Win10 Pro x86 VM says only 2 GB RAM available

[jw8]

Hello all,

I am using Proxmox VE 8.4.8 on a system with two Xeon cpus, 256 GB of RAM, and 4x 2TB nvme drives. I am using LVM-Thin storage. I have a Windows Server 2008 32-bit Data Center VM with 32 GB allocated that recognizes the full 32 GB just fine (as an aside, I know the DC version of the 32 bit does some weird stuff to recognize more than 3.40 GB; I just wanted to point out that I had another 32-bit type VM that wasn't limited to 2 GB available).

When I try to make a Windows 10 Pro 32-bit VM, I set it to allocate 4 GB of RAM. I am aware of the 32-bit limitation - it usually says "4.00 GB (3.40 GB usable)" under computer properties, which is fine.

However, it says "4.00 GB (2.00 GB usable)" and I am unable to make it use the normal ~3.40 GB. I read somewhere that it could be because I am using SeaBIOS, but I was unable to get past POST (couldn't boot to the Windows install ISO) when I enabled OVMF (UEFI) with the TPM set to both v1.2 and v2.0, and with the EFI disk set to even try that.

Things I have tried:
- Reinstalled the OS multiple times with both the retail disc I have and the ISO from Microsoft
- Disabled the memory ballooning device
- Tried with and without the quemu agent installed
- Used the latest Win 10 ISO image from Microsoft
- Fully updated the copy of Win 10 via Windows Update

I have added screenshots of my config for the SeaBIOS VM, but I also added the screenshot of the error I get when I try to make another VM in OVMF (UEFI) mode.

In UEFI mode I tried the following:
- The tutorial listed here: https://www.youtube.com/watch?v=js_Xoa0f8zM
- Disabled SecureBoot in the boot manager
- TPM device disabled, v1.2, and v2.0
- With and without the EFI disk

Any help in the right direction to get the ~3.40 GB of RAM working would be much appreciated, whether its SeaBIOS, UEFI, or otherwise. Thank you!

 

[LnxBil]

Have you checked the patch here?

I know the DC version of the 32 bit does some weird stuff to recognize more than 3.40 GB

That's not soo weird but actually pretty standard, it's called physical address extension PAE and it was a deliberate limitation of windows OSes to sell more expensive licenses (see link). Linux could do it since the last century. It also still works. Just tested with Debian 12 Bookworm 32-bit booting a PAE kernel:



This was with a default non-uefi/legacy install in PVE 8.

 

[jw8]

I have checked and tried the patch. It didn't seem to work (if you're thinking to increase the 4 GB cap to compensate for the 2 GB taken away, which would be fine). I did read on there that it might not work with newer/updated versions of Windows 10, which appears to be the case.

 

[jw8]

I just wanted to add that I believe the task manager of the VM vs a real dedicated system with Windows 10 Pro 32-bit might have a clue. I have attached both screenshots (the vm and the actual, real system equivalent), but the "hardware reserved" and the slots/type of DIMM modules make me think there is something to it.

Is there a way for me to emulate it in a way to make the VM think it has physical DIMMs installed?

Please ignore the 8/6 GB numbers; I currently have 8 GB allocated to that VM from trying the PAE patch and a few more things. Thanks for the help so far.

EDIT: I added a screenshot of the VM with 4 GB allocated for a more apples to apples comparison to show what I mean.