STRUCT V4L2_EXPORTBUFFER(9)

💅 struct v4l2_exportbuffer — Kernel API Manual, bestie edition

okay so real talk, this struct is the one that lets you yeet a video buffer out as a DMABUF file descriptor ✨ it's giving "handoff era" and honestly? iconic.

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✨ NAME ✨

struct v4l2_exportbuffer — export of video buffer as DMABUF file descriptor 🦋

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🎀 SYNOPSIS 🎀

struct v4l2_exportbuffer {
    __u32 type;
    __u32 index;
    __u32 plane;
    __u32 flags;
    __s32 fd;
    __u32 reserved[11];
 };

no cap, that's the whole layout 👑

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🌸 Members 🌸 (yes we're doing every single one, don't scroll)

• type — enum v4l2_buf_type; it's the buffer type, and heads up: type == *_MPLANE means you're in multiplanar buffer territory 🫶
• index — the id number of the buffer, aka which one you're talking about
• plane — index of the plane to be exported; for single plane queues it's just 0
• flags — flags for the newly created file; rn only O_CLOEXEC is supported, so go peek at the manual of the open syscall for the deets 👀
• fd — the file descriptor associated with DMABUF, and note that the driver sets this one, not you 💜
• reserved — drivers and applications must zero this array. literally mandatory. zero it. periodt.

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💖 Description 💖

so this struct holds the data used for exporting a video buffer as a DMABUF file descriptor. slay.

the buffer is identified by a 'cookie' that VIDIOC_QUERYBUF hands you — and it's literally the identical cookie you'd use to mmap the buffer into userspace, iykyk 🍓

⚠️ every reserved field must be set to zero. all of them. no exceptions, bestie.

and here's the lore: the field reserved0 is expected to become a structure 'type' that would allow an alternative layout of the struct's content. so because of that future glow-up, that field should not be used for any other extensions. do not repurpose it, I'm begging 🙈

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🔥 SEE ALSO 🔥

Kernel file ./include/uapi/linux/videodev2.h — and the whole friend group:

• struct v4l2_capability(9)
• struct v4l2_plane(9)
• struct v4l2_buffer(9)
• v4l2_timeval_to_ns(9)
• struct v4l2_selection(9)
• struct v4l2_plane_pix_format(9)
• struct v4l2_pix_format_mplane(9)
• struct v4l2_sdr_format(9)
• struct v4l2_meta_format(9)
• struct v4l2_format(9)
• struct v4l2_event_motion_det(9)
• struct v4l2_create_buffers(9)
• struct v4l2_remove_buffers(9)

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k that's the whole page, go export some buffers responsibly 🌈 this diva lives in ./include/uapi/linux and the version vibes are dated October 2026 — mwah, catch you in the next manpage 💋🎀