Frank
1e9d921b95
Live-verified on Dankclaw 2026-08-14: - official rocm/comfyui image is built PYTORCH_ROCM_ARCH=gfx942;gfx950 (datacenter only) -> torch.cuda.is_available() False on gfx1151 - AMD gfx1151-tagged PyTorch build (rocm/vllm:...gfx1151...pytorch_2.9.1) -> avail True, Radeon 8060S, cap (11,5); needs /dev/kfd + /dev/dri - torch.backends.vulkan is compiled out of standard wheels; no ComfyUI --vulkan flag exists; Vulkan is a dead end for ComfyUI - Lemonade Server does image gen via wrapped stable-diffusion.cpp, whose HIP kernels include gfx1151 -> works where ComfyUI's torch cannot New pages: ComfyUI ROCm and Vulkan, Lemonade and sd.cpp; ComfyUI.md qualified; compose stays --cpu until a gfx1151-enabled torch image is built
49 lines
2.4 KiB
Markdown
49 lines
2.4 KiB
Markdown
# Lemonade and sd.cpp
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Why Lemonade Server can do image generation on Strix Halo when ComfyUI cannot. Research from the Lemonade source repo (`lemonade-sdk/lemonade`, cloned 2026-08-14) and live verification.
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## The short answer
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Lemonade does not run ComfyUI. Its image-generation backend is a wrapped **stable-diffusion.cpp** (`leejet/stable-diffusion.cpp`) subprocess. sd.cpp is a ggml-family native C++ runtime that ships its own HIP kernels — and those kernels **include gfx1151**. ComfyUI runs on PyTorch, whose standard wheels omit gfx1151. Same hardware, different runtime, different result.
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## From the Lemonade source
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`src/cpp/server/backends/sdcpp/sdcpp_server.cpp`:
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- Image gen is `SDServer`, a `WrappedServer` around a prebuilt sd.cpp binary.
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- Downloads `sd-<version>-bin-Linux-Ubuntu-24.04-x86_64-<backend>.zip` from `leejet/stable-diffusion.cpp` releases.
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- Backends: `cpu, cuda, metal, rocm, vulkan`.
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- ROCm asset is `...-rocm-<version>.zip`; Vulkan is `...-vulkan.zip`.
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Backend support matrix (`docs/dev/backends-reference.md`):
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| Recipe | Backend | Device families |
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|--------|---------|-----------------|
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| `sd-cpp` | rocm | amd_gpu (gfx103X, gfx110X, **gfx1150, gfx1151, gfx1152**, gfx120X) |
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| `sd-cpp` | vulkan | amd_gpu; cpu; nvidia_gpu |
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| `thenoise` | rocm | amd_gpu (gfx1150, gfx1151, gfx1152) — experimental |
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**gfx1151 is explicitly supported** by sd.cpp's ROCm build. There is also a dedicated experimental `thenoise` ROCm backend targeting exactly the Strix Halo archs.
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## Engine comparison
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| | ComfyUI | Lemonade (sd.cpp) |
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|---|---|---|
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| Runtime | PyTorch | native C++ (ggml family) |
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| AMD path | needs PyTorch ROCm wheel with gfx1151 kernels — not in standard wheels | ships own HIP kernels, gfx1151 included |
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| On Strix Halo | CPU only (today) | ROCm GPU, or Vulkan fallback |
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| Interface | node graph web UI | server, OpenAI-style API, GUI/CLI |
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This mirrors llama.cpp on the same box: ggml-family runtimes ship their own gfx1151 HIP kernels and run on ROCm; PyTorch does not.
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## Relevance
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- If GPU image generation on Dankclaw matters, **Lemonade (or bare sd.cpp) is the working path today**.
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- ComfyUI's node graph is the cost of switching: Lemonade is not ComfyUI.
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- See [[ComfyUI ROCm and Vulkan]] for the PyTorch-side analysis showing a gfx1151-enabled torch would also make ComfyUI work.
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## See Also
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- [[ComfyUI ROCm and Vulkan]] — the PyTorch side of this question
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- [[ComfyUI]] — current CPU config
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- [[Dankclaw Stack]] |