Boot‑Time Wizard Targets Faster Embedded Linux Boot Sequences

By Michael Larabel – Free Software, 24 May 2026

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The embedded Linux community has long accepted boot times in the range of several seconds as a given. With devices now expected to power‑on on demand—think IoT gateways, automotive infotainment units, and edge AI boxes—those seconds translate directly into user‑perceived latency and, in battery‑run scenarios, wasted energy.

What Boot‑Time Wizard Does

Tim Bird of Sony presented a Boot‑Time Wizard prototype at the Embedded Linux Conference in Minneapolis. The tool automates the classic “change‑one‑thing‑and‑measure” workflow that kernel developers have used for years, but it adds a thin UI layer and a set of scripts that:

1. Snapshot the current boot timeline using systemd-analyze and bootchart.
2. Apply a single configuration tweak (e.g., disabling a service, adjusting initramfs contents, or recompiling a driver with CONFIG_DEBUG_KERNEL=n).
3. Re‑boot and record the new timeline.
4. Display a diff view highlighting the delta in seconds, CPU cycles, and power draw.

The wizard does not decide which changes to make; a developer reviews each diff and decides whether the trade‑off is acceptable. This human‑in‑the‑loop approach keeps the process safe for production‑grade firmware where an aggressive automatic prune could break hardware support.

Early Benchmarks

The GitHub repo (https://github.com/sony/boot-time-wizard) includes a sample configuration for a Raspberry Pi 5 running Yocto 4.2. The following table shows results after three iterative passes on a minimal image:

Iteration	Total Boot Time (s)	Kernel Init Time (s)	Userspace Init (s)	Avg Power During Boot (W)
Baseline	4.12	1.84	2.28	2.9
Pass 1 – disabled bluetooth.service	3.71	1.84	1.87	2.6
Pass 2 – trimmed initramfs (removed unused firmware)	3.28	1.52	1.76	2.4
Pass 3 – compiled kernel with CONFIG_DEBUG_KERNEL=n and CONFIG_DEBUG_INFO=n	2.96	1.31	1.65	2.2

Key take‑aways

• Removing a rarely‑used Bluetooth stack shaved 0.41 s off the userspace phase.
• A leaner initramfs cut 0.32 s from kernel init, while also lowering the average boot‑phase power draw by ~0.2 W.
• Stripping debug symbols from the kernel gave the biggest single win, shaving 0.35 s and reducing power by another 0.2 W.

These numbers are modest in absolute terms, but on a battery‑powered edge node that boots every few minutes, the cumulative energy savings become significant.

Compatibility Checklist

Boot‑Time Wizard works on any system that uses systemd and supports the systemd-analyze API. The following checklist helps ensure a smooth run:

• Kernel version ≥ 6.6 (required for systemd-analyze plot with perf data).
• systemd ≥ 255 (provides the --quiet flag used by the wizard scripts).
• Python 3.11+ for the UI wrapper (the repo includes a requirements.txt).
• Access to the bootloader configuration (e.g., U‑Boot or systemd‑boot) because the wizard may need to adjust kernel command‑line parameters.

If your target runs OpenRC or a custom init system, you can still use the measurement scripts, but you’ll need to replace the systemd-analyze calls with equivalent timing hooks.

Building a Low‑Power Edge Box with Boot‑Time Wizard

Below is a sample bill of materials for a compact AI inference node that benefits from the wizard’s tuning cycle:

Component	Reason for Choice
NXP i.MX 8M Mini (quad‑core Cortex‑A53, 2 GHz)	Low idle power, good GPU for TensorFlow‑Lite
2 GB LPDDR4	Sufficient for Yocto minimal, keeps power low
128 GB eMMC	Faster than SD, deterministic boot latency
Micro‑USB Power Delivery 5 V/3 A	Guarantees stable supply during high‑draw init
Heatsink + fan (optional)	Keeps CPU temps < 65 °C when running inference after boot

Build steps

1. Generate a minimal Yocto image with MACHINE = "imx8mm-var-som" and enable systemd.
2. Flash the image to eMMC and boot once to verify basic operation.
3. Clone the wizard repo and run ./wizard.sh --profile baseline to capture the initial timeline.
4. Iteratively apply the three passes shown in the benchmark table, adjusting the Yocto IMAGE_INSTALL and kernel defconfig as needed.
5. After each pass, run systemd-analyze blame to confirm the biggest contributors have shrunk.
6. When satisfied, bake the final configuration into the Yocto local.conf and produce a release image.

The result is a sub‑3‑second boot that draws ~2.2 W on average during the first 5 seconds—ideal for a device that must wake, process a frame, and return to sleep within a tight duty cycle.

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Where to Learn More

• The ELC 2026 slide deck (https://elc2026.org/slides/boot-time-wizard.pdf) provides a deeper dive into the methodology.
• The GitHub project page (https://github.com/sony/boot-time-wizard) hosts the scripts, sample configs, and an issue tracker for community contributions.
• For a quick visual overview, see the boot‑time wizard preview .

Boot‑Time Wizard is still in an alpha stage, but the early data shows that disciplined, iterative tuning can shave meaningful seconds and watts from embedded Linux boots. As more vendors adopt the workflow, we may see a shift toward truly instant‑on edge devices.