a workaround.
Reported-by: Steve Jones <steve@squaregoldfish.co.uk>
Reported-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>
Suggested-by: Joshua Oreman <oremanj@rwcr.net>
Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[debug] Expose pause() and more() debugging functions
Include the pause() and more() debugging functions within the general
iPXE debugging framework, by introducing DBGxxx_PAUSE() and
DBGxxx_MORE() macros.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Most of iPXE uses __attribute__((packed)) anyway, and PACKED conflicts
with an identically-named macro in the upstream EFI header files.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[build] Use weak definitions instead of weak declarations
This removes the need for inline safety wrappers, marginally reducing
the size penalty of weak functions, and works around an apparent
binutils bug that causes undefined weak symbols to not actually be
NULL when compiling with -fPIE (as EFI builds do).
A bug in versions of binutils prior to 2.16 (released in 2005) will
cause same-file weak definitions to not work with those
toolchains. Update the README to reflect our new dependency on
binutils >= 2.16.
Signed-off-by: Joshua Oreman <oremanj@rwcr.net>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Access to the gpxe.org and etherboot.org domains and associated
resources has been revoked by the registrant of the domain. Work
around this problem by renaming project from gPXE to iPXE, and
updating URLs to match.
Also update README, LOG and COPYRIGHTS to remove obsolete information.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Weak symbols are a useful tool in eliminating unnecessary dependencies
between object files, but they are somewhat dangerous because one must
remember to test the weak symbol against NULL before using it. To
rectify that, add macros for declaring weak functions that will return
a default value inline if the file defining them is not available at
link time.
Signed-off-by: Marty Connor <mdc@etherboot.org>
[linker] Add mechanism for subsystem-dependent configuration options
It is often the case that some module of gPXE is only relevant if the
subsystem it depends on is already being included. For instance,
commands to manage wireless interfaces are quite useless if no
compiled-in driver has pulled in the wireless networking stack. There
may be a user-modifiable configuration options for these dependent
modules, but even if enabled, they should not be included when they
would be useless.
Solve this by allowing the creation of config_subsystem.c, for
configuration directives like those in the global config.c that should
only be considered when subsystem.c is included in the final gPXE
build.
For consistency, move core/config.c to the config/ directory, where
the other config_subsystem.c files will eventually reside.
Signed-off-by: Marty Connor <mdc@etherboot.org>
[linker] Expand and correct symbol requirement macros
REQUIRE_SYMBOL() formerly used a formulation of symbol requirement
that would allow a link to succeed despite lacking a required symbol,
because it did not introduce any relocations. Fix by renaming it to
REQUEST_SYMBOL() (since the soft-requirement behavior can be useful)
and add a REQUIRE_SYMBOL() that truly requires.
Add EXPORT_SYMBOL() and IMPORT_SYMBOL() for REQUEST_SYMBOL()-like
behavior that allows one to make use of the symbol, by combining a
weak external on the symbol itself with a REQUEST_SYMBOL() of a second
symbol.
Signed-off-by: Marty Connor <mdc@etherboot.org>
[legal] Add mechanism for explicit per-file licence declarations
For partly historical reasons, various files in the gPXE source tree
are licensed under different, though compatible, terms. Most of the
code is licensed under GPLv2 with the "or later" clause, but there are
exceptions such as:
The string.h file, which derives from Linux and is licensed as
Public Domain.
The EFI header files, which are taken from the EDK2 source tree and
are licensed under BSD.
The 3c90x driver, which has a custom GPL-like licence text.
Introduce a FILE_LICENCE() macro to make licensing more explicit.
This macro should be applied exactly once to each source (.c, .S or
.h) file. It will cause a corresponding zero-sized common symbol to
be added to any .o files generated from that source file (and hence to
any final gPXE binaries generated from that source file). Determining
the applicable licences to generated files can then be done using e.g.
$ objdump -t bin/process.o | grep __licence
00000000 O *COM* 00000001 .hidden __licence_gpl2_or_later
indicating that bin/process.o is covered entirely by the GPLv2
with the "or later" clause, or
$ objdump -t bin/rtl8139.dsk.tmp | grep __licence
00033e8c g O .bss.textdata 00000000 .hidden __licence_gpl2_only
00033e8c g O .bss.textdata 00000000 .hidden __licence_gpl2_or_later
00033e8c g O .bss.textdata 00000000 .hidden __licence_public_domain
indicating that bin/rtl8139.dsk includes both code licensed under
GPLv2 (both with and without the "or later" clause) and code licensed
as Public Domain.
Determining the result of licence combinations is currently left as an
exercise for the reader.
[x86_64] Add support for compilation as an x86_64 binary
Currently the only supported platform for x86_64 is EFI.
Building an EFI64 gPXE requires a version of gcc that supports
__attribute__((ms_abi)). This currently means a development build of
gcc; the feature should be present when gcc 4.4 is released.
In the meantime; you can grab a suitable gcc tree from
git://git.etherboot.org/scm/people/mcb30/gcc/.git
[compiler] Allow for selective disabling of debug levels at runtime
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.
[legacy] Align legacy drivers' __shared data to the maximum possible
Some drivers that still use the legacy-driver wrapper (tg3 in particular)
apparently do not specify their alignment constraints properly. This
hack forces any __shared data to be maximally aligned.
Note that this provides only 16-byte alignment; it is not possible to
request alignment to any greater than 16 bytes using
__attribute__((aligned)), since the relocation code will preserve only 16
byte alignment (and operation under -DKEEP_IT_REAL cannot preserve more
that 16 byte alignment).
Idea proposed by Tim Hockin <thockin@google.com>
Michael Brown