vb2_fileio_is_active(9)

💅 vb2_fileio_is_active — like, the Kernel API Manual girlies know ✨

okay so bestie, welcome to the vb2_fileio_is_active(9) page from the Kernel API Manual. yes it's a whole mouthful, no i will not be pronouncing it out loud at a party. but it's actually such a tiny icon and it does exactly one little job, and it does it slayfully. let's go 🫶

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✨ NAME ✨

vb2_fileio_is_active — returns true if fileio is active. that's it. that's the whole vibe check.

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🦋 SYNOPSIS 🦋

bool vb2_fileio_is_active (struct vb2_queue *q );

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🎀 ARGUMENTS 🎀

• q — pointer to struct vb2_queue with your videobuf2 queue in it. literally just the queue. hand it over 💖

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🌸 DESCRIPTION 🌸

so this function returns true if read or write is used to stream the data, as opposed to stream I/O. two different streaming energy sources, and this is how you tell which one you're dealing with 👑

lowkey? it's almost never an important distinction. like, the vast majority of the time you can simply not care. but there ARE rare cases where it matters a lot, and one of those cases is a whole thing:

using read or write to stream a format that uses V4L2_FIELD_ALTERNATE is not allowed, because there's genuinely no way for you to pass the field information of each buffer to/from userspace. like, the plumbing just isn't there, bestie. it's giving "we don't have the infrastructure for that." 😭

so if you're writing a driver that supports this field format, you should check for this in the vb2_ops->queue_setup op, and reject it if this function returns true. main character driver behavior: know your limits, set your boundaries 💅

ngl, this is one of those "check before you commit" functions. the check is cheap, the consequences of skipping it are not 🚨

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👑 SEE ALSO 👑

the whole friend group, fr fr. also the Kernel file ./include/media/videobuf2-core.h — go say hi 🧚

• 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_prepare_buf(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_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)

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and that's the page!! 💖✨🎀 this little legend lives over in ./include/media, and it was dated October 2026 — so yeah, she's timestamped and everything. go forth and check your queue_setup, bestie, ily, bye 🦋💜🌸