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Frank 1e9d921b95 docs: research ComfyUI on ROCm and Vulkan for Strix Halo (gfx1151)

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

2026-08-13 20:40:47 -07:00

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Lemonade and sd.cpp

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.

The short answer

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.

From the Lemonade source

src/cpp/server/backends/sdcpp/sdcpp_server.cpp:

Image gen is SDServer, a WrappedServer around a prebuilt sd.cpp binary.
Downloads sd-<version>-bin-Linux-Ubuntu-24.04-x86_64-<backend>.zip from leejet/stable-diffusion.cpp releases.
Backends: cpu, cuda, metal, rocm, vulkan.
ROCm asset is ...-rocm-<version>.zip; Vulkan is ...-vulkan.zip.

Backend support matrix (docs/dev/backends-reference.md):

Recipe	Backend	Device families
`sd-cpp`	rocm	amd_gpu (gfx103X, gfx110X, gfx1150, gfx1151, gfx1152, gfx120X)
`sd-cpp`	vulkan	amd_gpu; cpu; nvidia_gpu
`thenoise`	rocm	amd_gpu (gfx1150, gfx1151, gfx1152) — experimental

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.

Engine comparison

	ComfyUI	Lemonade (sd.cpp)
Runtime	PyTorch	native C++ (ggml family)
AMD path	needs PyTorch ROCm wheel with gfx1151 kernels — not in standard wheels	ships own HIP kernels, gfx1151 included
On Strix Halo	CPU only (today)	ROCm GPU, or Vulkan fallback
Interface	node graph web UI	server, OpenAI-style API, GUI/CLI

This mirrors llama.cpp on the same box: ggml-family runtimes ship their own gfx1151 HIP kernels and run on ROCm; PyTorch does not.

Relevance

If GPU image generation on Dankclaw matters, Lemonade (or bare sd.cpp) is the working path today.
ComfyUI's node graph is the cost of switching: Lemonade is not ComfyUI.
See ComfyUI ROCm and Vulkan for the PyTorch-side analysis showing a gfx1151-enabled torch would also make ComfyUI work.

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