Disk issues on Hyper-V

[David Arroyo]

Hello,

I'm trying to run Dragonfly 5.8.0 on Hyper-V on my Windows 10 machine. Going off of this article from 2018[1], I created a Gen 1 VM with a legacy network adapter and used IDE for the virtual disk. However, when booting the system I see these errors in dmesg:

ad0: 81920MB <Virtual HD 1.1.0> at ata0-master WDMA2
ad0: FAILURE - SETFEATURES ENABLE WCACHE status=51<READY,DSC,ERROR> error=0
ad0: TIMEOUT - READ_DMA retrying (1 retry left) LBA=0
ad0: FAILURE - SETFEATURES ENABLE WCACHE status=51<READY,DSC,ERROR> error=0
ad0: TIMEOUT - READ_DMA retrying (0 retries left) LBA=0
ad0: FAILURE - SETFEATURES ENABLE WCACHE status=51<READY,DSC,ERROR> error=0
ad0: FAILURE - READ_DMA timed out LBA=0
ad0: reading primary partition table: error accessing offset 000000000000 for 512

Trying to read anything from the disk times out. If I switch the mode from WDMA2 to PIO4 I can read but writes give an I/O error:

# natacontrol mode ad0 PIO4
current mode = PIO4
# dd if=/dev/ad0 of=/dev/null bs=1M count=1
1+0 records in
1+0 records out
1048576 bytes transferred in 0.134417 secs (7800912 bytes/sec)
# dd if=/dev/zero of=/dev/ad0 bs=1M count=1
ad0: timeout waiting for write DRQ
dd: /dev/ad0: Input/output error
1+0 records in
0+0 records out
0 bytes transferred in 0.201104 secs (0 bytes/sec)

I tried turning on debug logging for Hyper-V but nothing was logged while I reproduced the issue. I then tried FreeBSD and Ubuntu VMs with the same configuration and didn't see the issue. I also tried switching the disk from the IDE controller to the SCSI controller, but when I did that, dragonfly couldn't see the disk any longer. 

I'm not sure where to go from here. I work with Linux at $dayjob, so I am not really familiar with Hyper-V *or* BSD. Has anyone else built a dragonfly VM on Hyper-V recently, and did you have any trouble? Does anyone have any advice for troubleshooting the read timeouts?

Cheers,
David

[1]: https://www.dragonflydigest.com/2018/09/28/21850.html