openflukeXVI · Apple MLX acceleration (welvet.mlx) / CHAPTER 23
Apple MLX: caps and dtype rejects
github.com/openfluke/welvet/nativemlxdarwin arm64
Why it exists
Unsupported mounts must hard-fail before any GPU work: not soft-fallback to Go labeled as MLX.
What it is
Print SupportedLayers, accept dense/float32, and show RequireLayer rejecting dense/float64.
Caps table
nativemlx.LayerSupported(layer, dtype) and SupportedLayers() mirror the welvet.mlx C ABI caps. SyncToMLX / RequireLayer refuse anything outside that table. Dense GPU compute rejects float64; host I/O stays Float32 activations with FormatNone parameter storage.
welvet.mlx 1.0.0 caps list the signed leaf ops (Dense, Softmax, RMSNorm, LayerNorm, CNN2/3, ConvT2/3, LSTM, Embedding, Residual, SwiGLU, MHA). Sequential is a container that mounts supported children: see §112. Full dtype matrix: FORWARD_CHECKLIST.md.
Requirements: chapter 110.
Go example
examples/111-apple-mlx-caps/main.go
cd welvet/examples/111-apple-mlx-caps && source ../env.sh && go run .// Print MLX caps and demonstrate RequireLayer rejects.
package main
import (
"fmt"
"log"
"runtime"
"strings"
"github.com/openfluke/welvet/nativemlx"
)
func main() {
if err := run(); err != nil {
log.Fatal(err)
}
}
func run() error {
if runtime.GOOS != "darwin" || runtime.GOARCH != "arm64" {
fmt.Println("SKIP: Apple MLX needs Apple silicon macOS and cgo")
return nil
}
if !nativemlx.Available() {
fmt.Println("SKIP: need libwelvet_mlx.dylib + Metal GPU")
return nil
}
layers := nativemlx.SupportedLayers()
fmt.Println("version", nativemlx.Version())
fmt.Println("supported_layers", strings.Join(layers, ","))
fmt.Println("dense/float32", nativemlx.LayerSupported("dense", "float32"))
fmt.Println("dense/float64", nativemlx.LayerSupported("dense", "float64"))
if err := nativemlx.RequireLayer("dense", "float32"); err != nil {
return fmt.Errorf("expected dense/float32 ok: %w", err)
}
fmt.Println("RequireLayer dense/float32: ok")
err := nativemlx.RequireLayer("dense", "float64")
if err == nil {
return fmt.Errorf("expected dense/float64 reject")
}
fmt.Println("RequireLayer dense/float64:", err)
return nil
}Output
version 1.0.0
supported_layers dense,softmax,rmsnorm,layernorm,cnn2,cnn3,convt2,convt3,lstm,embedding,residual,swiglu,mha
dense/float32 true
dense/float64 false
RequireLayer dense/float32: ok
RequireLayer dense/float64: nativemlx: reject dense/float64: not supported on MLX GPU (see SupportedLayers)Validate (harness)
cd welvet/examples/111-apple-mlx-caps && source ../env.sh && go run .