About
Helper scripts and source files adjusted from The PSCG's various Embedded Linux courses for the workshops given at the Open Source Summit/Embedded Linux Conference 2019 San Diego, FOSS North 2020, and a coulpe of other events,
"Understanding, Building and Researching Minimal (and not so minimal) Linux Systems" by Ron Munitz ron@thepscg.com (PSCG Holdings LTD / The PSCG)
Quick How-To
The tasks are deliberately divided into very simple scripts, so that the student will easily "know what does what" by the script name, without needing any special documentation, and without having to really look at the presentations
Before doing anything (in each terminal) $ . envsetup.sh first
Important notes about building busybox:
- Default architecture is x86_64
- It is possible to build busybox dynamically, and install the relevant libraries. It makes things more complex, so we build it statically.
- Building for other architectures: there is a well known conflict between the packages 'gcc-multilib' and the Ubuntu/Debian repository arm cross-tools. They DO NOT coesist, so you either have 'gcc-multilib' XOR one or all of 'gcc-7-aarch64-linux-gnu' 'gcc-7-arm-linux-gnueabi' 'gcc-aarch64-linux-gnu' 'gcc-arm-linux-gnueabi'
- To build for ARM: setup your variables as if it were before a kernel build. It works the same.
- For 32bit intel - ARCH doesn't matter. To build you must install 'gcc-multilib' (or your build will very fast fail for missing headers) and set LDFLAGS=-m32 CPPFLAGS=-m32 So for example change the corresponding lines on the build to: $ CPPFLAGS=-m32 LDFLAGS=-m32 make -j16 CONFIG_PREFIX=../wip_ramdisk install
Branches to use
As per the time of this commit, the latest work of the ramdisk is at the foss2020 branch. master branch aims for simplicity, and while it requires some changes, I do not have real intention to rebase at the moment. Note that while it is definitely possible to follow and do own your own, the repository is meant to accompany the workshops, and the exact contents vary according to the background, interests, and requests of the attendees.
For the FOSS2020 talks:
- foss2020 has the more complete version
- tiny-config has the minimal I/O config (see notes in the commit messages)
- Very thorough kernel config walkthrough are available at https://github.com/ronubo/mini-linux-kernel-config It is used (explained, and worked with) extensively in the My/The PSCG's Embedded Linux/Kernel/Research courses.
Added bonuses (used in other training of https://www.thepscg.com and other talks I give)
- busybox-init - teaches about the theory and practice of how a real-world busybox rootfs works
- userspace-dependency-hacking-exercise-solution - explains how to make dynamically linked executables work
Enjoy!