LLD fixes, warning and handling #2811
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Discard the eh_frame section when C++ exceptions are disabled. In principle the eh_frame may be used for other purposes such as backtracing when linking C programs, then Zephyr compiles each source file with '-fno-asynchronous-unwind-tables', thus keeping the eh_frame in the elf output just takes up space. When using gcc/ld, then the eh_frame is generally generally discarded per default, however for clang/lld it will be included but give a warning that the section is auto-placed. Some platforms already discards the eh_frame, so unify this for all targets. As eh_frame is now discarded in linker scripts then post processing step of removing the section during hex or bin conversion can also be removed. Upstream PR #: 88970 Signed-off-by: Torsten Rasmussen <[email protected]>
Move creation of last section id from ld linker script LONG() usage to C code with last section attribute. The use of `LONG()` works correctly with ld but lld emits a warning because .last_section section is not allocated as there are no matching input sections and discards the `LONG()` call, meaning the last section identifier will not be present in the flash. > ld.lld: warning: ignoring memory region assignment for > non-allocatable section '.last_section' Placing the last section id in `.last_section` in C code makes lld allocate the memory for the id and thereby create the output section with the correct output. Upstream PR #: 88970 Signed-off-by: Torsten Rasmussen <[email protected]>
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Cherry-pick of: 88970
This PR fixes warnings and handling happening with lld.
First commit fixes the warning:
Zephyr doesn't need the
.eh_framefor C code and even discards the section when converting the elf to bin / hex.gcc/ld per default discards the section, so there is no reason we should keep it for lld.
Second commit fixes the warning:
This is not just a warning but also results in the
LONG(<val>)command inside the linker script to be ignored by lld.Result is that the last section id is missing in the final output.
To ensure correct and identical behavior between ld and lld, the last section id is now linked into the final image through C code.