Hi Andy, >> The closest I got was to compile mathtest.c as though it were a >> kernel module. That failed during compile, since floating point >> operations are disallowed in the kernel (they use the SSE register, >> which must stay clean for userspace), > > Is that an RT-Preempt limitation? There are lots of FP operations in > kernel modules elsewhere in LinuxCNC. > However, you might need to use the realtime-safe functions from rtapi_math.h
Well, my experience with the kernel is that of a rank amateur, and more embarrassing, what I said about disallowing the SSE register is probably wrong: I think I came across a freebsd thread and wasn't paying attention. However, the kernel makefiles use the gcc options '-mno-sse' and '-mno-sse2' to turn off those extended instructions sets in my setup. It could be an rt-preempt thing, or anything else for all I know right now. This question will surely need to be addressed properly before LinuxCNC on rt-preempt works, so I'll next take a look to see how RTAI solves the problem. You're surely right that rtapi_math.h will be key. John ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers