Dwarf Debug Format

mohitmishra786/low-level-dev-skills/skills/debuggers/dwarf-debug-format

by mohitmishra786bdc58472fa9fNo license253 starsListed Oct 9, 2026Updated Oct 9, 2026Repository updated 3 months ago

DWARF debug format skill for understanding debug information. Use when inspecting DWARF sections with dwarfdump, working with split DWARF (.dwo files), setting up debuginfod for remote symbol resolution, or understanding how DWARF interacts with LTO and symbol stripping. Activates on queries about DWARF, .debug_info, .debug_line, dwarfdump, split DWARF, .dwo files, debuginfod, or debug info stripping.

Instructions onlySoftware Development

AI-generated overview

Guides inspection and management of DWARF debug information in binaries, including split DWARF, debuginfod and stripping.

What it does: This skill explains DWARF debug sections and how to inspect them with dwarfdump, readelf and llvm-dwarfdump, including how to read DIE tag and attribute structure. It covers split DWARF (.dwo/.dwp files), setting up and using debuginfod remote symbol servers, and how LTO and stripping affect debug information. It also describes producing separate debug files and linking them to stripped binaries.
When to use it: Use it when inspecting DWARF sections in an ELF binary, working with split DWARF sidecar files, configuring debuginfod for remote symbol resolution, or diagnosing missing debug symbols. It also fits questions about how LTO or stripping changes debug information.
Requirements: Requires debug tooling such as dwarfdump/libdwarf, readelf, llvm-dwarfdump, dwp, objcopy, strip and GDB, plus network access for debuginfod servers. Ships no scripts; instructions only.

DWARF Debug Format

Purpose

Guide agents through understanding and working with DWARF debug information: the key DWARF sections, using dwarfdump and readelf for inspection, split DWARF (.dwo files), debuginfod for remote symbol servers, and how LTO and stripping affect debug info.

Triggers

"What are the DWARF sections in an ELF binary?"
"How do I inspect DWARF debug info in a binary?"
"How does split DWARF work?"
"How do I set up debuginfod for automatic debug symbols?"
"Why does GDB say 'no debugging symbols found'?"
"How does LTO affect DWARF debug information?"

Workflow

1. DWARF sections overview

bash

# Show all sections in a binary (including DWARF)readelf -S prog | grep "\.debug"
# Common DWARF sections:# .debug_info      — types, variables, functions (DIEs — Debug Info Entries)# .debug_abbrev    — abbreviation table for .debug_info encoding# .debug_line      — line number table (source line → address mapping)# .debug_str       — string table for identifiers# .debug_loc       — location expressions (where variables live)# .debug_ranges    — non-contiguous address ranges for CUs# .debug_aranges   — fast lookup: address → compilation unit# .debug_pubnames  — global variable and function names# .debug_frame     — call frame information (for unwinding)# .debug_types     — type unit entries (DWARF 4+)# .debug_rnglists  — range lists (DWARF 5)# .debug_loclists  — location lists (DWARF 5)# .debug_addr      — address table (DWARF 5)# .debug_line_str  — line number string table (DWARF 5)

# Show all sections in a binary (including DWARF)readelf -S prog | grep "\.debug"
# Common DWARF sections:# .debug_info      — types, variables, functions (DIEs — Debug Info Entries)# .debug_abbrev    — abbreviation table for .debug_info encoding# .debug_line      — line number table (source line → address mapping)# .debug_str       — string table for identifiers# .debug_loc       — location expressions (where variables live)# .debug_ranges    — non-contiguous address ranges for CUs# .debug_aranges   — fast lookup: address → compilation unit# .debug_pubnames  — global variable and function names# .debug_frame     — call frame information (for unwinding)# .debug_types     — type unit entries (DWARF 4+)# .debug_rnglists  — range lists (DWARF 5)# .debug_loclists  — location lists (DWARF 5)# .debug_addr      — address table (DWARF 5)# .debug_line_str  — line number string table (DWARF 5)

2. Inspecting DWARF with dwarfdump

bash

# Install dwarfdumpapt-get install dwarfdump    # Ubuntu (part of libdwarf)brew install libdwarf        # macOS
# Dump all DWARF infodwarfdump prog
# Dump specific sectionsdwarfdump --debug-info prog        # types, variables, functionsdwarfdump --debug-line prog        # line number tabledwarfdump --debug-loc prog         # variable locationsdwarfdump --debug-frame prog       # call frame info
# readelf alternatives (less verbose)readelf --debug-dump=info prog | head -100readelf --debug-dump=lines prog | head -50
# llvm-dwarfdump (more readable output)llvm-dwarfdump progllvm-dwarfdump --debug-info prog | grep "DW_AT_name"llvm-dwarfdump --statistics prog   # summarize DWARF sizes

