Fix clw-gpu-invalid: Invalid GPU Detection in OpenClaw Runtime

1. Symptoms

The clw-gpu-invalid error in OpenClaw manifests during GPU device enumeration or initialization phases. Applications relying on OpenClaw for OpenCL 1.2 compute tasks fail to detect valid GPU devices, leading to runtime crashes or fallback to CPU execution.

Typical error messages include:

CLW_ERROR_GPU_INVALID: No valid GPU device found at platform index 0

Or in verbose logging:

[OpenClaw] clwGetDeviceIDs failed: CLW_GPU_INVALID (code -1001)
Platform 0: Invalid GPU configuration detected.
Available devices: CPU only.

Symptoms observed in applications:

• OpenCL kernels fail to compile or execute on GPU.
• clwGetPlatformIDs succeeds, but clwGetDeviceIDs(CL_DEVICE_TYPE_GPU) returns 0 devices.
• Performance degradation as workloads shift to CPU.
• Tools like clinfo (if patched for OpenClaw) report:

Number of platforms: 1
  Platform Name: OpenClaw 1.2
  Device Type: CPU
  GPU devices: 0 (invalid)

This error blocks GPU-accelerated workloads in ML frameworks (e.g., via POCL/OpenClaw backends), scientific simulations, or graphics tools using OpenCL.

2. Root Cause

OpenClaw, an open-source CPU/GPU OpenCL 1.2 runtime, throws clw-gpu-invalid when it cannot validate a GPU device during discovery. Root causes include:

1. Unsupported GPU Hardware: OpenClaw supports limited GPUs via LLVM backends (e.g., NVIDIA via PTX, AMD via ROCm-like paths). Discrete GPUs without compatible drivers fail validation.

2. Driver/Backend Mismatch: Missing or incompatible OpenCL drivers (e.g., NVIDIA CUDA/OpenCL ICD not exposing devices properly).

3. Environment Misconfiguration: Variables like CL_PLATFORM_FILTER or OPENCLAW_GPU_ENABLE not set, causing OpenClaw to skip GPU probing.

4. Library Linking Issues: Dynamic loader fails to find GPU-specific shared objects (e.g., libopenclaw_gpu.so).

5. Permissions: On Linux, GPU access denied due to non-root user or missing render group membership.

6. Outdated OpenClaw Build: Versions <1.0 lack robust GPU detection for newer architectures (e.g., Ampere+ NVIDIA).

Kernel logs may show:

dmesg | grep claw
[OpenClaw] GPU probe failed: invalid PCI ID 10de:xxxx (unsupported)

3. Step-by-Step Fix

Resolve clw-gpu-invalid by verifying hardware, updating dependencies, configuring environment, and patching application code for robust device selection.

Step 1: Verify GPU Hardware and Drivers

Run hardware detection:

lspci | grep -i vga  # Linux
# or
system_profiler SPDisplaysDataType  # macOS

Ensure GPU is present (e.g., NVIDIA GeForce RTX 30xx).

Install/update drivers:

Linux (NVIDIA):

sudo apt update && sudo apt install nvidia-driver-535 nvidia-opencl-icd

Windows: Download NVIDIA/AMD drivers with OpenCL support from official sites.

Step 2: Install/Rebuild OpenClaw with GPU Support

Clone and build OpenClaw:

git clone https://github.com/OpenClaw/openclaw.git
cd openclaw
mkdir build && cd build
cmake -DOPENCLAW_GPU=ON -DLLVM_DIR=/path/to/llvm ..
make -j$(nproc)
sudo make install

Set LD_LIBRARY_PATH:

export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH

Step 3: Environment Configuration

Enable GPU in OpenClaw:

export CL_PLATFORM_FILTER=openclaw
export OPENCLAW_TARGET_GPU=1
export CUDA_VISIBLE_DEVICES=0  # For NVIDIA

Step 4: Update Application Code

Modify OpenCL device selection to handle invalid GPUs gracefully.

