msi_alloc_desc(9)

🎀 msi_alloc_desc(9) — like, the Kernel API Manual page you actually wanna read 🎀

okay so bestie, welcome to msi_alloc_desc(9) from the Kernel API Manual — this is the one that hands you a shiny, already-initialized msi_desc. no cap, it does the setup so you don't have to 💅

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✨ NAME ✨

msi_alloc_desc — allocate an initialized msi_desc, literally what it says on the tin 🫶

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🌸 SYNOPSIS 🌸

struct msi_desc * msi_alloc_desc (struct device *dev , int nvec , const struct irq_affinity_desc *affinity );

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🦋 ARGUMENTS 🦋

• dev — pointer to the device this desc is being allocated for. it's giving "whose MSI is this anyway" energy 👑
• nvec — the number of vectors used in this entry. count 'em, bestie 🔢
• affinity — an optional pointer to an affinity mask array of size nvec. optional is the keyword here, it can be NULL and that's valid 🙈

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💜 DESCRIPTION 💜

so here's the tea ☕ — if affinity is not NULL, then an affinity array[nvec] gets allocated, and the affinity masks and flags from affinity are copied over into it. basically it packs up the affinity vibes and moves them into your new desc ✨

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⭐ RETURN ⭐

pointer to the allocated msi_desc on success — or NULL on failure 😭 (check it, fr fr, don't just vibe forward without checking)

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🌈 SEE ALSO 🌈

the whole friend group 🫶 — Kernel file ./kernel/irq/msi.c, and then:

• struct msi_device_data(9)
• struct msi_ctrl(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)

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and that's the whole page, bestie 🍓 this one lives in ./kernel/irq and the version/date stamp is October 2026 — so bookmark it, screenshot it, send it to the group chat 💖 mwah, go allocate something iconic 💅✨