The info I have on Memory allocation under Windows 7 and later states... Basically, the memory configured in BIOS is dedicated to graphics (“DVM” or dedicated video memory), but the OS is free to allocate more (“SVM” - system video memory and “SSM” - shared system memory), and usually does.
A colleague posted this feature in - NEW- Intel® Iris™, Iris™ Pro, and HD Graphics Driver update posted for Haswell and Broadwell version 220.127.116.1122. Please check the ReleaseNotes for more info.
Dedicated Memory Reporting
The graphics driver now reports some amount of fictitious “dedicated” graphics memory to the operating system (128MB by default) to work around applications issues in a number of games. These games incorrectly look for some amount of “dedicated” graphics memory because they weren’t coded with the unified memory architecture for processor graphics.
The amount reported can be modified or disabled if desired by changing the following registry value:
HKEY_LOCAL_MACHINE\Software\Intel\GMM, create a REG_DWORD value named “DedicatedSegmentSize”. The value is interpreted as number of MB to report (0-512MB). A value of 0 disables reporting the dummy memory segment. If the registry key/value is not found, the driver will report the default 128MB.