Intel support wrote this yesterday:
We just received feedback from the escalation point regarding the Hyper-V not working with certain amount of memory.
The issue has been replicated and a solution has been provided. In order to solve the issue, several settings need to be enabled in the BIOS. Please see the steps below for futher instructions:
Press F2 during POST->BIOS setup page->Advanced-> Processor Configuration ->
- set Intel(R) VT for Directed I/O to Enable
- set Coherency Support to Enable
- set ATS Support to Enable
- set Pass-through DMA Support to Enable
We tried and it didn't help :-(
Not any solution, no. We have reproduced this with other vendors NICs as well as with storage devices. Is not a LAN issue, but seems to be either an OS, or platform or OS & platform issue.
Our Server group has made this a priority and is actively investigating this.
A quick update for those still following this post.
We ahave a whole team dedicated to this activity. Preliminary reports are that a root cause may have been found. I am not able to convey the details of the investigation at this time. Investigation continues.
I will provide additional information as it becomes available.
There are some initial reports that for some, a temporary work-around is available in the existing BIOS. Apparently there is a "Maximize memory below 4GB" setting in the BIOS somewhere. If this is enabled it changes the way BIOS maps memory and does some other things that has been reported to alleviate this particular issue for some.
You might give this a try and see if it helps you.
The folks in charge are still working on determining how to proceed for a true fix of the issue.
More updates as available.