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Boot Time Presentations

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Status of Linux Boot-time Work [ELC 2026]

Presenter: Tim Bird, Sony Electronics Summary: Tim presents a summary of boot-time work in the past year. This includes patches mailined, or at least submitted for mainline, or in active development, for the kernel and U-boot. Also, the talk summarizes recent presentations at ELC, ELCE and Plumbers, and the major boot topics they covered. Finally, Tim presents his own work on a "boot time wizard", to automatically test different configurations and settings for Linux, to see their effect on boot time.

Bootph: A Swiss Army Knife for Boot Time Optimization [ELC 2026]

Presenters: Gokul Praveen & Beleswar Padhi, Texas Instruments Summary: Presents TI work on 'bootph', which is a system of annotating device tree entries to indicate which bootloader should load those entries. Early stage bootloaders do not need to load the entire device tree, but only the entries needed for that stage's operations. Once annotated, tools are used to create either a trimmed-down device tree, or to statically compile the device tree for a particular U-boot boot phase.

Boot time optimization for embedded devices [LPC 2025]

Presenters: Saravana Kannan, Summary: This talk covered some of the boot time optimizations that we've found to be helpful on Android systems that should apply equally well to embedded systems. Most of these guidelines have been launched in a public product and have been shown to work well.

Reducing Android Boot Times: Evaluating Proactive File Prefetching [LPC 2025]

Presenters: Akilesh Kailash, Summary: Proactive file prefetching has proven effective in reducing system boot times. This presentation details the evaluation of a prefetch solution for Android, inspired by its successful deployment on ChromeOS. We analyze its performance impact through Perfetto traces, confirming notable boot time reductions. The core of the implementation involves a two-phase "Record and Replay" process, and we will discuss the key integration challenges encountered on low memory devices.

Furthermore, we extend this investigation to virtualized environments, presenting I/O trace analysis for integrating the prefetch into a Debian OS running on the Android Virtualization Framework (AVF). We conclude by outlining next steps, focusing on continuous record/replay mechanisms and the utilization of new kernel tracepoints for enhanced observability.

Unified Boot Time Measurement: A Precise, Scalable Framework for Multi-Processor Systems [ELCE 2025]

Presenters: Vishnu Pratap Singh & Soumya Tripathy, Texas Instruments Summary:

This session introduces a unified boot time measurement framework that overcomes these limitations. Inspired by U-Boot’s bootstage mechanism, it leverages hardware timers to generate synchronized timestamps across heterogeneous subsystems. Instead of relying on fragmented logs, the framework writes boot markers to a reserved DDR memory region, enabling a Linux utility to extract and analyze the complete boot timeline via the devmem interface. This approach ensures end-to-end visibility, enabling developers to pinpoint inefficiencies, optimize boot sequences, and improve system responsiveness.

With the increasing complexity of embedded devices—ranging from IoT and industrial automation to automotive and networking—achieving fast and predictable boot times is more important than ever. This talk provides a vendor-agnostic, software-based approach to measuring and optimizing boot performance, benefiting developers working on custom Linux BSPs, embedded RTOS systems, and real-time applications.

The Cost of Security: Measuring and Reducing Boot-Time Impact [ELCE 2025]

Presenters: Michael Olbrich, Pengutronix Summary: As security becomes a top priority in embedded systems, features like Secure Boot are more critical than ever. However, these protections often come at the cost of increased boot time — a trade-off that’s especially painful in performance-sensitive environments.

This talk will look at the steps necessary for Secure Boot and typical security hardening features and examine the impact they have on boot speed, highlighting real-world examples and measurable overheads.

We will explore practical techniques to mitigate these slowdowns, and show how a well designed software architecture can help you achieve both faster and more secure boot processes.

Regression Testing Boot-time Performance in the Linux Kernel [ELC 2025]

Presenters: Tim Bird, Sony
Summary: Tim presents the rationale for creating a standard boot-time regression test. A number of obstacles complicate the creation and maintenance of an industry standardized test. Tim's proposed test utilizes an online collection of reference value data files. The proposed test collects data and compares results with reference values from a matching reference data file. Some results for long-running (and possibly optimizable) initcalls that were detected by the test, are presented. jent_mod_init() was found to have a boot-time regression with newer kernels, and its status was discussed.

