Implement GGUF metadata KV overrides (#1011)

* Implement GGUF metadata overrides

* whitespace fix

* Fix kv overrides.

* Fix pointer and pickle

* Match llama.cpp kv_overrides cli argument

---------

Co-authored-by: Andrei <abetlen@gmail.com>

llama_cpp/llama.py

@@ -735,6 +735,7 @@ class Llama:
         vocab_only: bool = False,
         use_mmap: bool = True,
         use_mlock: bool = False,
+        kv_overrides: Optional[Dict[str, Union[bool, int, float]]] = None,
         # Context Params
         seed: int = llama_cpp.LLAMA_DEFAULT_SEED,
         n_ctx: int = 512,
@@ -803,6 +804,7 @@ class Llama:
             vocab_only: Only load the vocabulary no weights.
             use_mmap: Use mmap if possible.
             use_mlock: Force the system to keep the model in RAM.
+            kv_overrides: Key-value overrides for the model.
             seed: RNG seed, -1 for random
             n_ctx: Text context, 0 = from model
             n_batch: Prompt processing maximum batch size
@@ -866,6 +868,34 @@ class Llama:
         self.model_params.use_mmap = use_mmap if lora_path is None else False
         self.model_params.use_mlock = use_mlock
 
+        self.kv_overrides = kv_overrides
+        if kv_overrides is not None:
+            n_overrides = len(kv_overrides)
+            self._kv_overrides_array = llama_cpp.llama_model_kv_override * (n_overrides + 1)
+            self._kv_overrides_array_keys = []
+
+            for k, v in kv_overrides.items():
+                key_buf = ctypes.create_string_buffer(k.encode("utf-8"))
+                self._kv_overrides_array_keys.append(key_buf)
+                self._kv_overrides_array[i].key = key_buf
+                if isinstance(v, int):
+                    self._kv_overrides_array[i].tag = llama_cpp.LLAMA_KV_OVERRIDE_INT
+                    self._kv_overrides_array[i].value.int_value = v
+                elif isinstance(v, float):
+                    self._kv_overrides_array[i].tag = llama_cpp.LLAMA_KV_OVERRIDE_FLOAT
+                    self._kv_overrides_array[i].value.float_value = v
+                elif isinstance(v, bool):
+                    self._kv_overrides_array[i].tag = llama_cpp.LLAMA_KV_OVERRIDE_BOOL
+                    self._kv_overrides_array[i].value.bool_value = v
+                else:
+                    raise ValueError(f"Unknown value type for {k}: {v}")
+
+            self._kv_overrides_array_sentinel_key = b'\0'
+
+            # null array sentinel
+            self._kv_overrides_array[n_overrides].key = self._kv_overrides_array_sentinel_key
+            self.model_params.kv_overrides = self._kv_overrides_array
+
         self.n_batch = min(n_ctx, n_batch)  # ???
         self.n_threads = n_threads or max(multiprocessing.cpu_count() // 2, 1)
         self.n_threads_batch = n_threads_batch or max(
@@ -2148,6 +2178,7 @@ class Llama:
             vocab_only=self.model_params.vocab_only,
             use_mmap=self.model_params.use_mmap,
             use_mlock=self.model_params.use_mlock,
+            kv_overrides=self.kv_overrides,
             # Context Params
             seed=self.context_params.seed,
             n_ctx=self.context_params.n_ctx,
@@ -2190,6 +2221,7 @@ class Llama:
             vocab_only=state["vocab_only"],
             use_mmap=state["use_mmap"],
             use_mlock=state["use_mlock"],
+            kv_overrides=state["kv_overrides"],
             # Context Params
             seed=state["seed"],
             n_ctx=state["n_ctx"],

llama_cpp/server/model.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import Optional, Union, List
+from typing import Dict, Optional, Union, List
 
 import llama_cpp
 
@@ -71,6 +71,23 @@ class LlamaProxy:
             chat_handler = llama_cpp.llama_chat_format.Llava15ChatHandler(
                 clip_model_path=settings.clip_model_path, verbose=settings.verbose
             )
+        
+        kv_overrides: Optional[Dict[str, Union[bool, int, float]]] = None
+        if settings.kv_overrides is not None:
+            assert isinstance(settings.kv_overrides, list)
+            kv_overrides = {}
+            for kv in settings.kv_overrides:
+                key, value = kv.split("=")
+                if ":" in value:
+                    value_type, value = value.split(":")
+                    if value_type == "bool":
+                        kv_overrides[key] = value.lower() in ["true", "1"]
+                    elif value_type == "int":
+                        kv_overrides[key] = int(value)
+                    elif value_type == "float":
+                        kv_overrides[key] = float(value)
+                    else:
+                        raise ValueError(f"Unknown value type {value_type}")
 
         _model = llama_cpp.Llama(
             model_path=settings.model,
@@ -81,6 +98,7 @@ class LlamaProxy:
             vocab_only=settings.vocab_only,
             use_mmap=settings.use_mmap,
             use_mlock=settings.use_mlock,
+            kv_overrides=kv_overrides,
             # Context Params
             seed=settings.seed,
             n_ctx=settings.n_ctx,

llama_cpp/server/settings.py

@@ -48,6 +48,10 @@ class ModelSettings(BaseSettings):
         default=llama_cpp.llama_mlock_supported(),
         description="Use mlock.",
     )
+    kv_overrides: Optional[List[str]] = Field(
+        default=None,
+        description="List of model kv overrides in the format key=type:value where type is one of (bool, int, float). Valid true values are (true, TRUE, 1), otherwise false.",
+    )
     # Context Params
     seed: int = Field(
         default=llama_cpp.LLAMA_DEFAULT_SEED, description="Random seed. -1 for random."