An `INSERT AFTER` directive no longer can refer to a different linker
script included with `-T path/to/script.ld`. Instead, this adds wrapper
linker scripts that just `INCLUDE` the three individual linker scripts.
This way, the xfa.ld can safely refer back to sections defined in
the vendor linker script.
For some reason, this approach cause the exact issue it fixes for
binutils 2.40 with the binutils in the CI. We stick with the old
linker flags with binutils prior 2.40 to be compatible with both
conflicting behaviors.
The best approach would be to come up with something that works across
different versions of binutils; but no such solution materialized.
Add `TARGET_ARCH_<ARCH>` for each architecture (e.g. `TARGET_ARCH_CORTEX` for
Cortex M) to allow users to overwrite the target triple for a specific arch
from ~/.profile or ~/.bashrc (or the like) without overwriting it for all others
as well.
Use the -gz option to compress ELF sections containing DWARF information.
This saves around 50% of disk space, without any side effects.
See https://gcc.gnu.org/onlinedocs/gcc-9.2.0/gcc/Debugging-Options.html#Debugging-Options
for more infomation on this option.
Some platforms have an outdated toolchain that does not support -gz so
the flag is blacklisted there. Even then, the results are quite impressive.
I used @cladmi's `buildtest` branch (https://github.com/cladmi/RIOT/tree/wip/du/buildtest)
with this change and compiled the `examples/default` application:
```
$ BUILD_IN_DOCKER=1 DOCKER="sudo docker" make -C examples/default buildtest-indocker
```
The size was obtained with:
```
$ find output -name "*.bin.bindirsize" -type f -exec tail -n1 '{}' \; | cut -f 1 | awk '{s+=$1} END {printf "%.0f", s}'
```
Results:
- Vanilla: 10328112 KB (~10GB).
- with -gz: 4982788 KB (~5GB).
This was inspired by #8496.
