STRUCT SCMI_VIO_MSG(9)

💅 struct scmi_vio_msg(9) — the Kernel API Manual, but make it make sense 🎀

okay so bestie, welcome to the Kernel API Manual entry for struct scmi_vio_msg. this little cutie is literally just a container of Transport PDU info — think of it as the group chat message envelope for SCMI-over-virtio. it's not doing the talking, it's holding the school bag 🎒 for the messages that do. no cap, it's giving "plumbing that eats" 💅

✨ NAME ✨

struct scmi_vio_msg — Transport PDU information, periodt 🫶

🌸 SYNOPSIS 🌸

look at her. she's beautiful. every field copied exactly, character for character, because we do not play with struct definitions 🔥

struct scmi_vio_msg {
    struct scmi_msg_payld *request;
    struct scmi_msg_payld *input;
    struct list_head list;
    unsigned int rx_len;
    unsigned int max_len;
    unsigned int poll_idx;
    enum poll_states poll_status;
    spinlock_t poll_lock;
    refcount_t users;
 };

🦋 Members 🦋

okay so let's do a vibe check on every single field, one by one, no skipping, that's the rule 💖

• request — the SDU used for commands. so like, this is the one that actually goes out and asks for stuff 🗣️
• input — the SDU used for (delayed) responses and notifications. the replies and the lil pings slide in here, sometimes fashionably late 🙈
• list — a list which scmi_vio_msg may be part of. yes bestie, she's a linkable icon, she can be in the group list 👑
• rx_len — input SDU size in bytes, once input has been received. so it's the real, actual size — but only once the input has actually landed, not before, don't be weird about it ⭐
• max_len — maximum allowed SDU size in bytes. the ceiling, the limit, the "don't try it" line 💀
• poll_idx — the last used index registered for polling purposes, if this message transaction reply was configured for polling. iykyk — polling mode only, otherwise it's just vibing there 🌈
• poll_status — the polling state for this message. current mood of the poll, basically ✨
• poll_lock — a lock to protect poll_status. hold the line bestie, that state stays safe 🧚
• users — a reference count to track this message's users, and to avoid premature freeing (and reuse) when polling and IRQ execution paths interleave. highkey the most important one — this is the "please don't free me while both paths are literally in the same room" guardian 🫶 honestly iconic

🔥 SEE ALSO 🔥

go read these next, they're all connected, it's a whole cinematic universe 🎬

• Kernel file ./drivers/firmware/arm_scmi/transports/virtio.c
• Theory of Operation(9)
• struct scmi_vio_channel(9)
• virtio_mark_txdone(9)
• virtio_poll_done(9)

⚠️ gentle reminder bestie: all of the above is documentation of the struct, not a tutorial on how to poke at it yourself — the manpage describes what's there, and that's it. no invented behaviour, we don't do that here 💜

and that's the whole page, we ate, no crumbs 🍓 this footer is coming to you straight from ./drivers/firmware/arm_scmi/tr..., dated October 2026, and yes it's still called struct scmi_vio_msg(9). slay, bye 😭👑