NAME

       dwz - DWARF optimization and duplicate removal tool

SYNOPSIS

       dwz [OPTION...] [FILES]

DESCRIPTION

       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
       representation  where  possible  and  by  reducing  the amount of duplication using techniques from DWARF
       standard appendix E - creating DW_TAG_partial_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.

OPTIONS

       -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.

       -h --hardlink
              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.

       -r --relative
              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.

       -q --quiet
              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 executable 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 containing more than COUNT DIEs at all.
              The default is 50 million DIEs.

       -? --help
              Print short help and exit.

       -v --version
              Print version number and short licensing notice and exit.

ARGUMENTS

       Command-line arguments should be the executables, shared libraries or their  stripped  to  file  separate
       debug information objects.

EXAMPLES

              $ 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/foobar-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 two.
              $ 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.
              $ dwz
       is equivalent to dwz a.out command.

SEE ALSO

       http://dwarfstd.org/doc/DWARF4.pdf , gdb(1).

AUTHORS

       Jakub Jelinek <jakub@redhat.com>.

                                                  15 June 2012                                            dwz(1)