dwz(1) General Commands Manual dwz(1)
dwz - DWARF optimization and duplicate removal tool
dwz [OPTION...] [FILES]
dwz is a program that attempts to optimize DWARF debugging information
contained in ELF shared libraries and ELF executables for size, by
replacing DWARF information representation with equivalent smaller rep-
resentation where possible and by reducing the amount of duplication
using techniques from DWARF standard appendix E - creating DW_TAG_par-
tial_unit compilation units (CUs) for duplicated information and using
DW_TAG_imported_unit to import it into each CU that needs it.
The tool handles DWARF 32-bit format debugging sections of versions 2,
3 and 4 and GNU extensions on top of those, though using DWARF 4 or
worst case DWARF 3 is strongly recommended.
The tool has two main modes of operation, without the -m option it
attempts to optimize DWARF debugging information in each given object
(executable or shared library) individually, with the -m option it
afterwards attempts to optimize even more by moving DWARF debugging
information entries (DIEs), strings and macro descriptions duplicated
in more than one object into a newly created ELF ET_REL object whose
filename is given as -m option argument. The debug sections in the
executables and shared libraries specified on the command line are then
modified again, referring to the entities in the newly created object.
-m FILE --multifile FILE
Multifile mode. After processing all named executables and
shared libraries, attempt to create ELF object FILE and put
debugging information duplicated in more than one object there,
afterwards optimize each named executable or shared library even
further if possible.
Look for executables or shared libraries hardlinked together,
instead of rewriting them individually rewrite just one of them
and hardlink the rest to the first one again.
-M NAME --multifile-name NAME
Specify the name of the common file that should be put into the
.gnu_debugaltlink section alongside with its build ID. By
default dwz puts there the argument of the -m option.
Specify that the name of the common file to be put into the
.gnu_debugaltlink section is supposed to be relative path from
the directory containing the executable or shared library to the
file named in the argument of the -m option. Either -M or -r
option can be specified, but not both.
Silence up some of the most common messages.
-o FILE --output FILE
This option instructs dwz not to overwrite the specified file,
but instead store the new content into FILE. Nothing is written
if dwz exits with non-zero exit code. Can be used only with a
single executable or shared library (if there are no arguments
at all, a.out is assumed).
-l COUNT --low-mem-die-limit COUNT
Handle executables or shared libraries containing more than
COUNT debugging information entries in their .debug_info section
using a slower and more memory usage friendly mode and don't
attempt to optimize that object in multifile mode. The default
is 10 million DIEs. There is a risk that for very large amounts
of debugging information in a single shared library or exe-
cutable there might not be enough memory (especially when dwz
tool is 32-bit binary, it might run out of available virtual
address space even sooner).
-L COUNT --max-die-limit COUNT
Don't attempt to optimize executables or shared libraries con-
taining more than COUNT DIEs at all. The default is 50 million
Print short help and exit.
Print version number and short licensing notice and exit.
Command-line arguments should be the executables, shared libraries or
their stripped to file separate debug information objects.
$ dwz -m .dwz/foobar-1.2.debug -rh \
bin/foo.debug bin/foo2.debug foo/lib/libbar.so.debug
will attempt to optimize debugging information in bin/foo.debug,
bin/foo2.debug and lib/libbar.so.debug (by modifying the files in
place) and when beneficial also will create .dwz/foobar-1.2.debug file.
.gnu_debugaltlink section in the first two files will refer to
../.dwz/foobar-1.2.debug and in the last file to ../../.dwz/foo-
bar-1.2.debug. If e.g. bin/foo.debug and bin/foo2.debug were
hardlinked together initially, they will be hardlinked again and for
multifile optimizations considered just as a single file rather than
$ dwz -o foo.dwz foo
will not modify foo but instead store the ELF object with optimized
debugging information if successful into foo.dwz file it creates.
$ dwz *.debug foo/*.debug
will attempt to optimize debugging information in *.debug and
foo/*.debug files, optimizing each file individually in place.
is equivalent to dwz a.out command.
http://dwarfstd.org/doc/DWARF4.pdf , gdb(1).
Jakub Jelinek <email@example.com>.
15 June 2012 dwz(1)