1dwz(1) General Commands Manual dwz(1)
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6 dwz - DWARF optimization and duplicate removal tool
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9 dwz [OPTION...] [FILES]
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12 dwz is a program that attempts to optimize DWARF debugging information
13 contained in ELF shared libraries and ELF executables for size, by
14 replacing DWARF information representation with equivalent smaller rep‐
15 resentation where possible and by reducing the amount of duplication
16 using techniques from DWARF standard appendix E - creating DW_TAG_par‐
17 tial_unit compilation units (CUs) for duplicated information and using
18 DW_TAG_imported_unit to import it into each CU that needs it.
19 The tool handles DWARF 32-bit format debugging sections of versions 2,
21 3 and 4 and GNU extensions on top of those, though using DWARF 4 or
22 worst case DWARF 3 is strongly recommended.
23 The tool has two main modes of operation, without the -m option it
25 attempts to optimize DWARF debugging information in each given object
26 (executable or shared library) individually, with the -m option it
27 afterwards attempts to optimize even more by moving DWARF debugging
28 information entries (DIEs), strings and macro descriptions duplicated
29 in more than one object into a newly created ELF ET_REL object whose
30 filename is given as -m option argument. The debug sections in the
31 executables and shared libraries specified on the command line are then
32 modified again, referring to the entities in the newly created object.
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35 -m FILE --multifile FILE
36 Multifile mode. After processing all named executables and
37 shared libraries, attempt to create ELF object FILE and put
38 debugging information duplicated in more than one object there,
39 afterwards optimize each named executable or shared library even
40 further if possible.
41 -h --hardlink
43 Look for executables or shared libraries hardlinked together,
44 instead of rewriting them individually rewrite just one of them
45 and hardlink the rest to the first one again.
46 -M NAME --multifile-name NAME
48 Specify the name of the common file that should be put into the
49 .gnu_debugaltlink section alongside with its build ID. By
50 default dwz puts there the argument of the -m option.
51 -r --relative
53 Specify that the name of the common file to be put into the
54 .gnu_debugaltlink section is supposed to be relative path from
55 the directory containing the executable or shared library to the
56 file named in the argument of the -m option. Either -M or -r
57 option can be specified, but not both.
58 -q --quiet
60 Silence up some of the most common messages.
61 -o FILE --output FILE
63 This option instructs dwz not to overwrite the specified file,
64 but instead store the new content into FILE. Nothing is written
65 if dwz exits with non-zero exit code. Can be used only with a
66 single executable or shared library (if there are no arguments
67 at all, a.out is assumed).
68 -l COUNT --low-mem-die-limit COUNT
70 Handle executables or shared libraries containing more than
71 COUNT debugging information entries in their .debug_info section
72 using a slower and more memory usage friendly mode and don't
73 attempt to optimize that object in multifile mode. The default
74 is 10 million DIEs. There is a risk that for very large amounts
75 of debugging information in a single shared library or exe‐
76 cutable there might not be enough memory (especially when dwz
77 tool is 32-bit binary, it might run out of available virtual
78 address space even sooner).
79 -L COUNT --max-die-limit COUNT
81 Don't attempt to optimize executables or shared libraries con‐
82 taining more than COUNT DIEs at all. The default is 50 million
83 DIEs.
84 -? --help
86 Print short help and exit.
87 -v --version
89 Print version number and short licensing notice and exit.
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92 Command-line arguments should be the executables, shared libraries or
93 their stripped to file separate debug information objects.
94
96 $ dwz -m .dwz/foobar-1.2.debug -rh \
97 bin/foo.debug bin/foo2.debug foo/lib/libbar.so.debug
98 will attempt to optimize debugging information in bin/foo.debug,
99 bin/foo2.debug and lib/libbar.so.debug (by modifying the files in
100 place) and when beneficial also will create .dwz/foobar-1.2.debug file.
101 .gnu_debugaltlink section in the first two files will refer to
102 ../.dwz/foobar-1.2.debug and in the last file to ../../.dwz/foo‐
103 bar-1.2.debug. If e.g. bin/foo.debug and bin/foo2.debug were
104 hardlinked together initially, they will be hardlinked again and for
105 multifile optimizations considered just as a single file rather than
106 two.
107 $ dwz -o foo.dwz foo
108 will not modify foo but instead store the ELF object with optimized
109 debugging information if successful into foo.dwz file it creates.
110 $ dwz *.debug foo/*.debug
111 will attempt to optimize debugging information in *.debug and
112 foo/*.debug files, optimizing each file individually in place.
113 $ dwz
114 is equivalent to dwz a.out command.
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117 http://dwarfstd.org/doc/DWARF4.pdf , gdb(1).
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120 Jakub Jelinek <jakub@redhat.com>.
121 15 June 2012 dwz(1)