STRUCT ACRN_MMIO_REQUEST(9)

💅 struct acrn_mmio_request(9) — like, the whole vibe

okay so bestie, welcome to the Kernel API Manual ✨ this one's all about struct acrn_mmio_request, and honestly? it's giving "small struct, big responsibilities" 🎀 it holds the info for a single MMIO I/O request, and we're gonna walk through it field by field, no cap 💖

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🌸 NAME 🌸

struct acrn_mmio_request — Info of a MMIO I/O request 🦋

like literally, that's the whole elevator pitch. this struct is the little envelope that says "hey, someone's touching memory-mapped I/O, here's the deets" 💌

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✨ SYNOPSIS ✨

here's the shape of it, bestie — copy it exactly, don't freestyle:

struct acrn_mmio_request {
    __u32 direction;
    __u32 reserved;
    __u64 address;
    __u64 size;
    __u64 value;
 };

look at that alignment. the __u32s up top, the __u64s chillin' below. it's giving organized. it's giving "I know my types" 👑

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🫶 Members 🫶

okay this is the part where we actually read the fields, and there are exactly five, so no skipping 💀

• direction — the access direction of this request (it's one of the ACRN_IOREQ_DIR_* values). read? write? that's what this lil guy tells you 👀
• reserved — reserved for alignment and should be 0. periodt. don't put stuff in it, it's not for you, it's for the alignment gods 🙈
• address — the access address of this MMIO I/O request. where in memory-mapped land we're poking around 📍
• size — the access size of this MMIO I/O request. how many bytes we're touching, lowkey important 🌸
• value — the read/write value of this MMIO I/O request. the actual payload — what got read, or what you're writing in there 💜

real talk: reserved = 0, always. it's not a suggestion, it's the whole point of the field 😭

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🦋 SEE ALSO 🦋

you want the whole friend group? say less, i got you 🫶 the kernel file ./include/uapi/linux/acrn.h is where all of these live, and here's every single one of them, in order, bestie:

• struct acrn_pio_request(9)
• struct acrn_pci_request(9)
• struct acrn_io_request(9)
• struct acrn_ioreq_notify(9)
• struct acrn_vm_creation(9)
• struct acrn_gp_regs(9)
• struct acrn_descriptor_ptr(9)
• struct acrn_regs(9)
• struct acrn_vcpu_regs(9)
• struct acrn_vm_memmap(9)
• struct acrn_ptdev_irq(9)
• struct acrn_pcidev(9)
• struct acrn_mmio_dev_res(9)
• struct acrn_mmiodev(9)
• struct acrn_vdev(9)
• struct acrn_msi_entry(9)
• struct acrn_cstate_data(9)
• struct acrn_pstate_data(9)
• struct acrn_ioeventfd(9)
• struct acrn_irqfd(9)

that's twenty, count 'em, all present and accounted for 💅

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okay that's the page!! this one came from ./include/uapi/linux and it's dated October 2026 — so like, future-coded of it 🌈 go forth, set reserved to 0, and slay 💖✨🎀