OK, I built a small test app, just a main that made this call. It didn't compile. When I built with gcc -march=i486 test.c, it built and ran fine. So, the compiler is OK (not really surprised, are you?). That means something isn't right with my build environment. I am running FC9, my co-workers are using Ubuntu 8.4(?). We use the same makefiles and build procedure. I edited the makefile that builds this library and added the -march=i486, but it didn't fix the problem. Here is the gcc line in the makefile. gcc -shared -fPIC -march=i486 -g -Wl,--version-script=merlotcore.ver -o $@ $^ $(XLIBS) Here is the source line. It is a one line function that calls ::InterlockedIncrement in Windows. lpValue is an unsigned int*. (Should the __sync... call actually use *lpValue? Is that the problem?) __sync_add_and_fetch( lpValue, 1 ); Here is the actual error text. ./mimio-mimiosys: symbol lookup error: /home/Chuck/SWEngineering/builds/latest/Debug/products/mimio/mimiosys.so: undefined symbol: __sync_add_and_fetch_4 I assume that the appended _4 is due to an function overload. Any ideas? Despite what it sounds like, I really do appreciate the help that I have been given. I am just very frustrated with this problem and my whole Linux experience. I can't seem to get anything to work. Chuck On Wed, 2008-12-03 at 18:18 -0800, David Daney wrote: > Charles Crisler wrote: > > Thank you. I had already found your reference. > > > > Which file contains the definition of this built-in function? > > > > It is built-in to the compiler (that is why it is called a "Built-in > function for atomic memory access"), so it doesn't really exist in any > file external to the compiler. The only place it is documented is in > the compiler's manual. > > > > I suppose that I could write a main() that called an increment function > > and that function could call this function. > > > > What would you need? If I supply just source it would seem that wouldn't > > be worth much. > > I don't really understand your question. > > You could look in the compiler's testsuite at these programs to see how > to use it: > > gcc/testsuite/gcc.dg/sync-1.c > gcc/testsuite/gcc.dg/sync-2.c > gcc/testsuite/gcc.dg/sync-3.c > > > > > My co-workers are using v. 4.2.4, though one just built the entire > > system with 4.3.2 and it did not have this problem. However, I would > > kind of like to isolate the problem before I upgrade, which is why I > > asked about the file it is defined in. I greped -inr > > "__sync_add_and_fetch" /usr/include/*.h and didn't find it. Since that > > module compiles without a warning, that suggests that the compiler found > > it. > > See above, it doesn't exist external to the compiler. > > > David Daney
