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dwz(1)											   dwz(1)

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  representa-
       tion  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 recom-
       mended.

       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) individu-
       ally, 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  sec-
	      tion  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  infor-
	      mation  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 debug-
	      ging 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, optimiz-
       ing 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)
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