/numproc=number
This switch sets the number of processors that Windows will run at startup. With this switch, you can force a multiprocessor system to use only the quantity of processors (number) that you specify. This switch can help you troubleshoot performance problems and defective CPUs.
/ONECPU
Causes Windows to use only one CPU on a multiprocessor system.
/PAE
Causes Ntldr to load Ntkrnlpa.exe, which is the version of the x86 kernel that is able to take advantage of x86 PAEs. The PAE version of the kernel presents 64-bit physical addresses to device drivers, so this switch is helpful for testing device driver support for large memory systems. Use the /PAE switch with the corresponding entry in Boot.ini to permit a computer that supports physical address extension (PAE) mode to start normally. In Safe Mode, the computer starts by using normal kernels, even if the /PAE switch is specified.
/pcilock
For x86-based systems, this switch stops the operating system from dynamically assigning hardware input, hardware output, and interrupt request resources to Peripheral Connect Interface (PCI) devices. With this switch, the BIOS configures the devices.
/RDPATH=
Specifies the path to a System Disk Image (SDI) file, which can be on the network, that the system will use to boot from. Often used in conjunction with the /RDIMAGEOFFSET= flag to indicate to NTLDR where in the file the system image starts.
/REDIRECT
Introduced with Windows XP. Used to cause Windows to enable Emergency Management Services (EMS) that reports boot information and accepts system management commands through a serial port. Specify serial port and baudrate used in conjunction with EMS with redirect= and redirectbaudrate= lines in the [boot loader] section of the Boot.ini file. Use this switch to turn on Emergency Management Services (EMS) on a Windows Server 2003, Enterprise Edition-based computer. For additional information about EMS, search on "Emergency Management Services" in Windows Help and Support.
To turn on EMS by editing the Boot.ini on an x86-based computer, edit both the [boot loader] section and the [operating systems] section of the Boot.ini file. To do this, configure the following entries:
- Under [boot loader], add one of the following required statements:
redirect=COMx
In this statement, replace x with one of the following COM port numbers:
1
2
3
4
redirect=USEBIOSSETTINGS
This statement permits the computer BIOS to determine the COM port to use for EMS.
- Under [boot loader], add the following option statement:redirectbaudrate=baudrateReplace baudrate with one of the following values:
9600
19200
57600
115200
By default, EMS uses the 9600 Kbps baud rate setting.
- Under [operating systems], add the /redirect option to the operating system entry that you want to configure to use EMS. The following example illustrates the use of these switches:
[boot loader]
timeout=30 default=multi(0) disk(0) rdisk(0)partition(1)\WINDOWS
redirect=COM1
redirectbaudrate=19200
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise" /fastdetect
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, EMS" /fastdetect /redirect
/safeboot:parameter
This switch causes Windows to start in Safe Mode. This switch uses the following parameters:
- minimal
- network
- safeboot:minimal(alternateshell)
You can combine other Boot.ini parameters with /safeboot:parameter. The following examples illustrate the parameters that are in effect when you select a Safe Mode option from the startup recovery menu.
Safe Mode with Networking
/safeboot:minimal /sos /bootlog /noguiboot Safe Mode with Networking
/safeboot:network /sos /bootlog /noguiboot Safe Mode with Command Prompt
/safeboot:minimal(alternateshell) /sos /bootlog /noguiboot
Note The /sos, /bootlog, and /noguiboot switches are not required with any one of these settings, but the switches can help with troubleshooting. These switches are included if you press F8 and then select one of the modes. Specifies options for a safe boot. You should never have to specify this option manually, since Ntldr specifies it for you when you use the F8 menu to perform a safe boot. (A safe boot is a boot in which Windows only loads drivers and services that are specified by name or group under the Minimal or Network registry keys under HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot.) Following the colon in the option you must specify one of three additional switches: MINIMAL, NETWORK, or DSREPAIR. The MINIMAL and NETWORK flags correspond to safe boot with no network and safe boot with network support, respectively. The DSREPAIR (Directory Services Repair) switch causes Windows to boot into a mode in which it restores the Active Directory directory service from a backup medium you present. An additional option you can append is (ALTERNATESHELL), which tells Windows to use the program specified by the HKLM\SYSTEM\CurrentControlSet\ SafeBoot\AlternateShell value as the graphical shell rather than to use the default, which is Windows Explorer.
/SCSIORDINAL:
Directs Windows to the SCSI ID of the controller. (Adding a new SCSI device to a system with an on-board SCSI controller can cause the controller's SCSI ID to change.) See Microsoft Knowledge Base article Q103625 for more information.
/SDIBOOT=
Used in Windows XP Embedded systems to have Windows boot from a RAM disk image stored in the specified System Disk Image (SDI) file.
/sos
The /sos switch displays the device driver names while they are being loaded. By default, the Windows Loader screen only echoes progress dots. Use this switch with the /basevideo switch to determine the driver that is triggering a failure.
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
99743 Purpose of the Boot.ini file in Windows 2000 or Windows NT
/userva
Use this switch to customize the amount of memory that is allocated to processes when you use the /3GB switch. This switch permits more page table entry (PTE) kernel memory but still maintains almost 3 GB of process memory space.
For additional information about how to use the /USERVA switch, click the following article number to view the article in the Microsoft Knowledge Base:
316739 How to use the /USERVA switch in the Boot.ini file to tune /3GB configurations
For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base: