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4.4. System Component Development

• 4.4.1. Auto-start Configuration
  • 4.4.1.1. Overview and Introduction
  • 4.4.1.2. Detailed Functionality
    • System Boot Process
      • From Kernel to init
    • Analysis of the init Process
    • /etc/init.d/rcS
  • 4.4.1.3. Porting and Development
    • Example: Creating an Initialization Script
      • Step 1: Create the Script File
      • Step 2: Edit the Script
      • Step 3: Set Permissions
  • 4.4.1.4. Common Issues
• 4.4.2. Integrating User Software into System Image
  • 4.4.2.1. Adding Files to the system Partition of the Root File System
  • 4.4.2.2. Creating a Dedicated Partition for Custom Files
    • Notes
    • Implementation Steps
      • 1. Modify the Partition Table
      • 2. Prepare Partition Content
      • 3. Verify and Generate Partition Image
      • 4. Integrate Build Script
      • 5. Automatically Mount the New Partition
      • 6. Package the Partition into the System Image
    • Verification
• 4.4.3. Root Filesystem Adaptation Guide
  • 4.4.3.1. Creating Root Filesystem with Buildroot
    • Buildroot Source Code
    • Prebuilt Root Filesystems
    • Building system
    • Building initramfs
    • Building QT Support Package
  • 4.4.3.2. Use Multistrap to create Ubuntu root file system
    • Precompiled root file system
    • Make system
  • 4.4.3.3. Using APPSDK for Application Development
    • Prerequisites
      • SDK Packager (developers producing the SDK)
      • SDK User (application developers)
    • Packaging the SDK
    • Installing the SDK
      • Mode 1: sudo mode (recommended)
      • Mode 2: no-sudo mode
    • Upgrade and Uninstall
      • Upgrade
      • Uninstall
      • dpkg -r vs dpkg -P Detailed Comparison
    • Compiling Applications with the SDK
      • Method 1: Compile directly with gcc
      • Method 2: CMake projects
      • Method 3: autotools projects
      • Method 4: Build X5 projects with make (platform_samples / hbre modules)
        • Install behavior of bare make for hbre modules
    • Verifying the SDK
    • SDK Directory Structure
    • version File
    • FAQ
      • source environment-setup reports “must be sourced, not executed”
      • Using sh to source reports “requires bash, not sh”
      • Linking hbre libraries reports “cannot find -lxxx”
      • Old version residue after SDK upgrade
      • SDK does not work after moving to another path
      • environment-setup still present after dpkg -r
      • dpkg asks how to handle environment-setup during reinstall/upgrade (conffile conflict)
      • Need to re-source after upgrading the SDK
    • Notes
• 4.4.4. System Miniaturization and Trimming
  • 4.4.4.1. Overview
  • 4.4.4.2. Introduction to System Trimming
  • 4.4.4.3. System Trimming Methods
    • U-Boot Trimming
    • Linux Kernel Trimming
      • Disable Kernel Features and Drivers
      • Modify Kernel Source Code
      • Other Trimming Directions
    • Root Filesystem Trimming
  • 4.4.4.4. Basic Principles of System Trimming
  • 4.4.4.5. System Trimming Examples
    • Minimal System Configuration
    • Minimal Kernel Configuration
    • Build and Test
      • Build New Image
      • Test the New Image
  • 4.4.4.6. Common Issues
    • Loss or Unavailability of Functionality
    • System Instability or Crashes
    • Dependency Issues
    • Performance Degradation
    • Compatibility Issues
  • 4.4.4.7. References
• 4.4.5. Quickstart Guide
  • 4.4.5.1. Overview
    • Prerequisites
  • 4.4.5.2. Image Preparation and Flashing
  • 4.4.5.3. Boot Time Comparison Before and After Optimization
    • Measurement Tools
  • 4.4.5.4. Integrating User Software into the Quickstart Image
    • Built-in User Software
    • Adding Boot-Time Startup Scripts
  • 4.4.5.5. Quickstart Boot Chain Optimization
    • U-Boot Optimization
      • Overview
      • U-Boot Quickstart Boot Flow Diagram
      • Key Boot Chain Changes
      • Quickstart Parameter Configuration
      • Redundant Feature and Boot Path Trimming
    • Kernel Optimization
      • Overview
