binutils-gdb/binutils/doc/debug.options.texi

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Add support to readelf and objdump for following links to separate debug information files. Hi Guys, I am applying the rather large patch attached to this email to enhance the readelf and objdump programs so that they now have the ability to follow links to separate debug info files. (As requested by PR 15152). So for example whereas before we had this output: $ readelf -wi main.exe Contents of the .debug_info section: [...] <15> DW_AT_comp_dir : (alt indirect string, offset: 0x30c) [...] With the new option enabled we get: $ readelf -wiK main.exe main.exe: Found separate debug info file: dwz.debug Contents of the .debug_info section (loaded from main.exe): [...] <15> DW_AT_comp_dir : (alt indirect string, offset: 0x30c) /home/nickc/Downloads/dwzm [...] The link following feature also means that we can get two lots of output if the same section exists in both the main file and the separate debug info file: $ readelf -wiK main.exe main.exe: Found separate debug info file: dwz.debug Contents of the .debug_info section (loaded from main.exe): [...] Contents of the .debug_info section (loaded from dwz.debug): [...] The patch also adds the ability to display the contents of debuglink sections: $ readelf -wk main.exe Contents of the .gnu_debugaltlink section: Separate debug info file: dwz.debug Build-ID (0x14 bytes): c4 a8 89 8d 64 cf 70 8a 35 68 21 f2 ed 24 45 3e 18 7a 7a 93 Naturally there are long versions of these options (=follow-links and =links). The documentation has been updated as well, and since both readelf and objdump use the same set of debug display options, I have moved the text into a separate file. There are also a couple of new binutils tests to exercise the new behaviour. There are a couple of missing features in the current patch however, although I do intend to address them in follow up submissions: Firstly the code does not check the build-id inside separate debug info files when it is searching for a file specified by a .gnu_debugaltlink section. It just assumes that if the file is there, then it contains the information being sought. Secondly I have not checked the DWARF-5 version of these link features, so there will probably be code to add there. Thirdly I have only implemented link following for the DW_FORM_GNU_strp_alt format. Other alternate formats (eg DW_FORM_GNU_ref_alt) have yet to be implemented. Lastly, whilst implementing this feature I found it necessary to move some of the global variables used by readelf (eg section_headers) into a structure that can be passed around. I have moved all of the global variables that were necessary to get the patch working, but I need to complete the operation and move the remaining, file-specific variables (eg dynamic_strings). Cheers Nick binutils PR 15152 * dwarf.h (enum dwarf_section_display_enum): Add gnu_debuglink, gnu_debugaltlink and separate_debug_str. (struct dwarf_section): Add filename field. Add prototypes for load_separate_debug_file, close_debug_file and open_debug_file. * dwarf.c (do_debug_links): New. (do_follow_links): New. (separate_debug_file, separate_debug_filename): New. (fetch_alt_indirect_string): New function. Retrieves a string from the debug string table in the separate debug info file. (read_and_display_attr_value): Use it with DW_FORM_GNU_strp_alt. (load_debug_section_with_follow): New function. Like load_debug_section, but if the first attempt fails, then tries again in the separate debug info file. (introduce): New function. (process_debug_info): Use load_debug_section_with_follow and introduce. (load_debug_info): Likewise. (display_debug_lines_raw): Likewise. (display_debug_lines_decoded): Likewise. (display_debug_macinfo): Likewise. (display_debug_macro): Likewise. (display_debug_abbrev): Likewise. (display_debug_loc): Likewise. (display_debug_str): Likewise. (display_debug_aranges): Likewise. (display_debug_addr); Likewise. (display_debug_frames): Likewise. (display_gdb_index): Likewise. (process_cu_tu_index): Likewise. (load_cu_tu_indexes): Likewise. (display_debug_links): New function. Displays the contents of a .gnu_debuglink or .gnu_debugaltlink section. (calc_gnu_debuglink_ctc32):New function. Calculates a CRC32 value. (check_gnu_debuglink): New function. Checks the CRC of a potential separate debug info file. (parse_gnu_debuglink): New