Section .debug_info in object file

[Pierre Habraken <Pierre dot Habraken at imag dot fr>]

A few days ago I posted a message about the fact that after launching
gdb to debug a program made of several C and Arm assembly language
files, the command 'info sources' lists C files only.

Richard explained me that the section '.debug_info' in a given object
file is supposed to contain a field (among others) named 'DW_AT_name'
containing the name of the source file from which this object file was
produced.
It appears that assembly object files (at least those which are produced
by Gas) does not include this field 'DW_AT_name' ; this could explain
that gdb does not see assembly language source files at the time it
opens the program being debugged.

Knowing that rises several questions:

- what is the structure of a '.debug_info' section ?
  Is this structure documented somewhere ?

- which tool can be used to examine the contents of a '.debug_info'
  section ? I tried to use arm-elf-objdump but the result which it
  displays is not formatted and checking it is not easy...

- is there a way to force gas to include a field 'DW_AT_name' in the
  object files it produces ?
  (an option on the command line ? a directive inside the source file ?)

- why would gdb be not able to retrieve an assembly language source file
  (together with its name) as long as no breakpoint is set by the user
  within this file, where it is able to retrieve this same source file
  as soon as a first breakpoint is set (though the name of the source
  file is not present in the object file) ?...

Thanks for any help.

Pierre

PS: I am using binutils 2.13 and gdb 5.2.1 compiled for arm-elf.
-- 
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Pierre HABRAKEN - mailto:Pierre.Habraken@imag.fr
Tél: 04 76 82 72 83 - Fax: 04 76 82 72 87
IMAG-LSR BP72 38402 SAINT MARTIN D'HERES Cedex
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