KeGetCurrentProcessorNumber where >8 CPU's

NTDEV
1

Is KeGetCurrentProcessorNumber supposed to work correctly where there
are more than 8 CPU’s in a system? I’m having a problem with my bus
driver (under xen) processing interrupts under Windows 2008 when there
are more than 8 CPU’s… I have no idea at this stage what is going on
but I would expect the same symptoms if KeGetCurrentProcessorNumber did
not work correctly for >8 CPUs…

Thanks

James

2

Are you sure it’s not a licensing issue? IIRC, Srv08 only supports 8 CPUs,
unless you get to the DataCenter edition, which supports 64.

The definition of “CPU” is a little vague, too. The Srv08 R2 spec refers to
“x64 Sockets”, which could mean a lot more “CPUs” if they are multi-core.

Ken

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of James Harper
Sent: Monday, December 07, 2009 10:05 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] KeGetCurrentProcessorNumber where >8 CPU’s

Is KeGetCurrentProcessorNumber supposed to work correctly where there
are more than 8 CPU’s in a system? I’m having a problem with my bus
driver (under xen) processing interrupts under Windows 2008 when there
are more than 8 CPU’s… I have no idea at this stage what is going on
but I would expect the same symptoms if KeGetCurrentProcessorNumber did
not work correctly for >8 CPUs…

Thanks

James

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3

>

Are you sure it’s not a licensing issue? IIRC, Srv08 only supports 8
CPUs,
unless you get to the DataCenter edition, which supports 64.

The definition of “CPU” is a little vague, too. The Srv08 R2 spec
refers to
“x64 Sockets”, which could mean a lot more “CPUs” if they are
multi-core.

It turned out to be a simple (stupid?) bug in my driver - I wasn’t
handling interrupt affinity correctly.

James

4

>

Are you sure it’s not a licensing issue? IIRC, Srv08 only supports 8
CPUs,
unless you get to the DataCenter edition, which supports 64.

I’m testing with Enterprise, and it’s in a virtualised environment.
Right now I’m giving the 2008 VM 12 x 1 core CPU’s and it sees them just
fine, although it’s horribly slow as the physical machine only has a
single quad core CPU on which to schedule the 12 virtual CPU’s :slight_smile:

James