topic Re: How to adjust DVMT pre-allocate memory? in Software Archive

How to adjust DVMT pre-allocate memory?

victorcall — Sat, 09 Aug 2008 03:13:46 GMT

Dear sir,

The problem I faced now is how the DVMT pre-allocate memory can be adjusted in Windows?

The pc is installed with Q35 chipset and GMA 3100. I tried to find the option that can adjust the DVMT in BIOS, but unfortunately no related option I can found.

So it is urgent for me to find out another method that can take the place of the setting in BIOS.

Is there anyone can help?

Thanks in advanced.

Re: How to adjust DVMT pre-allocate memory?

7oby — Sat, 09 Aug 2008 11:41:08 GMT

It's simple: If you BIOS doesn't allow you to change DVMT allocation, then you can't change it. You depend on whatever the BIOS gives you. Which is something out of this table p. 17:
http://www.intel.com/assets/pdf/whitepaper/307508.pdf

However DVMT allocation between Windows XP and Windows Vista is completely different. Read about the differences here section "Dynamic Video Memory":
http://software.intel.com/en-us/articles/intel-gma-3000-and-x3000-developers-guide

Having understood this, you'll recognized that in Windows Vista you always end up with up to 358MB Memory regardless of the BIOS. It looks like this:

While it uses currently 183MB it may use up to 358MB. Read this document to understand more about the differences in reporting memory in XP and Vista:
http://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/GraphicsMemory.doc

You understand that adding memory doesn't make you graphics card faster, do you? If you're looking for performance there's just one known tweak:
http://forum.notebookreview.com/showthread.php?p=3634860#post3634860

Re: How to adjust DVMT pre-allocate memory?

victorcall — Mon, 11 Aug 2008 07:56:35 GMT

Dear 7oby,

Thanks a lot for your quick respond, you are really very helpful!

That means I have no way to adjust the pre-allocated memory when the BIOS doesn't have such setting, right?

But I was told there were 2 way to allocate memory - BIOS allocation and Driver allocation, now the BIOS can't be adjusted(pre-fixed 8MB for Pre-Allocated Memory Size), can it be adjust through Driver allocation(I mean modify something in driver, like .inf file or else).

The reason is when I exist one of the old DOS mode software in Windows XP, the windows prompt BLUE SCREEN with the display driver error, I tried to set the Pre-Allocated Memory Size from 8MB to 1MB, this porblem disappeared. But the same software have to be run in another computer which is Q35 chipset and GMA 3100 that can't adjust the pre-allocated memory in BIOS.

This block me, I don't know how to slove this porblem.

Re: How to adjust DVMT pre-allocate memory?

7oby — Tue, 12 Aug 2008 10:03:40 GMT

The 1MB/8MB switch is deprecated. You may read here some more about this setting:
http://www.intel.com/support/graphics/intel845g/sb/cs-009077.htm

The 8MB default nowadays should accomodate for all use cases. It's interesting that you found an application that is sensitive to this setting.

Please try these two ways of launching your DOS mode Software in WinXP.

First try the compatiblity mode setting of WinXP:
http://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/appcompat.mspx

If that doesn't help, then install a virtualization software. For example VirtualBox is a free software:
http://www.virtualbox.org/
The best would be to install MS DOS 6.22 or FreeDos on this machine. Or install WinXP if you haven't anything else at hand. The VESA graphics driver that is provided by the virtualization software should be pretty compatible with your application.

If that's to difficult then try one of the VMWare appliances such as:
http://www.vmware.com/appliances/directory/126

Re: How to adjust DVMT pre-allocate memory?

victorcall — Mon, 18 Aug 2008 01:54:50 GMT

Dear 7oby,

Thank you very much!

Although it will difficlut for me to do that, I would like to have a try on it.

But the best way is to have someone can writea newBIOS and exec to the pc, is it right? LOL ^_^