Understanding the Windows 10 Boot Process

Windows 10 Boot Process

In order to properly troubleshoot Windows 10 startup problems (as you are required to do in exam MD-100 from Microsoft), it is critical that you understand the various phases of the boot process and the components involved. This post provides that information below:

Phase 1 – Preboot

In this phase, the PC’s firmware is in charge and initiates a POST and loads the firmware settings. Once all this works (hopefully), the system identifies a valid system disk and reads the MBR. The system then starts the Windows Boot Manager. This is located here: %SystemDrive%\bootmgr

Phase 2 – Windows Boot Manager

It is the job of the Windows Boot Manager to find and start the Windows loader (Winload.exe). This is located on the Windows boot partition – %SystemRoot%\system32\winload.exe

Phase 3 – Windows Operating System Loader

In this phase, essential drivers required to start the Windows kernel are loaded and the kernel starts to run. The key file here is %SystemRoot%\system32\ntoskrnl.exe

Phase 4 – Windows NT OS Kernel

The kernel loads the system registry hive into memory and loads the drivers that are marked as BOOT_START. The kernel then passes control to the session manager process (Smss.exe).

You can identify the phase you are in visually by what your computer is displaying and the LEDs that are on the system. I will follow up with additional posts on this subject so that you can easily tell what phase you are stuck at – and what you can do to fix things.

Thanks for reading, and be sure to check out my new MD-100 Windows 10 training at CBT Nuggets!

3 thoughts on “Understanding the Windows 10 Boot Process

  1. I am having problem with Windows 10 Loading. It works normal. However, in case of abrupt shutdown or Power failure, it takes approximately 25 minutes to load the Windows 10. After that it works normal.

  2. Windows Boot Manager: The file is located at C:\Windows\Boot\EFI\bootmgr.efi, not C:\bootmgr.(whatever file extension is used)
    Windows Loader: Which file is called: C:\Windows\System32\winload.exe or C:\Windows\System32\winload.efi?
    Windows Session Manager: The file is located at C:\Windows\System32\smss.exe

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