How to build a toolchain for arm cortex-m and cortex-r
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For up to date information on ARM toolchain building (also for Cortex-R and Cortex-M), please review the main ARM article.
Toolchain installation steps
Crossdev can almost build a functioning toolchain for embedded arm development. The toolchain can be created with the following steps:
Step 1:
root #crossdev --lenv 'USE="nano -nls -threads -unicode"' -s3 -t arm-unknown-eabiStep 2:
root #crossdev --lenv 'USE="nano -nls -threads -unicode"' --genv 'USE="cxx -nls -nptl -pch -pie -ssp" EXTRA_ECONF="--with-multilib-list=rmprofile --disable-decimal-float --disable-libffi --disable-libgomp --disable-libmudflap --disable-libquadmath --disable-shared --disable-threads --disable-tls"' -s4 -t arm-unknown-eabiStep 3:
root #emerge --ask cross-arm-unknown-eabi/newlibStep 4:
root #crossdev --lenv 'USE="nano -nls -threads -unicode"' --genv 'USE="cxx -nls -nptl -pch -pie -ssp" EXTRA_ECONF="--with-multilib-list=rmprofile --disable-decimal-float --disable-libffi --disable-libgomp --disable-libmudflap --disable-libquadmath --disable-shared --disable-threads --disable-tls"' -s4 --ex-gdb -t arm-unknown-eabiNow you'll have a functioning multilib / multiarch for embedded arm development with small code output size.
Big thanks to the Gentoo forum user rapsure who posted this instructions here.
Toolchain installation steps with hardware floating point
You may also want the toolchain to contain support for hardware floating point. In that case, use these instructions instead:
Step 1:
root #crossdev --lenv 'USE="nano -nls -threads -unicode"' -s3 -t arm-unknown-eabiStep 2:
root #crossdev --lenv 'USE="nano -nls -threads -unicode"' --genv 'USE="cxx -nls -nptl -pch -pie -ssp" EXTRA_ECONF="--with-multilib-list=rmprofile --disable-decimal-float --disable-libffi --disable-libgomp --disable-libmudflap --disable-libquadmath --disable-shared --disable-threads --disable-tls"' -s4 -t arm-unknown-eabiStep 3:
root #emerge --ask cross-arm-unknown-eabi/newlibStep 4:
root #crossdev --lenv 'USE="nano -nls -threads -unicode" EXTRA_ECONF="--enable-newlib-hw-fp"' --genv 'USE="cxx -nls -nptl -pch -pie -ssp" EXTRA_ECONF="--with-multilib-list=rmprofile --disable-decimal-float --disable-libffi --disable-libgomp --disable-libmudflap --disable-libquadmath --disable-shared --disable-threads --disable-tls"' -s4 --ex-gdb -t arm-unknown-eabi Note
I left the toolchain named arm-unknown-eabi because it is what the instructions previously used, but in my experience most IDEs expect the naming convention to be arm-none-eabi. It's perfectly alright to use these instructions with arm-none-eabi instead of arm-unknown-eabi for convenience.
I left the toolchain named arm-unknown-eabi because it is what the instructions previously used, but in my experience most IDEs expect the naming convention to be arm-none-eabi. It's perfectly alright to use these instructions with arm-none-eabi instead of arm-unknown-eabi for convenience.