STRUCT UTP_TRANSFER_CMD_DESC(9)

✨ NAME ✨

struct utp_transfer_cmd_desc — the UTP Command Descriptor (aka UCD, bestie, learn the acronym it's everywhere) 💅

(oh also hiii this is a page from the Kernel API Manual, welcome to the kernel, please wipe your feet 🫶)

🌸 SYNOPSIS 🌸

struct utp_transfer_cmd_desc {
    u8 command_upiu[ALIGNED_UPIU_SIZE];
    u8 response_upiu[ALIGNED_UPIU_SIZE];
    u8 prd_table[];
};

okay so it's giving very "three fields and a vibe" and honestly? iconic. no cap. ✨

🎀 Members 🎀

• command_upiu — bestie this is the Command UPIU Frame address, like the actual address, not a metaphor, it's command_upiu, it holds the Command UPIU Frame address 💖
• response_upiu — the Response UPIU Frame address. yes it's the sibling of the one above, they're matching, it's adorable, the way that commands and responses are literally in the same struct together 🦋
• prd_table — the Physical Region Descriptor 🌈: an array of SG_ALL struct ufshcd_sg_entry's. and listen — variant-specific fields may be present after each one, so don't go assuming the layout is uniform, that's the trap, iykyk 😭

lowkey important: prd_table[] is a flexible array member, so it lives at the end of the struct and it does not have a size baked in. highkey iconic of it. 👑

🧚 SEE ALSO 🧚

• Kernel file ./include/ufs/ufshci.h
• struct ufshcd_sg_entry(9)
• struct request_desc_header(9)
• struct utp_transfer_req_desc(9)

go read them, they're literally all connected, it's a whole friend group 🫶

okay that's the whole page, no notes 💜

✨ sign-off time ✨ this iconic little page lives in ./include/ufs, dated October 2026, and it's filed under struct utp_transfer_cmd_desc(9) — mwah, slay, periodt 💅🔥