The Buildroot user manual
https://nightly.buildroot.org/manual.pdfBuildroot is a tool that simplifies and automates the process of building a complete Linux system for an embedded system, using cross-compilation. In order to achieve this, Buildroot is able to generate a cross-compilation toolchain, a root filesystem, a Linux kernel image and a bootloader for your target.
buildroot – Gateworks
trac.gateworks.com/wiki/buildrootBuildroot. A Linux kernel without a root filesystem (aka rootfs) is useless. There are many sources for root filesystems including complete Linux distributions like Ubuntu (often too big, or limited in arch availability), pre-built root filesystems from vendors (often too limited), root filesystems built manually with Busybox (still often too limited) and more.