STRUCT DMXDEV(9)

💅 struct dmxdev(9) 💅

okay so bestie, gather round, because we're diving into the Kernel API Manual and this one is literally the blueprint for a digital TV demux device, no cap. it's giving "backstage pass to the whole demux operation" and i am obsessed. 🎀

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✨ NAME ✨

struct dmxdev — describes a digital TV demux device. that's it, that's the vibe. it's the main character struct that holds the entire demux life together. 👑

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🦋 SYNOPSIS 🦋

struct dmxdev {
    struct dvb_device *dvbdev;
    struct dvb_device *dvr_dvbdev;
    struct dmxdev_filter *filter;
    struct dmx_demux *demux;
    int filternum;
    int capabilities;
    unsigned int may_do_mmap:1;
    unsigned int exit:1;
  #define DMXDEV_CAP_DUPLEX 1;
    struct dmx_frontend *dvr_orig_fe;
    struct dvb_ringbuffer dvr_buffer;
  #define DVR_BUFFER_SIZE (10*188*1024);
    struct dvb_vb2_ctx dvr_vb2_ctx;
    struct mutex mutex;
    spinlock_t lock;
 };

look at her. every field is doing its job. iconic behavior honestly. 🫶

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🌸 Members 🌸

these are the squad members, and yes, each one has a role and each one ate:

• dvbdev — pointer to struct dvb_device associated with the demux device node. basically the demux node's official rep. 💖
• dvr_dvbdev — pointer to struct dvb_device associated with the dvr device node. same energy, but for the dvr side of things.
• filter — pointer to struct dmxdev_filter. the filter crew, linked up.
• demux — pointer to struct dmx_demux. the actual demux brain trust.
• filternum — number of filters. a count. a lil number. lowkey important.
• capabilities — demux capabilities as defined by enum dmx_demux_caps. this is where the flex-worthy features get declared. ✨
• may_do_mmap — flag used to indicate if the device may do mmap. permission slip energy, fr fr.
• exit — flag to indicate that the demux is being released. the goodbye flag. 😭
• dvr_orig_fe — pointer to struct dmx_frontend.
• dvr_buffer — embedded struct dvb_ringbuffer for DVB output. the ring buffer stays embedded, we love a self-contained queen.
• dvr_vb2_ctx — control struct for VB2 handler.
• mutex — protects the usage of this structure. do not skip the mutex, i'm begging. 🔥
• lock — protects access to dmxdev->filter->data. different lock, different job, same "respect it or regret it" energy.

bestie pls note: mutex and lock are two separate things guarding two separate things — don't be out here mixing them up 💀

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🧚 SEE ALSO 🧚

go read these next, they're all part of the same lore drop:

• Kernel file ./include/media/dmxdev.h
• enum dmxdev_type(9)
• enum dmxdev_state(9)
• struct dmxdev_feed(9)
• struct dmxdev_filter(9)
• dvb_dmxdev_init(9)
• dvb_dmxdev_release(9)

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and that's the whole page bestie, you understood it perfectly, i'm so proud 🥹

sign-off time: this masterpiece lives in ./include/media, dated October 2026, and it's brought to you as struct dmxdev(9). slay, periodt, go read the kernel. 💜🌈⭐