Fast Cross-Compile of Linux 2.6 for Armel

Unless you have new, high-powered, ARM system to build with, the fastest and most practical way to build software for armel (early ARM CPU versions) is to
cross-compile on an x86_64 machine (Debian and offshoots call this the amd64 architecture, even for non-AMD CPUs). This article is specifically about buildinga Linux 2.6 kernel. Obtaining a working toolchain that is able to build this old a kernel is probably the hardest part of the exercise. This supersedes

Building Old Software on Armel on Linux x64 (amd64)

The cross-compilation toolchains builtin to most
modern Linux distributions do not support older versions of GCC. For old kernels (and other software) that require GCC4 or lower for building, this poses a challenge. One either needs to build a cross-compilation toolchain or use virtualization. This article describes setting up a virtual ARM environment for doing armel (ARMv5) compilation using docker containers.