dwz(1)							      General Commands Manual							    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 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.

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)