[Bug]: Virtual Display not attached to desktop on Windows ARM (Snapdragon X) – not visible via DXGI / EnumDisplayMonitors

[rohitsangwan01]

Which OS?

Win11 Pro

Which release?

24H2

Driver Version

latest

Device Specifications

OS: Windows 11 ARM64
Device: Snapdragon X (Adreno X1-45 GPU)
Driver: Virtual Display Driver (latest from this repo)
Architecture: Native ARM64 build

Describe the bug

On Windows 11 ARM (Snapdragon X / Adreno GPU), the Virtual Display Driver successfully creates a display device and monitor, but it is not attached to the desktop.

As a result:

• The display does NOT appear in:

  • EnumDisplayMonitors
  • DXGI (IDXGIAdapter::EnumOutputs)
  • Higher-level libraries like display-info

• But it does appear in:

  • EnumDisplayDevices

This suggests the display exists but is not promoted to an active desktop output.

Observed Behavior

With Virtual Display Enabled

• EnumDisplayDevices:

  • Shows \\.\DISPLAY8

  • Description: Virtual Display Driver

  • Monitor present:

    \\.\DISPLAY8\Monitor0
    Generic PnP Monitor
    Flags: 0x2
    

• ❌ EnumDisplayMonitors:

  Total monitors: 1
  (only primary display)
  

• ❌ DXGI:

  Adapter 0: Qualcomm(R) Adreno(TM) X1-45 GPU
    Output 0: \\.\DISPLAY1
  

• ❌ display-info crate:

  Found 1 displays
  

---

Key Finding

The virtual display is present but not attached to the desktop.

From EnumDisplayDevices:

• Primary display:

  Flags: 0x5  (attached + active)
  

• Virtual display:

  Flags: 0x2  (NOT attached to desktop)
  

This explains why all modern APIs ignore it.

---

Additional Notes

• Windows Settings UI can show the display
• But it is not treated as an active desktop output
• Issue reproducible consistently on ARM64, but not on x86

Thanks for the great project 👍

Steps to reproduce

No response

Expected behavior

No response

Log File

Here is log Output from my debug program

=== SYSTEM INFO ===
ARCH: aarch64
OS: windows
Pointer Width: 64-bit
=== display-info crate ===
Found 1 displays
#0: DisplayInfo { id: 2776250164, raw_handle: HMONITOR(65537), x: 0, y: 0, width: 1440, height: 810, rotation: 0.0, scale_factor: 2.0, frequency: 120.0, is_primary: true }


---

Before Adding Virtual Display

---

Win32: EnumDisplayMonitors
Monitor 1: \.\DISPLAY1
Total monitors: 1



=== Win32: EnumDisplayDevices ===
Adapter 0:
Name: \.\DISPLAY1
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x5
Monitor 0:
Name: \.\DISPLAY1\Monitor0
Desc: Generic PnP Monitor
Flags: 0x3
Adapter 1:
Name: \.\DISPLAY2
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 2:
Name: \.\DISPLAY3
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 3:
Name: \.\DISPLAY4
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 4:
Name: \.\DISPLAY5
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 5:
Name: \.\DISPLAY6
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 6:
Name: \.\DISPLAY7
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 7:
Name: \.\DISPLAY8
Desc: Virtual Display Driver
Flags: 0x0



DXGI
Adapter 0: Qualcomm(R) Adreno(TM) X1-45 GPU
Output 0: \.\DISPLAY1
Desktop Coords: left=0 top=0 right=1440 bottom=810
Attached: true
Adapter 1: Qualcomm(R) Adreno(TM) X1-45 GPU
Adapter 2: Microsoft Basic Render Driver




---

After Adding Virtual Display

---


=== Win32: EnumDisplayMonitors ===
Monitor 1: \.\DISPLAY1
Total monitors: 1



=== Win32: EnumDisplayDevices ===
Adapter 0:
Name: \.\DISPLAY1
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x5
Monitor 0:
Name: \.\DISPLAY1\Monitor0
Desc: Generic PnP Monitor
Flags: 0x3
Adapter 1:
Name: \.\DISPLAY2
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 2:
Name: \.\DISPLAY3
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 3:
Name: \.\DISPLAY4
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 4:
Name: \.\DISPLAY5
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 5:
Name: \.\DISPLAY6
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 6:
Name: \.\DISPLAY7
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 7:
Name: \.\DISPLAY8
Desc: Virtual Display Driver
Flags: 0x0
Monitor 0:
Name: \.\DISPLAY8\Monitor0
Desc: Generic PnP Monitor
Flags: 0x2



=== DXGI ===
Adapter 0: Qualcomm(R) Adreno(TM) X1-45 GPU
Output 0: \.\DISPLAY1
Desktop Coords: left=0 top=0 right=1440 bottom=810
Attached: true
Adapter 1: Qualcomm(R) Adreno(TM) X1-45 GPU
Adapter 2: Microsoft Basic Render Driver




===================== WITH VDD ===================================

C:\Users\nbehn\Downloads>arm_display_test.exe
=== SYSTEM INFO ===
ARCH: aarch64
OS: windows
Pointer Width: 64-bit
=== display-info crate ===
Found 1 displays
#0: DisplayInfo { id: 2776250164, raw_handle: HMONITOR(65537), x: 0, y: 0, width: 1440, height: 810, rotation: 0.0, scale_factor: 2.0, frequency: 120.0, is_primary: true }

====================================================

=== Win32: EnumDisplayMonitors ===
Monitor 1: \.\DISPLAY1
Total monitors: 1

====================================================

=== Win32: EnumDisplayDevices ===
Adapter 0:
Name: \.\DISPLAY1
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x5
Monitor 0:
Name: \.\DISPLAY1\Monitor0
Desc: Generic PnP Monitor
Flags: 0x3
Adapter 1:
Name: \.\DISPLAY2
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 2:
Name: \.\DISPLAY3
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 3:
Name: \.\DISPLAY4
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 4:
Name: \.\DISPLAY5
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 5:
Name: \.\DISPLAY6
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 6:
Name: \.\DISPLAY7
Desc: Qualcomm(R) Adreno(TM) X1-45 GPU
Flags: 0x0
Adapter 7:
Name: \.\DISPLAY8
Desc: Virtual Display Driver
Flags: 0x0
Monitor 0:
Name: \.\DISPLAY8\Monitor0
Desc: Generic PnP Monitor
Flags: 0x2

====================================================

=== DXGI ===
Adapter 0: Qualcomm(R) Adreno(TM) X1-45 GPU
Output 0: \.\DISPLAY1
Desktop Coords: left=0 top=0 right=1440 bottom=810
Attached: true
Adapter 1: Qualcomm(R) Adreno(TM) X1-45 GPU
Adapter 2: Microsoft Basic Render Driver

====================================================

Done.

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