Cross-compiling boost 1.34.x and 1.35.0

There seem to be lots of people asking how to cross-compile boost and very few answers. One of the better answers works for v1.33.x but breaks with v1.34.0.

After digging around for a while trying to make it work I was finally given the answer by the esteemed Peter Hartley who had managed to cross-compile boost 1.34 as part of his Just The Linux distribution. His solution seems to work for v1.35.0 too.

The trick that had eluded me until that point was to tell both the user-config.jam file and bjam about the cross compiler.

Something like:

echo "using gcc : : nicearch-linux-g++ ;" > user-config.jam
make BJAM_CONFIG="-sGXX=nicearch-linux-g++" install

If, like me, you want to only generate static libraries and support multiple builds in the same tree then you might need a bit more cleverness:

build=/tmp/nicearch/build
staging=/tmp/nicearch/staging
CXX=nicearch-linux-g++
CC=nicearch-linux-gcc
mkdir -p $build $staging
echo "using gcc : : $CXX ;" > $build/user-config.jam
bjam --toolset=gcc -sGXX=$CXX -sGCC=$CC \
  --prefix=$staging --build-dir=$build \
  --user-config=$build/user-config.jam --without-python \
  variant=release link=static threading=multi

This should be relatively easy to turn into a buildroot package file but I'm no longer using buildroot to build boost so I didn't need to.