[Olsr-dev] [Commotion-dev] Can't talk between desktop OLSRd and Commotion OpenWRT boxes

[Mikael Nordfeldth]

Hans-Christoph Steiner asked me to post this bug report to the olsr-dev 
list, originally coming from the commotion-dev list: 
https://lists.chambana.net/pipermail/commotion-dev/2013-March/001175.html

Essentially the problem was that I couldn't run the olsrd in the Ubuntu 
PPA (at least on Quantal 12.10 64bit).
The following post reasons that it is due to the gcc -O2 switch being 
enabled by a Makefile-patch which was added with the .deb-packaging.

So this is a bug report for the .deb for (at least) 0.6.3 in Ubuntu 
quantal 64bit, as I have not tried it on any other platform. I'd be 
happy to help with further debugging.

2013-03-08 19:27, Hans-Christoph Steiner wrote:
> Right now, Debian squeeze and wheezy have 0.6.2, and Ubuntu has 0.6.1 
> and 0.6.3:
> http://packages.debian.org/search?keywords=olsrd
> http://packages.ubuntu.com/search?keywords=olsrd
> So the idea is to find out which version of these we can rely on, and 
> which we
> need to use replacements.

Gah. This seems way more advanced than what I can explain with my
knowledge. Nevertheless, I did find what caused my error, the -O2 gcc
optimization switch as patched by Debian package "hardening fixes":

1. I tried compiling various olsrd versions. All worked.
2. I tried compiling 0.6.3-5~quantal from 'apt-get source'. It didn't 
work.
3. I tried compiling the 0.6.3.orig source (same as above, without
debian patches) It worked.
4. None of the patches contained any networking code (except the json
plugin, but disabling it didn't have any effect anyway)
5. I found that removing the -O2 switch on line 227 in Makefile.inc, as
patched by 310-hardening-fixes.patch resolved my invalid argument
sendto(v4) issue:

  %.o: %.c
         @echo "[CC] $<"
-       $(CC) $(CFLAGS) $(CPPFLAGS) -c -o $@ $<
+       $(CC) -O2 $(CFLAGS) $(CPPFLAGS) -fPIE -c -o $@ $<


Reverting this (and even leaving the -fPIE there but removing -O2) 
makes
the resulting binary functional.


So the specific problem was caused by the -O2 parameter to gcc, I guess
making it a compiling/linking issue. I don't know enough about this
myself though, so I'm attaching ('O2-opts') the output of what that
level of optimizations means if anyone is interested (gcc -c -Q -O2
--help=optimizers)

More info on my build environment is below:

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.7.2-2ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs
--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.7 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--enable-gnu-unique-object --enable-plugin --enable-objc-gc
--disable-werror --with-arch-32=i686 --with-tune=generic
--enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.7.2 (Ubuntu/Linaro 4.7.2-2ubuntu1)


$ uname -a
Linux plexi 3.5.0-25-generic #39-Ubuntu SMP Mon Feb 25 18:26:58 UTC 
2013
x86_64 x86_64 x86_64 GNU/Linux

-- 
Mikael Nordfeldth
http://blog.mmn-o.se/
Xmpp/mail: (spam-protected)
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