Hi, I tried to following code because I was getting very weird errors in my main program. I create a variable ed which is initialized to zero on host and then copied over to the device and back to host without any manipulation. For some reason unknown to me, the value of the variable changes. Also, is there a better way to copy the variable back other than creating a numpy array for it? If I try copying it to a simple variable, it says "TypeError: expected a writeable buffer object". / 1 import pycuda.driver as cuda 2 import pycuda.autoinit 3 4 cuda.init() 5 assert cuda.Device.count() >= 1 6 7 dev = cuda.Device(0) 8 ctx = dev.make_context() 9 10 import numpy 11 12 ed = numpy.float32(0.0) 13 14 edd = cuda.mem_alloc(ed.nbytes) 15 16 cuda.memcpy_htod(edd, ed) 17 18 result = numpy.array([0.0]) 19 cuda.memcpy_dtoh(result, edd) 20 print ed 21 print result / *On running the program, I get the following output* / msid ~/python $ python cudaTest.py 0.0 [-0.00476747] ----------------------------------------------------------- PyCuda WARNING: I'm being asked to destroy a context that's part of the current context stack. ----------------------------------------------------------- I will pick the next lower active context from the context stack. Since this choice is happening at an unspecified point in time, your code may be making false assumptions about which context is active at what point. Call Context.pop() to avoid this warning. ----------------------------------------------------------- If Python is terminating abnormally (eg. exiting upon an unhandled exception), you may ignore this. ----------------------------------------------------------- terminate called after throwing an instance of 'cuda::error' what(): cuCtxPushCurrent failed: invalid value Aborted / Could someone please tell me why this is happening(pardon me if this is common knowledge) Thank you. Siddhardh