STRUCT MSI_DESC_DATA(9)

💅 struct msi_desc_data(9) 💅

okay bestie, so this is from the Kernel API Manual and it's literally about a generic MSI descriptor data struct — the ultimate low-stakes little container, no cap 🫶

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✨ NAME ✨

struct msi_desc_data — Generic MSI descriptor data. that's it, that's the whole vibe ✨

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🌸 SYNOPSIS 🌸

struct msi_desc_data {
    union msi_domain_cookie         dcookie;
    union msi_instance_cookie       icookie;
};

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🎀 MEMBERS 🎀

• dcookie — the cookie for MSI domain specific data, and it's required for irq_chip callbacks 🔥 so like, not optional bestie, it's giving mandatory.
• icookie — the cookie for the MSI interrupt instance, handed over by the usage site to the allocation function 🍓

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💖 DESCRIPTION 💖

the way that this data is implementation defined 😭 — meaning what's actually inside is up to whoever implements it, fr fr. like, PCI/IMS implementations get to define what the data means. and the MSI core? it ignores this data completely. literally does not care. main character struct with zero supervision 💅

ngl if you're looking for the MSI core to interpret anything in here — it won't. that's not its job, and honestly? iconic of it.

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🌈 SEE ALSO 🌈

• Kernel file ./include/linux/msi.h
• struct msi_msg(9)
• struct pci_msi_desc(9)
• union msi_domain_cookie(9)
• struct msi_desc(9)
• struct msi_dev_domain(9)
• msi_first_desc(9)
• msi_domain_for_each_desc(9)
• msi_for_each_desc(9)
• msi_msg_set_addr(9)
• msi_insert_msi_desc(9)
• msi_free_msi_descs_range(9)
• msi_free_msi_descs(9)
• struct msi_domain_ops(9)
• struct msi_domain_info(9)
• struct msi_domain_template(9)
• struct msi_parent_ops(9)

go read them all, i'll wait 🧚💜

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okay that's the whole page, ily, go slay your MSI code 💅✨ source is ./include/linux, dated October 2026, and it's struct msi_desc_data(9) — periodt 🎀