STRUCT MEI_MSG_HDR(9)

🎀 struct mei_msg_hdr(9) 🎀

okay so welcome to struct mei_msg_hdr — MEI BUS Interface Section, bestie! this page lives in the Kernel API Manual, and it's literally the whole personality of the MEI message header. sit down, grab a strawberry 🍓 drink, we're doing this.

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✨ SYNOPSIS ✨

struct mei_msg_hdr {
    u32 me_addr:8;
    u32 host_addr:8;
    u32 length:9;
    u32 reserved:3;
    u32 extended:1;
    u32 dma_ring:1;
    u32 internal:1;
    u32 msg_complete:1;
    u32 extension[];
};

look at her. bitfields and a flexible array member, she's giving main character energy fr fr 💅

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🌸 Members 🌸

• me_addr — the device address. that's the ME side of the convo, periodt.
• host_addr — the host address. the other half of the friendship bracelet 🫶
• length — message length. how much ✨stuff✨ is in this message.
• reserved — reserved. it's reserved. hands off, not for us 🙈
• extended — flags that the message has an extended header. yes queen, there's more header.
• dma_ring — message is on dma ring. she's on the ring!! 🎀
• internal — message is internal. for insiders only, iykyk.
• msg_complete — the last packet of the message. the finale, the last episode, the final rose 🌹
• extension — extension of the header. the bonus content, the deluxe edition 💖

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🔥 SEE ALSO 🔥

the whole fam is here, no gatekeeping:

Kernel file ./drivers/misc/mei/hw.h

• enum mei_hbm_status(9)
• enum mei_ext_hdr_type(9)
• struct mei_ext_hdr(9)
• struct mei_ext_meta_hdr(9)
• struct mei_ext_hdr_vtag(9)
• mei_ext_begin(9)
• mei_ext_last(9)
• struct mei_ext_hdr_gsc_h2f(9)
• struct mei_ext_hdr_gsc_f2h(9)
• mei_ext_next(9)
• mei_ext_hdr_len(9)
• struct mei_hbm_cl_cmd(9)
• enum hbm_host_enum_flags(9)
• struct hbm_host_enum_request(9)
• struct mei_client_properties(9)
• struct hbm_add_client_request(9)
• struct hbm_add_client_response(9)
• struct hbm_power_gate(9)
• struct hbm_client_connect_request(9)
• struct hbm_client_connect_response(9)
• struct hbm_notification_request(9)
• struct hbm_notification_response(9)
• struct hbm_notification(9)
• struct hbm_dma_mem_dscr(9)
• struct hbm_dma_setup_request(9)
• struct hbm_dma_setup_response(9)
• struct hbm_dma_ring_ctrl(9)
• struct hbm_capability_request(9)
• struct hbm_capability_response(9)
• struct hbm_client_dma_map_request(9)
• struct hbm_client_dma_unmap_request(9)
• struct hbm_client_dma_response(9)

like. that's a lot of friends and honestly? we love a lore-rich universe 💀

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ngl the <rainbow>reserved</rainbow> field is exactly what it says — reserved. don't be nosy, don't touch, that's not our business 🫶

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mwah, that's the page!! this one came from ./drivers/misc/mei and it's dated October 2026 — so mark your calendar bestie, and see you at struct mei_msg_hdr(9) again soon 💜✨