docs(voxtral_realtime): document CUDA Windows workflow

Add CUDA-Windows instructions to the Voxtral Realtime README, including export prerequisites and an example command.

Document Windows build steps via CMake workflow presets and add PowerShell run examples with and without the .ptd data file.

Note recommended CUDA architectures for int4 kernels, and reformat voxtral_realtime CMake presets without changing behavior.

Author: larryliu0820

examples/models/voxtral_realtime/CMakePresets.json

@@ -14,12 +14,16 @@
         {
             "name": "voxtral-realtime-cpu",
             "displayName": "Voxtral Realtime runner (CPU)",
-            "inherits": ["voxtral-realtime-base"]
+            "inherits": [
+                "voxtral-realtime-base"
+            ]
         },
         {
             "name": "voxtral-realtime-metal",
             "displayName": "Voxtral Realtime runner (Metal)",
-            "inherits": ["voxtral-realtime-base"],
+            "inherits": [
+                "voxtral-realtime-base"
+            ],
             "cacheVariables": {
                 "EXECUTORCH_BUILD_METAL": "ON"
             },
@@ -32,14 +36,19 @@
         {
             "name": "voxtral-realtime-cuda",
             "displayName": "Voxtral Realtime runner (CUDA)",
-            "inherits": ["voxtral-realtime-base"],
+            "inherits": [
+                "voxtral-realtime-base"
+            ],
             "cacheVariables": {
                 "EXECUTORCH_BUILD_CUDA": "ON"
             },
             "condition": {
                 "type": "inList",
                 "string": "${hostSystemName}",
-                "list": ["Linux", "Windows"]
+                "list": [
+                    "Linux",
+                    "Windows"
+                ]
             }
         }
     ],
@@ -48,20 +57,26 @@
             "name": "voxtral-realtime-cpu",
             "displayName": "Build Voxtral Realtime runner (CPU)",
             "configurePreset": "voxtral-realtime-cpu",
-            "targets": ["voxtral_realtime_runner"]
+            "targets": [
+                "voxtral_realtime_runner"
+            ]
         },
         {
             "name": "voxtral-realtime-metal",
             "displayName": "Build Voxtral Realtime runner (Metal)",
             "configurePreset": "voxtral-realtime-metal",
             "configuration": "Release",
-            "targets": ["voxtral_realtime_runner"]
+            "targets": [
+                "voxtral_realtime_runner"
+            ]
         },
         {
             "name": "voxtral-realtime-cuda",
             "displayName": "Build Voxtral Realtime runner (CUDA)",
             "configurePreset": "voxtral-realtime-cuda",
-            "targets": ["voxtral_realtime_runner"]
+            "targets": [
+                "voxtral_realtime_runner"
+            ]
         }
     ],
     "workflowPresets": [
@@ -108,4 +123,4 @@
             ]
         }
     ]
-}
+}

examples/models/voxtral_realtime/README.md

@@ -97,6 +97,7 @@ python export_voxtral_rt.py \
 | `xnnpack` | ✓ | ✓ | `4w`, `8w`, `8da4w`, `8da8w` |
 | `metal` | ✓ | ✓ | none (fp32) or `fpa4w` (Metal-specific 4-bit) |
 | `cuda` | ✓ | ✓ | `4w`, `8w` |
+| `cuda-windows` | ✓ | ✓ | `4w`, `8w` |
 
