Presentation on theme: "Windows Vista Boot process. All the computer running Windows vista have the same start up sequence: Power-on self test (POST) phase Initial startup phase."— Presentation transcript:
Windows Vista Boot process
All the computer running Windows vista have the same start up sequence: Power-on self test (POST) phase Initial startup phase BOOTMGR Phase BCD (Boot Configuration Database) phase Windows Loader phase
Power-on Self Test When the system is turned on the CMOS loads the BIOS and then runs POST During the POST the basic hardware components are checked Initial Startup Phase The MBR is responsible for locating and then initializing the boot sector on the active partition The MBR no longer looks for NTLDR. The new boot loader in vista is Bootmgr.
Bootmgr Phase The function of the Windows Boot Manager is to read the boot configuration data(BCD) and display an operating system selection menu, as NTLDR in Windows XP, A big difference is that the Windows Boot Manager is invoked by pressing the space bar instead of the F8 function key. The F8 key still remains assigned for advanced boot options once the Windows Boot Manager menu appears. BOOTMGR is a hidden file in C:\ that is necessary to load the system BOOTMGR looks for active partition BOOTMGR reads the BCD file from the \boot directory on the active partition
BCD (Boot Configuration Database) phase The BCD (boot configuration database) contains various configuration parameters( this information was previously stored in the boot.ini) Boot Configuration Data contain the menu entries that are presented by the Windows Boot Manager, just as boot.ini contained the menu entries that were presented by NTLDR. The following are some menu entries: 1. Options to boot Windows by invoking winload.exe. 2. Options to resume Windows from hibernation by invoking winresume.exe. 3. Options to boot a prior version of the Windows NT family by invoking its NTLDR. 4. Options to load and to execute a Volume Boot Record. 5. Boot Configuration Data allows for the third party integration so anyone can implement tools like diagnostics or recovery options. There is also a hidden folder in C:\, named BOOT that contain inside the BCD file. BCD is a binary file that can be edited only with BCDEDIT tool. This file has the same function that BOOT.INI has in the system based in XP
If there is more than one operating system installed on our PC (other Vista version or any other pre-Vista version of Windows). It shows us a menu (similar operation to BOOT.INI in the system based in NT core) in which we can select the desired OS. The boot process in this case shows the following 2 lines menu: -Legacy (pre-Longhorn) Microsoft Windows Operating System -Microsoft Windows When windows vista is selected, BOOTMGR transfer control to the Windows Loader (winload.exe) or winresume.exe in case the system was hibernated. Windows loader Phase The function of winload.exe is equivalent to the operating system loader function of NTLDR in Windows XP. Winloader loads drivers that are set to start at boot and then transfers the control to the windows kernel. There is no msgina.dll in windows vista ( the shell draws the login screen)
Difference between XP & Vista Windows XP bootup process: System is powered on The CMOS loads the BIOS and then runs POST Looks for the MBR on the bootable device, and loads NTLDR The BIOS/CMOS transfers control to the NTLDR NTLDR first looks for Hiberfil.sys ( if present, the system resumes from where it was hibernated) if the hiberfil.sys is not present, NTLDR looks for boot.ini If you have more than one operating system installed on your computer, Boot.ini will give you the option to choose the operating system to boot from. The selected operating system then boots, in windows XP involves the loading of the kernelwindows XP
After system services and user required DLLs are loaded, finally msgina.dll brings up the login screen.login screen When the user logs on, the system checks for the user’s credentials in the SAM, if the credentials are correct, the user profile is loaded from documents and settings folder. This brings up the desktop and at that point, the ControlSets are copied to the CurrentControlSet in the registry. Now, the system is considered booted.
Windows Vista boot-up process: System is powered on The CMOS loads the BIOS and then runs POST. Looks for the MBR on the bootable device. Through the MBR the boot sector is located and the BOOTMGR is loaded. BOOTMGR looks for active partition. BOOTMGR reads the BCD file from the \boot directory on the active partition The BCD (boot configuration database) contains various configuration parameters( this information was previously stored in the boot.ini) When windows vista is selected, BOOTMGR transfer control to the Windows Loader (winload.exe) or winresume.exe in case the system was hibernated.
Winloader loads drivers that are set to start at boot and then transfers the control to the windows kernel. There is not msgina.dll in windows vista ( the shell draws the login screen) the difference starts at the MBR. In windows vista, NTLDR was replaced by three new boot loader components, supposedly designed to load windows quicker and more securely. Those components are; Windows Boot Manager (Bootmgr.exe) Windows OS Loader (Winload.exe) Windows Resume Loader (Winresume.exe) Windows Boot Manager reads the boot configuration data (BCD) and display an operating system selection menu to the user Windows OS loader is the operating system boot loader. It is invoked by the windows boot manager in order to load the operating system kernel (ntoskrnl.exe) and boot-class device drivers. Windows Resume loader replaces the Hiberfil.sys. Msgina.dll was used on windows XP to change custom login screens, but not in vista