Architecture

How a Blueberry system is put together, from power-on to login shell.

Boot sequence

firmware ─► GRUB ─► vmlinuz ─► initramfs /init (PID 1)
                                 │
                                 ├─ bbtest cmdline?     ─► run /etc/selftest, print result, halt
                                 ├─ bbinstall cmdline?  ─► unattended blueberry-install, halt
                                 ├─ bbtui cmdline?      ─► interactive TUI installer
                                 ├─ root= cmdline?      ─► resolve UUID, mount disk → switch_root → systemd/runit
                                 └─ otherwise           ─► interactive live login shell

/init (in src/initramfs/) is a small script that:

mounts /proc, /sys, /dev and populates /dev,
inspects the kernel cmdline to choose a path,
either drops to a live shell, runs the self-test, launches the installer, or

mounts a disk install and hands off to PID 1.

Init systems

	Used by
systemd	Default — journald, logind, networkd/resolved, NetworkManager, OpenSSH
runit	Opt-in (`INIT=runit`) — a small supervision tree for RAM-first / minimal builds

The live initramfs is busybox-based either way; only the installed rootfs (STAGEDIR) changes with INIT. The runit stage scripts live in src/init/; the systemd units in src/systemd/. See doc/INIT.md.

The installed server

A disk install boots GRUB → kernel → systemd (PID 1) with bash as the login shell. The base image carries the systemd runtime closure plus a real server userland (procps-ng, psmisc, lsof, GNU tools, networking, ufw, man) so the machine is usable with nothing extra installed. Everything else comes from the mirror via bpm.

The supply chain

packages/<name>/bpm.toml
        │  tools/build-bpm-pkg.sh  (ephemeral Arch container, bpmbuild)
        ▼
   .bpm  ──scp──►  mirror  ──tools/bpmrepo.sh──►  bpm.index (+ .sig)
                                                              │  HTTPS
                                                              ▼
                                                        bpm install (SHA-256 + ed25519 verified)

The Arch container is the build toolchain only; the installed system depends on no external mirror. See Overview and doc/ARCHITECTURE.md.