Microserver Gen8 with Nvidia A2 and L4 GPUs VM Passthrough

I made and interesting discovery while experimenting with older hardware HP MicroServer Gen8 (2012) that supposedly cannot run modern NVIDIA data-center GPUs like the A2 or L4 (2023) because the platform only exposes a 24GB PCIe prefetchable window. On paper these GPUs require far more address space, so initialization fails.

However, there is a way to perform BAR negotiation during initialization that can fit inside the Gen8 window, which makes it possible to run these GPUs inside a VM on the Microserver Gen8. Result: a decade-old microserver running modern GPU workloads inside a VM.

I wrote up the full explanation and setup steps for anyone still running these little machines here:

https://medium.com/@aletik/the-impossible-nvidia-gpus-ca48ac425efc