The toolchain is the set of all the tools needed to effectively compile a specific software to a binary version, enabling the user to run it. In our specific domain, the toolchain allows us to create a system image ready to be flashed to our Android device. The interesting part is that the toolchain allows us to create a system image for an architecture that is different from our current one: odds are that we are using an x86 system and we want to create a system image targeting an ARM (Advanced RISC Machine) device. Compiling software targeting an architecture different from the one on our host system is called cross-compilation.
The Internet offers a couple of handy solutions for this task—we can use the standard toolchain, available with the AOSP (Android Open Source Project) or we can use an alternative, very popular toolchain, the Linaro toolchain. Both toolchains will do the job—compile every single C/C++ file for the ARM architecture.
As usual, even the toolchain...