      • Compression Algorithm and Compiler Optimization
    • System Optimization
      • Overview
      • Main Changes
      • Lightweight init
      • Parallel boot service startup
      • Driver module load script optimization
      • Root filesystem trimming
    • Display Application Optimization
      • Overview
      • Code Location and Directory Structure
      • Display Application Startup Flow
      • Running the Application
  • 4.4.5.6. FAQ
    • How to load custom kernel modules
    • How to enable OTA (A/B partition) configuration
• 4.4.6. ION System Debugging Guide
  • 4.4.6.1. Overview
    • ION Memory Regions
    • Characteristics of ION Memory
    • ION Region Allocation Rules
      • ION Region Adjustment Method
  • 4.4.6.2. ION Usage Methods
    • ION Region Size Adjustment Method
      • Method to Adjust ION Regions in Linux Device Tree
      • Method to Adjust ION Regions in U-Boot
    • ION Debugging Methods
      • View Statistics of Each ION Region
      • View Statistics of Clients Allocated ION Memory
    • ION Region Name Mapping Table
  • 4.4.6.3. Adjusting ION Region Size Based on Application Scenarios
    • Theoretical Calculation of ION Resource Usage
      • Camera-related Modules
        • HBN Framework
        • Background Service Programs
      • VPU
        • H.264 Encoding
        • H.265 Encoding
      • BPU
    • Validating Theoretical Values
      • Camera Modules
      • BPU Module
      • Other Modules
    • Modify and Apply ION Region Configuration
• 4.4.7. Log System Introduction
  • 4.4.7.1. Introduction to Linux Log System
    • Log Buffer
    • Log Writing Interfaces
      • printk Function
      • Common Logging Interfaces in Drivers
      • Interfaces for Use Without a Device Structure
      • Application-Level Log Interfaces
    • Log Extraction
      • Console
      • /dev/kmsg
      • syslogd
  • 4.4.7.2. Log Directory Structure
    • Log Partition
    • Log Partition Content Description
  • 4.4.7.3. Log Management
    • Log Processes
      • Log Process Information Explanation
      • Log Process Startup Order Explanation
    • Log Management Methods
      • hobot-log Script Overview
      • Customizing the Log System for Users
    • pstore
      • Pstore Mechanism
      • Configuring pstore
      • pstore Log Archiving
      • pstore usage example
  • 4.4.7.4. log debug
    • log debugging notes
    • How to preserve effective logs during system hang
    • How to effectively obtain logs from the time of issue
  • 4.4.7.5. Recording AB/BAK abnormal switch reasons
    • Introduction
    • hrut_switch_reason tool usage
      • On-device tool
      • PC tool
      • Usage examples
      • Test case construction
        • mmc
        • flash
    • View via cmdline
    • View via system log
• 4.4.8. Information Security Development Guide
  • 4.4.8.1. Introduction to security hardware
    • Overview
      • Introduction
      • Security Algorithms
    • Hardware Security Driver
      • Driver Source Code
      • Enabling Hardware Security
        • Kernel Configuration
        • DTS Configuration
        • Loading the Driver
    • Notes
  • 4.4.8.2. FDE Full disk encryption
    • Overview
      • Introduction
      • FDE Principle
      • Terminology
    • FDE Tools
      • cryptsetup
        • Working Principle
      • dm-crypt
        • Working Principle
    • X5 FDE User Password Management
    • X5 FDE Usage
      • System Partition Encryption
        • Solution Principle
        • Usage Method
          • Change the system partition verification method to crypt
          • Create system FDE image
          • User root key
          • Build and Boot
      • User Partition Encryption: key-hobot Solution
        • Add New Partition
        • Add FDE Configuration in hb-crypttab
        • Create Mount Point Directory in Root Filesystem
        • Build and Boot
      • User Partition Encryption: key-file Solution
        • Solution Principle
        • Usage Method
          • 1. Add Partition and Build Script
          • 2. Encryption/Decryption Key File
