unexplained Segmentation fault

Discussion created by amitporat on Dec 27, 2010
Latest reply on Dec 28, 2010 by himanshu.gautam


I'm new to OpenCL, and I learn it by trying to write simple app.

I've changed MatrixTranspose code to MatrixRotate and stumble upon strange error which seem like a compiler error. I'm using SDK2.3 and HD5450

If i'm using "globalIdx" insted of "(groupIdx*blockSize + localIdx)" I get the right process, but they should contain the same value (been checked)  so it is very confusing.

Some explanation please.


__kernel void matrixRotate(__global float * output, __global float * input, __local float * block, const uint width, const uint height, const uint blockSize ) { uint globalIdx = get_global_id(0); uint globalIdy = get_global_id(1); uint localIdx = get_local_id(0); uint localIdy = get_local_id(1); /* copy from input to local memory */ block[localIdy*blockSize + localIdx] = input[globalIdy*width + globalIdx]; /* wait until the whole block is filled */ barrier(CLK_LOCAL_MEM_FENCE); uint groupIdx = get_group_id(0); uint groupIdy = get_group_id(1); /* calculate the corresponding target location for transpose by inverting x and y values*/ uint m = (height -1); uint targetGlobalIdx = m- (groupIdy*blockSize + localIdy) ; uint targetGlobalIdy = (groupIdx*blockSize + localIdx); //!!!!! using globalIdx solve the problem but WHY !!!! /* calculate the corresponding raster indices of source and target */ uint targetIndex = targetGlobalIdy*width + targetGlobalIdx; uint sourceIndex = localIdy * blockSize + localIdx; output[targetIndex] = block[sourceIndex]; }