| There are
number of BOOT.INI switches that are useful for
driver developers that wish to test their drivers
under a variety of different system configurations
without having to have a separate machine for
every one. For example, limiting the amount of
memory NT sees can be useful for stressing memory
loads, and limiting the number of processors for
testing scalability. I've compiled a complete list
of the options that BOOT.INI currently supports.
Switches new to Win2K are in red. This list is
reproduced in the Startup, Shutdown and Crashes
chapter of Inside
Windows 2000, 3rd Ed., where you'll find more
information about the boot process. |
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| /PAE |
This has NTLDR load
ntkrnlpa.exe, which is the version of the x86
kernel that is able to take advantage of Intel
Physical Address Extensions (PAE), even when a
system doesn't have more than 4GB of physical
memory. PAE permits an x86 sytem to have up to
64GB of physical memory, but an operating system
must be specially coded to use memory beyond 4GB
(the standard x86 limit). The PAE-version of the
Win2K kernel presents 64-bit physical addresses to
device drivers, so this switch is helpful for
testing device driver support for large memory
systems. |
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| /NOPAE |
This switch forces NTLDR to load
the non-PAE version of the Win2K kernel, even if
the system is detected as supporting x86 Physical
Address Extensions (PAE) and has more than 4GB of
physical memory. |
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| /NOLOWMEM |
This switch
requires that the /PAE switch be present and that
the system have more than 4GB of physical memory.
If these conditions hold, then the PAE-enabled
version of the Win2K kernel, ntkrnlpa.exe, will
not use the first 4GB of physical memory. Instead,
it will load all applications and device drivers,
and allocate all memory pools, from above that
boundary. This switch is useful only to test
device driver compatability with large memory
systems. |
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| /NOGUIBOOT |
When this option is specified
the VGA video driver responsible for presenting
bit mapped graphics during Win2K's boot process is
not initialized. The driver is used to display
boot progress information, as well as to print the
Blue Screen crash screen, so disabling it will
disable Win2K's ability to do those things as
well. |
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| /FASTDETECT |
When you
dual boot NT 4.0 and Win2K the Win2K version of
NTDETECT.COM is used during the boot process. In
Win2K detection of parallel and serial devices is
performed by plug-and-play device drivers, but NT
4.0 expects NTDETECT to perform the detection.
Thus, specifying FASTDETECT causes NTDETECT to
skip parallel and serial device enumeration for a
boot into Win2K, whereas ommitting the switch has
NTDETECT perform enumeration for a boot into NT
4.0. For Win2K boots the switch is present and for
boots into NT 4 the switch is omitted. |
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| /BOOTLOG |
Specifying
this switch will result in NT writing a log of the
boot to the file %SystemRoot%\NTBTLOG.TXT. The log
has entries that detail which drivers load and do
not load during the boot process. Here is example
output from a log (note that the log file is un
UNICODE):
Microsoft
(R) Windows NT (R) Version 5.0
Loaded
driver \WINNT\System32\ntoskrnl.exe
Loaded driver \WINNT\System32\hal.dll
Loaded driver \WINNT\System32\BOOTVID.dll
Loaded driver pci.sys
Loaded
driver isapnp.sys
Loaded
driver intelide.sys
... |
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| /SAFEBOOT: |
You
should never have to specify this option manually,
since NTLDR does it for you when you use the F8
menu to perform a safe boot. 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. A safe boot is a boot where NT
only loads drivers and services that are specified
by name or group in the Minimal or Network
Registry keys under
HKLM\System\CurrentControlSet\Control\SafeBoot.
The DSREPAIR (Directory Services Repair) switch
causes NT to boot into a mode where it restores
the Active Directory from a backup medium you
present.
An additional option that
you can append is "(ALTERNATESHELL)". This tells
NT to use the program specified by
HKLM\System\CurrentControlSet\SafeBoot\AlternateShell
as the graphical shell, rather than to use the
default which is Explorer. |
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/PERFMEM=
/PERFPAGES= |
These flags are not likely to be
supported in the final release of Windows 2K, as
they are used to have NT reserve physical memory
for the purposes of Basic Block Testing (BBT).
There is only one reference I've been able to find
BBT: the transcript
(posted at Microsoft's web site) of the US vs.