function. Reads a CRC value out of a .gnu_debuglink section. (check_gnu_debugaltlink): New function. (parse_gnu_debugaltlink): New function. Reads the build-id value out of a .gnu_debugaltlink section. (load_separate_debug_info): New function. Finds and loads a separate debug info file. (load_separate_debug_file): New function. Attempts to find and follow a link to a separate debug info file. (free_debug_memory): Free the separate debug info file information. (opts_table): Add "follow-links" and "links". (dwarf_select_sections_by_letters): Add "k" and "K". (debug_displays): Reformat. Add .gnu-debuglink and .gnu_debugaltlink. Add an extra entry for .debug_str in a separate debug info file. * doc/binutils.texi: Move description of debug dump features common to both readelf and objdump into... * objdump.c (usage): Add -Wk and -WK. (load_specific_debug_section): Initialise the filename field in the dwarf_section structure. (close_debug_file): New function. (open_debug_file): New function. (dump_dwarf): Load and dump the separate debug info sections. * readelf.c (struct filedata): New structure. Contains various variables that used to be global: (current_file_size, string_table, string_table_length, elf_header) (section_headers, program_headers, dump_sects, num_dump_sects): Move into filedata structure. (cmdline): New global variable. Contains list of sections to dump by number, as specified on the command line. Add filedata parameter to most functions. (load_debug_section): Load the string table if it has not already been retrieved. (close_file): New function. (close_debug_file): New function. (open_file): New function. (open_debug_file): New function. (process_object): Process sections in any separate debug info files. * doc/debug.options.texi: New file. Add description of =links and =follow-links options. * NEWS: Mention the new feature. * elfcomm.c: Have the byte gte functions take a const pointer. * elfcomm.h: Update prototypes. * testsuite/binutils-all/dw5.W: Update expected output. * testsuite/binutils-all/objdump.WL: Update expected output. * testsuite/binutils-all/objdump.exp: Add test of -WK and -Wk. * testsuite/binutils-all/readelf.exp: Add test of -wK and -wk. * testsuite/binutils-all/readelf.k: New file. * testsuite/binutils-all/objdump.Wk: New file. * testsuite/binutils-all/objdump.WK2: New file. * testsuite/binutils-all/linkdebug.s: New file. * testsuite/binutils-all/debuglink.s: New file. gas * testsuite/gas/avr/large-debug-line-table.d: Update expected output. * testsuite/gas/elf/dwarf2-11.d: Likewise. * testsuite/gas/elf/dwarf2-12.d: Likewise. * testsuite/gas/elf/dwarf2-13.d: Likewise. * testsuite/gas/elf/dwarf2-14.d: Likewise. * testsuite/gas/elf/dwarf2-15.d: Likewise. * testsuite/gas/elf/dwarf2-16.d: Likewise. * testsuite/gas/elf/dwarf2-17.d: Likewise. * testsuite/gas/elf/dwarf2-18.d: Likewise. * testsuite/gas/elf/dwarf2-5.d: Likewise. * testsuite/gas/elf/dwarf2-6.d: Likewise. * testsuite/gas/elf/dwarf2-7.d: Likewise. ld * testsuite/ld-avr/gc-section-debugline.d: Update expected output.
2017-11-15 19:34:03 +08:00
@c This file contains the entry for the -w/--debug-dump (readelf) and
@c -W/--dwarf (objdump) option that is common to both readelf and objdump.
Displays the contents of the DWARF debug sections in the file, if any
are present. Compressed debug sections are automatically decompressed
(temporarily) before they are displayed. If one or more of the
optional letters or words follows the switch then only those type(s)
of data will be dumped. The letters and words refer to the following
information:
@c Please Keep This Table Alpha Sorted.
@table @code
@item a
@itemx =abbrev
Displays the contents of the @samp{.debug_abbrev} section.
@item A
@itemx =addr
Displays the contents of the @samp{.debug_addr} section.
@item c
@itemx =cu_index
Displays the contents of the @samp{.debug_cu_index} and/or
@samp{.debug_tu_index} sections.
@item f
@itemx =frames
Display the raw contents of a @samp{.debug_frame} section.
@item F
@item =frame-interp
Display the interpreted contents of a @samp{.debug_frame} section.
@item g
@itemx =gdb_index
Displays the contents of the @samp{.gdb_index} and/or
@samp{.debug_names} sections.
@item i
@itemx =info
Displays the contents of the @samp{.debug_info} section. Note: the
output from this option can also be restricted by the use of the
@option{--dwarf-depth} and @option{--dwarf-start} options.
