forked from unom/punktfunk
enricobuehlerandClaude Opus 5
e5e68f1d24
Both come straight out of the first compositor-less bring-up (P3), on a two-GPU box: PUNKTFUNK_DRM_CARD=<n> pins SDL's KMSDRM device index. SDL enumerates /dev/dri/card* and takes the first it can open, which is regularly the wrong one: it chose the card a live compositor already held DRM master on and died at swapchain creation, while the idle card with the connected display sat unused. Kept an explicit operator choice rather than auto-detection — deciding "is this card already mastered" needs the very ioctl that taking master IS, so any in-process guess would be fragile. The swapchain error now carries what to actually check. "vkCreateSwapchainKHR: Initialization of an object has failed" is useless to someone bringing up a kiosk; on the kmsdrm backend it now names the pinned card and lists the three real causes in order (no connected connector / another DRM master / NVIDIA). Empty on every other backend, where it would be noise. The NVIDIA note is measured, not guessed: on NVIDIA proprietary + kmsdrm, Vulkan enumerates the GPU AND the display (VK_KHR_display reports the connected HDMI connector) and still fails — as root, with nvidia_drm.modeset=Y, on a card no compositor was using. Not permissions, not DRM master; their direct-display path wants the display leased via vkAcquireDrmDisplayEXT and SDL's kmsdrm surface path does not do that. Plan: punktfunk-planning design/embedded-arm64-client.md §P3 Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>