> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/ikawrakow/ik_llama.cpp/llms.txt
> Use this file to discover all available pages before exploring further.

# Build options

> CMake flags and environment variables for building ik_llama.cpp

## Prerequisites

On Debian/Ubuntu:

```bash theme={null}
apt-get update && apt-get install build-essential git libcurl4-openssl-dev curl libgomp1 cmake
```

## CMake flags

Pass flags to the initial `cmake -B build` invocation.

| Flag                       | Default | Description                                                                                                        |
| -------------------------- | ------- | ------------------------------------------------------------------------------------------------------------------ |
| `GGML_NATIVE`              | `OFF`   | Optimize for the host CPU (`-march=native`). Turn off when cross-compiling.                                        |
| `GGML_CUDA`                | `OFF`   | Build with CUDA support. Requires the NVIDIA CUDA Toolkit. Defaults to native CUDA architecture detection.         |
| `CMAKE_CUDA_ARCHITECTURES` | auto    | Target a specific GPU compute capability, e.g. `86` for RTX 30-series.                                             |
| `GGML_RPC`                 | `OFF`   | Build the RPC backend for distributed inference across machines.                                                   |
| `GGML_IQK_FA_ALL_QUANTS`   | `OFF`   | Enable all KV cache quantization types for Flash Attention (beyond the default `f16`, `q8_0`, `q6_0`, and `bf16`). |
| `GGML_NCCL`                | `ON`    | Enable NCCL for multi-GPU communication. Set to `OFF` to disable.                                                  |
| `LLAMA_SERVER_SQLITE3`     | `OFF`   | Build SQLite3 support into `llama-server` (required for the mikupad web UI).                                       |

**CPU build example**

```bash theme={null}
cmake -B build -DGGML_NATIVE=ON
cmake --build build --config Release -j$(nproc)
```

**CUDA build example**

```bash theme={null}
cmake -B build -DGGML_NATIVE=ON -DGGML_CUDA=ON -DCMAKE_CUDA_ARCHITECTURES=86
cmake --build build --config Release -j$(nproc)
```

## Environment variables

Set these in the shell before invoking `llama-server` or any other tool.

| Variable                          | Description                                                                                                                                                 |
| --------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `CUDA_VISIBLE_DEVICES`            | Restrict which GPUs are visible. Example: `CUDA_VISIBLE_DEVICES=0,2` uses the first and third GPU only.                                                     |
| `GGML_CUDA_ENABLE_UNIFIED_MEMORY` | Set to `1` to enable CUDA Unified Memory, allowing the GPU to access host RAM when VRAM is exhausted. Useful for large models on systems with limited VRAM. |

```bash theme={null}
CUDA_VISIBLE_DEVICES=0,2 llama-server --model /models/model.gguf -ngl 999
```

<Note>
  The only fully supported compute backends are CPU (AVX2 or better, ARM NEON
  or better) and CUDA. ROCm, Vulkan, and Metal are available but not actively
  maintained.
</Note>