dwarf-debug-format

Name: dwarf-debug-format
Author: mohitmishra786

227installs19forks

How to install dwarf-debug-format?

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

$npx -y skills add mohitmishra786/low-level-dev-skills --skill dwarf-debug-format

Installs into the current project.

Summary

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. Activate

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SKILL.md

1	# DWARF Debug Format
2
3	## Purpose
4
5	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.
6
7	## Triggers
8
9	- "What are the DWARF sections in an ELF binary?"
10	- "How do I inspect DWARF debug info in a binary?"
11	- "How does split DWARF work?"
12	- "How do I set up debuginfod for automatic debug symbols?"
13	- "Why does GDB say 'no debugging symbols found'?"
14	- "How does LTO affect DWARF debug information?"
15
16	## Workflow
17
18	### 1. DWARF sections overview
19
20	```bash
21	# Show all sections in a binary (including DWARF)
22	readelf -S prog \| grep "\.debug"
23
24	# Common DWARF sections:
25	# .debug_info — types, variables, functions (DIEs — Debug Info Entries)
26	# .debug_abbrev — abbreviation table for .debug_info encoding
27	# .debug_line — line number table (source line → address mapping)
28	# .debug_str — string table for identifiers
29	# .debug_loc — location expressions (where variables live)
30	# .debug_ranges — non-contiguous address ranges for CUs
31	# .debug_aranges — fast lookup: address → compilation unit
32	# .debug_pubnames — global variable and function names
33	# .debug_frame — call frame information (for unwinding)
34	# .debug_types — type unit entries (DWARF 4+)
35	# .debug_rnglists — range lists (DWARF 5)
36	# .debug_loclists — location lists (DWARF 5)
37	# .debug_addr — address table (DWARF 5)
38	# .debug_line_str — line number string table (DWARF 5)
39	```
40
41	### 2. Inspecting DWARF with dwarfdump
42
43	```bash
44	# Install dwarfdump
45	apt-get install dwarfdump # Ubuntu (part of libdwarf)
46	brew install libdwarf # macOS
47
48	# Dump all DWARF info
49	dwarfdump prog
50
51	# Dump specific sections
52	dwarfdump --debug-info prog # types, variables, functions
53	dwarfdump --debug-line prog # line number table
54	dwarfdump --debug-loc prog # variable locations
55	dwarfdump --debug-frame prog # call frame info
56
57	# readelf alternatives (less verbose)
58	readelf --debug-dump=info prog \| head -100
59	readelf --debug-dump=lines prog \| head -50
60
61	# llvm-dwarfdump (more readable output)
62	llvm-dwarfdump prog
63	llvm-dwarfdump --debug-info prog \| grep "DW_AT_name"
64	llvm-dwarfdump --statistics prog # summarize DWARF sizes
65	```
66
67	### 3. Reading DWARF DIE structure
68
69	```text
70	# Sample dwarfdump output for a variable
71	DW_TAG_compile_unit
72	DW_AT_producer : "GNU C17 13.2.0"
73	DW_AT_language : DW_LANG_C11
74	DW_AT_name : "main.c"
75	DW_AT_comp_dir : "/home/user/project"
76
77	DW_TAG_subprogram
78	DW_AT_name : "add"
79	DW_AT_type : <0x42> → points to int type DIE
80	DW_AT_low_pc : 0x401130 ← function start address
81	DW_AT_high_pc : 0x401150 ← function end address
82
83	DW_TAG_formal_parameter
84	DW_AT_name : "a"
85	DW_AT_type : <0x42>
86	DW_AT_location : DW_OP_reg5 (rdi) ← lives in register rdi
87
88	DW_TAG_formal_parameter
89	DW_AT_name : "b"
90	DW_AT_location : DW_OP_reg4 (rsi) ← lives in register rsi
91	```
92
93	Tags (DW_TAG_*): `compile_unit`, `subprogram`, `variable`, `formal_parameter`, `typedef`, `structure_type`, `member`, `array_type`, `pointer_type`, `base_type`
94
95	Attributes (DW_AT_*): `name`, `type`, `location`, `low_pc`, `high_pc`, `byte_size`, `encoding`, `file`, `line`
96
97	### 4. Split DWARF (.dwo files)
98
99	Split DWARF separates debug info from the linked binary into `.dwo` sidecar files, reducing linker input size:
100
101	```bash
102	# Compile with split DWARF
103	gcc -g -gsplit-dwarf -O2 -c main.c -o main.o
104	# Creates: main.o (object without full DWARF) + main.dwo (debug info)
105
106	# Link (linker only processes small .o files, not large DWARF)
107	gcc main.o -o prog
108	# prog references main.dwo but doesn't embed it
109
110	# GDB finds .dwo files via DW_AT_GNU_dwo_name attribute in prog
111	gdb prog # works if main.dwo is in the same directory
112
113	# Inspect the split reference
114	readelf -S prog \| grep "\.gnu_debuglink\\|dwo"
115	dwarfdump prog \| grep "dwo_name" # shows path to .dwo files
116
117	# Package .dwo files into a single .dwp for distribution
118	dwp -o prog.dwp prog # GNU dwp tool
119	llvm-dwp -o prog.dwp prog # LLVM version
120	# With .dwp next to prog, GDB finds all debug info
121	```
122
123	### 5. debuginfod — remote debug symbol server
124
125	`debuginfod` serves debug symbols, source code, and executables via HTTP:
126
127	```bash
128	# Client: configure to use a debuginfod server
129	export DEBUGINFOD_URLS="https://debuginfod.elfutils.org/"
130
131	# GDB uses it automatically when symbols are missing
132	gdb /usr/bin/git
133	# GDB will fetch debug sym

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dwarf-debug-format

227installs19forks

View on GitHub

How to install dwarf-debug-format?

