pbus_select_window(9)

okay bestie, welcome to pbus_select_window(9) from the Kernel API Manual — this is the kernel page that picks a bridge window for a resource, and it’s lowkey iconic 🎀✨

🌸 NAME 🌸

pbus_select_window — select bridge window for a resource 💅

✨ SYNOPSIS ✨

copy this exactly, no cap:

struct resource * pbus_select_window (struct pci_bus *bus , const struct resource *res );

🫶 ARGUMENTS 🫶

• bus — PCI bus 🚌
• res — Resource 🍓

💖 DESCRIPTION 💖

okay so the whole vibe: select the bridge window for res. If the resource is already assigned, return the current bridge window. periodt. 🦋

For memory resources, the selection is done as follows — follow the little flowchart in your head, bestie:

• Any non-prefetchable resource is put into the non-prefetchable window.
• If there is no prefetchable MMIO window, put all memory resources into the non-prefetchable window.
• If there’s a 64-bit prefetchable MMIO window, put all 64-bit prefetchable resources into it and place 32-bit prefetchable memory into the non-prefetchable window.
• Otherwise, put all prefetchable resources into the prefetchable window.

👑 RETURN 👑

the bridge window resource or NULL if no bridge window is found. that’s the whole answer — NULL means no bridge window found, fr fr. 😭

🦋 SEE ALSO 🦋

• Kernel file ./drivers/pci/setup-bus.c
• pci_dev_res_add_to_list(9), pbus_select_window_for_type(9), reassign_resources_sorted(9), assign_requested_resources_sorted(9), pbus_size_io(9), pbus_size_mem(9)

cute sign-off: source/version is ./drivers/pci, dated October 2026, and this page is pbus_select_window(9) 💜