Improving Linux Boot Time for Automotive Use Cases [ELC 2025]

Presenters: Brian Masney & Eric Chanudet, Red Hat
Summary: A number of kernel and user-space optimizations are presented. Kernel optimizations included removing unused subsystems and debugging options (trimming the kernel config), disabling logs, optimizing setup_arch for ARM64, deferring page struct setup to after SMP is initialized, and using expedited RCU. Other kernel optimizations involved skipping speed renegotiatin if the firmware had already done it, and removing redundant GPIO reset and polling delays in the ethernet bringup. User-space optimizations included parallelizing init, trimming systemd and SELinux, and minimizing initrafms. Avoiding reinitialized hardware already configured by firmware was important.

Early Ethernet with Linux [ELC 2025]

Presenters: Keerthy Jagadeesh, Texas Instruments
Summary: This talk provides information on how to start ethernet in under 2 seconds using a variety of techniques. The kernel is optimized by reducing size, switching the filesystem and SD hardware, disabling device tree nodes, and other techniques. A tiny rootfs is used. The ethernet PHY is initialized and ethernet autonegotiating is started by an MCU, in parallel with kernel startup. Systemd service initialization was reordered to prioritize dependencies for ethernet functionality.

“Early Boot and Late Attach” of Remote Processors for Time Critical Applications [ELC 2025]

Presenters: Beleswar Prasad Padhi & Vaishnav Mohandas Achath, Texas Instruments
Summary: This talk presents the technique of using other processors (MCUs) on an SoC to start hardware before the Linux kernel comes up on the main processors. It discusses using remoteproc IPC in Linux to communicate with software on the MCUs after the kernel is running. Different vendors use different mechanisms to identify the state of remote processors. Some examples of issues and how they were debugged are presented.

Boot-Time Bird-of-a-Feather (BOF) session [ELC 2025]

Presenters: Tim Bird, Sony
Summary: Tim reviews instrumentation, tools for data collection and analysis, and techniques for reducing boot time. He also discusses Kernel patches that are being worked on, as well as documentation projects on the boot data wiki, and sections of the elinux wiki.

U-Boot’s new standard boot and what’s next [ELC 2025]

Presenters: Simon Glass, Canonical
Summary: This talk describes the current features and challenges for U-boot. It introduces a new mechanism "bootflow", to handle automated booting in a way that is superior to using U-boot environment variables. New features to allow more configuration (including removing the cmdline) can yield a system that boots to Linux in 100 milliseconds.

Accelerating Linux Kernel Boot-Up for Large Multi-Core Systems [LPC 2024]

Presenters: Saurabh Singh Sengar, Srivatsa Bhat, Microsoft
Summary: This talks described optimizations to boot machines with thousands of CPUs. Techniques used are deferring calculations, and parallelizing CPU hotplug to bring up cores asynchronously instead of sequentially.

Productizing the Linux boot time tweaks and tricks – an engineering problem [LPC 2024]

Presenter: Khasim Syed Mohammed, Texas Instruments
Summary: This talk presents some of the challenges to productizing boot time optimizations, including handling combined use cases, accellerated MCU cores and "Linux late attach" (handing pre-initialized hardware off to the kernel), and determining how to package documentation and fixes for optimizations for delivery to customers.

Boot time testing with ftrace [LPC 2024]

Presenter: Laura Nao, Collabora
Summary: This session discusses how to leverage existing tracing tools to monitor key events in the boot sequence and proposes building a kselftest to automate this process. This involves identifying critical functions to trace, configuring ftrace (e.g. through bootconfig), parsing trace data, and comparing it to user-provided reference values to detect significant boot time regressions.

