add bf16 check (#587)

src/axolotl/utils/config.py

@@ -4,6 +4,7 @@
 import os
 
 import torch
+from transformers.utils import is_torch_bf16_gpu_available
 
 from axolotl.utils.bench import log_gpu_memory_usage
 from axolotl.utils.models import load_model_config
@@ -89,6 +90,14 @@ def normalize_config(cfg):
 
 
 def validate_config(cfg):
+    if is_torch_bf16_gpu_available():
+        if not cfg.bf16 and not cfg.bfloat16:
+            LOG.info("bf16 support detected, but not enabled for this configuration.")
+    else:
+        if cfg.bf16 or cfg.bfloat16:
+            raise ValueError(
+                "bf16 requested, but AMP is not supported on this GPU. Requires Ampere series or above."
+            )
     if cfg.max_packed_sequence_len and cfg.sample_packing:
         raise ValueError(
             "please set only one of max_packed_sequence_len (deprecated soon) or sample_packing"