DRM_CAP_VBLANK_HIGH_CRTC(9)

💅 DRM_CAP_VBLANK_HIGH_CRTC(9) 💅

okay so bestie, welcome to the Kernel API Manual — this one's a tiny little corner of the DRM header files and it's honestly iconic in how small it is. Let's go 🫶

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✨ NAME ✨

DRM_CAP_VBLANK_HIGH_CRTC — and that's literally it, no tagline, no description, the manpage just puts the name there and dips 💀 (the original line is DRM_CAP_VBLANK_HIGH_CRTC - with nothing after the dash, and we're keeping it that way, no cap).

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🦋 SYNOPSIS 🦋

DRM_CAP_VBLANK_HIGH_CRTC

that's the whole synopsis. one line. main character energy, honestly 👑

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🌸 DESCRIPTION 🌸

okay so here's the tea:

• If it's set to 1, the kernel supports specifying a CRTC index in the high bits of drm_wait_vblank_request.type. The docs write that CRTC index reference using the literal ref markup :ref:`CRTC index<crtc_index>` — yep, that exact string, character for character, iykyk 🔥

and the second thing you need to know:

• Starting kernel version 2.6.39, this capability is always set to 1. always. it's not a maybe, it's not a vibe check, it's just 1 forever 💅

so like — if you're on anything even remotely modern, this bit is gonna be 1 when you read it. the kernel already decided. periodt. ✨

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🎀 SEE ALSO 🎀

all the neighbors, bestie, and there are so many of them — the whole DRM squad pulled up 😭

• Kernel file ./tools/perf/trace/beauty/include/uapi/drm/drm.h
• struct drm_gem_close(9)
• struct drm_gem_flink(9)
• struct drm_gem_open(9)
• struct drm_gem_change_handle(9)
• DRM_CAP_DUMB_BUFFER(9)
• DRM_CAP_DUMB_PREFERRED_DEPTH(9)
• DRM_CAP_DUMB_PREFER_SHADOW(9)
• DRM_CAP_PRIME(9)
• DRM_PRIME_CAP_IMPORT(9)
• DRM_PRIME_CAP_EXPORT(9)
• DRM_CAP_TIMESTAMP_MONOTONIC(9)
• DRM_CAP_ASYNC_PAGE_FLIP(9)
• DRM_CAP_CURSOR_WIDTH(9)
• DRM_CAP_CURSOR_HEIGHT(9)
• DRM_CAP_ADDFB2_MODIFIERS(9)
• DRM_CAP_PAGE_FLIP_TARGET(9)
• DRM_CAP_CRTC_IN_VBLANK_EVENT(9)
• DRM_CAP_SYNCOBJ(9)
• DRM_CAP_SYNCOBJ_TIMELINE(9)
• DRM_CAP_ATOMIC_ASYNC_PAGE_FLIP(9)
• DRM_CLIENT_CAP_STEREO_3D(9)
• DRM_CLIENT_CAP_UNIVERSAL_PLANES(9)
• DRM_CLIENT_CAP_ATOMIC(9)
• DRM_CLIENT_CAP_ASPECT_RATIO(9)
• DRM_CLIENT_CAP_WRITEBACK_CONNECTORS(9)
• DRM_CLIENT_CAP_CURSOR_PLANE_HOTSPOT(9)
• DRM_CLIENT_CAP_PLANE_COLOR_PIPELINE(9)
• struct drm_syncobj_eventfd(9)
• DRM_IOCTL_GEM_CLOSE(9)
• DRM_IOCTL_PRIME_HANDLE_TO_FD(9)
• DRM_IOCTL_PRIME_FD_TO_HANDLE(9)
• DRM_IOCTL_MODE_RMFB(9)
• DRM_IOCTL_MODE_CREATE_DUMB(9)
• DRM_IOCTL_MODE_GETFB2(9)
• DRM_IOCTL_SYNCOBJ_EVENTFD(9)
• DRM_IOCTL_MODE_CLOSEFB(9)
• DRM_IOCTL_SET_CLIENT_NAME(9)
• DRM_IOCTL_GEM_CHANGE_HANDLE(9)
• struct drm_event(9)
• DRM_EVENT_VBLANK(9)
• DRM_EVENT_FLIP_COMPLETE(9)
• DRM_EVENT_CRTC_SEQUENCE(9)

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and that's the whole page, bestie — tiny page, huge friend group 🌈

signing off with the source/version vibes: ./tools/perf/trace/beauty/incl... and the date, October 2026 — luv u, go read about vblanks 💖🎀🦋