Bootstrapping an environment

Bootstrapping is the process of creating an environment which allows the cross-compilation of packages.

./init.sh builds a cross-compilation toolchain in sysroot/ by default. The path to the sysroot can be changed by setting the SYSROOT environment variable.

Note: one should not build several toolchains for different targets in the same sysroot

The following packages are built by init.sh:

Package	Host triplet	Target triplet	Notes
binutils	A	B	binutils stage 1, used to link by gcc stage 1
gcc (and libgcc)	A	B	gcc stage 1, used to compile the next step only
linux headers	n/a	n/a	required by libc
musl	B	n/a	libc, used by gcc stage 2
zlib	B	n/a	zlib, used by binutils stage 2 while running
libstdc++	B	n/a	used by gcc stage 2, requires libc
binutils	B	B	binutils stage 2
gcc (with libgcc and libstdc++)	B	B	gcc stage 2, used to cross-compile packages

Note: one last compilation of gcc (stage 3) will be necessary for a final system, but it is treated as a casual package and not discussed here.

Once built, the second gcc can be used to cross-compile packages on the target.

Using the toolchain

A toolchain can be used by updating PATH:

PATH="$(pwd)/sysroot/tools/bin:$PATH"

The above command assumes we are in the boostrap/ directory.