DRM_CAP_TIMESTAMP_MONOTONIC(9)

✨ DRM_CAP_TIMESTAMP_MONOTONIC ✨

Okay bestie, so this is a page from the Kernel API Manual, and it's about one lil' capability flag called DRM_CAP_TIMESTAMP_MONOTONIC. The original NAME section is literally just the flag name with no description attached — iconic minimalist behavior, honestly. 💅

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✨ SYNOPSIS ✨

DRM_CAP_TIMESTAMP_MONOTONIC

That's the whole thing. Short and sweet, no arguments, no drama. 🎀

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🌸 DESCRIPTION 🌸

So here's the tea, bestie. This capability controls which clock the kernel uses when it stamps timestamps on your events. 🔥

• If it's set to 0, the kernel will report timestamps with CLOCK_REALTIME in struct drm_event_vblank.
• If it's set to 1, the kernel will report timestamps with CLOCK_MONOTONIC.

And if you're sitting there like "girl what even are those clocks," don't stress — check clock_gettime(2) for the definition of these clocks. iykyk 🫶

Now, the timeline of it all, because history matters:

• Starting from kernel version 2.6.39, the default value for this capability is 1.
• Starting kernel version 4.15, this capability is always set to 1.

So yeah, it's basically locked in at 1 now. Main character energy that never leaves. 👑

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🦋 SEE ALSO 🦋

Okay so this list is LONG and honestly kind of iconic — the kernel really said "let me introduce you to everyone." No gatekeeping here, periodt. 💜

In the kernel file, the page points at:

• ./tools/perf/trace/beauty/include/uapi/drm/drm.h

Structs and flags:

• 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_VBLANK_HIGH_CRTC(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_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)

The ioctls:

• 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)

And the events:

• struct drm_event(9)
• DRM_EVENT_VBLANK(9)
• DRM_EVENT_FLIP_COMPLETE(9)
• DRM_EVENT_CRTC_SEQUENCE(9)

That's the whole squad. Go read them, they're all slaying in their own way. 🌈

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Lowkey a reminder bestie: if you're on a kernel 4.15 or newer, this thing is always 1, so the 0 case is purely a vintage-collector situation. Don't come for me, that's just what the page says. 🙈

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💖 That's the whole page, fr fr — from the Kernel API Manual, sourced from a path starting ./tools/perf/trace/beauty/incl..., dated October 2026, and yes the header and footer both spell out DRM_CAP_TIMESTAMP_MONOTONIC(9) like the little matching bookends they are. Obsessed. 🎀✨🦋