Issue iPXE booting win10 1709 hyper-v vm

[aggieNick02]

We are seeing issues with our gen-2 VMs on 1709. I'm not certain it is the 1709 upgrade that broke them, but nothing else changed in our setup (that I know of).

We have VMs with good checkpoints that used to iPXE boot and fallthrough to local boot of a windows 10 image just fine. Now after the fallthrough windows will just spin for a while and eventually bluescreen with DRIVER_PNP_WATCHDOG. On the next attempt it will complain with errorcode 0xc0000001.

If I restore the good checkpoint, remove the iPXE boot option, and then start the VM, everything works fine. So it is definitely an iPXE<->Hyper-V interaction issue. Frustrating that Microsoft apparently broke this. I'm off to see what I can find about it and will report back if I find anything.