NTLDR

• , the main boot loader itself
• , required for booting an NT-based OS, detects basic hardware information needed for successful boot

History

Command-line interface

Example

Startup process

1. Accesses the file system on the boot drive.
2. If Windows was put in the hibernation state, the contents of hiberfil.sys are loaded into memory and the system resumes where it left off.
3. Otherwise, reads boot.ini and prompts the user with the boot menu accordingly.
4. If a non NT-based OS is selected, NTLDR loads the associated file listed in boot.ini and gives it control.
5. If an NT-based OS is selected, NTLDR runs ntdetect.com, which gathers information about the computer's hardware.
6. Starts Ntoskrnl.exe, passing to it the information returned by ntdetect.com.

   boot.ini

Example

NT kernel switches

• ' — Forces x86-based systems to increase the virtual address space allocated for user programs to 3 GB, and to decrease to 1 GB allocated to the kernel and to executive components. Used for some programs that require more than the standard 2 GB allocated to user programs and 2 GB allocated to the system. Some configurations of Windows Server 2003 that run virtual memory-intensive applications such as database servers or Microsoft Exchange Server 2003 may require this switch or may benefit from improved performance. Activating this option may break VMR-9 video. Activating this option may also cause audio problems with Creative SB X-Fi series sound cards with. These problems may be connected to the way that Creatives drivers handle memory over 2 GB.
• ' — Forces the system into standard 640×480 16-color VGA mode by using a video device driver that is compatible with any video adapter. If the operating system fails to load due to a faulty or incorrectly configured video driver, this switch allows the system to load, so the user may then remove, update, or roll back the video driver causing the problem. Using this switch in conjunction with the switch helps to determine the driver that is triggering a failure.
• ' — Sets the baud rate of the debug port that is used for kernel debugging. Use of this switch automatically enables the switch. Specifies an override for the default baud rate at which a remote kernel debugger host will connect. Example:.
• ' — Turns on boot logging to a file named.
• ' — Displays an alternate 640×480 16-color custom bitmap. The bitmap must be saved in the \Windows directory with the name. Use with the switch.
• ' — Specifies the amount of memory, in megabytes, that Windows cannot use. Use this parameter to confirm a performance problem or other problems that are related to RAM depletion.
• ' — Use with the switch and the switch to selects the IEEE 1394 interface channel through which kernel debugging communications will flow.
• ' — Loads the kernel debugger at OS startup, but it remains inactive until a Stop error occurs. With this switch, the COM port can be used for normal operations while Windows is running. If Windows crashes, the switch converts the port to a debug port.
• ' — Turns on the kernel debugger when Windows starts. Unlike the switch, uses the COM port whether you use debugging or not.
• ' — Specifies the COM port to use for the debug port. By default, uses COM2 if it exists. Otherwise, the default is COM1. Use of this switch automatically enables the switch.
• ' — Turns off serial and bus mouse detection for the specified port, or for all ports if none are specified. Use this switch when there is a component other than a mouse attached to a serial port during the startup process. Ports may be separated with commas to turn off more than one port.
• ' — Defines the Hardware Abstraction Layer that is loaded at startup. This switch is useful to try out a different HAL before you rename the file to. This switch is also useful when you want to try to switch between starting in multiprocessor mode and starting in single processor mode. To do this, use this switch with the switch. filename must be in System32 directory. It can be a simple file, hard link, but not a symbolic link or a junction point.
• ' — Defines the kernel that is loaded at startup. With this switch, the user can switch between a debug-enabled kernel that is full of debugging code and a regular kernel. Same limitations for filename location and type as for /HAL switch.
• ' — Specifies the maximum amount of RAM, in megabytes, that Windows can use. However, the switch does not account for memory holes. Therefore, it is recommended to use the switch instead.
• ' — This option is used by Windows Preinstallation Environment and loads the Registry SYSTEM hive as a volatile hive such that changes made to it in memory are not saved back to the hive image.
• ' — Turns off debugging. This scenario can cause a Stop Error if a program has a debug hardcoded breakpoint in its software.
• ' — This option is only available on 32-bit versions of Windows when running on processors supporting Data Execution Prevention. It enables DEP, which results in the memory manager marking pages containing data as no-execute so that they cannot be executed as code. This can be useful for preventing malicious code from exploiting buffer overflow bugs with unexpected program input in order to execute arbitrary code. No-execute protection is always enabled on 64-bit versions of Windows on processors that support no-execute protection. There are several options the user can specify with this switch:
• * ' — Enables DEP for core system images and those specified in the DEP configuration dialog.
• * ' — Enables DEP for all images except those specified in the DEP configuration dialog.
• * ' — Enables DEP on all images.
• * ' — Disables DEP.
• ' — Displays the device driver names while they are being loaded. Use with the switch to determine the driver that is triggering a failure.
• ' — Forces Ntldr to load the non-Physical Address Extension version of the Windows kernel, even if the system is detected as supporting x86 PAEs and has more than 4 GB of physical memory.
• ' — Replaced by the absence of the switch. Disables serial mouse detection on the specified COM ports. Using without specifying a COM port disables serial mouse detection on all COM ports.
• ' — Sets the number of processors that Windows will run at startup. With this switch, the user can force a multiprocessor system to use only the quantity of processors that you specify. Useful for troubleshooting performance problems and defective CPUs.
• ' — Equivalent to using. Causes Windows to use only one CPU on a multiprocessor system.
• ' — Enables Physical Address Extension support. In Safe Mode, the computer starts by using normal kernels, even if the switch is specified.
• ' — For x86-based systems, this stops the operating system from dynamically assigning hardware input, hardware output, and interrupt request resources to PCI devices. Instead, the BIOS configures the devices.
• ' — Turns on Emergency Management Services on a Windows Server 2003, Enterprise Edition-based computer. To turn on EMS by editing the Boot.ini on an x86-based computer, edit both the section and the section of the Boot.ini file.
• ' — Causes Windows to start in Safe Mode. You must include the colon plus one of the three types listed above. An additional option the user can append is, which tells Windows to use the program specified by the value as the graphical shell rather than to use the default, which is Windows Explorer. The user can also combine other parameters with. The following examples illustrate the parameters that are in effect when you select a Safe Mode option from the startup recovery menu.
• * Safe Mode — Default: Uses a minimal set of device drivers and services to start Windows.
• * Safe Mode with Networking — Default mode together with the drivers necessary to load networking.
• * Safe Mode with Command Prompt — Default mode, except that Cmd.exe starts instead of Windows Explorer.
• * Windows in Directory Services Restore Mode — Performs a directory service repair.
• ' — Disables the graphical boot screen and uses the NT4 style text-boot, listing the Windows build number, version number, etc. In Windows 2000 and XP, the text is rendered inside the CHKDSK bitmap.
• ' — Specifies that Windows uses the Power Management Timer timer settings instead of the Time Stamp Counter timer settings if the processor supports the PM_TIMER settings. By default, Windows Server 2003 Service Pack 2 uses the PM timer for all multiprocessor APIC or ACPI HALs. If you are not running Windows Server 2003 SP2, you must force the computer to use the PM timer by using the switch.
• ' — Customizes the amount of memory, in megabytes, that is allocated to processes when using the switch. This switch permits more page table entry kernel memory but still maintains almost 3 GB of process memory space.
• ' — Directs Ntldr to boot the Windows boot sector stored in.
• ' — Directs Ntldr to boot the MS-DOS boot sector stored in.
• ' — Instructs the Windows core time function to ignore the year that the computer's real-time clock reports and instead use the one indicated. Example:.