This repo contains scripting that lays out the process of building an initramfs, kernel, and root filesystem from (pretty much) scratch.
The resulting triplet of (initramfs,kernel,rootfs) is booted using qemu for testing.
Can probably clone and run make all to build the three,
and then make run to run in qemu.
Tested on archlinux and ubuntu 18.04
- Docker
- sudo
- wget
- git
- qemu
- cpio
base-devel or build-essential
Extra for Ubuntu
- flex
- bison
- libelf-dev
0_build_initramfs.sh contains the implementation of
creating an initramfs from a downloaded statically compiled
Busybox binary.
1_build_rootfs.sh runs the archlinux docker container
in order to create an archlinux base installation/root
file system for the initramfs to switch to during
the early boot process.
2_build_kernel.sh clones Linux from Torvalds' github
page, builds a bzImage with defconfig and places it
in this repo's output folder.
Note, cloning the whole linux repo takes forever.
You can get your own kernel/bzImage and put it in output
to skip this step.
3_run_qemu.sh will boot a qemu/kvm guest in your terminal
window and boot into the build initramfs+kernel+rootfs.
Login to root user.
Basic networking and editing with vim is available.
setup the archlinux rootfs with locale and such
Might be the reason why can't
man systemd or man systemd.network inside the guest.
can't do this in a chroot, so have to do it once booted in qemu
pacman-key --init
pacman-key --populate