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  • 1.  How to Troubleshoot KVM Passthrough Preventing VM Boot?

    Posted Jun 03, 2023 06:10 PM

    I passed through a USB 3.2 Controller.  No problems.  But, when I have my KVM plugged into one of the ports on the USB Controller, the VM boot does not get past the VMWare splashscreen.

    Processor: AMD Ryzen Threadripper PRO 5955WX
    Motherboard: Gigabyte MC62-G40
    USB Controller: Allegro Pro USB-C 8-Port PCIe Card (USB3C-8PM-E)
    KVM: Rextron 4 Ports 8K DisplayPort 1.4 KVM Switch With USB 3.2 Gen 1 (PAAG-E3114B)
    Host OS    : VMWare vSphere ESXi 8.0 Update 1
    Guest OS: Windows 10 Enterprise 22H2 x64 (also tried with Win11 and Linux)

    The USB PCIe card I added has 4 separate controllers.  I have 1 assigned to passthrough to each of 4 VMs.  Other than the VM with my KVM plugged into the external USB port of the USB Controller that's passedthrough, there have been no problems.  I've tried having the KVM plugged into different VMs with different OS's, (i.e. Windows 11 Enterprise, Linux) and the VM boot will not progress past the VMWare splash screen in this KVM is plugged into it, (I attached a screenshot of the splash screen for reference).

    If I unplug the KVM, then boot the VM, and then re-attach the KVM, it works fine.  I get full functionality out of the KVM (keyboard, mouse, and any other USB peripherals plugged into the KVM's built in USB hubs).  I've tried unplugging all of the USB peripherals from the KVM while booting, but the problem remains.  This leads me to believe that the problem is specific to the hubs built internally into the KVM. 

    I also passthrough other PCIe devices, (video card, network card) and I passthrough USB devices explicitly (Corsair PSU, Corsair Fan Controller, USB SSD stick).  I have tried not passing them through as a troubleshooting step, but it didn't help.

    Windows Device Manager doesn't show any yellow bings or other obvious signs of distress, (I attached a screenshot for reference).  The chipset used on the USB controller is ASMedia, so I did some research and found out that there might be a better driver.  I performed the driver update successfully, but the problem remains.

    I looked through the vmware.log file of an unsuccessful boot for errors and I couldn't see anything that looks germane to this issue.  I attached said log to this post in case someone else can find something helpful.  I tried comparing the file to one from a successful boot and didn't see any differences that stood out.

    At this point I do not know where else to look, or what else to try.

    Any suggestions?

    Attachment(s)

    log
    vmware.log   128 KB 1 version


  • 2.  RE: How to Troubleshoot KVM Passthrough Preventing VM Boot?

    Posted Jun 07, 2023 12:51 AM

    Well, I couldn't solve this one, but I bypassed it. I swapped one of the video cards I was using that took up two slots for one that takes up only one slot. Now that I had an open slot, I used a USB Controller card with the Renesas NEC uPD720201 chipset. That chipset has no problems and works like a charm. I passed this new USB Controller to my VM, plugged the KVM into it instead, and voilà, no more problems. I'd like to know how to fix the base problem, but I can live with the workaround.