ELD User Guide

This document describes usage of ELD

• 1. Getting started
  • 1.1. About the linker
  • 1.2. Source
  • 1.3. Summary of the linker features
  • 1.4. What the linker can accept as input
  • 1.5. What the linker outputs
• 2. Supported Linking Modes
  • 2.1. Static Linking
  • 2.2. Dynamic Linking
  • 2.3. Partial Linking
  • 2.4. PIE
  • 2.5. Shared Libraries
• 3. Supported Targets
• 4. Linker Script
  • 4.1. Overview
  • 4.2. Basic script syntax
  • 4.3. Script commands
  • 4.4. Expressions
  • 4.5. Symbol assignments
  • 4.6. NOCROSSREFS
  • 4.7. OVERLAY
  • 4.8. Output Section Description
  • 4.9. Syntax
  • 4.10. Output Section Data
  • 4.11. Sorting input sections
  • 4.12. Controlling Physical addresses
  • 4.13. GNU-compatibility
  • 4.14. PRINT Command
  • 4.15. Version Scripts
• 5. Linker Diagnostics
  • 5.1. Diagnostic Reports
  • 5.2. Linker Map Files
• 6. ELD (debugging guide)
  • 6.1. Big picture
  • 6.2. Entry point and driver selection
  • 6.3. Argument parsing and preprocessing
  • 6.4. Input actions (what gets fed to the linker)
  • 6.5. Link pipeline overview (doLink -> Linker)
  • 6.6. Prepare phase (Linker::prepare)
  • 6.7. Normalize phase (Linker::normalize)
  • 6.8. Resolve + layout + emit (Linker::link)
  • 6.9. Internal inputs and “internal sections”
  • 6.10. Section merging (input sections -> output sections)
  • 6.11. String merging (MergeString fragments)
  • 6.12. Relocations: read -> scan -> apply -> (optional) emit reloc sections
  • 6.13. Dynamic relocations (what creates .rel[a].dyn / .rel[a].plt)
  • 6.14. Garbage collection (--gc-sections)
  • 6.15. Fragment model (Fragment / FragmentRef)
  • 6.16. Map files (layout printers)
  • 6.17. Reproducing failures (tarball + mapping file)
  • 6.18. Crash/signal behavior (what gets written on a crash)
  • 6.19. Where failures typically come from (symptoms -> pipeline stage)
  • 6.20. Practical debugging checklist
  • 6.21. Debugging runtime crashes in ELD-built images
• 7. Shared Library Versioning
  • 7.1. Overview
  • 7.2. Key Concepts
  • 7.3. ABI vs API
  • 7.4. Backward Compatibility
  • 7.5. Best Practices
  • 7.6. Nuances
  • 7.7. SONAME Usage Example
  • 7.8. Semantic Versioning Example
  • 7.9. ABI vs API Example
  • 7.10. Symbolic Link Structure
  • 7.11. Nuances
• 8. GNU ELF Symbol Versioning
  • 8.1. A. Minimal Working Example (C + GNU ld)
  • 8.2. Goal
  • 8.3. Example files
  • 8.4. Build & Run
  • 8.5. Inspecting the Result
• 9. Image Structure and Generation
  • 9.1. Processor-specific flags
• 10. Image layout
  • 10.1. Linker terminology
  • 10.2. Image layout
• 11. Linker Plugins
  • 11.1. Linker Plugins
  • 11.2. Linker Plugin Examples
  • 11.3. Linker Plugin API Usage and Reference
• 12. Linker Optimization Features
• 13. ELF TOOLS
• 14. LTO Support
  • 14.1. Overview
  • 14.2. Background: LLVM LTO
  • 14.3. ELD LTO model
  • 14.4. LTO switch reference
  • 14.5. Examples
  • 14.6. References
• 15. Getting Image Details
  • 15.1. Overview
  • 15.2. Supported Diagnostic Options
• 16. Command-line options
  • 16.1. Common options for all the backends
  • 16.2. Input remapping options
  • 16.3. Using --start-lib / --end-lib
  • 16.4. MEMORY-related options
  • 16.5. PIE options
  • 16.6. ARM and AArch64 specific options
  • 16.7. Hexagon specific options
  • 16.8. RISCV specific options
  • 16.9. -z keyword options
  • 16.10. Linker version directive
  • 16.11. Record command line
• 17. Target Specific Features
  • 17.1. Hexagon
  • 17.2. ARM
  • 17.3. AArch64
  • 17.4. RISCV
• 18. SFrame Support
  • 18.1. Overview
  • 18.2. SFrame vs EhFrame
  • 18.3. Command Line Options
  • 18.4. Usage Examples
  • 18.5. Section Processing
  • 18.6. Supported Architectures
  • 18.7. Integration with Debugging Tools
  • 18.8. Garbage Collection Behavior
  • 18.9. Error Handling
  • 18.10. Performance Considerations
  • 18.11. Best Practices
  • 18.12. Troubleshooting
• 19. Editor Support
  • 19.1. Overview
  • 19.2. Vim Syntax Highlighting
• 20. Linker support and frequently asked questions!!!
  • 20.1. General Linker Questions
  • 20.2. Input File to Linker
  • 20.3. Linker Script General Questions
  • 20.4. Linker Script PHDRS
  • 20.5. MEMORY command: common issues and fixes
  • 20.6. String Merging
  • 20.7. Hexagon
  • 20.8. RISC-V
  • 20.9. Usage
  • 20.10. Linker Plugin Framework
  • 20.11. Symbol Resolution
  • 20.12. Build time issues
  • 20.13. Hexagon
  • 20.14. ARM
  • 20.15. Runtime issues
  • 20.16. Improving your image/build
  • 20.17. LinkerPlugin API

Developer Docs

• 1. AArch64 Relocation Reference
• 2. ARM Relocation Reference
• 3. Adding a New Backend to ELD
• 4. ELD Code Coverage Guide
• 5. Hexagon Relocation Reference
• 6. GNU IFunc support
• 7. RISC-V Relocation Reference
• 8. x86-64 Relocation Reference

User guide

• ELD User Guide (PDF)

Indices and tables

• Index

• Module Index

• Search Page

• Build Dashboard