Extreme Pi Boot Optimization

Original Article ↗ Hacker News Discussion ↗

Project context & reactions

  • Many find the 3.5s Pi boot-to-photo pipeline impressive, especially for applications like trail cameras or custom camera rigs.
  • Several note that commercial trail cams achieve sub‑second response and are better engineered for optics, robustness, and battery life, but lack custom sensing/network features users want.

Is Raspberry Pi the right tool?

  • Strong recurring theme: for “wake, take photo, upload, sleep” tasks, microcontrollers (ESP32, Pico W, etc.) are seen as more appropriate due to far lower power and instant startup.
  • Counterpoint: the Pi HQ camera (IMX477, 12MP) and other high‑end / MIPI cameras are beyond the capabilities of common ESP32‑CAM modules (limited RAM, 2MP sensors, DMA into PSRAM, no MIPI).
  • Some suggest newer/other chips (ESP32‑P4, STM32, RK3399 SBCs) with MIPI CSI and ISPs as better middle ground.

Development effort vs. optimal hardware

  • Multiple commenters stress that Pi wins on development speed: high‑level languages, mature camera/Wi‑Fi stacks, and existing libraries make it easy to prototype and “ship” hobby or low‑volume devices.
  • Re‑implementing the same thing on an MCU (C, RTOS/bare metal, camera/Wi‑Fi drivers) is seen as a large motivation‑killing step unless this is a production product.

Boot-time and system optimization techniques

  • Discussion of using Buildroot, minimal kernels, initramfs with a single statically linked binary, and disabling unnecessary services to cut boot time.
  • Suggestions include using start_cd.elf, custom PID 1 instead of full init, alternative OSes (Plan 9, *BSD, Circle bare‑metal), and avoiding slow networking waits (DHCP/NTP).
  • Some note that firmware/bootloader time can dominate on PCs and SBCs.

Power consumption and “race to idle”

  • Pi hardware is criticized for poor low‑power/sleep support; Zero/Zero 2 lack deep sleep, and typical Pi idle draw (~3W) is contrasted with IoT devices at tens of mW.
  • Coral boards are praised for having proper suspend+RTC wake, but their future availability is questioned.
  • Debate around CPU turbo: higher frequency increases power per unit time, but can reduce total energy if the system can shut down sooner (“race to idle”). Several emphasize that only measurements resolve the trade‑off.
  • Some are surprised that lowering input voltage to the Pi’s regulator reduced energy use.

Openness and firmware

  • Concern that proprietary Pi boot firmware (GPU/bootcode) prevents deeper optimization, though the underlying RTOS is now open‑sourced; licensing and Broadcom control still limit full openness.