@item k
@itemx =links
Displays the contents of the @samp{.gnu_debuglink} and/or
@samp{.gnu_debugaltlink} sections. Also displays the link to a
separate dwarf object file (dwo), if one is specified by the
DW_AT_GNU_dwo_name or DW_AT_dwo_name attributes in the
@samp{.debug_info} section.
Add support to readelf and objdump for following links to separate debug information files. Hi Guys, I am applying the rather large patch attached to this email to enhance the readelf and objdump programs so that they now have the ability to follow links to separate debug info files. (As requested by PR 15152). So for example whereas before we had this output: $ readelf -wi main.exe Contents of the .debug_info section: [...] <15> DW_AT_comp_dir : (alt indirect string, offset: 0x30c) [...] With the new option enabled we get: $ readelf -wiK main.exe main.exe: Found separate debug info file: dwz.debug Contents of the .debug_info section (loaded from main.exe): [...] <15> DW_AT_comp_dir : (alt indirect string, offset: 0x30c) /home/nickc/Downloads/dwzm [...] The link following feature also means that we can get two lots of output if the same section exists in both the main file and the separate debug info file: $ readelf -wiK main.exe main.exe: Found separate debug info file: dwz.debug Contents of the .debug_info section (loaded from main.exe): [...] Contents of the .debug_info section (loaded from dwz.debug): [...] The patch also adds the ability to display the contents of debuglink sections: $ readelf -wk main.exe Contents of the .gnu_debugaltlink section: Separate debug info file: dwz.debug Build-ID (0x14 bytes): c4 a8 89 8d 64 cf 70 8a 35 68 21 f2 ed 24 45 3e 18 7a 7a 93 Naturally there are long versions of these options (=follow-links and =links). The documentation has been updated as well, and since both readelf and objdump use the same set of debug display options, I have moved the text into a separate file. There are also a couple of new binutils tests to exercise the new behaviour. There are a couple of missing features in the current patch however, although I do intend to address them in follow up submissions: Firstly the code does not check the build-id inside separate debug info files when it is searching for a file specified by a .gnu_debugaltlink section. It just assumes that if the file is there, then it contains the information being sought. Secondly I have not checked the DWARF-5 version of these link features, so there will probably be code to add there. Thirdly I have only implemented link following for the DW_FORM_GNU_strp_alt format. Other alternate formats (eg DW_FORM_GNU_ref_alt) have yet to be implemented. Lastly, whilst implementing this feature I found it necessary to move some of the global variables used by readelf (eg section_headers) into a structure that can be passed around. I have moved all of the global variables that were necessary to get the patch working, but I need to complete the operation and move the remaining, file-specific variables (eg dynamic_strings). Cheers Nick binutils PR 15152 * dwarf.h (enum dwarf_section_display_enum): Add gnu_debuglink, gnu_debugaltlink and separate_debug_str. (struct dwarf_section): Add filename field. Add prototypes for load_separate_debug_file, close_debug_file and open_debug_file. * dwarf.c (do_debug_links): New. (do_follow_links): New. (separate_debug_file, separate_debug_filename): New. (fetch_alt_indirect_string): New function. Retrieves a string from the debug string table in the separate debug info file. (read_and_display_attr_value): Use it with DW_FORM_GNU_strp_alt. (load_debug_section_with_follow): New function. Like load_debug_section, but if the first attempt fails, then tries again in the separate debug info file. (introduce): New function. (process_debug_info): Use load_debug_section_with_follow and introduce. (load_debug_info): Likewise. (display_debug_lines_raw): Likewise. (display_debug_lines_decoded): Likewise. (display_debug_macinfo): Likewise. (display_debug_macro): Likewise. (display_debug_abbrev): Likewise. (display_debug_loc): Likewise. (display_debug_str): Likewise. (display_debug_aranges): Likewise. (display_debug_addr); Likewise. (display_debug_frames): Likewise. (display_gdb_index): Likewise. (process_cu_tu_index): Likewise. (load_cu_tu_indexes): Likewise. (display_debug_links): New