wolfBoot/tools/squashelf

squashelf

squashelf is a command-line utility that processes ELF (Executable and Linkable Format) files. It extracts PT_LOAD segments, optionally filters them based on specified Load Memory Address (LMA) ranges, sorts them by LMA, and writes them to a new, reorganized ELF file. The output ELF file contains only the selected PT_LOAD segments and their corresponding data, potentially omitting the Section Header Table (SHT).

Purpose

This tool can be useful for:

• Creating stripped-down ELF files containing only loadable code and data segments.
• Preparing ELF files for specific bootloaders or embedded systems environments that primarily work with PT_LOAD segments.

Usage

squashelf [options] <input.elf> <output.elf>

Options

• -n, --nosht: Omit the Section Header Table (SHT) from the output ELF. By default, a minimal SHT with a single NULL section is created. Omitting the SHT shouldn't have any effect on loaders that only use PT_LOAD segments, but may cause tools like readelf to complain. Leave it in for max compatibility, or remove it for the smallest possible elf file.

• -r <min>-<max>[,<min>-<max>...], --range <min>-<max>[,<min>-<max>...]: Specify one or more LMA ranges. Only PT_LOAD segments fully contained within any of these ranges (inclusive of min, exclusive of max) will be included in the output. Addresses can be provided in decimal or hexadecimal (using 0x prefix). Multiple ranges can be specified by separating them with commas. Example: -r 0x10000-0x20000,0x30000-0x40000 or -r 65536-131072,196608-262144.

• -v, --verbose: Enable verbose output, providing detailed information about the processing steps, segment selection, and file operations.

• -z, --zero-size-segments: Include segments with zero file size in the output. By default, these segments are excluded.

• -h, --help: Display a help message with detailed information about all available options and examples.

Examples

• Extract all PT_LOAD segments from input.elf, sort them by LMA, and write them to output_all.elf with a minimal SHT:

  squashelf input.elf output_all.elf
  

• Extract PT_LOAD segments from input.elf that fall within the LMA range 0x80000000 to 0x8FFFFFFF, omit the SHT, and write the result to output_filtered.elf:

  squashelf --nosht --range 0x80000000-0x8FFFFFFF input.elf output_filtered.elf
  

• Extract segments from multiple memory regions with verbose output:

  squashelf -v --range 0x10000000-0x20000000,0x30000000-0x40000000 input.elf output_multi.elf
  

• Include zero-size segments and show detailed processing information:

  squashelf -v -z --range 0x10000000-0x20000000 input.elf output_with_zeros.elf
  

• Display help message with all options and examples:

  squashelf --help