Windows 10 guest w. tools shows duplicate disks if set to AHCI


After guest tools have been installed, Windows 10 shows the same disks twice in Device Manager and in Disk Management. Both duplicates can be formatted, mounted, and written to. After reboot, one of the duplicate drives will be show as offline, but can be mounted and written to again. One of the two drives will be have QEMU in the title, the other will have XENSRC. There will be one duplicate per VHD assigned to the guest.

This issue could be fixed by editing XC-Windows/xenvdb/xen.c. Lines 1490-1495 could be changed to exclude the AND condition (no longer checking for 768) so all PV disks are ignored.


Dell Latitude 7490
1.8.0 BIOS, UEFI, TPM2
Stable 9 Build 6524
Windows 10 1803 - Legacy
Windows 10 1809 - Legacy

Validation Steps

  1. Install OpenXT Stable 9 Build 6524, UEFI

  2. Install Windows 10 guest VM (1803 or 1809, legacy)

  3. Check hdtype for guest VM. Confirm AHCI

  4. Observe 1 HD listed in dskmgmt and/or device manager per VHD assigned to guest

  5. Install guest tools and reboot guest VM

  6. Observe 2 HD listed in dskmgmt and/or device manager per VHD assigned to guest

  7. Change hdtype from AHCI to IDE and boot guestVM

  8. Observe 1 HD listed in dskmgmt and device mananger per VHD assigned to guest


Chris Rogers
April 26, 2019, 3:48 PM

, would like your opinions on this.

The issues experienced by the downstream that prompted the use of the DEBUG_BOOT_EMULATED flag and blocking the load of all PV disks aren't observed on OpenXT, and as far as I can tell, this behaviour of seeing the QEMU disk and PV Disk in Device Manager has been around for awhile.

I'm recommending we close this as Won't Fix.

Andrew Jones
May 1, 2019, 3:45 PM

After working with Chris on this issue we have determined that the duplicate disks are seen only when HDTYPE is set to AHCI. When set to IDE the duplicates do not appear. I am updating the ticket title and validation steps to include this new information.
We have also determined that this same behaviour is seen in linux, so I will be linking this ticket to

Nicholas Tsirakis
June 25, 2019, 9:00 PM

Installed Win10-1803 w/ tools on stable-9 rc1, only seeing one disk (QEMU HARDDISK) in Device Manager.
Edit: drive is AHCI as described in ticket.





Andrew Jones



QA Assignee

Nicholas Tsirakis

QA Image URL


Epic Link

Fix versions

Affects versions