Does this path ever change? or is it always static?

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UPD trial method:

When pulling / inserting the device - does not change

When turning off / on the device - does not change

When removing / restoring a device - does not change

When rebooting - does not change

Additional question:

How is this path assigned?

What if 2 identical devices are stuck in turn into the same USB?

Will they be assigned the same address or different?

  • Most likely, yes, if you plug in vidyuhi in another pci-e . But it must be checked. - don Rumata
  • @donRumata is interested not in vidyuha, but in any device. Does the address remain static if the device remains in the same PCI/USB , etc. PCI/USB and simply turns off / on - deleted / restored. Recovers - meaning the updated hardware configuration after removing the device (rescan) to return it. - Vipz
  • Well, with usb - in general it is easy to check right now. I do not have a Windows handy, but it would be interesting to find out too. - don Rumata
  • ven and dev denote the manufacturer and the device, rev apparently a device revision. These values ​​are tied to the very piece of iron - teran
  • read on docs.microsoft.com/en-us/windows-hardware/drivers/install ... ... - teran 8:51 pm

1 answer 1

The path to the device instance is the Device Instance ID , a string that uniquely identifies the device instance in the system. Its content is determined by the bus controller driver to which the device is connected. Consists of two parts:

  • The device type identifier. Usually includes the bus name, manufacturer code and / or model code and is independent of the connection port.

  • Device instance ID (when two devices of the same type are connected to the computer, the instance ID is used to distinguish between them). In general, it is a function of the serial number of the device and / or the connection port.

Device Instance ID is guaranteed to be saved when the system reboots (that is, when the computer is turned off and then turned on with the same device on the same port). In all other cases, for example, when switching a device to another port or reinstalling its driver, the consistency of the Device Instance ID is generally not guaranteed.

Specifically for USB devices, when using a standard USB controller driver: if the device has a serial number, it will be assigned the same Instance ID when connected to another port. If the device does not have a serial number or it matches the serial number of another device already connected (which can happen when manufacturers do not bother with unique numbers, but use something like 12345678), then the Instance ID will be based on the port number and will not be saved when switching to another port. Most storage devices usually have a serial number, and USB keyboards and mice usually do not.

It should be remembered that standard drivers for USB 3.0 controllers appeared only with Windows 8. Therefore, on previous systems, non-standard drivers are used for them, which may have a different behavior.