Initiatives in boot time reduction - boot time markers, boot phases and profile-guided optimizations [LPC 2024]

Presenter: Tim Bird, Sony
Summary: This session discusses 1) boot time markers, 2) boot phases, and 3) profile-guided boot-time optimizations. Boot-time markers is a proposed set of well-define measurement points in the Linux boot process, used for testing improvements and regressions in boot time. "Boot phases" refers to dividing the kernel boot process into two distinct phases: a time-critical phase and non-time-critical (or deferred) phase, Profile-guided boot-time optimizations refers to utilizing run-time data from one instantiation of the kernel to drive the optimization of subsequent instantiations.

Accelerating Linux Boot Time: Techniques and Strategies for Optimal Performance [DevConf.US 2024]

Presenters: Eric Curtin, Ed Chong, Brian Masney RedHat
Summary: The presentation provided a variety of strategies and techniques to optimize boot time, from measuring boot performance to specific optimizations within systemd, kernel, and filesystem configurations. The presentation discusses tools such as systemd-analyze, and several specific optimizations including expedited RCU, use of EROFS, and minimizing initramfs.

Deferred Memblocks Init for Boot Time Reduction [ELC 2024]

Presenter: Sudarshan Rajagopalan, Qualcomm
Summary: This talk presents work to reduce boot time by bringing up the system with just a subset of memory (say 1G). Then, after kernel/userspace init, the remaining blocks of RAM are initialized in an asynchronous parallel fashion using the memory hotplug framework in the Linux kernel (utilizing the parallelism of the SMP system). This is done using kthreads within the kernel or by a userspace service. On systems with large RAM, this saves up to 200 ms (20 to 30 ms per GB).

Software Optimization for Early Linux Boot for Time Critical Applications [ELC 2024]

Presenters: Aashvij Shenai, Soumya Tripathy, Texas Instruments
Summary: This talk covers requirements in automotive for quick kernel boot and I/O: audio chime in 200ms, a splash screen in 500ms, a Linux kernel boot in 1s and a display app in 1.5s. Optimizations in the areas of PMIC choice, bootmedia, ROM, bootloaders, OS kernel, filesystem and user-space applications are discussed. Different methods of initializing hardware and handing off control between heterogeneous cores is presented. The stripped down Linux kernel is tuned carefully to avoid removing any configs required for a fast boot. Several kernel drivers have their probe order changed to avoid deferrals. A tiny filesystem is used. The boot time was reduced from over 25 seconds to about 1 second.

Unlocking the Potential of Suspend to RAM Using Linux in a Multi-Core, Multi-Firmware Automotive SoC [ELC 2024]

Presenter: Gregory Clement, Bootlin
Summary: This talk discusses Suspend to RAM (S2R) on a sophisticated SoC featuring diverse CPU cores, and multiple firmware components, including open-source ones like TF-A, U-Boot, and OP-TEE. This implementation handles a case where the SoC is entirely powered off during S2R. TF-A memory in SRAM is stored to DDR, which is put in self-refresh mode. On restore, TF-A and DM firmware images are reloaded.

Resolve and standardize early access to hardware for automotive industry with Linux [LPC 2023]

Presenter: Khasim Syed Mohammed, Texas Instruments
Summary: The presentation covers automotive use cases where audio, graphics, CAN bus, ethernet and camera streams need to come up very quickly (between 100ms and 500ms from cold boot). Current solutions are presented, and there is a proposal to standardize methods for "Linux late attach", where hardware is initialized by firmware and handed off to the Linux kernel.

Improving kexec boot time [LPC 2023]

Presenter: Usama Arif, TikTok
Summary: This session covers work done to reduce kernel boot times in a typical server configuration by up to 80%, including parallelizing smpboot, optimizing TSC synchronization, and the work in progress to streamline the initialization of struct pages when using HugeTLB Vmemmap Optimization (HVO). Additionally, optimizations such as skipping PCI probe for certain devices and skipping purgatory are covered. Other areas which still take significant boot time, such as enabling ACPI interpreter and ACPI table loads are also discussed.

The Resurrection of Ureadahead and Speeding up the Boot Process and Preloading Applications [ELCE 2023]

Presenter: Steven Rostedt, Google
Summary: The history and current status of ureadahead is discussed. Google has been maintaining a version as part of the ChromeOS project. Steve explains what ureadahead used to do as well as what he has done to improve it. ureadhead can be used to parallelize pre-fetching of pages for an executable image. In ChromeOS testing, ureadeahead saved about 1.2 seconds (about 14.5% reduction) of boot time.

