Passthrough questions

[kameleon]

First a little background: I have a customer who has a windows NT 4.0 machine that runs a specific piece of machinery for their operation. I have been tasked with migrating it to newer hardware as you can imagine how old the hardware it is running on now is! (Hint: slot1 Pentium2 and 2x 4GB HDD!!!!). I cannot change the OS as it is hard setup for this environment so I figured moving it to a virtual environment would be ideal. This is supposed to be a fill in while they source a new piece of hardware but that can take up to 5 years so here we are. The PC has a PCI SCSI card that the machinery interfaces with and an LPT "key" to allow the software to run.

With all that said here is what I am looking at.

I figured virtualizing the machine and using passthrough for the SCSI card, LPT port (or possibly a USB to LPT adapter if I can make that work), and possibly the PCI video card so accessing the pc will be no different to the workers on the floor.

Questions:

Has anyone done something similar? If so any tips?
Should I be able to do the USB to LPT on the host machine and just pass through the LPT port?
Should I be able to pass through an AGP or PCI video card to the guest while keeping the onboard video for the host?
Anything else I'm not thinking of?

Thanks

[Martin]

As passthrough support was only available for Linux hosts up to Virtualbox 6.0.x and never really worked I don't think that is a solution for your problem.

[scottgus1]

As Martin mentioned, PCI passthrough is removed in 6.1.x, because most PCI cards are really PCIe nowadays, and PCIe passthrough wasn't in the code, according to the developers.

That said, PCI passthrough is still in 6.0.x, and you very extremely likely have a PCI card on that old hardware.

Virtual machines have timing issues. If you're running a CNC machine, etc., precision movement, the virtual environment may not keep up with the machine. However, a NT4.0 guest can't take up that much of a modern I5, for example; there might be enough spare cycles there to make for good operation. Only way is to try it.

USB-to-Parallel adapters typically only implemented printer support, not true complete enhanced parallel protocols which the dongle might require. Stick to getting the host parallel port into the guest, see Enabling and Configuring Parallel (LPTx) Ports.

If you get the dongle and SCSI PCI card into the guest you won't need the video card.

Another alternative: hunt up old-but-still-working XP-compatible PCs, for hardware backups for that old PC. try using an XP-level Macrium Reflect restore CD on the NT4 PC to image those drives, etc.

[kameleon]

As Martin mentioned, PCI passthrough is removed in 6.1.x, because most PCI cards are really PCIe nowadays, and PCIe passthrough wasn't in the code, according to the developers.

That said, PCI passthrough is still in 6.0.x, and you very extremely likely have a PCI card on that old hardware.

Virtual machines have timing issues. If you're running a CNC machine, etc., precision movement, the virtual environment may not keep up with the machine. However, a NT4.0 guest can't take up that much of a modern I5, for example; there might be enough spare cycles there to make for good operation. Only way is to try it.

USB-to-Parallel adapters typically only implemented printer support, not true complete enhanced parallel protocols which the dongle might require. Stick to getting the host parallel port into the guest, see Enabling and Configuring Parallel (LPTx) Ports.

If you get the dongle and SCSI PCI card into the guest you won't need the video card.

Another alternative: hunt up old-but-still-working XP-compatible PCs, for hardware backups for that old PC. try using an XP-level Macrium Reflect restore CD on the NT4 PC to image those drives, etc.

Thanks for that. Yes, I could easily run an older version. Knowing that 6.0, or 5.2 for that matter, should work I'll give it a try. It should be alot easier than my alternative of trying Proxmox with QEMU and/or KVM. I definitely have PCI cards in there, no PCIe to be found on the motherboard

This is actually a plate setter, think of it like a negative printer. So timing should not be an issue.

If the host LPT can be used I'll try that instead of the usb to LPT.

Even with the SCSI and LPT I will need a way for the technicians to interface with the machine. Ideally the end user won't know the difference when we virtualize it.