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

$npx -y skills add mohitmishra786/low-level-dev-skills --skill dwarf-debug-format

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# DWARF Debug Format
2
3	## Purpose
4
5	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.
6
7	## Triggers
8
9	- "What are the DWARF sections in an ELF binary?"
10	- "How do I inspect DWARF debug info in a binary?"
11	- "How does split DWARF work?"
12	- "How do I set up debuginfod for automatic debug symbols?"
13	- "Why does GDB say 'no debugging symbols found'?"
14	- "How does LTO affect DWARF debug information?"
15
16	## Workflow
17
18	### 1. DWARF sections overview
19
20	```bash
21	# Show all sections in a binary (including DWARF)
22	readelf -S prog \| grep "\.debug"
23
24	# Common DWARF sections:
25	# .debug_info — types, variables, functions (DIEs — Debug Info Entries)
26	# .debug_abbrev — abbreviation table for .debug_info encoding
27	# .debug_line — line number table (source line → address mapping)
28	# .debug_str — string table for identifiers
29	# .debug_loc — location expressions (where variables live)
30	# .debug_ranges — non-contiguous address ranges for CUs
31	# .debug_aranges — fast lookup: address → compilation unit
32	# .debug_pubnames — global variable and function names
33	# .debug_frame — call frame information (for unwinding)
34	# .debug_types — type unit entries (DWARF 4+)
35	# .debug_rnglists — range lists (DWARF 5)
36	# .debug_loclists — location lists (DWARF 5)
37	# .debug_addr — address table (DWARF 5)
38	# .debug_line_str — line number string table (DWARF 5)
39	```
40
41	### 2. Inspecting DWARF with dwarfdump
42
43	```bash
44	# Install dwarfdump
45	apt-get install dwarfdump # Ubuntu (part of libdwarf)
46	brew install libdwarf # macOS
47
48	# Dump all DWARF info
49	dwarfdump prog
50
51	# Dump specific sections
52	dwarfdump --debug-info prog # types, variables, functions
53	dwarfdump --debug-line prog # line number table
54	dwarfdump --debug-loc prog # variable locations
55	dwarfdump --debug-frame prog # call frame info
56
57	# readelf alternatives (less verbose)
58	readelf --debug-dump=info prog \| head -100
59	readelf --debug-dump=lines prog \| head -50
60
61	# llvm-dwarfdump (more readable output)
62	llvm-dwarfdump prog
63	llvm-dwarfdump --debug-info prog \| grep "DW_AT_name"
64	llvm-dwarfdump --statistics prog # summarize DWARF sizes
65	```
66
67	### 3. Reading DWARF DIE structure
68
69	```text
70	# Sample dwarfdump output for a variable
71	DW_TAG_compile_unit
72	DW_AT_producer : "GNU C17 13.2.0"
73	DW_AT_language : DW_LANG_C11
74	DW_AT_name : "main.c"
75	DW_AT_comp_dir : "/home/user/project"
76
77	DW_TAG_subprogram
78	DW_AT_name : "add"
79	DW_AT_type : <0x42> → points to int type DIE
80	DW_AT_low_pc : 0x401130 ← function start address
81	DW_AT_high_pc : 0x401150 ← function end address
82
83	DW_TAG_formal_parameter
84	DW_AT_name : "a"
85	DW_AT_type : <0x42>
86	DW_AT_location : DW_OP_reg5 (rdi) ← lives in register rdi
87
88	DW_TAG_formal_parameter
89	DW_AT_name : "b"
90	DW_AT_location : DW_OP_reg4 (rsi) ← lives in register rsi
91	```
92
93	Tags (DW_TAG_*): `compile_unit`, `subprogram`, `variable`, `formal_parameter`, `typedef`, `structure_type`, `member`, `array_type`, `pointer_type`, `base_type`
94
95	Attributes (DW_AT_*): `name`, `type`, `location`, `low_pc`, `high_pc`, `byte_size`, `encoding`, `file`, `line`
96
97	### 4. Split DWARF (.dwo files)
98
99	Split DWARF separates debug info from the linked binary into `.dwo` sidecar files, reducing linker input size:
100
101	```bash
102	# Compile with split DWARF
103	gcc -g -gsplit-dwarf -O2 -c main.c -o main.o
104	# Creates: main.o (object without full DWARF) + main.dwo (debug info)
105
106	# Link (linker only processes small .o files, not large DWARF)
107	gcc main.o -o prog
108	# prog references main.dwo but doesn't embed it
109
110	# GDB finds .dwo files via DW_AT_GNU_dwo_name attribute in prog
111	gdb prog # works if main.dwo is in the same directory
112
113	# Inspect the split reference
114	readelf -S prog \| grep "\.gnu_debuglink\\|dwo"
115	dwarfdump prog \| grep "dwo_name" # shows path to .dwo files
116
117	# Package .dwo files into a single .dwp for distribution
118	dwp -o prog.dwp prog # GNU dwp tool
119	llvm-dwp -o prog.dwp prog # LLVM version
120	# With .dwp next to prog, GDB finds all debug info
121	```
122
123	### 5. debuginfod — remote debug symbol server
124
125	`debuginfod` serves debug symbols, source code, and executables via HTTP:
126
127	```bash
128	# Client: configure to use a debuginfod server
129	export DEBUGINFOD_URLS="https://debuginfod.elfutils.org/"
130
131	# GDB uses it automatically when symbols are missing
132	gdb /usr/bin/git
133	# GDB will fetch debug sym

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