Most of the code here is based on code from the Homebrew armeabi taps by Emmanuel Blot.
This repositories contsains scripts to build the following projects for ARMv7em targets:
- LLVM/Clang 9.0.0rc1 (including LLD)
- Newlib 3.1.0: Configured in a nano configuration, to reduce size for bare-metal applications.
- libcompiler-rt, version 9.0.0rc1 from the LLVM project. Includes a patch to prevent using double precision floating point instructions, which are available on some ARMv7em targets (M7f), but not all (M4f).
- libc++ (plus libc++abi and libunwind), version 9.0.0rc1 from the LLVM project.
Some features are disabled, namely threading.
Includes my patch D65348, enabling
<atomic>header.
The toolchain can be built into a docker image
by running
docker build -t burnpanck/llvm-armeabi-newlib .
in the top-level directory.
Alternatively, the toolchain can be built outside of docker
on an UNIX-like system by executing
TOOLCHAIN_ROOT=/path/to/toolchain/root ./build.sh
The image is still rough around the edges; environment variables are not set, that needs to be done while using. The following are generally needed:
PATH=/toolchain/bin:$PATH: The location ofclang,clang++,lldetc.- SYSROOT: Is that needed at all?
- Header include paths:
/toolchain/
- Library search paths:
This toolchain has successfully been applied to compile working bare-metal firmware for Cortex M4F. However, the toolchain requires some manual work, i.e.
- The header
<iostream>seems to fail with a missing symbollocale_t.
The original sources fail to compile, because implementations make use of double precision instructions, which are unavailable on ARM M4f. The patch excludes those builtins from the build, which will then be replaced by generic implementations.