msi_capability_init(9)

🌸 NAME 🌸

okay so this is msi_capability_init(9) from the Kernel API Manual, and its whole vibe is: configure device's MSI capability structure ✨ (yes, literally that, bestie).

🦋 SYNOPSIS 🦋

int msi_capability_init (struct pci_dev *dev , int nvec , struct
       irq_affinity *affd );

🎀 ARGUMENTS 🎀

• dev — pointer to the pci_dev data structure of the MSI device function 🫶
• nvec — number of interrupts to allocate 🌟
• affd — description of automatic IRQ affinity assignments (may be NULL) 🙈

🔥 DESCRIPTION 🔥

This is the glow-up: it sets up the MSI capability structure of the device with the requested number of interrupts. Periodt.

Then the return-value lore, iykyk:

• 0 means the successful setup of an entry with the new MSI IRQ — slay ✅
• a negative return value means there was an error — not the vibe 😭
• a positive return value means the number of interrupts which could have been allocated — so it’s giving you the count, bestie 🔢

💜 SEE ALSO 💜

Kernel file ./drivers/pci/msi/msi.c is in the group chat, plus all these linked icons:

• pci_msi_supported(9)
• pci_msi_mask_irq(9)
• pci_msi_unmask_irq(9)
• pci_msi_vec_count(9)
• msix_prepare_msi_desc(9)
• msix_capability_init(9)
• pci_msix_write_tph_tag(9)

byeee 💖 source/version check: ./drivers/pci/msi · October 2026 · msi_capability_init(9) — that’s the cute little sign-off, no cap 🎀