Issue with PCI Passthrough and USB Controller

[Shaunzer1]

I'm trying to make an XP VM work with a PCI comms card. https://www.gridconnect.com/products/pci-express-data-highway-plus-and-dh485-adapters?variant=899924...

After adding the PCI card into the VM hardware the VM would not boot correctly and get stuck at the boot screen.

If I remove the USB controller then the VM will boot and I can configure the card.

The VM is 32bit XP and its allowing me to allocate 3500MB Ram

Am I hitting some limitations? and is there away around this issue? 

Could I add a PCI USB card or will I still need the USB Controller for this?

[ptarnawski]

Yes, you are hitting some limitations. 32-bit Windows XP can only address up to 4 GB of RAM, so allocating 3500 MB is already pushing the limit. Adding a PCI card will further reduce the amount of available RAM, which could be why the VM is not booting properly.

There is a workaround for this. You can install a PCI USB card instead of a PCI comms card. This will allow you to connect the comms device to the VM through a USB port, which will not take up any RAM.

Here are the steps on how to do it:

1. Install the PCI USB card in your physical computer.
2. Create a new VM in your virtualization software.
3. When you are configuring the hardware for the VM, select the PCI USB card as the USB controller.
4. Install the drivers for the comms device on the VM.
5. Connect the comms device to the USB port on the VM.

The VM should now be able to boot and recognize the comms device.

Here are some additional things to keep in mind:

• Make sure that the PCI USB card is compatible with your physical computer and the virtualization software that you are using.
• Make sure that the drivers for the comms device are compatible with the version of Windows XP that you are running on the VM.
• If you are still having trouble getting the VM to boot, you can try reducing the amount of RAM that you have allocated to the VM.