          • 3. Add Encryption Partition Build Script
          • 4. Source Files for User Encrypted Partition
          • 5. Build
        • Boot Verification
  • 4.4.8.3. FBE File encryption
    • FBE File Encryption
      • Overview
      • X5-FBE Usage
        • Using External Key
        • Using X5 Derived Key
  • 4.4.8.4. Safe start
    • X5 Secure Boot Overview
    • Uboot & BL2 CFG Verification
      • Process Overview
        • PC-side Signing Process
        • Board-side Verification Process
      • Key Management
        • Generation and Programming of Uboot and BL2 CFG Keys
    • Kernel & Rootfs Verification
      • Overview of AVB and dm-verity
      • AVB and dm-verity Verification Process
      • Key Management
        • Generation and Programming of User Keys
    • Software Version Anti-Rollback
      • Introduction
      • Enabling Anti-Rollback Function
      • Setting and Updating Anti-Rollback Version
      • Limitations
    • Enabling Secure Boot
      • Configuring eFuse
      • Checking if Secure Boot is Enabled
      • Configuring System Image
      • Enabling dm-verity on OEM Partition
        • Add OEM Partition in Partition Table
        • Add Mount Point
        • Configure Auto-mount
        • Packaging OEM Image
        • Notes on oem Partition Upgrade
    • Verifying Secure Boot
  • 4.4.8.5. boot encrypt
    • boot encryption introduction
    • boot encryption usage
      • boot encryption principle
      • Enabling boot encryption
    • boot key storage
      • boot encryption key storage
      • U-Boot retrieving the key
        • Method 1: Retrieve via DTS
          • Usage
        • Method 2: Retrieve via RPMB
          • RPMB Introduction
          • Usage
  • 4.4.8.6. TEE
    • ARM TrustZone
      • System Architecture
      • CPU Privilege Levels
      • Glossary
    • About X5 TEE
      • Implementation Mechanism
      • Firmware Acquisition
      • Version Information
        • BL31
        • OP-TEE
    • TA Development
      • Overview
      • Building TA
      • TA Signing and Encryption
        • TA Signing
          • Generate a New Private Key File
          • Replace Public Key in OP-TEE OS
          • Compile TA
        • TA Encryption
          • Enable TA Encryption
          • Modify Key File
          • Compile TA
          • Notes
      • Building TA Separately
      • Deploying TA
  • 4.4.8.7. eFuse Burning
    • X5 eFuse Introduction
      • Overview
      • X5 eFuse Features
    • BL2 eFuse Programming
      • eFuse Configuration File
      • eFuse Power Control and Programming Status
        • eFuse Programming Status
        • eFuse Power Control
        • Usage Example
    • U-Boot Read/Write eFuse
      • Read eFuse
        • Read Specific eFuse Bank Value
      • Write eFuse
      • Notes
    • Linux Read/Write eFuse
      • API Reference
      • Data Structures
        • efuse_type
        • efuse_info
      • Interface Descriptions
        • drobot_efuse_read
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
        • drobot_efuse_write
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
    • Notes
      • Procedure for Enabling Secure Boot
      • Forcibly Enabling Debug Port
    • X5 Customer Root RSA Key Hash Burning and Usage
      • Introduction
      • Replacement of Customer Root RSA Private Key
      • Burning Customer Root Public Key Hash
        • BL2_CFG Burning
        • hbre libefuse Burning
          • Example of Official Interface Usage
          • Debug Interface Example
        • Dump eFuse Burn Status
      • Image Compilation
      • Notes
  • 4.4.8.8. secure storage
    • X5 Secure Storage Introduction
    • KEY Management
      • File Encryption/Decryption Key Management
        • SSK (Secure Storage Key)
        • TSK (Trusted Application Storage Key)
        • FEK (File Encryption Key)
      • RPMB KEY Management
    • Secure Storage Operation Interfaces
      • Basic Information
      • Return Value Description
      • API Reference
      • Interface Descriptions
        • drobot_st_file_load
