save_pretrained 4-bit models with bitsandbytes
With the latest version of bitsandbytes (0.39.0) library, isn't it possible to serialize 4-bit models then?

Thus this section should be updated to allow the user to save these models.
https://github.com/huggingface/transformers/blob/68d53bc7178866821282f45732c1e465f5160fa6/src/transformers/modeling_utils.py#LL1704C36-L1704C36

I'm mainly looking at this article to see what got produced lately in the area: https://huggingface.co/blog/4bit-transformers-bitsandbytes

I aim to quantize a model to 4-bit, enabling it to be used in e.g., GPT4all and other CPU platforms.
cc @younesbelkada <|||||>Hi @westn 
Thanks for the issue, I don't think 4bit models are serializable yet. Let me double check that with the author of bitsandbytes and get back to you<|||||>Also note that 4bit / 8bit is also applicable to GPU / CUDA devices, you cannot run quantized models with bitsandbytes on a CPU device<|||||>Hi @westn 
Currently it is not possible to save 4bit models but this is in the roadmap of bitsandbytes for the next releases. We will keep you posted!<|||||>Hi, @younesbelkada , Whether 4bits/8bits models can be saved now?<|||||>Hi @jameswu2014 
Thanks for the heads up, currently 4bit saving is not possible, however, 8bit saving is possible, check: https://huggingface.co/docs/transformers/main_classes/quantization#push-quantized-models-on-the-hub