vb2_core_prepare_buf(9)

💖 vb2_core_prepare_buf(9) 💖

okay bestie, so this one lives in the Kernel API Manual section, and it's basically the handoff moment — where a buffer stops being userspace's problem and becomes the kernel's problem. iconic, honestly.

---

✨ NAME ✨

vb2_core_prepare_buf — Pass ownership of a buffer from userspace to the kernel.

like, literally passing the aux cord. no cap 🎀

---

🌸 SYNOPSIS 🌸

int vb2_core_prepare_buf (struct vb2_queue *q , struct vb2_buffer *vb ,
void *pb );

---

🦋 ARGUMENTS 🦋

• q — pointer to struct vb2_queue with videobuf2 queue. yes, the whole queue. main character energy 👑
• vb — pointer to struct vb2_buffer. the buffer itself, hi bestie 🫶
• pb — buffer structure passed from userspace to the v4l2_ioctl_ops->vidioc_prepare_buf handler in the driver. this is the one that travelled all the way from userspace, so be nice to it ✨

---

💅 DESCRIPTION 💅

Videobuf2 core helper to implement the VIDIOC_PREPARE_BUF operation. It's called internally by VB2 by an API-specific handler, like videobuf2-v4l2.h. so you're not usually the one calling it — VB2 is, through one of its little API-specific middlemen. iykyk 💫

The passed buffer should have been verified. that's the vibe check, and it already happened before you got here 🙈

This function calls the vb2_ops->buf_prepare callback in the driver (if provided), in which driver-specific buffer initialization can be performed. so if your driver has opinions about how a buffer should get set up, this is where it gets to say them. slay 🔥

ngl, the "if provided" is doing real work there — the callback is optional, so don't go assuming it'll always fire.

---

⭐ RETURN ⭐

returns zero on success; an error code otherwise. zero is the good one, obviously. anything else? not the vibe 💀

---

🌈 SEE ALSO 🌈

Kernel file ./include/media/videobuf2-core.h, plus honestly the entire extended universe:

• enum vb2_memory(9)
• struct vb2_mem_ops(9)
• struct vb2_plane(9)
• enum vb2_io_modes(9)
• enum vb2_buffer_state(9)
• struct vb2_buffer(9)
• struct vb2_ops(9)
• struct vb2_buf_ops(9)
• struct vb2_queue(9)
• vb2_queue_allows_cache_hints(9)
• vb2_plane_vaddr(9)
• vb2_plane_cookie(9)
• vb2_buffer_done(9)
• vb2_discard_done(9)
• vb2_wait_for_all_buffers(9)
• vb2_core_querybuf(9)
• vb2_core_reqbufs(9)
• vb2_core_create_bufs(9)
• vb2_core_remove_bufs(9)
• vb2_core_qbuf(9)
• vb2_core_dqbuf(9)
• vb2_core_streamon(9)
• vb2_core_streamoff(9)
• vb2_core_expbuf(9)
• vb2_core_queue_init(9)
• vb2_core_queue_release(9)
• vb2_queue_error(9)
• vb2_mmap(9)
• vb2_get_unmapped_area(9)
• vb2_core_poll(9)
• vb2_read(9)
• vb2_write(9)
• vb2_thread_fnc(9)
• vb2_thread_start(9)
• vb2_thread_stop(9)
• vb2_is_streaming(9)
• vb2_fileio_is_active(9)
• vb2_get_num_buffers(9)
• vb2_is_busy(9)
• vb2_get_drv_priv(9)
• vb2_set_plane_payload(9)
• vb2_get_plane_payload(9)
• vb2_plane_size(9)
• vb2_start_streaming_called(9)
• vb2_clear_last_buffer_dequeued(9)
• vb2_get_buffer(9)
• vb2_buffer_in_use(9)
• vb2_verify_memory_type(9)
• vb2_request_object_is_buffer(9)
• vb2_request_buffer_cnt(9)

---

and that's the page, bestie!! 🌟 it shipped from the ./include/media source directory in October 2026, so go forth and prepare those buffers responsibly 💖🎀🦋