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
          • 【Notes】
          • 【Compatibility】
          • 【Example Code】
        • drobot_st_file_store
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
          • 【Notes】
          • 【Compatibility】
          • 【Example Code】
        • drobot_force_rpmb_key_ready
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
          • 【Notes】
          • 【Compatibility】
          • 【Example Code】
        • drobot_is_st_file_exist
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
          • 【Notes】
          • 【Compatibility】
          • 【Example Code】
        • drobot_st_file_delete
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
          • 【Notes】
          • 【Compatibility】
          • 【Example Code】
        • drobot_st_file_rename
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
          • 【Notes】
          • 【Compatibility】
          • 【Example Code】
        • drobot_get_device_unlock
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
          • 【Notes】
          • 【Compatibility】
          • 【Example Code】
        • drobot_set_device_unlock
          • 【Function Declaration】
          • 【Function Description】
          • 【Parameter Description】
          • 【Return Value】
          • 【Notes】
          • 【Compatibility】
          • 【Example Code】
    • Secure Storage Operation Commands
      • Basic Information
      • Usage
• 4.4.9. OTA
  • 4.4.9.1. OTA Functionality and Introduction
    • Overview and Introduction
    • System Partition Table
    • Detailed Functional Description
      • Seamless OTA Update
        • AB Partition Seamless Update
        • BAK Upgrade
        • GOLDEN Upgrade
      • Partition Flashing Methods
        • Full-Image Upgrade
        • Differential Image Upgrade (eMMC only)
      • OTA Security Measures
        • Image Rollback Protection
          • Enable antirollback
          • Version Number Retrieval
        • OTA Version Verification
        • Partition Verification
      • OTA Upgrade Process
    • Introduction to the OTA Packaging Module
      • Packaging Images
        • Usage of Packaging Tool
        • Full Image Packaging Method
        • Differential Image Packaging Method
      • Signing Keys
      • OTA Upgrade Package Introduction
        • Package Structure
        • OTA Configuration File
    • OTA Upgrade End Introduction
      • ota_tool Usage
      • ota_tool Implementation
        • ota_update_all_img Implementation
        • ota_boot_check Implementation
  • 4.4.9.2. OTA API
    • Error Types Returned by Dynamic Library Interfaces
    • Interface List
      • otaInitLib
        • 【Example Code】
      • otaDeinitLib
        • 【Example Code】
      • otaGetLibVersion
        • 【Example Code】
      • otaRequestStart
        • 【Example Code】
      • otaGetResult
        • 【Example Code】
      • otaGetProgress
        • 【Example Code】
      • otaGetUpdatingImageName
        • 【Example Code】
      • otaGetSysVersion
        • 【Example Code】
      • otaGetPartition
        • 【Example Code】
      • otaSetPartition
        • 【Example Code】
      • otaGetOwnerFlag
        • 【Example Code】
      • otaMarkOTASuccessful
        • 【Example Code】
      • otaCheckUpdate
        • 【Example Code】
      • otaClearFlags
        • 【Example Code】
      • otaPartitionSync
        • 【Example Code】
• 4.4.10. USB Flash Drive Update Function
  • 4.4.10.1. Overview and Introduction
    • Introduction
    • Prerequisites
  • 4.4.10.2. Feature Description
    • Update Types
    • Update Directory Layout
    • Update Procedure
      • Step 1: Prepare the update image file
      • Step 2: Insert the USB flash drive
      • Step 3: Power on the device
    • Serial Log Reference
  • 4.4.10.3. Upgrade Steps
    • Pre-upgrade Checks
    • Full-image update
    • Split full-image update
    • Partition Upgrade
    • Manual usbupdate
  • 4.4.10.4. Porting Guide
    • Code Paths
    • Code Integration
    • Update Flowchart:
  • 4.4.10.5. Common Issues
    • How to determine if the device supports automatic USB flash drive update?
