Hello everyone, Just a quick followup. This problem is now resolved. There is no breakage in gcc, just a problem in the Fedora icu package. That package contains some sed scripts in the "SPEC" (build description meta) file that intentionally were munging the Makefiles used to build ICU such that "nostdlib" was being given to gcc and it was never using libgcc.
The intention of the person who made this change apparently was to prevent linking the standard math library into icu, but unfortunately a rather unusual solution was chosen. On some systems, one can almost get away with this because __sync_synchronize happens to be implemented in such a fashion that it is optimized into inline emitted assembly. On ARM, that isn't the case. In addition, it is likely that telling GCC not to link in core libraries like libgcc will lead to other breakage later. I have requested the package be fixed to remove the sed scripts and have temporarily (just to solve our problem in the Fedora ARM community) had "-lgcc" added to the linker flags as a very hackish solution for today. Thanks for the replies, and I apologize for the noise. I have learned a great deal about gcc atomics over the past few days. I have also learned that debugging packages requires that you build the package *exactly* as it is in the spec file, not just by running configure/make as therein ;) Jon.
