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# Breaking changes in Spconv 2.x for spconv 1.x users

* ```spconv.xxx``` move to ```spconv.pytorch.xxx```, change all ```import spconv``` to ```import spconv.pytorch as spconv``` and ```from spconv.xxx import``` to ```from spconv.pytorch.xxx import```.
* ```use_hash``` and ```fused_bn``` in Sparse Convolution is removed, we only use hash table in 2.x.
* ```x.features = F.relu(x.features)``` now raise error. use ```x = x.replace_feature(F.relu(x.features))``` instead.
* weight layout has been changed to RSKC (native algorithm) or KRSC (implicit gemm), no longer RSCK (spconv 1.x). RS is kernel size, C is input channel, K is output channel.
* all util ops are removed (pillar scatter/nms/rbbox_iou...)
* VoxelGenerator has been replaced by Point2VoxelGPU[1-4]d/Point2VoxelCPU[1-4]d.
* spconv < 2.1 don't support CPU. spconv 2.1+ support cpu for debug usage.

* test spconv 1.x model in spconv 2.x: set environment variable before run program. Linux: ```export SPCONV_FILTER_HWIO="1"```, Windows powershell: ```$Env:SPCONV_FILTER_HWIO = "1"```. **WARNING** test spconv 1.x model don't support implicit gemm algorithm, you need to train from scratch with spconv 2.x and select ConvAlgo.MaskSplitImplicitGemm.