I have two main gaming VMs that I have been using to run multi-player VR sessions, Vanaheim (Vive oriented) and Muspelheim (Oculus oriented) .  The two VMs are almost identical in composition and creation, except for what PCI devices are assigned for each VM.  Vanaheim always boots up successfully.  But Muspelheim will often (~50%) hang at either the BIOS screen or the Windows 10 Loading screen, prior to the spinning circles.  On a failing run, I don't see anything in the VM log files to indicate something bad has happened.  The CPU utilization shows all 8 CPUs running near 100% during initialization, then all go to zero while one stays up at near 100%.  This CPU stays active forever, but the boot never advances. I've left it in this state for hours without resolution.

 

What can I do to characterize and debug this issue?  

 

Assuming all things are equal, it might be a simple as a corrupt install.

 

For me, my first step would be making a new vm and assign it the pci devices from the one that isn't booting well. If the problem persists, then you know the issue probably has something to do with your devices. If it works fine, then the disk image is the likely culprit. 

Can I create VMs that use the same image with different PCI devices mapped?  This might be a way for me to isolate the installation vs. the HW.  If the Vanaheim image is able to run fine with all the Muspelheim dedicated HW, then the problem is probably with the installation.

 

Windows might get picky about the uuid of the vm...I don't recall... other os's don't mind as much. You can make a copy of the .img file (I do this for safety incase I screw something up, that way I don't mess up the working one) create a new vm using the template manager using the copied image and give it the pci devices with no problem. Don't know if it will boot though. I don't use windows all that often.