function. Displays the contents of a .gnu_debuglink or .gnu_debugaltlink section. (calc_gnu_debuglink_ctc32):New function. Calculates a CRC32 value. (check_gnu_debuglink): New function. Checks the CRC of a potential separate debug info file. (parse_gnu_debuglink): New function. Reads a CRC value out of a .gnu_debuglink section. (check_gnu_debugaltlink): New function. (parse_gnu_debugaltlink): New function. Reads the build-id value out of a .gnu_debugaltlink section. (load_separate_debug_info): New function. Finds and loads a separate debug info file. (load_separate_debug_file): New function. Attempts to find and follow a link to a separate debug info file. (free_debug_memory): Free the separate debug info file information. (opts_table): Add "follow-links" and "links". (dwarf_select_sections_by_letters): Add "k" and "K". (debug_displays): Reformat. Add .gnu-debuglink and .gnu_debugaltlink. Add an extra entry for .debug_str in a separate debug info file. * doc/binutils.texi: Move description of debug dump features common to both readelf and objdump into... * objdump.c (usage): Add -Wk and -WK. (load_specific_debug_section): Initialise the filename field in the dwarf_section structure. (close_debug_file): New function. (open_debug_file): New function. (dump_dwarf): Load and dump the separate debug info sections. * readelf.c (struct filedata): New structure. Contains various variables that used to be global: (current_file_size, string_table, string_table_length, elf_header) (section_headers, program_headers, dump_sects, num_dump_sects): Move into filedata structure. (cmdline): New global variable. Contains list of sections to dump by number, as specified on the command line. Add filedata parameter to most functions. (load_debug_section): Load the string table if it has not already been retrieved. (close_file): New function. (close_debug_file): New function. (open_file): New function. (open_debug_file): New function. (process_object): Process sections in any separate debug info files. * doc/debug.options.texi: New file. Add description of =links and =follow-links options. * NEWS: Mention the new feature. * elfcomm.c: Have the byte gte functions take a const pointer. * elfcomm.h: Update prototypes. * testsuite/binutils-all/dw5.W: Update expected output. * testsuite/binutils-all/objdump.WL: Update expected output. * testsuite/binutils-all/objdump.exp: Add test of -WK and -Wk. * testsuite/binutils-all/readelf.exp: Add test of -wK and -wk. * testsuite/binutils-all/readelf.k: New file. * testsuite/binutils-all/objdump.Wk: New file. * testsuite/binutils-all/objdump.WK2: New file. * testsuite/binutils-all/linkdebug.s: New file. * testsuite/binutils-all/debuglink.s: New file. gas * testsuite/gas/avr/large-debug-line-table.d: Update expected output. * testsuite/gas/elf/dwarf2-11.d: Likewise. * testsuite/gas/elf/dwarf2-12.d: Likewise. * testsuite/gas/elf/dwarf2-13.d: Likewise. * testsuite/gas/elf/dwarf2-14.d: Likewise. * testsuite/gas/elf/dwarf2-15.d: Likewise. * testsuite/gas/elf/dwarf2-16.d: Likewise. * testsuite/gas/elf/dwarf2-17.d: Likewise. * testsuite/gas/elf/dwarf2-18.d: Likewise. * testsuite/gas/elf/dwarf2-5.d: Likewise. * testsuite/gas/elf/dwarf2-6.d: Likewise. * testsuite/gas/elf/dwarf2-7.d: Likewise. ld * testsuite/ld-avr/gc-section-debugline.d: Update expected output.
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@item K
@itemx =follow-links
Display the contents of any selected debug sections that are found in
a linked, separate debug info file. This can result in multiple
versions of the same debug section being displayed if both the main
file and the separate debug info file contain sections with the same
name.
In addition, when displaying DWARF attributes, if a form is found that
references the separate debug info file, then the referenced contents
will also be displayed.
