STRUCT PCI_DOE_MB(9)

okay bestie, so we're deep in the Kernel API Manual today and the page is struct pci_doe_mb(9). it's giving "small struct, big responsibilities" and honestly? obsessed. let's get into it 🫶

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🎀 NAME 🎀

struct pci_doe_mb — the state for a single DOE mailbox. one mailbox, one struct, no sharing, no cap 💅

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✨ SYNOPSIS ✨

struct pci_doe_mb {
    struct pci_dev *pdev;
    u16 cap_offset;
    struct xarray feats;
    wait_queue_head_t wq;
    struct workqueue_struct *work_queue;
    unsigned long flags;
  #ifdef CONFIG_SYSFS;
    struct device_attribute *sysfs_attrs;
  #endif;
 };

like, look at her. iconic layout. note the #ifdef CONFIG_SYSFS; in there — yes, that's conditional, and yes, you gotta respect it 🌸

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🌈 Members 🌈

okay so every single field, one by one, no skipping, we're doing the full tour 🧚

• pdev — the PCI device that this mailbox belongs to. her home. her origin story 💖
• cap_offset — the capability offset. the coordinates of where the magic lives ✨
• feats — array of the features that are supported, encoded as long values. like a little roster of what she can do 🎀
• wq — wait queue for the work item. she queues, she waits, she slays 🦋
• work_queue — the queue of pci_doe_work items. it's literally a queue of work, main character energy 🔥
• flags — a bit array of PCI_DOE_FLAG_* flags. bit array!! bit array!! 💅
• sysfs_attrs — array of sysfs device attributes. (this one's chillin' behind CONFIG_SYSFS, iykyk) 🌸

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💜 DESCRIPTION 💜

so this state is what manages a single DOE mailbox capability. one struct, one capability, that's the whole vibe.

and here's the thing, bestie — listen closely: all fields should be considered opaque to the consumers. literally all of them. don't go poking at her internals, don't try to be cute with it, that's not the assignment 🙈

how it actually works: the structure gets created by pci_doe_create_mb, and then you pass it into the helpers below. that's it. that's the flow. chef's kiss 👑

ngl, "opaque" is doing a lot of heavy lifting in that sentence. respect it. do not reach into the struct. fr fr 💀

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🦋 SEE ALSO 🦋

the whole friend group, keep them close, they're all linked 👑:

• Kernel file ./drivers/pci/doe.c
• struct pci_doe_task(9)
• pci_doe_create_mb(9)
• pci_doe_destroy_mb(9)
• pci_doe_supports_feat(9)
• pci_doe_submit_task(9)
• pci_doe(9)
• pci_find_doe_mailbox(9)

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and that's the page, bestie 🍓 this whole thing lives over in ./drivers/pci, it's dated October 2026, and it's part of the Kernel API Manual. go forth, treat the struct as opaque, and slay 💖✨