ECE 424 Embedded Systems

Design

Lecture 11: Embedded Platform Boot Sequence

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Introduction

• What is boot sequence?• Why we care?

• 2 or 3 phases─ BIOS/fireware: from processor reset vector─ OS boot loader: from storage devices─ OS

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Multi-core/threads Boot• Basic terms

─ Thread, core, package and SOC, • Bootstrap processor (BSP), Aps• Wait-for-SIPI state: wait for startup inter processor

interrupt

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Image Storage Technologies

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S1: Power Sequencing

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S2: Reset• Reset vector: the location of these initial

processor instructions─ Inel 16 bytes

• Hardware and software reset

• Operation modes─ Real─ Flat protected mode─ Segmented protected mode

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S3: Early Initialization • CPU and memory controller initialization

─ CPU─ IA Microcode update─ Device Initialization─ Memory Configuration─ Post-memory setup─ Shadowing─ AP Initialization

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S4: Advanced Initialization

• Platform related initialization, peripheral-specific

─ GPIO─ Interrupt/Cache controller─ Timers─ PCIe bus─ Image storage

• …

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S5: Boot Loader• Identifying the image and handoff to the image• See next slides for overall boot flow

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PXE (Networking Booting)

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Announcement• Read chapter 7 for OS overview• Friday, 9/21 Exam 1• HW and Lab due

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