usb_make_path(9)

✨ usb_make_path(9) ✨

okay so this is from the Kernel API Manual bestie, and it's literally the glow-up guide for building a stable device path in the USB tree 🌳💖

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🌸 NAME 🌸

usb_make_path — returns stable device path in the usb tree

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🎀 SYNOPSIS 🎀

int usb_make_path (struct usb_device *dev , char *buf , size_t size );

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🦋 ARGUMENTS 🦋

• dev — the device whose path is being constructed 👑 (yes, this one, the main character)
• buf — where to put the string 🫶 like the little home you're building the path into
• size — how big is buf? 🤨 the question we must ask

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💅 RETURN 💅

Length of the string (that's > 0 bestie, we love a positive number ✨) or negative if size was too small 😭 tragedy, honestly.

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🔥 NOTE 🔥

okay this is the part where it gets good. This identifier is intended to be "stable", reflecting physical paths in hardware — think physical bus addresses for host controllers, or ports on USB hubs 💫. That makes it stay the same until systems are physically reconfigured, by re-cabling a tree of USB devices or by moving USB host controllers. Periodt. 🎯

Adding and removing devices — including virtual root hubs in host controller driver modules — does not change these path identifiers. Neither does rebooting or re-enumerating. ngl these are way more useful identifiers than changeable ("unstable") ones like bus numbers or device addresses 🙈💀. Unstable identifiers could never fr fr.

With a partial exception for devices connected to USB 2.0 root hubs, these identifiers are also predictable 👀. So long as the device tree isn't changed, plugging any USB device into a given hub port always gives it the same path. Because of the use of "companion" controllers, devices connected to ports on USB 2.0 root hubs (EHCI host controllers) will get one path ID if they are high speed, and a different one if they are full or low speed 🌀. iykyk.

⚠️ lowkey important: that partial exception is real — same port, different speed, different path. don't come for me, that's just how companion controllers vibe 😌

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🌈 SEE ALSO 🌈

Kernel file ./include/linux/usb.h

• struct usb_host_endpoint(9)
• struct usb_interface(9)
• usb_set_intfdata(9)
• struct usb_interface_cache(9)
• struct usb_host_config(9)
• struct usb_device(9)
• usb_hub_for_each_child(9)
• usb_interface_claimed(9)
• USB_DEVICE(9)
• USB_DEVICE_VER(9)
• USB_DEVICE_INTERFACE_CLASS(9)
• USB_DEVICE_INTERFACE_PROTOCOL(9)
• USB_DEVICE_INTERFACE_NUMBER(9)
• USB_DEVICE_INFO(9)
• USB_INTERFACE_INFO(9)
• USB_DEVICE_AND_INTERFACE_INFO(9)
• USB_VENDOR_AND_INTERFACE_INFO(9)
• struct usb_driver(9)
• struct usb_device_driver(9)
• struct usb_class_driver(9)
• module_usb_driver(9)
• struct urb(9)
• usb_fill_control_urb(9)
• usb_fill_bulk_urb(9)
• usb_fill_int_urb(9)
• usb_urb_dir_in(9)
• usb_urb_dir_out(9)
• struct usb_sg_request(9)

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✨ that's the whole page, bestie, you ate it up ✨ 💖

this gem lives in ./include/linux, dated October 2026 — mwah, kisses, study well and go build some stable paths 🎀🦋💜