dl_iterate_phdr missing in libc

Carmelo Amoroso carmelo73 at gmail.com
Sat Jan 12 08:33:33 UTC 2008

Mike Frysinger wrote:
> On Friday 11 January 2008, Carmelo AMOROSO wrote:
>> I'm facing a problem when statically linking an app with
>> sh4-linux-uclibc-g++
>> caused by the missing symbol dl_iterate_phdr as below:
>> sh4-linux-uclibc-g++ -static main.c
>> /opt/STM/STLinux-2.3/devkit/sh4_uclibc/lib/gcc/sh4-linux-uclibc/4.2.1/libgc
>> c_eh.a(unwind-dw2-fde-glibc.o): In function `_Unwind_Find_FDE':
>> /home/macaroni/users/products/stm2.3/build/packages/stm-cross-gcc-sh4_uclib
>> c/BUILD/gcc-4.2.1/objdir/gcc/../../gcc/unwind-dw2-fde-glibc.c:430: undefined
>> reference to `dl_iterate_phdr'
> static is the devil ;)
Hi Mike,
yes, but it seems a lot of people in embedded world prefer it,
likely they have concerns on performance.

>> Indeed the symbols is defined into the ld.so (not used when statically
>> linked) and into libdl.a
> yep
>> but, being libgcc_eh.a requiring this symbol, it will not find it even
>> if -ldl is passed.
> what a pain huh
>> I've checked glibc and found that dl_iterate_phdr in into libc instead
>> od ld.so and libdl.a
>> A comment in uclibc dl-elf.c says explicitly:
>> "we want this in ld.so and libdl.a but nowhere else"
>> Could someone explain this to me ?
> it's a symbol only used by symbol related stuff which is why we put it there.  
> the comment is to cover the fact we *dont* want it in say libdl.so.
>> I need to fix immediately into uclibc-nptl sh4
> isnt it always ?
>> adding the symbol into the libc too, as it is required by an our
>> customer on production, but I'd like to have a common fix also for the
>> trunk. 
> looks like we'll need to relocate it to libc.a from libdl.a
> -mike

Yes, I don't want to keep it into libdl.a and libc.a, only ld.so and libc.a.
Anyway the dl_iterate_phdr implementation needs to handle the statically linked application too,
as glibc actually does. I'll provide a patch for review soon.

Further, basing on Bernds suggestion, I'm building gcc with a patch to use generic unwind-dw2
implementation. Anyway we are discussing what is the best solution for us.


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