Transcript Windows Vista Boot process

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
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The MBR no longer looks for NTLDR. The new boot loader in vista is Bootmgr.
Bootmgr Phase
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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.
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BOOTMGR is a hidden file in C:\ that is necessary to load the system
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BOOTMGR looks for active partition
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BOOTMGR reads the BCD file from the \boot directory on the active partition
BCD (Boot Configuration Database) phase
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The BCD (boot configuration database) contains various configuration parameters( this information was
previously stored in the boot.ini)
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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.
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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
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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
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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
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The function of winload.exe is equivalent to the operating system loader function of NTLDR in Windows
XP.
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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:
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System is powered on
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The CMOS loads the BIOS and then runs POST
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Looks for the MBR on the bootable device, and loads NTLDR
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The BIOS/CMOS transfers control to the NTLDR
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NTLDR first looks for Hiberfil.sys ( if present, the system resumes from where it was hibernated)
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if the hiberfil.sys is not present, NTLDR looks for boot.ini
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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.
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The selected operating system then boots, in windows XP involves the loading of the kernel
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After system services and user required DLLs are loaded, finally msgina.dll brings up the login screen.
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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.
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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:
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System is powered on
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The CMOS loads the BIOS and then runs POST.
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Looks for the MBR on the bootable device.
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Through the MBR the boot sector is located and the BOOTMGR is loaded.
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BOOTMGR looks for active partition.
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BOOTMGR reads the BCD file from the \boot directory on the active partition
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The BCD (boot configuration database) contains various configuration parameters( this information was
previously stored in the boot.ini)
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When windows vista is selected, BOOTMGR transfer control to the Windows Loader (winload.exe) or
winresume.exe in case the system was hibernated.
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Winloader loads drivers that are set to start at boot and then transfers the control to the windows
kernel.
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There is not msgina.dll in windows vista ( the shell draws the login screen)
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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)
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Windows Boot Manager reads the boot configuration data (BCD) and display an operating system
selection menu to the user
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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.
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Windows Resume loader replaces the Hiberfil.sys.
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Msgina.dll was used on windows XP to change custom login screens, but not in vista