Questions about ``[PATCH] GCC side of .eh_frame_hdr support (take 3)''

Wed Apr 24 14:34:00 GMT 2002

On Wed, Apr 24, 2002 at 01:09:42PM -0500, Loren James Rittle wrote:
> Are these optimized EH frames readable by the unwinder in unwind-dw2-fde.c?

Yes. There is nothing unusual about these modified EH frames.
We eliminated some duplicate information is all.
> Do I need to add this to the port's configuration file for any port
> that might someday use GNU ld 2.12+? (Based on comment in alpha/elf.h,
> I suspect it is not strictly required when unwind-dw2-fde.c is used by
> a port.)
>> #if defined(HAVE_LD_EH_FRAME_HDR)
> #define LINK_EH_SPEC "%{!static:--eh-frame-hdr} "
> #endif

It is not required until
 (1) The OS implements dl_iterate_phdr or some equivalent functionality,
 (2) unwind-dw2-fde.c is suitably modified (a-la unwind-dw2-fde-glibc)
 to use (1).
> (I should not ask the obvious question: Why is something which depends
> solely upon the GNU ld version being added on a per-port basis?
> Perhaps adding it to config/elfos.h would have been wiser. Oh well.)

*shrug* I suppose Jakub was trying to save a bit of space in
the binary for those systems that never use the eh-frame-hdr.
> (I suspect so.) Does this likely mask a binutils and/or gcc port bug
> that should be tracked down?

Likely a binutils bug.
> The only difference I could detect with readelf(1) between GNU ld
> 2.12.1 without --traditional-format and GNU ld 2.12.1 with
> --traditional-format was the size of .eh_frame:

Look at the output of readelf -wf.
> Trick question: What does --traditional-format mean to GNU ld 2.12.1
> when it *is* the native linker for the system? ;-)

Don't fiddle with the bits. ;-)
r~