Issue iPXE booting win10 1709 hyper-v vm

[Paulman9]

We are using ipxe via FOG to image machines. It seems after the 1709 update, our (gen 1) hyper-v vms started having issues with ipxe. Attempting to network boot a vm after 1709 (that worked before with no changes) the machine will freeze at "ipxe initializing devices..." and loads up 100% on one core of the cpu. I have left the machine for at least 3 days without it progressing, so I'm pretty sure it has failed at that point. We were using an old version of undionly.kpxe, so I tried the latest master (47849 as of when I built it) and had the same problem.
I tried the intel and ipxe.kpxe files included with fog, which were probably old versions but exhibited the same behavior. Strangely gen 2 vms work without any issues. After much trial and error, I finally compiled an undionly.kpxe that functioned properly in FOG. Commenting out these lines allowed ipxe to continue correctly:
#define DOWNLOAD_PROTO_HTTPS
#define IMAGE_TRUST_CMD
#define CERT_CMD
Unsure why, yet it funtions properly for me now. While I do not need any https or certificate functionality, to me this seems like a bug or issue with compatibility with windows 1709 that you collectively may want to know about. If I have left out any relevant information, let me know and I'll try to respond.

[NiKiZe]

You should probably report this to Microsoft since it seems to be an regression in Gen1 VMs in that Windows 10 version. This was also mentioned on IRC so might get more attention via some other channels as well.

[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.

[aggieNick02]

I just confirmed that the issue I was seeing is caused by one of the cumulative updates for Win10 1709. I started with a clean Win10 1709 image (with no updates) and a Hyper-V VM configured to PXE boot first and fall through to a windows image second.

VM PXE booted and fell through to windows just fine.

Gave the machine internet and applied the latest 1709 updates, restarted.

VM PXE booted and hung trying to boot windows.

Let the machine update to 1803.

VM PXE booted and fell through to windows just fine.

[NiKiZe]

(2018-05-11 19:54)aggieNick02 Wrote:  Let the machine update to 1803.

VM PXE booted and fell through to windows just fine.

Thanks for reporting back.
Just to be clear, this now works in 1803? while an update to 1709 breaks it?

[aggieNick02]

(2018-05-11 21:56)NiKiZe Wrote:  Thanks for reporting back.
Just to be clear, this now works in 1803? while an update to 1709 breaks it?

Exactly. If it is interesting/helpful, I can narrow down which 1709 update broke it. It works fine in the initial release of 1709 (16299.15) but not in what was the latest on the day I tested (16299.402).

[NiKiZe]

(2018-05-15 15:07)aggieNick02 Wrote:  Exactly. If it is interesting/helpful, I can narrow down which 1709 update broke it. It works fine in the initial release of 1709 (16299.15) but not in what was the latest on the day I tested (16299.402).

I think it's perfect just as it is if anyone has issues and need to use 1709 then they now know where to start Big Thanks!