    • USB drive inserted but no update occurs
    • Checking the update result
    • Update failure
    • emmc_disk.img exceeds 4 GB per file
• 4.4.11. Low Power Mode Debugging Guide
  • 4.4.11.1. Overview and Introduction
  • 4.4.11.2. Detailed Explanation of Low Power Debugging
  • 4.4.11.3. Dynamic Voltage and Frequency Scaling (DVFS)
    • Frequency and Voltage Adjustment Methods
      • CPU Frequency and Voltage Scaling
      • BPU Frequency Scaling
      • GPU 3D Frequency Scaling
      • DDR Frequency Scaling
      • Dynamic Adjustment Explanation
        • Load-Based Dynamic Adjustment
        • Temperature-Based Dynamic Adjustment
        • Other Dynamic Adjustment Strategies
    • Porting and Development
      • Kernel Configuration
      • Linux Power Management Core Framework
      • DVFS Testing
    • Common DVFS Issues
  • 4.4.11.4. Suspend and Resume
    • Suspend and Resume Methods
      • Suspend Command
      • Resume Commands
    • Porting and Development
      • Kernel Configuration
      • Overview of Linux System Suspend / Resume Process
    • System Suspend and Wake-up Testing
    • Common Suspend/Resume Issues
  • 4.4.11.5. Typical Scenario Power Consumption
• 4.4.12. System Performance Optimization Guide
  • 4.4.12.1. Overview
    • Analysis of Causes of Performance Issues
      • Causes of CPU Performance Issues
      • Causes of Memory Performance Issues
      • Causes of Disk Performance Issues
      • Causes of Network Performance Issues
      • Causes of System Configuration Issues
    • Performance Optimization Goals
    • Performance Optimization Layers
    • Fundamental Principles of Performance Optimization
  • 4.4.12.2. Performance Diagnostic Tools
    • top
      • How top Works
      • Description of /proc/stat and /proc/loadavg Files
      • Difference Between CPU Utilization and Load Average
      • Limitations of top
      • top Command Options
      • Usage of top
      • Introduction to htop
    • mpstat
      • Principle of mpstat
      • mpstat Parameter Description
      • Usage of mpstat
      • mpstat Example
    • pidstat
      • Principle of pidstat
      • pidstat Parameter Description
      • Usage of pidstat
      • pidstat Examples
    • iostat
      • iostat Parameter Description
      • Usage of iostat
      • iostat Example
      • Explanation and Common Misunderstandings of iowait
    • vmstat
      • Principle of vmstat
      • vmstat Parameter Explanation
      • vmstat Usage Instructions
      • vmstat Example
    • free
      • Principle of free
      • free Parameter Explanation
      • free Usage Instructions
      • free Example
    • uptime
      • Principle of uptime
      • uptime Parameter Description
      • uptime Usage Instructions
      • uptime Examples
    • sar
      • sar Principle
      • sar Parameter Description
      • sar Usage Instructions
      • sar Examples
      • Common sar Commands
    • iozone
    • iperf3
    • netstat
      • How netstat works
      • netstat Parameter Descriptions
      • netstat Usage Guide
      • netstat Examples
      • Brief Introduction to ss
    • Summary of Performance Diagnosis Tools
    • Introduction to Other Performance Analysis Tools
  • 4.4.12.3. System Optimization Strategies
    • CPU Optimization
      • Adjusting Process Priority
      • Reducing Context Switching
      • CPU Affinity
      • Real-time Optimization
    • Memory Optimization
      • Swap Management
      • Transparent Huge Pages (THP)
      • OOM Killer Configuration
    • Storage Optimization
      • File System Selection
      • I/O Scheduler Selection
      • Reducing Write Operations
      • Flash Wear Leveling
      • Enabling TRIM Support
    • Network Optimization
      • TCP Parameter Tuning
      • Multi-queue NIC
      • Connection Limit
  • 4.4.12.4. Application Optimization
    • Coding Principles
    • Daemon Thread Optimization
    • Dynamic Library Loading Optimization
      • Reduce Loading of Unused Dynamic Libraries
      • Reorganize Dynamic Library Structure
      • Compile Dynamic Libraries into Static Libraries
      • Use dlopen for Dynamic Library Loading
  • 4.4.12.5. Introduction to the USE Method
    • Core Concepts of the USE Method
    • Workflow of the USE Method
    • Performance Analysis Steps Based on the USE Method
    • USE Method Metrics List
  • 4.4.12.6. Case Study
    • Writing Test Cases
    • Test Analysis
      • High-Load Task Simulation
      • Simulating frequent context switches
      • Simulating excessive interrupt handling
  • 4.4.12.7. References