STRUCT MPT3_IOCTL_BTDH_MAPPING(9)

✨ struct mpt3_ioctl_btdh_mapping 💅

okay so bestie, this is a page from the Kernel API Manual and it's literally about struct mpt3_ioctl_btdh_mapping — the mapping-info struct, iykyk 🎀. It's giving "how do I turn a handle into a bus/id and back again" energy, and ngl it's kind of iconic.

Here's the breakdown of what's inside it, one field at a time, no skips:

• @hdr — the generic header, just vibing at the top 🫶
• @id — the target device identification number
• @bus — the SCSI bus number that the target device exists on
• @handle — the device handle for the target device
• @rsvd — reserved (not for you, bestie 🙈)

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🌸 SYNOPSIS 🌸

struct mpt3_ioctl_btdh_mapping {
    struct mpt3_ioctl_header hdr;
    uint32_t id;
    uint32_t bus;
    uint16_t handle;
    uint16_t rsvd;
 };

look at that layout. immaculate. the alignment? ate. 🔥

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🦋 Members 🦋

the member list is above, and honestly the struct speaks for itself — every field is a little main character in its own right 💖

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👑 Description 👑

okay so this is the part where the actual lore drops, and it's a two-way street, literally:

• Wanna get a bus/id? the application sets handle to a valid handle, and bus/id to 0xFFFF. ✨
• Wanna get the device handle instead? the application sets bus/id to a valid value, and handle to 0xFFFF. 💅

so yes — 0xFFFF is the "idk, you tell me" of this struct. you fill in one side, you leave the other side as 0xFFFF, and the kernel does its little magic trick. no cap, that's the whole vibe. 🧚

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🌈 SEE ALSO 🌈

go read these next, bestie, they're all in the same friend group:

• Kernel file ./drivers/scsi/mpt3sas/mpt3sas_ctl.h struct
• mpt3_ioctl_header(9)
• struct mpt3_ioctl_diag_reset(9)
• struct mpt3_ioctl_pci_info(9)
• struct mpt3_ioctl_iocinfo(9)
• struct mpt3_ioctl_eventquery(9)
• struct mpt3_ioctl_eventenable(9)
• struct MPT3_IOCTL_EVENTS(9)
• struct mpt3_ioctl_eventreport(9)
• struct mpt3_ioctl_command(9)
• struct mpt3_diag_register(9)
• struct mpt3_diag_unregister(9)
• struct mpt3_diag_query(9)
• struct mpt3_diag_release(9)
• struct mpt3_diag_read_buffer(9)
• struct mpt3_addnl_diag_query(9)
• struct mpt3_enable_diag_sbr_reload(9)
• struct mpt3_passthru_command(9)

like, the whole squad. 🫶

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and that's the whole page!! 💖 this one lives over in ./drivers/scsi/mpt3sas — that's the source, and the version/date on the tin is October 2026. periodt. 🌟