Microsoft trial from February 2, 1999. In the
transcript Jim Allchin is on the stand and
responds to questions about BBT by DOJ attorney
David Boies, saying that it is a performance
optimizing system Microsoft uses on code before
releases in order to minimize their paging
footprints.
PERFMEM specifies the
physical memory to reserve in MB, and PERFPAGES in
number of pages - they should not be specified
together. A pointer to the reserved BBT buffer is
inserted in the Thread Environment Block (TEB) of
every thread, but there appears to be no other
references to the buffer in Beta 3. |
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| /INTAFFINITY |
This new switch
directs the multiprocessor HAL (HALMPS.DLL) to set
interrupt affinities such that only the highest
numbered processor in an SMP will receive
interrupts. Without the switch the HAL defaults to
its normal behavior of letting all processors
receive interrupts. |
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| /MAXPROCSPERCLUSTER= |
It seems that the multiprocessor HAL
in Win2K (HALMPS.DLL) has the ability to work with
multiprocessors that are made up of
tightly-coupled clusters of smaller
multiprocessors. For example, if you had an 8-way
system that was made up of 2 4-way clusters, the
processor IDs of each processor would have to be
specified in a cluster-oriented manner by the HAL.
The maximum cluster size is 4 and the default is 0
(system is not based on clusters). Example:
/MAXPROCSPERCLUSTER=3. |
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| /TIMERES= |
On the multiprocessor HAL
(HALMPS.DLL) this option will set the resolution
of the system timer. The argument is a number
interpreted in 100's of nanoseconds, but the rate
will be set to the closest resolution the HAL
supports that is not larger than the one
requested. The HAL supports the following
resolutions:
| 100's of nanoseconds |
milliseconds |
| 9766 |
.98 |
| 19532 |
2.0 |
| 39063 |
3.9 |
| 78125 |
7.8 |
The
default resolution is 7.8ms. The system timer
resolution affects the resolution of waitable
timers. Example: /TIMERES=9000 would set the timer
to a resolution of .98ms. |
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| /YEAR= |
This option is obviously present for Y2K
testing. Specifying it causes NT core time
function to ignore the year that the computer's
real-time clock reports and instead use the one
indicated. Thus, the year used in the switch
affects every piece of software on the system,
including the NT kernel. Example: /YEAR=2001.
Note: this option is only available on NT 4.0,
Service Pack 4 and later, and Windows 2000. |
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| /USE8254 |
This switch is intended for systems with older
BIOS's. It instructs the NT HAL to use the 8254
timer chip as its base timer. See Microsoft
KB Article Q169901 for more information. |
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| /MAXMEM= |
This option will limit NT to using only the
amount of memory you specify. The number is
interpreted as MB. Example: /MAXMEM=16 would limit
NT to using 16MB of the system's memory. |
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| /BURNMEMORY= |
This option will cause NT to "forget" about
the amount of memory specified, which limits
memory like /MAXMEM. The value specified is
interpreted as MB. Example: /BURNMEMORY=128 would
have NT discard 128MB of the physical memory on
the machine as unusable. |
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| /ONECPU |
This option will have NT only enable one CPU
of a multiprocessor system. |
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| /NUMPROC= |
Only the number of CPUs specified will be
enabled. Example: /NUMPROC=2 on a 4-way system
will cause 2 of the 4 processors to be unused by
NT. |
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| /SOS |
Causes NT to print information about what
drivers are being loaded as the system boots. |
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| /BASEVIDEO |
Causes NT to use the standard VGA display
driver when moving to GUI mode. |
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| /NODEBUG |
Prevents kernel-mode debugging from being
initialized. Overrides the specification of any of
the three debug-related switches, /DEBUG,
/DEBUGPORT and /BAUDRATE. |
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| /CRASHDEBUG |
If you include this switch, the kernel
debugger is loaded when the system boots, but
remains inactive unless a crash occurs. This
allows the COM port that you specify (or COM1 by
default) to be available for other use while the
system is running. |
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| /DEBUG |
Enables kernel-mode debugging. |
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| /DEBUGPORT= |
Enables kernel-mode debugging and specifies an
override for the default serial port (COM1) to
which a remote debugee is connected. Example:
/DEBUGPORT=COM2. |
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| /BAUDRATE= |
Enables kernel-mode debugging and specifies an
override for the default baud rate (19200) at
which a remote debugee will connect. Example:
/BAUDRATE=115200. |