Booting Automotive ECUs Really Fast with Modern Security Features [ELCE 2022]

Presenter: Brendan Le Foll, BMW Car IT GmbH
Summary: Brendan will explain what is different about using Linux in the automotive segment specifically around the boot time requirements and other interesting performance indicators which are maybe different to other industries. We will show how we use yocto/poky with a mix of android derived features as well as genivi/covesa components to implement internally 10 automotive control units in infotainment, telematics, instrument cluster and body domains. The talk will center around how to handle the challenging 2 seconds rear view camera KPI in Linux userspace as well as other lifecycle KPIs (shutdown, suspend to ram) using a relatively classic systemd/glibc Linux whilst having modern security features enabled (secure boot, dm-verity, ipsec & selinux). We will especially focus on how we configure multiple different SOC platforms to achieve these goals and what hardware characteristics are most important to achieve fast boot times. The talk will then discuss the specific patches and configuration BMW proposed to systemd specifically to allow an 'early' boot target. We would also like to use the opportunity to understand if other industries have similar issues around boot times and if we could work together to jointly maintain a systemd 'fast' profile.

Boot-Time Optimization for the Real World [ELCE 2020]

Presenter: Michael Olbrich, Pengutronix e.K.
Summary: There have been many talks about boot-time optimization in the past. For the most part, the only goal was a minimum boot-time. It's a good way to show the optimization techniques and gives a nice wow effect. But the end result is rarely usable in real world projects. So instead of looking for new ways to reduce the boot-time just a little bit more, this talk will look at boot-time optimization in a larger context. "The device needs to boot faster" is often stated but the actual requirements behind this are often more complex. We will look at typical requirements and possible solutions beyond general boot-time optimization. And while booting as fast as possible is nice, in most cases there are other more important requirements, which are often related to security or reliability. This talk will look at possible optimizations in this context. What are the consequences of an optimization and what trade-offs are possible? And last but not least, let's talk about the hardware. The choices made while designing a device can have a big impact on the boot-time. Therefore this talk will end with advices for hardware design criteria and component decisions to keep in mind to boot fast.

Timing Boot Time Reduction Techniques [ELCE 2019]

Presenter: Michael Opdenacker, Bootlin
Summary: The talk presented methods to optimize kernel boot time, such as toolchain options, kernel compression options, kernel command line parameters, eliminating unnecessary copying in the bootloader, optimizing storage performance and using U-Boot's Falcon mode. Michael also showed tools to identify parts which can be eliminated (such as finding all the files not accessed during the boot sequence) or optimized. Total techniques reduced boot time (to first camera frame displayed) from 9.45 seconds to 2.4 seconds.

We Need to Talk About Systemd: Boot Time Optimization for the New init daemon [ELCE 2019]

Presenter: Chris Simmonds, 2net
Summary: This talk gives and introduction to systemd, and systemd-analyze, and shows how to eliminate services that are not used for a critical app. Chris compares the speed and complexity of busybox, System V init, and systemd init processes. Initial trimming reduced boot time by 35 seconds.

Introduction to NAND Flash Aware Hibernation-based Boot [ELC 2019]

Presenter: Kyungsik Lee, LG Electronics
Summary: The slides cover existing boot time reduction and
hibernation boot techniques and talks about new proposal
for hibernation boot.

Improving Embedded Systems Boot Time by Hibernation: An Overview on the State of the Art and a Case of Study on i.MX family of Processors [ELC 2019]

Presenter: Nicola La Gloria & Laura Nao, Kynetics LLC
Summary: This Presentation will provide the current state of the
kernel development of Hibernation on ARM architectures
and details tests on the popular i.MX family of processors.

Secure Updates for a Memory Constrained XIP System [ELC 2019]

Presenter: Vitaly Wool, Konsulko
Summary: This session details updates using XIP stands for eXecute In Place
– a technology that allows code to be executed directly from flash
without copying the code to RAM first.

