PAE/3GB Switches

NTDEV
1

Is there any way to tell the PAE/3GB switches are being used other than looking at the BOOT.INI file ?
I mean, is there any function or global variable that returns the status of PAE/3GB ?

Thanks.
Inaki.

2

To get the current options used during the boot, you can look here.

HKLM\System\CurrentControlSet\Control\SystemStartOptions

To determine for other entries, I believe you need to process the boot.ini
yourself.

Thanks,

Rob

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of I?aki Castillo
Sent: Friday, October 15, 2004 2:15 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] PAE/3GB Switches

Is there any way to tell the PAE/3GB switches are being used other than
looking at the BOOT.INI file ?

I mean, is there any function or global variable that returns the status of
PAE/3GB ?

Thanks.

Inaki.

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as: unknown lmsubst tag argument: ‘’
To unsubscribe send a blank email to xxxxx@lists.osr.com

3

Try ExIsProcessorFeaturePresent for PAE (ask for PF_PAE_ENABLED). For 3GB check the value of MmSystemRangeStart or MmHighestUserAddresss.

Of course, PAE will be on (in long mode) for all amd64 processors, but may (or may not) be on for x86. I don’t think MmSystemRangeStart is a good value to check without also confirming that you are on an x86 (ah, but that at least is a COMPILE time issue, not a run-time issue).

Regards,

Tony

Tony Mason

Consulting Partner

OSR Open Systems Resources, Inc.

http://www.osr.com

Looking forward to seeing you at the Next OSR File Systems Class October 18, 2004 in Silicon Valley!

From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of I?aki Castillo
Sent: Friday, October 15, 2004 2:15 PM
To: ntdev redirect
Subject: [ntdev] PAE/3GB Switches

Is there any way to tell the PAE/3GB switches are being used other than looking at the BOOT.INI file ?

I mean, is there any function or global variable that returns the status of PAE/3GB ?

Thanks.

Inaki.

Questions? First check the Kernel Driver FAQ at http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as: unknown lmsubst tag argument: ‘’
To unsubscribe send a blank email to xxxxx@lists.osr.com