From Peter Rudolph on ROS Users: https://code.ros.org/lurker/thread/20130303.105941.7106c801.en.html

He guys!
I tried to solved and it seems solved! First i will explain the problem itself: while de-/serializing unaligned pointercasts are done. normally this is not a problem! but since newer versions of arm-gcc use float support with options -mfloat-abi=hard/softfp, there are many possibilities to hit this alignment fault, because NEON instructions must be aligned! This is a very big problem... compiling ROS with -Wcast-align shows the potential lines! Solving this by setting "-mno-unaligned-access" as compiler-flag does NOT work! Every prebuilt-compiler i used seemed to ignore this switch.

example from www, demonstrates the error (compile it w/o any optimization(-O0), else compiler will re-align the pointercast, but this won't work for ROS, since everything is built w/ optimization(-O2)):

include <stdio.h>

int main(int argc, char* argv[])
{
char attribute ((aligned(32))) buffer[8] = { 0 };
float* fval_p;

fval_p = (float*)&buffer[1];
*fval_p = 0.1234;

printf("\nfloat at &buf[1] is %f\n", *fval_p);

return 0;

}

Build my own example from this, to check what works correctly and serious...

Only possibility was to hack the correct lines in roscpp_serialization. I only changed the lines from pointercasts to simple memcpy's and now everything seems to work fine! No alignment faults, no bus errors, no kernel exceptions! Tried a lightweight openni version, my own robot stack, and gmapping! navigation stack will follow!

Due to having no time now, patchfile will follow, too!

Regards,
sem23