[Dwarf-Discuss] Doubts in DWARF spec 4

Ian Lance Taylor iant at google.com
Tue Nov 12 06:48:56 PST 2013


On Mon, Nov 11, 2013 at 7:15 PM, Malu Sasi <malu.sasi at nestgroup.net> wrote:
>
> We are having some doubts while building elf's using new GCC (4.8.1) with DWARF-4. When we build elfs with "-gdwarf-4", and analyzed the parsed details using "readelf",
>
> 1. It was seen that the ".debug_line" section always shows the version as "2". But from Appendix F of DWARF 4 spec(page 289, figure 97), we expect it to be "4". Can anyone please clarify why version number of ".debug_line" section is "2" instead of "4". Is it that we need to manually add some other option while building elf?


When you use newer versions of GCC with newer versions of the GNU
binutils, GCC does not generate the DWARF line or frame information
directly.  Instead it adds pseudo-ops to the assembly code and the
assembler emits the actual debug info.  This is better because the
assembler has better information about exact PC values than the
compiler does.

The assembler currently always generates DWARF version 2 line number
information.  I don't know of any problems that might cause, but I am
not an expert.


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