# Install dwarfdumpapt-get install dwarfdump    # Ubuntu (part of libdwarf)brew install libdwarf        # macOS
# Dump all DWARF infodwarfdump prog
# Dump specific sectionsdwarfdump --debug-info prog        # types, variables, functionsdwarfdump --debug-line prog        # line number tabledwarfdump --debug-loc prog         # variable locationsdwarfdump --debug-frame prog       # call frame info
# readelf alternatives (less verbose)readelf --debug-dump=info prog | head -100readelf --debug-dump=lines prog | head -50
# llvm-dwarfdump (more readable output)llvm-dwarfdump progllvm-dwarfdump --debug-info prog | grep "DW_AT_name"llvm-dwarfdump --statistics prog   # summarize DWARF sizes

3. Reading DWARF DIE structure

text

# Sample dwarfdump output for a variableDW_TAG_compile_unit  DW_AT_producer  : "GNU C17 13.2.0"  DW_AT_language  : DW_LANG_C11  DW_AT_name      : "main.c"  DW_AT_comp_dir  : "/home/user/project"
  DW_TAG_subprogram    DW_AT_name    : "add"    DW_AT_type    : <0x42>  → points to int type DIE    DW_AT_low_pc  : 0x401130  ← function start address    DW_AT_high_pc : 0x401150  ← function end address
    DW_TAG_formal_parameter      DW_AT_name  : "a"      DW_AT_type  : <0x42>      DW_AT_location : DW_OP_reg5 (rdi)   ← lives in register rdi
    DW_TAG_formal_parameter      DW_AT_name  : "b"      DW_AT_location : DW_OP_reg4 (rsi)   ← lives in register rsi

# Sample dwarfdump output for a variableDW_TAG_compile_unit  DW_AT_producer  : "GNU C17 13.2.0"  DW_AT_language  : DW_LANG_C11  DW_AT_name      : "main.c"  DW_AT_comp_dir  : "/home/user/project"
  DW_TAG_subprogram    DW_AT_name    : "add"    DW_AT_type    : <0x42>  → points to int type DIE    DW_AT_low_pc  : 0x401130  ← function start address    DW_AT_high_pc : 0x401150  ← function end address
    DW_TAG_formal_parameter      DW_AT_name  : "a"      DW_AT_type  : <0x42>      DW_AT_location : DW_OP_reg5 (rdi)   ← lives in register rdi
    DW_TAG_formal_parameter      DW_AT_name  : "b"      DW_AT_location : DW_OP_reg4 (rsi)   ← lives in register rsi

Tags (DW_TAG_*): compile_unit, subprogram, variable, formal_parameter, typedef, structure_type, member, array_type, pointer_type, base_type

Attributes (DW_AT_*): name, type, location, low_pc, high_pc, byte_size, encoding, file, line

4. Split DWARF (.dwo files)

Split DWARF separates debug info from the linked binary into .dwo sidecar files, reducing linker input size:

bash

# Compile with split DWARFgcc -g -gsplit-dwarf -O2 -c main.c -o main.o# Creates: main.o (object without full DWARF) + main.dwo (debug info)
# Link (linker only processes small .o files, not large DWARF)gcc main.o -o prog# prog references main.dwo but doesn't embed it
# GDB finds .dwo files via DW_AT_GNU_dwo_name attribute in proggdb prog    # works if main.dwo is in the same directory
# Inspect the split referencereadelf -S prog | grep "\.gnu_debuglink\|dwo"dwarfdump prog | grep "dwo_name"    # shows path to .dwo files
# Package .dwo files into a single .dwp for distributiondwp -o prog.dwp prog        # GNU dwp toolllvm-dwp -o prog.dwp prog   # LLVM version# With .dwp next to prog, GDB finds all debug info

# Compile with split DWARFgcc -g -gsplit-dwarf -O2 -c main.c -o main.o# Creates: main.o (object without full DWARF) + main.dwo (debug info)
# Link (linker only processes small .o files, not large DWARF)gcc main.o -o prog# prog references main.dwo but doesn't embed it
# GDB finds .dwo files via DW_AT_GNU_dwo_name attribute in proggdb prog    # works if main.dwo is in the same directory
# Inspect the split referencereadelf -S prog | grep "\.gnu_debuglink\|dwo"dwarfdump prog | grep "dwo_name"    # shows path to .dwo files
# Package .dwo files into a single .dwp for distributiondwp -o prog.dwp prog        # GNU dwp toolllvm-dwp -o prog.dwp prog   # LLVM version# With .dwp next to prog, GDB finds all debug info

5. debuginfod — remote debug symbol server

debuginfod serves debug symbols, source code, and executables via HTTP:

bash

# Client: configure to use a debuginfod serverexport DEBUGINFOD_URLS="https://debuginfod.elfutils.org/"
# GDB uses it automatically when symbols are missinggdb /usr/bin/git# GDB will fetch debug symbols from debuginfod if not locally installed
# Explicit fetchdebuginfod-find debuginfo /usr/bin/git     # fetch debug infodebuginfod-find source /usr/bin/git        # fetch source
# Distribution servers# Fedora:  https://debuginfod.fedoraproject.org/# Ubuntu:  https://debuginfod.ubuntu.com/# Debian:  https://debuginfod.debian.net/# elfutils: https://debuginfod.elfutils.org/
# Configure in GDB(gdb) set debuginfod enabled on(gdb) set debuginfod verbose 1
# Set up your own debuginfod serverdebuginfod -d /var/cache/debuginfod -p 8002 /path/to/binaries/export DEBUGINFOD_URLS="http://localhost:8002"