Introduction to Memory Constrained XIP System [ELC 2019]

Presenter: Vitaly Wool, Konsulko
Summary: This presentation provides information about the execution of code directly
from flash without copying the code to ram first.

BoF LinuxBoot: Linux as Firmware [ELC 2018]

Presenter: Chris Koch & Gan Shun, Google
Summary: This presentation covers methods to reduce drivers and firmware in a Linux system for efficient and faster boot.

A Pragmatic Guide to Boot-Time Optimization [ELCE 2017]

Presenter: Chris Simmonds
Summary: This presentation covers From power-on to starting qtdemo app boot was reduced from 11.76 seconds to 2.83 seconds, using a variety of techniques. Tools shown were: grabserial, bootchart, bootgraph. Reduction techniques shown were: running the app as init, removing unused filesystem (BTRFS), adding 'quiet' to command line, removing unused drivers, reducing zImage size, removing u-boot bootdelay, and using u-boot falcon mode.

Improving the Bootup Speed of AOSP [ELC 2017]

Presenter: Bernhard Rosenkranzer, Linaro
Summary: This presentation provides information about the
approaches to improve time from cold start to UI.

How to Boot Linux in One Second [ELC 2015 ELCE 2015]

Presenter: Jan Altenberg, Linutronix, GmbH
Summary: This presentation covers some technical basic, optimizations
in boot-loader, kernel, file-system and application.
ARMv5 based device is taken as a use-case.

Fastboot Tools and Techniques [ELC 2015]

Presenter: John Mehaffey, Mentor Graphics
Summary: This presentation talks fastboot, a mechanism
to boot the Embedded system faster.

Tutorial: Useful systemd Functionalities Without systemd [ELCE 2015]

Presenter: Bartosz Golaszewski, BayLibre
Summary: This presentation talks about ACME, sigrok and faster boot.

Update on Boot Time Reduction Techniques with Figures [ELC 2014]

Presenter: Michael Opdenacker, Free Electrons
Summary: This session covers extensive details about Linux
boot time reduction methodology and resources.

Linux Quickboot [ELC 2014]

Presenter: Tristan Lelong, Adeneo Embedded
Summary: This session covers different mechanisms that exist
to optimize boot time and ways to integrate them to
achieve the best time on a custom board with fully
loaded kernel running.

12 Lessons Learnt in Boot Time Reduction [ELCE 2014]

Presenter: Andrew Murray, Embedded Bits Limited
Summary: This presentation explains different ways to reduce boot time.
Also describes pros and cons of those methods.

Boot Time Optimizations [ELCE 2012]

Presenter: Alexandre Belloni, Adeneo Embedded
Summary: This presentation talks about boot time optimizations,
it's use cases, kernel compression, SMP and file systems.

Snapshot Booting on Embedded Linux [ELC 2011]

Presenter: Kang Dongwook (ETRI)
Summary: This presentation discusses about a fastboot mechanism
called snapshot booting for achieving faster boot times.

Faster Resume For More Energy Savings on MeeGo [ELC 2011]

Presenter: Yoshiya Hirase (Nokia)
Summary: This presentation discusses about hibernation to
handset devices for more energy saving.

Linux without a boot loader [ELC 2010]

Presenter: Greg Ungerer
Summary: This session explores options to boot Linux faster
without the boot loader.

The Right Approach to Minimal Boot Times [ELCE 2010]

Presenter: Andrew Murray
Summary: This presentation gives information about principles
behind boot time reduction, an approach to boot time reduction
with a Case study on " MS7724 'Ecovec'".

This included a < 1 second QT cold Linux boot case study for an SH7724 with some additional information about 'function re-ordering' in user-space

Similar slides with < 1 second case study for OMAP3530EVM can be found here

Barebox: Booting Linux Fast and Fancy [ELCE 2010]

Presenter: Robert Schwebel and Sascha Hauer
Summary: This presentation provides information about
Barebox project, it's history, development resources,
hardware support and also Linux booting sequence.

Lightweight Prelinker for Kernel Modules [ELCE 2010]

Presenter: Carmelo Amoroso and Rosario Contarino
Summary: This presentation gives information about fast boot, kernel
modules and Prelinker. It states pros and cons of Prelinker
and it's strategy.