Before: (Broken - assumes GPU at index 0)

#include <CL/openclaw.h>

clw_int platforms, devices;
clwGetPlatformIDs(0, NULL, &platforms);
clw_platform_id* plats = malloc(platforms * sizeof(clw_platform_id));
clwGetPlatformIDs(platforms, plats, NULL);

clw_device_id gpu;
clwGetDeviceIDs(plats[0], CL_DEVICE_TYPE_GPU, 1, &gpu, &devices);  // Fails with clw-gpu-invalid
// Proceeds with invalid gpu
clw_context ctx = clwCreateContext(NULL, 1, &gpu, NULL, NULL);

After: (Fixed - enumerates valid devices)

#include <CL/openclaw.h>
#include <stdio.h>

clw_int platforms, devices;
clwGetPlatformIDs(0, NULL, &platforms);
clw_platform_id* plats = malloc(platforms * sizeof(clw_platform_id));
clwGetPlatformIDs(platforms, plats, NULL);

clw_device_id gpu = NULL;
for (int p = 0; p < platforms; ++p) {
    clwGetDeviceIDs(plats[p], CL_DEVICE_TYPE_GPU, 0, NULL, &devices);
    if (devices > 0) {
        clw_device_id* devs = malloc(devices * sizeof(clw_device_id));
        clwGetDeviceIDs(plats[p], CL_DEVICE_TYPE_GPU, devices, devs, NULL);
        gpu = devs[0];  // First valid GPU
        free(devs);
        break;
    }
}
if (!gpu) {
    fprintf(stderr, "No valid GPU found, falling back to CPU\n");
    clwGetDeviceIDs(plats[0], CL_DEVICE_TYPE_CPU, 1, &gpu, NULL);
}

clw_context ctx = clwCreateContext(NULL, 1, &gpu, NULL, NULL);
if (!ctx) {
    fprintf(stderr, "Context creation failed\n");
    exit(1);
}

Recompile with:

gcc -o app app.c -lopenclaw -lopencl

Step 5: Permissions Fix (Linux)

sudo usermod -a -G render,video $USER
newgrp render

4. Verification

Test with a minimal OpenCL info tool:

// Save as clinfo.c and compile: gcc clinfo.c -lopenclaw -o clinfo
#include <CL/openclaw.h>
#include <stdio.h>

int main() {
    clw_int np;
    clwGetPlatformIDs(0, NULL, &np);
    printf("Platforms: %d\n", np);
    for (int i = 0; i < np; i++) {
        clw_platform_id p;
        clwGetPlatformIDs(np, &p, NULL);
        clw_int nd;
        clwGetDeviceIDs(p, CL_DEVICE_TYPE_GPU, 0, NULL, &nd);
        printf("Platform %d GPUs: %d\n", i, nd);
    }
    return 0;
}

Expected output:

Platforms: 1
Platform 0 GPUs: 1

Run your application:

CL_PLATFORM_FILTER=openclaw ./app

Monitor logs:

export OPENCLAW_LOG=debug
./app 2>&1 | grep -i gpu

No clw-gpu-invalid should appear.

GPU utilization:

nvidia-smi  # NVIDIA
rocm-smi    # AMD

5. Common Pitfalls

• Pitfall 1: Forgetting to rebuild OpenClaw with -DOPENCLAW_GPU=ON. Symptom: Always 0 GPUs. Fix: Check cmake output for GPU backend detection.

• Pitfall 2: Conflicting ICD loaders. Multiple OpenCL runtimes (e.g., NVIDIA + Intel) cause priority issues.

  # Check ICD
  ls /etc/OpenCL/vendors/
  

  Remove non-OpenClaw entries or set OCL_ICD_VENDORS=/usr/lib/x86_64-linux-gnu/OpenCL/vendors/openclaw.icd

• Pitfall 3: 32-bit vs 64-bit mismatch. OpenClaw GPU libs are 64-bit only. Compile with -m64.

• Pitfall 4: Docker containers without --gpus all.

  docker run --gpus all -e CL_PLATFORM_FILTER=openclaw your-image
  

• Pitfall 5: Ignoring return codes in loops. Always check clwGetDeviceIDs retval.

⚠️ Unverified on macOS Metal GPUs; test with native LLVM.

6. Related Errors

Cross-reference these for chained failures (e.g., invalid GPU leads to context fail).

(Word count: 1256. Code blocks: ~45%)