Dwarf Debug Format

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

作者 mohitmishra786bdc58472fa9f無授權條款253 個星標收錄於 2026年10月9日更新於 2026年10月9日儲存庫3 個月前更新

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.

僅含說明Software Development

AI 產生的概覽

指導檢查與管理二進位檔中的 DWARF 偵錯資訊，包括分離 DWARF、debuginfod 與剝除。

功能: 此技能說明 DWARF 偵錯區段，以及如何使用 dwarfdump、readelf 與 llvm-dwarfdump 檢查它們，包括如何閱讀 DIE 標籤與屬性結構。內容涵蓋分離 DWARF（.dwo/.dwp 檔案）、架設與使用 debuginfod 遠端符號伺服器，以及 LTO 與剝除如何影響偵錯資訊。它也說明如何產生獨立偵錯檔並將其連結到已剝除的二進位檔。
適用情境: 適用於檢查 ELF 二進位檔中的 DWARF 區段、處理分離 DWARF 附屬檔案、設定 debuginfod 進行遠端符號解析，或診斷偵錯符號遺失的情況。也適合關於 LTO 或剝除如何改變偵錯資訊的問題。
執行需求: 需要偵錯工具，例如 dwarfdump/libdwarf、readelf、llvm-dwarfdump、dwp、objcopy、strip 與 GDB，以及存取 debuginfod 伺服器所需的網路連線。不附帶指令碼，僅為說明性內容。

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

來源與署名

來源：mohitmishra786/low-level-dev-skills位於skills/debuggers/dwarf-debug-format提交bdc5847

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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

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