STRUCT ISST_IF_MBOX_CMD(9)

💖 struct isst_if_mbox_cmd — the mail-box-command glow-up 💖

okay so this is a page from the Kernel API Manual, and the star of the show is struct isst_if_mbox_cmd(9). yes bestie, we're doing kernel structs today, and honestly? it's giving "small struct, big responsibilities" ✨

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🌸 NAME 🌸

struct isst_if_mbox_cmd — the structure that defines a mail box command 🎀

like, that's literally its whole job. it defines a mailbox command. iconic behavior fr.

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✨ SYNOPSIS ✨

here's the whole vibe, verbatim, no cap:

struct isst_if_mbox_cmd {
    __u32 logical_cpu;
    __u32 parameter;
    __u32 req_data;
    __u32 resp_data;
    __u16 command;
    __u16 sub_command;
    __u32 reserved;
 };

look at her. seven fields, perfectly aligned, main character energy 💅

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🦋 Members 🦋

let's go field by field, bestie, because every single one matters:

• logical_cpu — the logical CPU number you use to get the target PCI device 🖥️ like, this is how you point at the right device, iykyk
• parameter — the mailbox parameter value. yes. that's the whole description. she's mysterious, she's lowkey, she's parameter 💜
• req_data — the request data for the mailbox 📨 the actual ask
• resp_data — the response data for the mailbox command response 📬 the actual answer, bestie, the reply, the "we got back to you"
• command — the mailbox command value. the what are we even doing here field 👑
• sub_command — the mailbox sub command value. the okay but more specifically field 🎀
• reserved — unused, so set it to 0. and when I say set it to 0, I mean set it to 0 🙈 don't get cute with it, don't put a little 1 in there for fun, just 0

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💀 Description 💀

so basically: this is the structure you use to specify a mailbox command that's gonna be sent to PUNIT 🔥 that's it, that's the whole description, and honestly it ate.

no extra lore. no secret tricks. just a struct holding a mailbox command destined for PUNIT, and now you know exactly which field does what. periodt 💖

ngl bestie, treat reserved right — it's unused and it wants to be 0. that's not a suggestion, that's the spec 🌈

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⭐ SEE ALSO ⭐

go read these next, bestie, the whole extended universe is right here:

• Kernel file ./include/uapi/linux/isst_if.h
• struct isst_if_platform_info(9)
• struct isst_if_cpu_map(9)
• struct isst_if_cpu_maps(9)
• struct isst_if_io_reg(9)
• struct isst_if_io_regs(9)
• struct isst_if_mbox_cmds(9)
• struct isst_if_msr_cmd(9)
• struct isst_if_msr_cmds(9)
• struct isst_core_power(9)
• struct isst_clos_param(9)
• struct isst_if_clos_assoc(9)
• struct isst_if_clos_assoc_cmds(9)
• struct isst_tpmi_instance_count(9)
• struct isst_perf_level_info(9)
• struct isst_perf_level_control(9)
• struct isst_perf_feature_control(9)
• struct isst_perf_level_data_info(9)
• struct isst_perf_level_fabric_info(9)
• struct isst_perf_level_cpu_mask(9)
• struct isst_base_freq_info(9)
• struct isst_turbo_freq_info(9)

that's the whole friend group 🫶 and yes, isst_if_mbox_cmds(9) with the extra s is a different struct — plural energy, do not confuse them, I'm begging 😭

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and that's the page!! this one lives in ./include/uapi/linux, dated October 2026, and it's filed under struct isst_if_mbox_cmd(9) in the Kernel API Manual ✨ go forth and send your mailbox commands to PUNIT responsibly, bestie 💅🎀💖