On Wed, 12 May 2010, Bino Gopal wrote:
Well thought I'd share my results as a data point:
Got a Lenovo (aka IBM) T61 laptop from circa late 2007. It's the Santa
Rosa mobile platform, specifically an Intel Core 2 Duo Merom 2nd gen
processor (T7500 @ 2.2Ghz). I don't know what the exact chipset is
(anyone know an easy way to find that with an app...?) but in any case
the chipset it what usually came with that chip.
So I installed Win7 Ent 64-bit (and remember I only have 4GB TOTAL
memory installed) and on the System screen, the machine went from saying
3.2GB usable out of the 4GB installed (which was with Win7 32-bit), to
just saying a plain 4GB RAM installed with nothing missing...
So it looks like even though I only have 4GB physical memory, the MMIO
devices don't need to reserve any of my 4GB of memory b/c they can map
above it (I assume up to 8GB in my case). So based on the KB article, I
assume if I upgraded to 8GB of RAM, it would show 7.2GB of RAM b/c then
the devices would still need to map and since 8GB is their max, it would
take away from my physical memory...I'll see if I can get 8GB of RAM for
it and test this out! ;)
Incorrect unfortunately. There were so many complaints/questions from
people with the "I have 4GB installed why does it only say 3.5GB" that
Microsoft now reports the INSTALLED memory as the full 4GB, but you still
can't use it all. I believe in 32bit Windows 7 you can see the true
number in task manager or process explorer.
http://msdn.microsoft.com/en-us/library/aa366778%28v=VS.85%29.aspx
Microsoft isn't kidding when they say 4GB for windows 7. They are not
mapping things above that. They just removed showing you the real number
in the system tab.
Christopher Fisk
