mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-26 22:51:01 +00:00
96 lines
3.0 KiB
Plaintext
96 lines
3.0 KiB
Plaintext
Fundamental design decision:
|
|
|
|
- the sizes of external and internal types are assumed to be the same.
|
|
This leaves byte ordering aside. While assuming this the code can be
|
|
greatly simplified and speed increases. Since no change violating this
|
|
assumption is in sight this is believed to be a worthwhile optimization.
|
|
|
|
- the ABI of the backend modules is not guaranteed. Really, no guarantee
|
|
whatsoever. We are enforcing this in the code. The modules and their
|
|
users must match. No third-party EBL module are supported or allowed.
|
|
The only reason there are separate modules is to not have the code for
|
|
all architectures in all the binaries.
|
|
|
|
- although the public libraries (libasm, libdw) have a stable API and are
|
|
backwards ABI compatible they, and the elfutils tools, do depend on each
|
|
others internals, and on internals of libelf to provide their interfaces.
|
|
So they should always be upgraded in lockstep when packaging the tools
|
|
and libraries separately. For one example of how to do that, see the
|
|
config/elfutils.spec.
|
|
|
|
Some notes:
|
|
|
|
- old GNU ld's behavior wrt DSOs seems to be severely broken.
|
|
|
|
y.o reference foo()
|
|
y1.o defines foo(), references bar()
|
|
y2.o defines bar()
|
|
libbar.so defines bar()
|
|
|
|
Running
|
|
|
|
gcc -o y y.o -lbar y1.o y2.o
|
|
|
|
uses the bar() definition from libbar.so and does not mention the definition
|
|
in y2.o at all (no duplicate symbol message). Correct is to use the
|
|
definition in y2.o.
|
|
|
|
|
|
y.o reference foo()
|
|
y1.o defines foo(), references bar()
|
|
y2.o in liby2.a defines bar()
|
|
libbar.so defines bar()
|
|
|
|
Running
|
|
|
|
gcc -o y y.o -lbar y1.o -ly3
|
|
|
|
has to use the definition in -lbar and not pull the definition from liby3.a.
|
|
|
|
|
|
- the old linker follows DT_NEEDED entries and adds the objects referenced
|
|
this way which define a symbol which is needed as a DT_NEEDED to the
|
|
generated binary. This is wrong since the DT_NEEDED changes the search
|
|
path in the object (which is breadth first).
|
|
|
|
|
|
- the old linker supported extern "C++", extern "java" in version scripts.
|
|
I believe this implementation is severly broken and needs a redesign
|
|
(how do wildcards work with these languages*?). Therefore it is left
|
|
out for now.
|
|
|
|
|
|
- what should happen if two sections in different files with the same
|
|
name have different types and/or the flags are different
|
|
|
|
|
|
- section names in input files are mostly irrelevant. Exceptions:
|
|
|
|
.comment/SHT_PROGBITS in strip, ld
|
|
|
|
.debug \
|
|
.line |
|
|
.debug_srcinfo |
|
|
.debug_sfnames |
|
|
.debug_aranges |
|
|
.debug_pubnames |
|
|
.debug_info |
|
|
.debug_abbrev |
|
|
.debug_line |
|
|
.debug_abbrev > DWARF sections in ld
|
|
.debug_line |
|
|
.debug_frame |
|
|
.debug_str |
|
|
.debug_loc |
|
|
.debug_macinfo |
|
|
.debug_weaknames |
|
|
.debug_funcnames |
|
|
.debug_typenames |
|
|
.debug_varnames /
|
|
|
|
Sections created in output files follow the naming of special section
|
|
from the gABI.
|
|
|
|
In no place is a section solely indentified by its name. Internal
|
|
references always use the section index.
|