dwarf2 problem

[Franz Sirl]

At 19:22 29.06.00, Richard Henderson wrote:
>On Thu, Jun 29, 2000 at 08:21:11AM -0400, Ed Hepler wrote:
> > It is compiled using:
> >
> >   m68k-elf-gcc -m68000 -gdwarf-2 -O2 -Tv68k.ld -o hello hello.c
>[...]
> > it returns:Reading symbols from hello... Dwarf Error: bad offset
> > (0x1677c) in compilation unit header (offset 0x0 + 6).
>
>It's quite obvious from your typescript what the problem is:
>
>   3 .debug_abbrev 000028ac  00018068  00018068  0000a060  2**0
>                   CONTENTS, READONLY, DEBUGGING
>   4 .debug_info   00018a17  0001a914  0001a914  0000c90c  2**0
>                   CONTENTS, READONLY, DEBUGGING
>   5 .debug_line   000093fa  0003332b  0003332b  00025323  2**0
>                   CONTENTS, READONLY, DEBUGGING
>   6 .debug_pubnames 00000921  0003c725  0003c725  0002e71d  2**0
>                   CONTENTS, READONLY, DEBUGGING
>   7 .debug_aranges 000004e0  0003d046  0003d046  0002f03e  2**0
>                   CONTENTS, READONLY, DEBUGGING
>
>All the dwarf[12] sections should be forced to address zero in
>your linker script.  If you'll examine one of the distributed
>link scripts you'll find
>
>   /* DWARF 1 */
>   .debug          0 : { *(.debug) }
>   .line           0 : { *(.line) }
>   /* GNU DWARF 1 extensions */
>   .debug_srcinfo  0 : { *(.debug_srcinfo) }
>   .debug_sfnames  0 : { *(.debug_sfnames) }
>   /* DWARF 1.1 and DWARF 2 */
>   .debug_aranges  0 : { *(.debug_aranges) }
>   .debug_pubnames 0 : { *(.debug_pubnames) }
>   /* DWARF 2 */
>   .debug_info     0 : { *(.debug_info) }
>   .debug_abbrev   0 : { *(.debug_abbrev) }
>   .debug_line     0 : { *(.debug_line) }
>   .debug_frame    0 : { *(.debug_frame) }
>   .debug_str      0 : { *(.debug_str) }
>   .debug_loc      0 : { *(.debug_loc) }
>   .debug_macinfo  0 : { *(.debug_macinfo) }
>   /* SGI/MIPS DWARF 2 extensions */
>   .debug_weaknames 0 : { *(.debug_weaknames) }
>   .debug_funcnames 0 : { *(.debug_funcnames) }
>   .debug_typenames 0 : { *(.debug_typenames) }
>   .debug_varnames  0 : { *(.debug_varnames) }

Binutils in CVS (not binutils-2.10) or hjl's binutils-2.10.0.9 are smart 
enough to handle this without help from a linker script. I discovered this 
bug a while ago when I tried to load an PPC860 linux kernel compiled with 
-gdwarf-2 with our emulator. Our ELF loader complained with a warning. Alan 
Modra then fixed it soon afterwards.

Franz.