STRUCT HV_MSI_DESC(9)

💅 struct hv_msi_desc(9) 💅

okay bestie, welcome to the Kernel API Manual ✨ and specifically to struct hv_msi_desc(9) — yes that's the page name, yes we're doing this, and yes you're gonna get it. sit down, hydrate, let's go 🫶

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✨ NAME ✨

struct hv_msi_desc — and honestly? that's it. the manpage gives us nothing else here. a whole dash. the void. main character energy with no backstory 💀 (we love a mystery though, so keep reading, the SYNOPSIS has the tea ☕)

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🌸 SYNOPSIS 🌸

here's the whole struct, character for character, no cap:

struct hv_msi_desc {
    u8 vector;
    u8 delivery_mode;
    u16 vector_count;
    u32 reserved;
    u64 cpu_mask;
 };

like… look at her. so compact. so iconic. let's meet the members 🎀

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🦋 Members 🦋

• vector — the IDT entry. that's the whole description. no notes 💅
• delivery_mode — as defined in Intel's Programmer's Reference Manual, Volume 3, Chapter 8. yeah, that's the homework. go read chapter 8, i'll wait 🧚
• vector_count — the number of contiguous entries in the Interrupt Descriptor Table that this Message-Signaled Interrupt is occupying. and for "MSI", as first defined in PCI 2.2, this can be between 1 and…
• 32 — okay so ngl, the manpage formatting literally split this off into its own entry and i'm not gonna lie to you about it 🙈 this is the rest of the line above: 32. so, 1 and 32. and then — For "MSI-X," as first defined in PCI 3.0, this must be 1, because each MSI-X table entry would have its own descriptor. periodt, no exceptions 🔥
• reserved — empty space. she's just vibing. padding queen 👑
• cpu_mask — all the target virtual processors. every single one. the whole group chat 🫶

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💜 SEE ALSO 💜

first up, the location tea: Kernel file ./drivers/pci/controller/pci-hyperv.c struct — that's where she lives 🏠

and now the full squad, because bestie has a lot of friends and we are NOT leaving anyone out:

• hv_msi_desc2(9)
• struct tran_int_desc(9)
• hv_irq_retarget_interrupt(9)
• hv_pci_generic_compl(9)
• devfn_to_wslot(9)
• wslot_to_devfn(9)
• _hv_pcifront_read_config(9)
• _hv_pcifront_write_config(9)
• hv_pcifront_read_config(9)
• hv_pcifront_write_config(9)
• hv_pci_read_config_compl(9)
• hv_read_config_block(9)
• hv_pci_write_config_compl(9)
• hv_write_config_block(9)
• hv_register_block_invalidate(9)
• hv_msi_free(9)
• hv_compose_msi_msg(9)
• hv_pcie_init_irq_domain(9)
• get_bar_size(9)
• survey_child_resources(9)
• prepopulate_bars(9)
• create_root_hv_pci_bus(9)
• q_resource_requirements(9)
• new_pcichild_device(9)
• get_pcichild_wslot(9)
• pci_devices_present_work(9)
• hv_pci_start_relations_work(9)
• hv_pci_devices_present(9)
• hv_pci_devices_present2(9)
• hv_eject_device_work(9)
• hv_pci_eject_device(9)
• hv_pci_onchannelcallback(9)
• hv_pci_protocol_negotiation(9)
• hv_pci_free_bridge_windows(9)
• hv_pci_allocate_bridge_windows(9)
• hv_allocate_config_window(9)
• hv_pci_enter_d0(9)
• hv_pci_query_relations(9)
• hv_send_resources_allocated(9)
• hv_send_resources_released(9)
• hv_pci_probe(9)
• hv_pci_remove(9)

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lowkey the whole drivers/pci/controller directory is a friend group and this struct is the one who brings the snacks 🍓

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and that's the page!! 💖 sign-off time: this lives over in ./drivers/pci/controller, dated October 2026, and it's filed under struct hv_msi_desc(9). slay, you read the whole thing, i'm so proud of you 🎀✨👑