Add support to readelf and objdump for following links to separate debug information files. Hi Guys, I am applying the rather large patch attached to this email to enhance the readelf and objdump programs so that they now have the ability to follow links to separate debug info files. (As requested by PR 15152). So for example whereas before we had this output: $ readelf -wi main.exe Contents of the .debug_info section: [...] <15> DW_AT_comp_dir : (alt indirect string, offset: 0x30c) [...] With the new option enabled we get: $ readelf -wiK main.exe main.exe: Found separate debug info file: dwz.debug Contents of the .debug_info section (loaded from main.exe): [...] <15> DW_AT_comp_dir : (alt indirect string, offset: 0x30c) /home/nickc/Downloads/dwzm [...] The link following feature also means that we can get two lots of output if the same section exists in both the main file and the separate debug info file: $ readelf -wiK main.exe main.exe: Found separate debug info file: dwz.debug Contents of the .debug_info section (loaded from main.exe): [...] Contents of the .debug_info section (loaded from dwz.debug): [...] The patch also adds the ability to display the contents of debuglink sections: $ readelf -wk main.exe Contents of the .gnu_debugaltlink section: Separate debug info file: dwz.debug Build-ID (0x14 bytes): c4 a8 89 8d 64 cf 70 8a 35 68 21 f2 ed 24 45 3e 18 7a 7a 93 Naturally there are long versions of these options (=follow-links and =links). The documentation has been updated as well, and since both readelf and objdump use the same set of debug display options, I have moved the text into a separate file. There are also a couple of new binutils tests to exercise the new behaviour. There are a couple of missing features in the current patch however, although I do intend to address them in follow up submissions: Firstly the code does not check the build-id inside separate debug info files when it is searching for a file specified by a .gnu_debugaltlink section. It just assumes that if the file is there, then it contains the information being sought. Secondly I have not checked the DWARF-5 version of these link features, so there will probably be code to add there. Thirdly I have only implemented link following for the DW_FORM_GNU_strp_alt format. Other alternate formats (eg DW_FORM_GNU_ref_alt) have yet to be implemented. Lastly, whilst implementing this feature I found it necessary to move some of the global variables used by readelf (eg section_headers) into a structure that can be passed around. I have moved all of the global variables that were necessary to get the patch working, but I need to complete the operation and move the remaining, file-specific variables (eg dynamic_strings). Cheers Nick binutils PR 15152 * dwarf.h (enum dwarf_section_display_enum): Add gnu_debuglink, gnu_debugaltlink and separate_debug_str. (struct dwarf_section): Add filename field. Add prototypes for load_separate_debug_file, close_debug_file and open_debug_file. * dwarf.c (do_debug_links): New. (do_follow_links): New. (separate_debug_file, separate_debug_filename): New. (fetch_alt_indirect_string): New function. Retrieves a string from the debug string table in the separate debug info file. (read_and_display_attr_value): Use it with DW_FORM_GNU_strp_alt. (load_debug_section_with_follow): New function. Like load_debug_section, but if the first attempt fails, then tries again in the separate debug info file. (introduce): New function. (process_debug_info): Use load_debug_section_with_follow and introduce. (load_debug_info): Likewise. (display_debug_lines_raw): Likewise. (display_debug_lines_decoded): Likewise. (display_debug_macinfo): Likewise. (display_debug_macro): Likewise. (display_debug_abbrev): Likewise. (display_debug_loc): Likewise. (display_debug_str): Likewise. (display_debug_aranges): Likewise. (display_debug_addr); Likewise. (display_debug_frames): Likewise. (display_gdb_index): Likewise. (process_cu_tu_index): Likewise. (load_cu_tu_indexes): Likewise. (display_debug_links): New function. Displays the contents of a .gnu_debuglink or .gnu_debugaltlink section. (calc_gnu_debuglink_ctc32):New function. Calculates a CRC32 value. (check_gnu_debuglink): New function. Checks the CRC of a potential separate debug info file. (parse_gnu_debuglink): New function. Reads a CRC value out of a .gnu_debuglink section. (check_gnu_debugaltlink): New function. (parse_gnu_debugaltlink): New function. Reads the build-id value out of a .gnu_debugaltlink section. (load_separate_debug_info): New function. Finds and loads a separate debug info file. (load_separate_debug_file): New function. Attempts to find and follow a link to a separate debug info file. (free_debug_memory): Free the separate debug info file