Revamp the dynamic library shim

This switches the default llama.cpp to be CPU based, and builds the GPU variants
as dynamically loaded libraries which we can select at runtime.

This also bumps the ROCm library to version 6 given 5.7 builds don't work
on the latest ROCm library that just shipped.

llm/llm.go

@@ -22,8 +22,7 @@ type LLM interface {
 	Close()
 }
 
-// Set to false on linux/windows if we are able to load the shim
-var ShimPresent = false
+var AvailableShims = map[string]string{}
 
 func New(workDir, model string, adapters, projectors []string, opts api.Options) (LLM, error) {
 	if _, err := os.Stat(model); err != nil {
@@ -82,15 +81,23 @@ func New(workDir, model string, adapters, projectors []string, opts api.Options)
 	opts.RopeFrequencyBase = 0.0
 	opts.RopeFrequencyScale = 0.0
 	gpuInfo := gpu.GetGPUInfo()
-	if gpuInfo.Driver == "ROCM" && ShimPresent {
-		return newRocmShimExtServer(model, adapters, projectors, ggml.NumLayers(), opts)
-	} else {
-		// Rely on the built-in CUDA/Metal based server which will fall back to CPU
-		return newLlamaExtServer(model, adapters, projectors, ggml.NumLayers(), opts)
-	}
+	return newLlmServer(gpuInfo.Library, model, adapters, projectors, ggml.NumLayers(), opts)
 }
 
 // Give any native cgo implementations an opportunity to initialize
 func Init(workdir string) error {
 	return nativeInit(workdir)
 }
+
+func newLlmServer(library, model string, adapters, projectors []string, numLayers int64, opts api.Options) (extServer, error) {
+	if _, libPresent := AvailableShims[library]; libPresent && library != "default" {
+		srv, err := newDynamicShimExtServer(AvailableShims[library], model, adapters, projectors, numLayers, opts)
+		if err == nil {
+			return srv, nil
+		}
+		log.Printf("Failed to load dynamic library - falling back to CPU mode %s", err)
+	}
+
+	return newDefaultExtServer(model, adapters, projectors, numLayers, opts)
+
+}