can a 64 bit guest on a 32 bit host use > 2GB RAM

[jimbo45]

Hi everybody

I was wondering if all the RAM > 2GB can be acessed by a 64 bit GUEST such as Vista or Windows 7 running on a 32 Bit host (Windows XP PRO) when the machine has say 6 or 8 GB RAM. The Host is limited I know to 2GB with the 32 bit OS but does the CPU Virtualisation etc allow the guest 64 bit machine see more than the 2GB the host sees.

Documentation is unclear on what happens here.

Cheers

jimbo

[ksc · Accepted solution]

The maximum memory from a host that a guest can use depends on how much physical memory the host OS kernel can address.

In your specific case, Windows XP is only capable of seeing 4GB of memory (though in reality, the amount is somewhat smaller because of the chipset configuration ... I've seen anywhere from 2.75GB to 3.75GB available).

32-bit Linux and 32-bit Server editions of Windows can go up to 64GB of host RAM because the drivers are PAE-aware. 64-bit OSes have no bounds at all.

[jimbo45]

Thanks - I thought it might be something like that.

I'm going to switch to SUSE 64 bit host for continuing to test W7 X64. The large / big kernel (SUSE 11.1) supports > 4GB RAM and installs very easily even on a sallish laptop.

Cheers

Jimbo