Technical information about /onecpu option in boot.ini

In Windows XP you can set the option /onecpu in the boot.ini file, to force
Windows to run on one cpu when running on a multicore system.

Can anybody give me link to a page or document where I can get some
information about what exactly happens when booting with this option?

I want to know if the second (or the other) core(s) are disabled or not. Is
it possible that a other program can run on the other cores??

Thanks,
Vampy

Vampy20 wrote:
> In Windows XP you can set the option /onecpu in the boot.ini file,
> to force Windows to run on one cpu when running on a multicore
> system.
>
> Can anybody give me link to a page or document where I can get some
> information about what exactly happens when booting with this
> option?
>
> I want to know if the second (or the other) core(s) are disabled or
> not. Is it possible that a other program can run on the other
> cores??

The boot.ini options will only allow Windows to see/utilize however many
CPU/cores you specify. (/numproc= is the one you should probably be using.)

/NUMPROC=
This switch sets the number of processors that Windows NT will run at
startup. This will help test out performance problems and defective CPUs.
For example, /NUMPROC=3

/ONECPU
This switch is part of Compaq's HAL. The switch tells Windows NT to use only
1 CPU at startup. This will enable you to run a single CPU in a multikernel
configuration. For example, /ONECPU.

If you use /numproc=1 on a system with multiple cores - you end up with only
one core being used and the other cores are *not* available in your windows
session. You can set the affinity manually through task manager for a given
process - or you can use one of many applications to start an application
with different affinity depending on your needs.

--
Shenan Stanley
MS-MVP
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