information. (opts_table): Add "follow-links" and "links". (dwarf_select_sections_by_letters): Add "k" and "K". (debug_displays): Reformat. Add .gnu-debuglink and .gnu_debugaltlink. Add an extra entry for .debug_str in a separate debug info file. * doc/binutils.texi: Move description of debug dump features common to both readelf and objdump into... * objdump.c (usage): Add -Wk and -WK. (load_specific_debug_section): Initialise the filename field in the dwarf_section structure. (close_debug_file): New function. (open_debug_file): New function. (dump_dwarf): Load and dump the separate debug info sections. * readelf.c (struct filedata): New structure. Contains various variables that used to be global: (current_file_size, string_table, string_table_length, elf_header) (section_headers, program_headers, dump_sects, num_dump_sects): Move into filedata structure. (cmdline): New global variable. Contains list of sections to dump by number, as specified on the command line. Add filedata parameter to most functions. (load_debug_section): Load the string table if it has not already been retrieved. (close_file): New function. (close_debug_file): New function. (open_file): New function. (open_debug_file): New function. (process_object): Process sections in any separate debug info files. * doc/debug.options.texi: New file. Add description of =links and =follow-links options. * NEWS: Mention the new feature. * elfcomm.c: Have the byte gte functions take a const pointer. * elfcomm.h: Update prototypes. * testsuite/binutils-all/dw5.W: Update expected output. * testsuite/binutils-all/objdump.WL: Update expected output. * testsuite/binutils-all/objdump.exp: Add test of -WK and -Wk. * testsuite/binutils-all/readelf.exp: Add test of -wK and -wk. * testsuite/binutils-all/readelf.k: New file. * testsuite/binutils-all/objdump.Wk: New file. * testsuite/binutils-all/objdump.WK2: New file. * testsuite/binutils-all/linkdebug.s: New file. * testsuite/binutils-all/debuglink.s: New file. gas * testsuite/gas/avr/large-debug-line-table.d: Update expected output. * testsuite/gas/elf/dwarf2-11.d: Likewise. * testsuite/gas/elf/dwarf2-12.d: Likewise. * testsuite/gas/elf/dwarf2-13.d: Likewise. * testsuite/gas/elf/dwarf2-14.d: Likewise. * testsuite/gas/elf/dwarf2-15.d: Likewise. * testsuite/gas/elf/dwarf2-16.d: Likewise. * testsuite/gas/elf/dwarf2-17.d: Likewise. * testsuite/gas/elf/dwarf2-18.d: Likewise. * testsuite/gas/elf/dwarf2-5.d: Likewise. * testsuite/gas/elf/dwarf2-6.d: Likewise. * testsuite/gas/elf/dwarf2-7.d: Likewise. ld * testsuite/ld-avr/gc-section-debugline.d: Update expected output.
2017-11-15 19:34:03 +08:00
@item l
@itemx =rawline
Displays the contents of the @samp{.debug_line} section in a raw
format.
@item L
@item =decodedline
Displays the interpreted contents of the @samp{.debug_line} section.
@item m
@itemx =macro
Displays the contents of the @samp{.debug_macro} and/or
@samp{.debug_macinfo} sections.
@item o
@itemx =loc
Displays the contents of the @samp{.debug_loc} and/or
@samp{.debug_loclists} sections.
@item p
@itemx =pubnames
Displays the contents of the @samp{.debug_pubnames} and/or
@samp{.debug_gnu_pubnames} sections.
@item r
@itemx =aranges
Displays the contents of the @samp{.debug_aranges} section.
@item R
@itemx =Ranges
Displays the contents of the @samp{.debug_ranges} and/or
@samp{.debug_rnglists} sections.
@item s
@itemx =str
Displays the contents of the @samp{.debug_str}, @samp{.debug_line_str}
and/or @samp{.debug_str_offsets} sections.
@item t
@itemx =pubtype
Displays the contents of the @samp{.debug_pubtypes} and/or
@samp{.debug_gnu_pubtypes} sections.
@item T
@itemx =trace_aranges
Displays the contents of the @samp{.trace_aranges} section.
@item u
@itemx =trace_abbrev
Displays the contents of the @samp{.trace_abbrev} section.
@item U
@itemx =trace_info
Displays the contents of the @samp{.trace_info} section.
@end table
Note: displaying the contents of @samp{.debug_static_funcs},
@samp{.debug_static_vars} and @samp{debug_weaknames} sections is not
currently supported.
@item --dwarf-depth=@var{n}
Limit the dump of the @code{.debug_info} section to @var{n} children.
This is only useful with @option{--debug-dump=info}. The default is
to print all DIEs; the special value 0 for @var{n} will also have this
effect.
With a non-zero value for @var{n}, DIEs at or deeper than @var{n}
levels will not be printed. The range for @var{n} is zero-based.
@item --dwarf-start=@var{n}
Print only DIEs beginning with the DIE numbered @var{n}. This is only
useful with @option{--debug-dump=info}.
If specified, this option will suppress printing of any header
information and all DIEs before the DIE numbered @var{n}. Only
siblings and children of the specified DIE will be printed.
This can be used in conjunction with @option{--dwarf-depth}.