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Exposing >4GB Graphics Card Memory to VM using DDA

    Question

  • Hello,

    We have a Hyper-V Server 2016 with a PCIe graphics card with 8GB of memory exposed via DDA to a Windows 10 VM, but we can only see 4GB of graphics card RAM available from inside the VM. We used the "Set-VM -HighMemoryMappedIoSpace 8000MB" command and from the hypervisor we can see 8GB allocated, but it's not available from within the VM.

    Is there an artificial limit within Hyper-V that is restricting DDA from exposing greater than 4GB of graphics memory? Or are we simply doing something wrong?

    Thanks,

    Trevor


    Wednesday, January 25, 2017 8:10 AM

All replies

  • Hi Trevor,

    >>Is there an artificial limit within Hyper-V that is restricting DDA from exposing greater than 4GB of graphics memory?

    I checked all the documents I could find, but I'm afraid I could only find the command that you have already run. I could not find related information about the limit.

    I would wait for later official documents and post here if I got any updates.

    Best Regards,

    Leo


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    Thursday, January 26, 2017 6:01 AM
    Moderator
  • Thanks for taking the time to reply Leo. Yeah, I'm also a little frustrated at the lack of official documentation surrounding DDA - just a few blog posts and 'see how you go with it'. Very, very few people even seem to know anything about it.

    Anyone want to kick this in the direction of the virtualization team?

    Thursday, January 26, 2017 4:50 PM
  • Hi Trevorx,

    >>Anyone want to kick this in the direction of the virtualization team?

    Not sure if the limit is by design. I would keep you update when I confirmed if it is by design or configuration issue.

    Best Regards,

    Leo


    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Friday, February 03, 2017 6:16 AM
    Moderator
  • Thanks Leo, appreciate it :-)
    Wednesday, February 08, 2017 11:09 AM