Boot overview

The Qualcomm^® Linux^® system software boot image is loaded by the device as part of the boot process, which executes predefined instructions stored in read‑only memory (ROM). The Linux kernel initializes the operating system and configures hardware devices after essential subsystems and drivers are loaded. Once initialization is complete, the kernel mounts the file systems, making them available for use to applications and users. The boot image is automatically loaded when the device is powered on, for information about setting up the Qualcomm Linux boot image, see Build Boot in the build firmware section. This guide explains the supported boot features, the architecture of a cold boot (which starts from a power-off state), and the interfaces for the Qualcomm Linux system software. Additionally, this guide provides instructions covering: unified extensible firmware interface (UEFI) application development for EDK II, U-Boot support and configuration, devicetree (DT) configuration interfaces, debug logs, and system boot verification.

• Boot architecture The system runs the boot loader software when powered on, serving as an interface for loading the operating system and other required applications. Qualcomm chipsets, including the ones supported by Qualcomm Linux, use a multistage boot process.
• APSS cold boot flow Describes the cold boot sequence from PBL execution through XBL, Qualcomm TEE, Qualcomm Hypervisor, UEFI, systemd-boot, and Linux kernel launch.

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Next steps

Set up your development environment