Enable or disable bf16 support based on availability (#1116)

src/axolotl/utils/config.py

@@ -61,6 +61,14 @@ def normalize_config(cfg):
         cfg.device_map = {"": int(os.environ.get("LOCAL_RANK", 0))}
         cfg.batch_size = cfg.batch_size * cfg.world_size
 
+    if cfg.bf16 == "auto":
+        if is_torch_bf16_gpu_available():
+            LOG.debug("bf16 support detected, enabling for this configuration.")
+            cfg.bf16 = True
+        else:
+            LOG.debug("bf16 support not detected, disabling for this configuration.")
+            cfg.bf16 = False
+
     if cfg.device == "mps":
         cfg.load_in_8bit = False
         cfg.tf32 = False