Dear buildroot list.

[Rob Landley]

Sorry to ask a uClibc question on the buildroot list, but I don't know where 
else to go.

The short thing seems to be that gcc 4.0.2 wants to call dl_iterate_phdr, and 
Erik removed it here: 
http://www.uclibc.org/cgi-bin/viewcvs.cgi?rev=9216&view=rev

The long explanation:

I'm trying to get gcc 4.0.2 to build against uClibc, starting with the 
invocation I made to get 3.2 to build and figuring out what new breakage the 
gcc developers managed to come up with.  Basically I ran a few sed 
invocations against the gcc sources (both to teach it about uClibc and to 
prefix its directories with /tools, ala Linux From Scratch chapter 5), did 
a ./configure, and ran "make quickstrap".  Voiala, cross compiler.

Unfortunately, gcc 4.0 contains a package "libmudflap" which is A) evil, B) 
totally undocumented.  Even google can't tell me what this thing does or 
whether I actually need it.  All I know is it breaks the build.

During its ./configure (which doesn't run during the top level ./configure but 
during the make quickstrap: THANK you, gcc developers!), it tries to create 
and run an executable using the half-finished compiler the system is 
building.  (Ha ha, if you were using a cross-compiler you'd have specified a 
different --target!)  Of course this compiler was told to link its binaries 
against uClibc, which I haven't installed yet, so this fails with can't find 
crt0.  Right.

So I install uClibc (0.9.27, I still need to upgrade busybox tar to understand 
the "--exclude" option before 0.9.28's headers will install), re-run the 
thing, and now it's complaining it can't find dl_iterate_phdr:

/home/landley/newbuild/firmware-build/tools/sources/gcc-build/gcc/libgcc_s.so: 
undefined reference to `dl_iterate_phdr'

Which there are indeed calls to in the source code:

landley at driftwood:~/newbuild/firmware-build/tools/sources/gcc-4.0.2$ find . | 
xargs grep dl_iterate_phdr
./gcc/ChangeLog.6:      (_Unwind_FindTableEntry): Use dl_iterate_phdr.
./gcc/unwind-dw2-fde-glibc.c:   segment and dl_iterate_phdr to avoid 
register/deregister calls at
./gcc/unwind-dw2-fde-glibc.c:  if (dl_iterate_phdr 
(_Unwind_IteratePhdrCallback, &data) < 0)
./gcc/config/ia64/fde-glibc.c:  if (dl_iterate_phdr 
(_Unwind_IteratePhdrCallback, &data) < 0)

Does anyone have any obvious suggestions?  Why was it removed from uClibc?  
This is not something upgrading to 0.9.28 is likely to fix because according 
to subversion the symbol is still missing.  Should I just try to chop it out 
of the source code?

Rob

P.S.  I patched gcc/unwind-dw2-fde-glibc.c to replace the call with if(0), and 
it seems to have built.  I think the only reason it should ever want to do 
stack unwinding is for debugging or c++, neither of which I'm currently 
using.  But I thought I should mention it anyway...