Quantitative analysis of system initialization in embedded Linux systems [ELC 2009]

Presenter: Andre Puschmann
Summary: This presentation analyzes time taken by different layers
during boot time and initialization.

Update on Boot Time Reduction Techniques [ELCE 2009]

Presenter: Michael Opdenacker
Summary: This presentation discusses various techniques to reduce
boot time such as LZO kernel decompression, jffs2, disabling
console output, disabling auto IP config etc.

How We Got a 3D Application Booting in 5 Seconds Under Linux [ELCE 2009]

Presenter: Grégory Clement
Summary: This presentation talks about the boot process, time measurement
techniques for optimizations.

LKM Fast Loader Based on ELF Hash Table [ELCE 2009]

Presenter: Carmelo Amoroso
Summary: This presentation discusses various strategies to speed-up
kernel boot times with a modular kernel.

Tools and Techniques for Reducing Bootup Time [ELCE 2008]

Presenter: Tim Bird
Summary: This presentation discusses about the tools used such as
grab-serial for system-wide measurement, bootchart, strace
and process trace that can be used for boot time reduction.

Tims Fastboot Tools has online materials in support of this presentation

Reducing Boot Time: Technique for Fast Boot Linux [MV Vision 2008]

Presenter: Christopher Hallinan, Monta Vista Summary: Shows techniques used on a Freescale MPC8349, including U-boot optimization
(removing PCI and IDE support) and turning on NOR checksummming, kernel size
reduction, XPI, Preset LPJ, and deferred filesystem mounting.

It has good descriptions of U-boot config options and options to reduce kernel size Presented at Monta Vista Vision conference in 2008.

A fast booting technology on embedded Linux - mass production perspective [CELF Korean Jamboree 2008]

Presenter: HoJoon Park, Electrons and Telecommunications Research Institute (ETRI)
Summary: Explains several different reduction techniques used for different phases of bootup time.


Parallelizing Linux Boot on CE Devices [ELCE 2007]

Presenter: Vitaly Wool, Embedded Alley Solutions, Inc.
Summary: Describes async driver initialization in the kernel, and async init
script startup (using upstart and initng) for user space.

Bootup Technologies BOF [ELC 2007]

Presenter: Elias Kesh
Summary: These slides discuss about different charters of
Boot Technology Work Group (BTWG).

Parallelizing Linux boot on CE Devices [ELCE 2007]

Presenter: Vitaly Wool
Summary: These slides give information on boot up time, boot time
profiling, sequence driver init, asynchronous driver init.

Linux Suspend-to-Disk Objectives for Consumer Electronic Devices [ELCE 2007]

Presenter: Vitaly Wool
Summary: This presentation discusses about Suspend-to-Disk(STD),
compares with Suspend-to-Ram(STR), pros and cons of STD,
and also use case for CE devices.

Visualizing resource usage during initialization of embedded systems [ELC 2006]

Presenter: Matthew Klahn
Summary: This presentation does a quantitative analysis of resource
utilization during booting and initialization.

Boot-Time Optimization - results of applying currently available solutions [ELC 2006]

Presenter: Prof. Nicholas Mc Guire
Summary: The presentation discusses various optimizations that
can be applied in the kernel for faster boot time.

Boot Up Time Reduction for Digital Still Cameras [OLS 2006]

Presenter: Chanju Park, Youngjun Jang, Kyuhyung Kimg and Kyugju Hyun of Samsung Electronics
Summary: Proof-of-acceptability study for Linux use in digital still cameras,
including Preset LPJ, quiet console, deferred driver loading (using modules),
hardware initialization start in bootloader, deferred memory allocation, etc.

Reducing Startup Time in Embedded Linux Systems [CELF Member Conference 2003]

Presenter: Tim Bird, Sony Electronics
Summary: Describes overview of Linux boot delays, and some existing boot-up
time reduction techniques and strategies, including:
Kernel Execute-in-place (XIP), Probe/ calibration elimination,
Concurrent driver initialization, Parallel RC scripts, Deferred driver loading,
and late FS journal log replay.

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