# Client: configure to use a debuginfod serverexport DEBUGINFOD_URLS="https://debuginfod.elfutils.org/"
# GDB uses it automatically when symbols are missinggdb /usr/bin/git# GDB will fetch debug symbols from debuginfod if not locally installed
# Explicit fetchdebuginfod-find debuginfo /usr/bin/git     # fetch debug infodebuginfod-find source /usr/bin/git        # fetch source
# Distribution servers# Fedora:  https://debuginfod.fedoraproject.org/# Ubuntu:  https://debuginfod.ubuntu.com/# Debian:  https://debuginfod.debian.net/# elfutils: https://debuginfod.elfutils.org/
# Configure in GDB(gdb) set debuginfod enabled on(gdb) set debuginfod verbose 1
# Set up your own debuginfod serverdebuginfod -d /var/cache/debuginfod -p 8002 /path/to/binaries/export DEBUGINFOD_URLS="http://localhost:8002"

6. LTO and DWARF

LTO affects DWARF debug information significantly:

bash

# Full LTO: DWARF is generated after link-time optimization# Variables and functions may be merged, inlined, or eliminatedgcc -flto -O2 -g main.c util.c -o prog# DWARF in prog reflects post-LTO state (may lose some info)
# Thin LTO (better for debug info preservation)clang -flto=thin -O2 -g main.c util.c -o prog
# For best debug info with LTO: use -Og or separate debug buildgcc -Og -g main.c util.c -o prog_debug     # no LTO, full debuggcc -O2 -flto main.c util.c -o prog_fast   # LTO, limited debug
# Rust: LTO discard debug info by default in non-release profiles[profile.dev]lto = "off"    # preserves debug info

# Full LTO: DWARF is generated after link-time optimization# Variables and functions may be merged, inlined, or eliminatedgcc -flto -O2 -g main.c util.c -o prog# DWARF in prog reflects post-LTO state (may lose some info)
# Thin LTO (better for debug info preservation)clang -flto=thin -O2 -g main.c util.c -o prog
# For best debug info with LTO: use -Og or separate debug buildgcc -Og -g main.c util.c -o prog_debug     # no LTO, full debuggcc -O2 -flto main.c util.c -o prog_fast   # LTO, limited debug
# Rust: LTO discard debug info by default in non-release profiles[profile.dev]lto = "off"    # preserves debug info

7. Stripping and separate debug files

bash

# Strip binary (remove DWARF for distribution)strip --strip-debug prog -o prog.stripped
# Keep separate debug fileobjcopy --only-keep-debug prog prog.debugstrip --strip-debug prog# Link stripped binary to its debug fileobjcopy --add-gnu-debuglink=prog.debug prog
# GDB finds debug file automaticallygdb prog    # loads prog.debug via .gnu_debuglink
# Or use eu-strip (elfutils) — creates both in one stepeu-strip -f prog.debug prog
# Verify debug linkreadelf -n prog | grep "Debug\|debuglink"
# Check DWARF size contributionllvm-dwarfdump --statistics prog | grep "file size"size --format=SysV prog | sort -k2rn | head -15

# Strip binary (remove DWARF for distribution)strip --strip-debug prog -o prog.stripped
# Keep separate debug fileobjcopy --only-keep-debug prog prog.debugstrip --strip-debug prog# Link stripped binary to its debug fileobjcopy --add-gnu-debuglink=prog.debug prog
# GDB finds debug file automaticallygdb prog    # loads prog.debug via .gnu_debuglink
# Or use eu-strip (elfutils) — creates both in one stepeu-strip -f prog.debug prog
# Verify debug linkreadelf -n prog | grep "Debug\|debuglink"
# Check DWARF size contributionllvm-dwarfdump --statistics prog | grep "file size"size --format=SysV prog | sort -k2rn | head -15

Related skills

Use skills/debuggers/debug-optimized-builds for debugging with split-DWARF builds
Use skills/debuggers/core-dumps for using debuginfod with core dump analysis
Use skills/binaries/elf-inspection for general ELF section inspection
Use skills/build-systems/build-acceleration for split-DWARF to speed up linking

Source and attribution

Source:mohitmishra786/low-level-dev-skillsinskills/debuggers/dwarf-debug-formatat commitbdc5847

License: No license

Content belongs to its original authors. SourceWeft indexes it from a public repository.

Report or request removal

Dwarf Debug Format

DWARF Debug Format

Purpose

Triggers

Workflow

1. DWARF sections overview

2. Inspecting DWARF with dwarfdump

3. Reading DWARF DIE structure

4. Split DWARF (.dwo files)

5. debuginfod — remote debug symbol server

6. LTO and DWARF

7. Stripping and separate debug files

Related skills

Source and attribution

More from mohitmishra786/low-level-dev-skills

Zig Debugging

Simd Intrinsics

Zig Cross

Rustc Basics

Zig Cinterop

Zig Build System

More in Software Development

Playground

M5 Onboard

Cardputer Buddy

Web Design Guidelines

Vercel React Native Skills

Vercel React Best Practices