STRUCT MSI_CTRL(9)

Okay so this is the struct msi_ctrl(9) page from the Kernel API Manual, and we are gonna get you fluent in it, bestie 💖

🎀 NAME 🎀

struct msi_ctrl — MSI internal management control structure. That's the whole name, no cap.

✨ SYNOPSIS ✨

       struct msi_ctrl {
           unsigned int                    domid;
           unsigned int                    first;
           unsigned int                    last;
           unsigned int                    nirqs;
        };

💅 Members 💅

• domid — ID of the domain on which management operations should be done. Periodt.
• first — First (hardware) slot index to operate on.
• last — Last (hardware) slot index to operate on.
• nirqs — The number of Linux interrupts to allocate. Can be larger than the range due to PCI/multi-MSI. Yes, that's the note, bestie — it can be bigger than the range.

🦋 SEE ALSO 🦋

Kernel file: ./kernel/irq/msi.c — that's the spot. And here's the whole friend group, lowkey iconic:

• struct msi_device_data(9)
• msi_alloc_desc(9)
• msi_domain_insert_msi_desc(9)
• msi_domain_free_msi_descs_range(9)
• msi_domain_add_simple_msi_descs(9)
• msi_setup_device_data(9)
• __msi_lock_descs(9)
• __msi_unlock_descs(9)
• msi_domain_first_desc(9)
• msi_next_desc(9)
• msi_domain_get_virq(9)
• msi_device_populate_sysfs(9)
• msi_device_destroy_sysfs(9)
• msi_domain_set_affinity(9)
• msi_create_irq_domain(9)
• msi_create_parent_irq_domain(9)
• msi_parent_init_dev_msi_info(9)
• msi_create_device_irq_domain(9)
• msi_remove_device_irq_domain(9)
• msi_match_device_irq_domain(9)
• msi_domain_alloc_irqs_range_locked(9)
• msi_domain_alloc_irqs_range(9)
• msi_domain_alloc_irqs_all_locked(9)
• msi_domain_alloc_irq_at(9)
• msi_device_domain_alloc_wired(9)
• msi_domain_free_irqs_range_locked(9)
• msi_domain_free_irqs_range(9)
• msi_domain_free_irqs_all_locked(9)
• msi_domain_free_irqs_all(9)
• msi_device_domain_free_wired(9)
• msi_get_domain_info(9)
• msi_device_has_isolated_msi(9)

That's the page, bestie 🫶 Source/version: ./kernel/irq; date: October 2026; footer title: struct msi_ctrl(9). Slay ✨