OEMs can also implement their own UEFI flashing application. Microsoft provides a UEFI flashing application which can be used in non-manufacturing scenarios. This OS is used specifically for installing updates.įull Flash Update (FFU) image flashing mode refers to a UEFI application that flashes an OS image to device storage. The update OS is a minimal OS environment provided by Microsoft. The following diagram illustrates this process at a high level.įollowing are additional details about some of the components in this diagram: The UEFI environment launches the Windows Boot Manager, which determines whether to boot to Full Flash Update (FFU) image flashing or device reset mode, to the update OS, or to the main OS. These applications can utilize UEFI drivers and services. The firmware boot loaders boot the UEFI environment and hands over control to UEFI applications written by the SoC vendor, Microsoft, and OEMs. The device is powered on and runs the SoC-specific firmware boot loaders, which initialize the hardware on the device and provide emergency flashing functionality. When a Windows 10 device is turned on, it goes through the following high-level process: This topic provides an overview of the boot process, and it describes the SoC firmware boot loaders, UEFI, and Windows Boot Manager in more detail.

Windows Boot Manager provided by Microsoft. UEFI (Unified Extensible Firmware Interface) environment provided by the SoC vendor.

To accommodate each of these scenarios, the Windows 10 boot process uses the following components:įirmware boot loaders provided by the System on Chip (SoC) vendor. Afterwards, the device needs to ensure that the device is booting into the appropriate OS depending on if the user wants to perform an update or a restore on the device, or if the user wants to boot the device into the main OS. After the device's firmware initializes all the hardware, the device needs to ensure that there is enough power to boot. Some information in this section may apply only to Windows 10 Mobile and certain processor architectures.Ī device running Windows 10 has several requirements for booting into the OS.

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