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| /BREAK |
Causes the HAL to stop at a
breakpoint at HAL initialization. The first thing
that the NT kernel does when it initializes is to
initialize the HAL, so this breakpoint is the
earliest one possible. The HAL will wait
indefinitely at the breakpoint until a debugger
connection is made. If the switch is used without
the /DEBUG switch the system will Blue Screen with
STOP code of 0x00000078 (PHASE0_EXCEPTION). |
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/KERNEL=
/HAL= |
These options specify overrides of
NTLDR's selection of the file named NTOSKRNL.EXE
in the system root (<winnt>\system32) as the
kernel's image file and of the file named HAL.DLL
as the HAL image file. They are extremely useful
for alternating between a checked kernel
environment and a free kernel environment. If you
wish to boot into a checked environment that
consists solely of the checked kernel and HAL,
which is typically all that is needed to test
drivers, follow these steps on a system installed
with the free build (retail NT):
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1. Copy the checked version of the kernel
from the checked build distribution CD to your
<winnt>\system32 directory, naming it
NTOSKCHK.EXE. If you are on a uniprocessor then
copy NTOSKRNL.EXE, otherwise on a multiprocessor
copy NTKRNLMP.EXE. Note that the kernel file
name must be a 8.3-style short names. |
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2. Copy the checked version of
the HAL from the checked build distribution CD
to your <winnt>\system32 directory, naming
it HALCHK.DLL. To determine which HAL to copy,
go into your <winnt>\repair directory and
open setup.log in Notepad. Search for HAL.DLL
and you'll find a line like
"\WINNTF\system32\hal.dll="halmps.dll","1a01c".
The name to the right of the equal sign is the
name of the HAL you should copy. Note that the
kernel file name must be a 8.3-style short
names. |
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3. Make a copy of the default line in the
system's BOOT.INI. |
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4. In the string description of the boot
selection add something that indicates that the
new selection will be for a checked build
environment e.g. "Windows NT Server Version 4.0
CHECKED". |
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5. Add the following to the end of the new
selection's line: /KERNEL=NTOSKCHK.EXE
/HAL=HALCHK.DLL | You're
done. Now you can select the new line to boot into
a checked environment or select the pre-existing
selection to boot into the free build. |
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| /3GB |
This switch made its debut in NT
4.0 Service Pack 3 and is supported on all later
releases of NT. It will cause the split between
the user and system portions of NT's virtual
address map to move from 2GB user, 2GB system to
3GB user, 1GB system. Giving virtual memory
intensive applications like database servers a
larger address space can improve their
performance. Note, however that for an application
to take advantage of this feature two additional
conditions must hold: The system must be part of
the NT Enterprise suite (SP3 is not) and the
application must be flagged as a 3GB-aware
application. See Microsoft
KB Article Q171793 for additional
information. |
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| /WIN95 |
This switch is only pertinent on a
triple-boot system that has DOS, Win9x and Windows
NT installed. Specifying the /WIN95 switch directs
NTLDR to boot the Win9x boot sector stored in
BOOTSECT.W40. See Microsoft
KB Article Q157992 for more information. |
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| /WIN95DOS |
This switch is only pertinent on a
triple-boot system that has DOS, Win9x and Windows
NT installed. Specifying the /WIN95DOS switch
directs NTLDR to boot the DOS boot sector stored
in BOOTSECT.DOS. See Microsoft
KB Article Q157992 for more information. |
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| /PCILOCK |
Stops Windows NT from dynamically assigning
IO/IRQ resources to PCI devices and leaves the
devices configured by the BIOS. See Microsoft
KB Article Q148501 for more information. |
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| /NOSERIALMICE=[COMx | COMx,y,z...]
|
Disables serial mouse detection of
the specified COM port(s). Use this switch if you
have a component other than a mouse attached to a
serial port during the startup sequence. If you
use /NOSERIALMICE without specifying a COM port,
serial mouse detection is disabled on all COM
ports. See Microsoft
KB Article Q131976 for more information. |
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| /SCSIORDINAL: |
Adding a new SCSI device to a system with an
on-board SCSI controller can cause the
controller's SCSI ID to change, so you use this
switch to direct NT to the SCSI ID of the
controller. See Microsoft
KB Article Q103625 for more information. |
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| Thanks to Jonas Fischer for pointing out
the PCILOCK and NOSERIALMICE switches. Thanks to
Rob Green for information on the FASTDETECT
switch. |
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