 Metal backend provides Apple GPU acceleration. CUDA backend provides NVIDIA GPU
 acceleration via AOTInductor.
@@ -171,6 +172,38 @@ Alternatively, you can build torchao with Metal support while installing ExecuTo
 EXECUTORCH_BUILD_KERNELS_TORCHAO=1 TORCHAO_BUILD_EXPERIMENTAL_MPS=1 ./install_executorch.sh
 ```
 
+### CUDA-Windows Export
+
+Before running `cuda-windows` export, make sure these requirements are set up:
+- `x86_64-w64-mingw32-g++` is installed and on `PATH` (mingw-w64 cross-compiler).
+- `WINDOWS_CUDA_HOME` points to the extracted Windows CUDA package directory.
+
+Example setup on Ubuntu (refer to [Parakeet README](../../parakeet/README.md) for detailed extraction steps):
+
+```bash
+# Ensure the WINDOWS_CUDA_HOME environment variable is set
+export WINDOWS_CUDA_HOME=/opt/cuda-windows/extracted/cuda_cudart/cudart
+```
+
+Export the model for Windows CUDA (example with int4 quantization):
+
+```bash
+python export_voxtral_rt.py \
+    --model-path ~/models/Voxtral-Mini-4B-Realtime-2602 \
+    --backend cuda-windows \
+    --dtype bf16 \
+    --output-dir ./voxtral_rt_exports \
+    --qlinear-encoder 4w \
+    --qlinear-encoder-packing-format tile_packed_to_4d \
+    --qlinear 4w \
+    --qlinear-packing-format tile_packed_to_4d \
+    --qembedding 8w
+```
+
+This generates:
+- `model.pte`
+- `aoti_cuda_blob.ptd`
+
 ### Options
 
 | Flag | Default | Description |
@@ -228,6 +261,18 @@ make voxtral_realtime-metal
 This builds ExecuTorch with Metal backend support. The runner binary is at
 the same path as above. Metal exports can only run on macOS with Apple Silicon.
 
+### CUDA-Windows
+
+On Windows (PowerShell), use CMake workflow presets directly from the executorch root directory. Note that if you exported the model with 4-bit quantization, you may need to specify your GPU's compute capability (e.g., `80;86;89;90;120` for Ampere, Lovelace, Hopper, and Blackwell) to avoid "invalid device function" errors at runtime, as the `int4mm` kernels require SM 80 or newer.
+
+```powershell
+$env:CMAKE_CUDA_ARCHITECTURES="80;86;89;90;120"
+cmake --workflow --preset llm-release-cuda
+Push-Location examples/models/voxtral_realtime
+cmake --workflow --preset voxtral-realtime-cuda
+Pop-Location
+```
+
 ## Run
 
 The runner requires:
@@ -237,35 +282,37 @@ The runner requires:
 - A 16kHz mono WAV audio file (or live audio via `--mic`)
 - For CUDA: `aoti_cuda_blob.ptd` — delegate data file (pass via `--data_path`)
 
-```bash
-cmake-out/examples/models/voxtral_realtime/voxtral_realtime_runner \
-    --model_path voxtral_rt_exports/model.pte \
-    --tokenizer_path ~/models/Voxtral-Mini-4B-Realtime-2602/tekken.json \
-    --preprocessor_path voxtral_rt_exports/preprocessor.pte \
+### Windows (PowerShell)
+
+```powershell
+.\cmake-out\examples\models\voxtral_realtime\Release\voxtral_realtime_runner.exe `
+    --model_path voxtral_rt_exports\model.pte `
+    --tokenizer_path C:\path\to\tekken.json `
+    --preprocessor_path voxtral_rt_exports\preprocessor.pte `
     --audio_path input.wav
 ```
 
 For CUDA, include the `.ptd` data file:
 
-```bash
-cmake-out/examples/models/voxtral_realtime/voxtral_realtime_runner \
-    --model_path voxtral_rt_exports/model.pte \
-    --data_path voxtral_rt_exports/aoti_cuda_blob.ptd \
-    --tokenizer_path ~/models/Voxtral-Mini-4B-Realtime-2602/tekken.json \
-    --preprocessor_path voxtral_rt_exports/preprocessor.pte \
+```powershell
+.\cmake-out\examples\models\voxtral_realtime\Release\voxtral_realtime_runner.exe `
+    --model_path voxtral_rt_exports\model.pte `
+    --data_path voxtral_rt_exports\aoti_cuda_blob.ptd `
+    --tokenizer_path C:\path\to\tekken.json `
+    --preprocessor_path voxtral_rt_exports\preprocessor.pte `
     --audio_path input.wav
 ```
 
 For streaming, add `--streaming`. This requires a model exported with
 `--streaming`. The runner processes audio in 80ms steps, computing mel
 and running the encoder+decoder incrementally.
 
-```bash
-cmake-out/examples/models/voxtral_realtime/voxtral_realtime_runner \
-    --model_path voxtral_rt_exports/model.pte \
-    --tokenizer_path ~/models/Voxtral-Mini-4B-Realtime-2602/tekken.json \
-    --preprocessor_path voxtral_rt_exports/preprocessor.pte \
-    --audio_path input.wav \
+```powershell
+.\cmake-out\examples\models\voxtral_realtime\Release\voxtral_realtime_runner.exe `
+    --model_path voxtral_rt_exports\model.pte `
+    --tokenizer_path C:\path\to\tekken.json `
+    --preprocessor_path voxtral_rt_exports\preprocessor.pte `
+    --audio_path input.wav `
     --streaming
 ```
 
@@ -285,6 +332,17 @@ ffmpeg -f avfoundation -i ":0" -ar 16000 -ac 1 -f f32le -nostats -loglevel error
 
 Ctrl+C stops recording and flushes remaining text.
 
+**Windows (PowerShell):**
+
+```powershell
+.\cmake-out\examples\models\voxtral_realtime\Release\voxtral_realtime_runner.exe `
+  --model_path C:\path\to\voxtral_rt_exports\model.pte `
+  --data_path C:\path\to\voxtral_rt_exports\aoti_cuda_blob.ptd `
+  --tokenizer_path C:\path\to\tekken.json `
+  --preprocessor_path C:\path\to\voxtral_rt_exports\preprocessor.pte `
+  --audio_path C:\path\to\input.wav
+```
+
 **CUDA:** Add `--data_path voxtral_rt_exports/aoti_cuda_blob.ptd` to all
 run commands above when using the CUDA backend.