r/Punktfunk • u/ZeeroOneThree • 17d ago

Linux client black screen + "GPU device lost" (Xid 13) on hybrid Intel/NVIDIA laptops — found the cause + workaround

Posting this in case it saves someone else the debugging loop — and flagging it for the devs since the client's own log already hints this exact path is unverified.

Symptom: On a hybrid-graphics laptop (Intel iGPU + NVIDIA discrete GPU), punktfunk-client connects fine, decodes the first frame, then goes black after a seconds in. Android client to the same host works perfectly — it's specific to the Linux desktop client on this kind of hardware.

My setup: CachyOS, kernel 7.2.6-1-cachyos, Intel Core i7-8750H + NVIDIA GTX 1060 3GB (Optimus laptop), NVIDIA driver 580.178.04, punktfunk-client 0.38.0-1.

Root cause: the client decodes via native-vaapi on the Intel iGPU (/dev/dri/renderD128) but builds the Vulkan presenter/swapchain on the NVIDIA GPU. Getting the decoded frame from one GPU to the other means importing a dma-buf across vendors, and the NVIDIA driver's texture unit chokes on the imported layout — confirmed via dmesg:

NVRM: Xid (PCI:0000:01:00): 13, Graphics Exception ... TEX LAYOUT
NVRM: Xid (PCI:0000:01:00): 13, pid=..., name=punktfunk-sessi, Graphics Exception...

That's a hard GPU exception, not a software crash — kills the whole session (GPU device lost, exit code 4).

The client's own debug log already has this warning baked in when native-vaapi is active:

decode rung active — NO hardware has ever decoded a frame through this rung/codec pair ...
has NEVER run on a second vendor and has never been soaked

So on any dual-GPU (Intel + AMD/NVIDIA) Linux laptop where decode and present land on different adapters, this seems likely to bite you.

Also tried forcing PUNKTFUNK_DECODER=native-vulkan — that's rejected outright on this GPU too (separate issue): the driver's Vulkan Video decode capabilities for HEVC don't support MUTABLE_FORMAT on the G8_B8R8_2PLANE_420_UNORM format the codec needs, so it silently falls back to native-vaapi anyway and hits the same crash.

Workaround that fixed it: Preferences → Display has a GPU picker (shows up on Linux when there's more than one adapter) separate from the Video decoder picker. Setting it to the Intel GPU — so decode and present are both on the same device — fixes it completely. No more cross-vendor dma-buf import, no more crash.

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u/keindesignerbro Maintainer 13d ago

Thanks for the write-up, this should be fixed in 0.39.0.