Re: memory remapping, 4gb memory on 945gt

Parag Warudkar
2008-01-04T23:03:23Z

H. Peter Anvin <hpa <at> zytor.com> writes:

>
> Supposedly WinXP-32 doesn't use memory over 4 GB even if it is available
> (a market-segmentation decision of the part of Microsoft, to force
> people to buy WinServer 2003; WinXP SP2 does PAE so there is no
> technical reason.) This probably has disincentivized hardware vendors
> from providing support for remapping the memory from the aperture above
> the 4 GB mark. The logic isn't all that trivial, especially if the
> aperture size is configurable, so I can understand why they would punt.
>

The reason according to Microsoft is that enabling PAE induced driver
incompatibilities - to me it sounds quite plausible given the quality of drivers
for consumer versions of XP/Vista and the fact that 4GB RAM in consumer class
machine is a newer thing.

There is a KB document detailing the reasons for disabling >4Gb RAM in XP SP2
and later 32-bit OSes - http://support.microsoft.com/kb/888137 .

Parag