speed-up-pi-boot-times.md

1) Measure (so you know what to kill)

systemd-analyze
systemd-analyze blame
systemd-analyze critical-chain

These show kernel vs userspace time and the slowest units. (wiki.archlinux.org)

2) Hardware + firmware quick wins

• Boot from NVMe (Pi 5) and put it first in the boot order:

  sudo -E rpi-eeprom-config --edit
  # e.g. try NVMe first, then SD:
  BOOT_ORDER=0xf416

  (Right-to-left order; f=retry). (jeffgeerling.com)

• Keep only the devices you’ll ever boot from in BOOT_ORDER (don’t include USB/network if unused) to avoid probe timeouts. (Volumio Community)

3) Filesystem: remove boot blockers

• Read-only root (overlayfs) via raspi-config (“Performance → Overlay FS”). This avoids fsck and journaling delays.

  • On Bookworm, raspi-config sets overlayroot=tmpfs; if external drives turn read-only, change to overlayroot=tmpfs:recurse=0 (or tune /etc/overlayroot.conf). (Raspberry Pi Stack Exchange)

• If you can’t go RO, at least add fsck.mode=skip to /boot/firmware/cmdline.txt (or /boot/cmdline.txt pre-Bookworm) to skip filesystem checks on clean boots. (Ask Ubuntu)

• Mount noatime on your RW partitions to cut write work during boot. (General Linux best-practice.)

Bookworm moved the boot partition to /boot/firmware—that’s where config.txt/cmdline.txt live now. (Raspberry Pi)

4) Kill waits and unused hardware

• Headless? Disable radios and audio in /boot/firmware/config.txt:

  dtoverlay=disable-wifi
  dtoverlay=disable-bt
  dtparam=audio=off
  

  (Saves driver init time.) (Raspberry Pi Stack Exchange)

• Don’t block on networking at boot:

  • Mask whatever “wait-online” you have (varies by image):

    sudo systemctl mask systemd-networkd-wait-online.service || true
    sudo systemctl mask NetworkManager-wait-online.service || true

    Or configure wait-online to --any / specific interface only. (wiki.archlinux.org)

  • If you use dhcpcd, run it in background (doesn’t hold boot) or use a static IP. (bbs.archlinux.org)

• Boot to console, not desktop (unless you need a GUI):

  sudo systemctl set-default multi-user.target

  Then only start your app. (You can still launch a compositor later.)

5) Trim userspace to the bone

Disable services you don’t need (examples—pick from your systemd-analyze blame output):

sudo systemctl disable --now bluetooth.service hciuart.service avahi-daemon.service triggerhappy.service

Re-run systemd-analyze blame and repeat until only essentials remain. (Red Hat Documentation)

6) Optional but impactful

• Remove serial console from /boot/firmware/cmdline.txt if you don’t use it (drop console=serial0,115200 so the kernel isn’t spewing to UART).
• Autologin straight to your app (TTY): make getty@tty1 autologin and exec your binary; or even use init=/usr/bin/your-app to make your process PID 1 for ultra-fast boots (advanced; you must mount /proc,/sys,/dev yourself). (docs.kernel.org)
• Custom/minimal OS (Buildroot/BusyBox + only built-in drivers + LZ4 kernel): this is how folks get ~2–3s to app on older Pis; <5s is easy. (bootlin.com)

7) A concrete “<5s” recipe (Pi OS Lite → headless service)

1. NVMe first in BOOT_ORDER and update EEPROM. (jeffgeerling.com)
2. Enable overlay FS (or add fsck.mode=skip). (Raspberry Pi Stack Exchange)
3. systemctl set-default multi-user.target and mask wait-online. (wiki.archlinux.org)
4. Disable Wi-Fi/BT/audio overlays and unneeded services. (Raspberry Pi Stack Exchange)
5. Autostart your app on TTY1; keep network coming up in the background.

That combo typically lands around 1–2s kernel + 2–3s userspace on Pi 5 with NVMe—i.e. ~3–5s to your app. Community reports show even ~4.0–4.5s to a full desktop with aggressive trimming. (forums.raspberrypi.com)

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