XP32 - 4GB ram given to VM, only 3GB available in XP, is this normal?

[BobTheDog]

Hi Guys,

I have a XP Vm here that I have given 4GB, in windows task manager only 3145192Kb is shown in the Total Physical Memory metric.

System info shows 4096MB available so 1GB has gone missing.

I understand pci stuff usually uses a bit of the high memory but a whole GB! Is this normal?

Thanks for any help

Andy

[dtracey]

Hi Bob,

Yes - in a 32 bit OS the maximum memory that an OS can see and use is between 3 - 3.5GB

If you need to see more than 4GB in an OS you will need to install the 64bit version.

Hope that clears things up!

Dan

[WoodyZ]

What you're seeing is normal and has nothing to do with Fusion or virtualization and is a limitation of 32-bit Windows XP.

[BobTheDog]

Hi Dan,

Thanks for the answer.

How near they get to 4GB is usually determined by the PCI bus memory mapping on the machine.

The main PCI buss memory usage is usually the video card but the VM one is only 128MB.

On Other hardware based machines with 128MB video cards you can easily see 3.75GB available ram.

So I was really wondering if it was usual for VMWare Fusion to allocate 1GB to map PCI cards?

Thanks

Andy

[JondorZ]

I think it's normal. When i run my windows xp pro using boot camp, the system properties only shows 3GB RAM. I have 4GB of ram in my macbook pro.

maybe this will explain to you:

"PCI reserves some RAM after you install more

than 3GB in a machine. It's the way it is and nothing you can do about

it. It should increase I/O performance, IIRC, by reserving some RAM for

PCI stuff.

Again, there is nothing wrong, what you are seeing it

what is supposed to happen, and you need to do nothing. BTW, the /3GB

switch isn't going to change anything for you, please don't use it

unless you know exactly what it does. It WILL NOT allow the OS to use

all 4GB of RAM."

extracted from

[ColoradoMarmot]

Good description of the issue (depending on which SP you're running it'll either report available, or installed RAM):

And info on the 3GB switch

[jshrek]

I have a physical machine running  Win XP Pro SP3 with 4GB installed, with /3GB switch in boot.init and  when I click My Computer > Properties it shows 3.75GB og memory  (which is correct because of PCI allocation).

I  installed Win Xp Pro SP3 in Fusion v4 (MacBook Pro with 8GB installed  RAM) and assigned 4096MB of RAM but properties only shows 3.00GB. I have  tried the /3GB and /PAE switches in boot.ini as well but it does not  change. If I change assigned RAM to 3072MB properties will still show  3.00GB as well. And yes, I shut down virtual machine before changing  assigned ram and also reboot virtual machine after making boot.ini  changes.

Thanks

[WoodyZ]

Have a look at : Virtual machine memory limits and hardware versions

[ColoradoMarmot]

Keep in mind that even with the switch, not everything can use more than 2GB (most apps can't).

If you really do need more than 2GB, run Win7 or XP x64.