STRUCT DVB_VB2_CTX(9)

📦 version 7.3.1, in nixpkgs unstable

💅 struct dvb_vb2_ctx(9) 💅

okay so bestie, welcome to the Kernel API Manual — this page is all about struct dvb_vb2_ctx, and it's literally the control struct for VB2 handler. that's the whole name tag. iykyk 🎀

✨ NAME ✨

struct dvb_vb2_ctx — control struct for VB2 handler. no cap, that's it, that's the vibe.

🦋 SYNOPSIS 🦋

struct dvb_vb2_ctx {
    struct vb2_queue        vb_q;
    spinlock_t slock;
    struct list_head        dvb_q;
    struct dvb_buffer       *buf;
    int offset;
    int remain;
    int state;
    int buf_siz;
    int buf_cnt;
    int nonblocking;
    enum dmx_buffer_flags flags;
    u32 count;
    char name[DVB_VB2_NAME_MAX + 1];
 };

look at her. iconic. every field accounted for, nothing skipped, we respect the struct in this house 🫶

🌸 MEMBERS 🌸

okay so let's meet the cast, one by one, main character energy for each:

  • vb_q — pointer to struct vb2_queue with videobuf2 queue. she's the plug 🔌
  • slock — spin lock used to protect buffer filling at dvb_vb2.c. do NOT skip her, she's holding the whole thing together fr fr.
  • dvb_q — List of buffers that are not filled yet. the "waiting room" energy 💀
  • buf — Pointer to the buffer that are currently being filled. (yes the original grammar said "that are", we're keeping it, it's canon 💖)
  • offset — index to the next position at the buf to be filled. the lil bookmark of progress ✨
  • remain — How many bytes are left to be filled at buf. the countdown, the suspense, the drama 😭
  • state — bitmask of buffer states as defined by enum dvb_vb2_states. bitmask bestie, not a single mood, a whole spectrum.
  • buf_siz — size of each VB2 buffer.
  • buf_cnt — number of VB2 buffers. (yes, buf_siz and buf_cnt are different things, don't mix them up, i'm begging 🙈)
  • nonblocking — If different than zero, device is operating on non-blocking mode. zero = blocking, nonzero = we do NOT wait, we move 🌈
  • flags — buffer flags as defined by enum dmx_buffer_flags. Filled only at DMX_DQBUF. DMX_QBUF should zero this field. ⚠️ like — this is a real rule, not a suggestion, the zeroing is not optional.
  • count — monotonic counter for filled buffers. Helps to identify data stream loses. Filled only at DMX_DQBUF. DMX_QBUF should zero this field. same deal as flags, bestie: fill at DMX_DQBUF, zero at DMX_QBUF, periodt. the monotonic-ness is the whole point — drops get caught that way 👑
  • name — name of the device type. Currently, it can either be "dvr" or "demux_filter". that's the entire roster, just those two, don't invent a third one 🔥
lowkey important reminder: both flags and count say "Filled only at DMX_DQBUF. DMX_QBUF should zero this field." — two different fields, same exact rule. write it on your hand if u have to 💀

🧚 SEE ALSO 🧚

Kernel file ./include/media/dvb_vb2.h plus the whole friend group:

go read them all, they're all slay, this struct doesn't exist in a vacuum bestie 🌟

and that's the page!! 💜 this lil manual lives at ./include/media, dated October 2026, and its official title card reads struct dvb_vb2_ctx(9) — mwah, bye, go fill some buffers responsibly 🎀✨

📦 where this page comes from