pipiwau的部落格

在DVMT5.0的spec中提到，WinXP的做法跟Win7的做法是不同的。

XP下，System BIOS需要對ACPI的OpRegion 中的DVMT Graphics Memory Size做Configuration.

For less than 1 GB Total System Memory = 128 MB Maximum; For 1 GB to < 1.5 GB
Total System Memory = 512 MB Maximum; For 1.5 GB to < 2 GB Total System Memory
= 768 MB Maximum; For 2 GB and Above Total System Memory = 1GB Maximum.

Win7下，BIOS只宣告Pre-allocated的Memory。

OSRAM Size = Dependent on system configuration; (See OS Property Page for value)
DVM = Pre-allocated Memory;
SVM = MAX(128 – DVM, 0);
SSM = MIN ([ (OS Ram Size – 512) / 2 ] - SVM ) ;
Total Graphics Memory = DVM + SSM + SVM;

Detail要看DVMT5.0的Spec。

而上述的Pre-allocated的Memory應該是指BIOS中的IGD Memory，也就是去設定CPU內(或MCH)中，Graphics Mode Select(GMS) register。