What more is required to use these symbols? "unresolved external symbol _DEVPKEY_Device_RemovalPolicy"

General
1

When any of these defines are included in the code, they produce an ‘unresolved external symbol’ error from the linker:

const auto getPropResult = SetupDiGetDevicePropertyW(
    hDevInfo,
    &did,
    &DEVPKEY_Device_RemovalPolicy,  // Ask for the "removal policy"
    &devPropType,
    (BYTE*)buffer,
    sizeof(buffer),
    &dwSize,
    0);

Error LNK2001 unresolved external symbol _DEVPKEY_Device_RemovalPolicy

There is this inconclusive Q/A which does not help:

unresolved external symbol _DEVPKEY_Device_BusReportedDeviceDesc

What is still missing after Devpkey.h is included?

2

The linker error LNK2001 unresolved external symbol _DEVPKEY_Device_RemovalPolicy (or similar for other DEVPKEY_ constants like DEVPKEY_Device_HardwareIds) typically means the symbol is declared in a header, but not defined in any linked library.

Problem Summary:

  • You included Devpkey.h, which provides the declaration of DEVPKEY_Device_RemovalPolicy, but not its definition.
  • These property keys are defined as DEVPROPKEY structures, and while they’re declared in the header, their actual definitions (the backing storage) are in a library you also need to link against.

Solution:

To resolve this issue, you need to:

Link against Cfgmgr32.lib

This library contains the definitions of many DEVPKEY_ constants.

Additional Notes:

  • The DEVPKEY_ values are extern const variables in the Windows SDK. The linker needs to resolve them to a compiled library object, not just the header.
  • This applies to:
    • DEVPKEY_Device_RemovalPolicy
    • DEVPKEY_Device_BusReportedDeviceDesc
    • DEVPKEY_Device_HardwareIds, etc.

Example fix in your build:

If you’re using MSVC (Visual Studio), add this to your .cpp file:

#pragma comment(lib, "Cfgmgr32.lib")

Or, if you’re using a build system like MSBuild or CMake, ensure Cfgmgr32.lib is in your link settings.