The bintools dumpbin tool. A tool for viewing the internals of an a.out
formatted object file.
Like other bintools, using dumpbin is simple and straight forward. Running
the tool without any arguments displays the various command line options.
bintools> dumpbin
usage: dumpbin [options] filename
-t dump text segment
-d dump data segment
-r dump relocations
-s dump symbols
-a dump all
You can view the see details of a particular object file as follows:
bintools> dumpbin main.o
Dump of file: main.o
File Type: OBJECT FILE
File Header
-----------
Magic Number: 0x107
Text Segment size: 0x00BC (188) bytes
Data Segment size: 0x0012 (18) bytes
BSS Segment size: 0x0000 (0) bytes
Symbol Table size: 0x0014 (20) bytes
Main Entry Point: 0x0000
Text reloc count: 0x0019 (25) entries
Data reloc count: 0x0000 (0) entries
The first thing dumpbin does is to check that the file appears to be a valid
a.out file. If not a warning is displayed and dumpbin terminates.
Then dumpbin determines whether the file is an OBJECT file or
an EXECUTABLE file.
Since UNIX object file formats are also valid executables files the only real difference between OBJECT and EXECUTABLE files is the existence of relocation table entries.
Finally, dumpbin reports the details of the various segments, symbol tables
and relocation entries.
For historical reasons the code segment is called
textand the uninitialized data segments is calledbss.
Using the -t and/or -d options will also dump the contents of the text and/or
data segments.
Note that segments, especially in a fully linked executable image, can be quite large!
bintools> dumpbin -t main.o
Dump of file: main.o
File Type: OBJECT FILE
File Header
-----------
Magic Number: 0x107
Text Segment size: 0x00BC (188) bytes
Data Segment size: 0x0012 (18) bytes
BSS Segment size: 0x0000 (0) bytes
Symbol Table size: 0x0014 (20) bytes
Main Entry Point: 0x0000
Text reloc count: 0x0019 (25) entries
Data reloc count: 0x0000 (0) entries
Text segment (hex)
------------------
0000: 0D 00 00 14 0A 0D 00 00 - 16 00 00 18 16 0C 00 1D [................]
0010: 02 16 06 00 1D 02 0D 00 - 00 16 06 00 0D 00 00 16 [................]
0020: 06 00 0D 00 00 0D A0 00 - 0D 3A 00 0D 5A 00 0D 61 [.........:..Z..a]
0030: 00 0D 6B 00 0D 93 00 10 - 37 00 02 17 02 63 02 FF [..k.....7....c..]
0040: 02 10 01 00 01 01 00 00 - 04 17 04 61 04 01 04 10 [...........a....]
0050: 03 FF FF 03 10 00 03 03 - 00 0E 0D 00 00 0D AC 00 [................]
0060: 0E 06 FF 05 10 00 08 01 - 0C FF 0E 13 FF FF 13 10 [................]
0070: 00 14 10 16 00 01 18 19 - FE FF 19 03 00 16 FE FF [................]
0080: 15 FE FF 16 FE FF 15 FE - FF 16 04 00 15 04 00 1A [................]
0090: FE FF 0E 1D 01 1E 01 1D - 03 1D 09 1E 09 1E 03 0E [................]
00A0: 14 03 1D 01 1E 01 04 01 - 11 A2 00 0E 1D 02 1D 04 [................]
00B0: 1E 02 17 0C 17 F4 17 10 - 18 1E 02 0E 00 00 00 00 [................]
Using the -r option will dump the contents of the text and data relocation
tables. Relocation table entries mark the location of references to code and
data that the linker will have to fixup when code/data segments are moved and
when the address of external symbols are resolved.
bintools> dumpbin -r main.o
Dump of file: main.o
File Type: OBJECT FILE
File Header
-----------
Magic Number: 0x107
Text Segment size: 0x00BC (188) bytes
Data Segment size: 0x0012 (18) bytes
BSS Segment size: 0x0000 (0) bytes
Symbol Table size: 0x0014 (20) bytes
Main Entry Point: 0x0000
Text reloc count: 0x0019 (25) entries
Data reloc count: 0x0000 (0) entries
.text segment relocations
-------------------------
0001 size: 2 (bytes) External _rtlInit
0006 size: 2 (bytes) External malloc
0009 size: 2 (bytes) External systick
000D size: 2 (bytes) Segment: .data
0012 size: 2 (bytes) Segment: .data
0017 size: 2 (bytes) External _strcpy
001A size: 2 (bytes) Segment: .data
001D size: 2 (bytes) External _strlen
0020 size: 2 (bytes) Segment: .data
0023 size: 2 (bytes) External _zeromem
0026 size: 2 (bytes) Segment: .text
0029 size: 2 (bytes) Segment: .text
002C size: 2 (bytes) Segment: .text
002F size: 2 (bytes) Segment: .text
0032 size: 2 (bytes) Segment: .text
0035 size: 2 (bytes) Segment: .text
0038 size: 2 (bytes) Segment: .text
0046 size: 2 (bytes) Segment: .data
0057 size: 2 (bytes) Segment: .data
005B size: 2 (bytes) External _strlen
005E size: 2 (bytes) Segment: .text
007B size: 2 (bytes) Segment: .data
008A size: 2 (bytes) Segment: .data
008D size: 2 (bytes) Segment: .data
00A9 size: 2 (bytes) Segment: .text
And finally the -s option will dump the contents of the symbol table. The
symbol table lists all the named memory locations in the code/data segments.
When the linker needs to resolve an external symbol by name it uses the
symbol table to find its address for patching relocation entries.
bintools> dumpbin -s main.o
Dump of file: main.o
File Type: OBJECT FILE
File Header
-----------
Magic Number: 0x107
Text Segment size: 0x00BC (188) bytes
Data Segment size: 0x0012 (18) bytes
BSS Segment size: 0x0000 (0) bytes
Symbol Table size: 0x0014 (20) bytes
Main Entry Point: 0x0000
Text reloc count: 0x0019 (25) entries
Data reloc count: 0x0000 (0) entries
Symbols
-------
_zeromem public external segment offset: 0 (0x0000)
_rtlInit public external segment offset: 0 (0x0000)
malloc public external segment offset: 0 (0x0000)
systick public external segment offset: 0 (0x0000)
_strlen public external segment offset: 0 (0x0000)
_strcpy public external segment offset: 0 (0x0000)
lives .data segment offset: 0 (0x0000)
switch .data segment offset: 2 (0x0002)
timer .data segment offset: 3 (0x0003)
score .data segment offset: 4 (0x0004)
prompt .data segment offset: 6 (0x0006)
target .data segment offset: 12 (0x000C)
_main .text segment offset: 0 (0x0000)
testMath .text segment offset: 58 (0x003A)
testBranches .text segment offset: 90 (0x005A)
testLogic .text segment offset: 97 (0x0061)
testLoadStore .text segment offset: 107 (0x006B)
testStack .text segment offset: 147 (0x0093)
testForLoop .text segment offset: 160 (0x00A0)
_foo .text segment offset: 172 (0x00AC)