To install:

1. Copy mirror.dll to %winnt%\system32, mirror.sys to %winnt%\system32\drivers

2. These are added during .inf file installation:
        Sets registry values (where '#' is a number):
                HKLM\System\CurrentControlSet\Services\mirror
                device#\Device Description "Microsoft Mirror Driver" (SZ)
                device#\Installed Display Drivers "mirror" (MULTI_SZ)
                device#\MirrorDriver 0x1 (DWORD)
                device#\xxx possibly other keys
                enum\xxx keys for enumerating devices

3. When invoking the mirrored driver on a mirrored device:

To change the settings for your mirrored device, you must know the '\\.\DISPLAY#' name
associated with your mirrored display. In the case of multiple instances, '#' will be
a different number. This can be found by iterating through the available display devices
using EnumDisplayDevices(). For reference/testing only, this information can be
found under the following key:

        HKLM\Hardware\DeviceMap\Video

To attach the mirrored device to the desktop pdev list, you must add a registry value
'Attach.ToDesktop' = 0x1. Subsequent ChangeDisplaySettings() will then dynamically load
the mirrored display driver for use.

HKLM\SYSTEM\CurrentControlSet\Hardware Profiles\Current\System\CurrentControlSet\
        Services\mirror [where 'mirror' is short name of mirrored surface]
            device#\Attach.ToDesktop 0x1 (DWORD)

To disable the attachment, set 'Attach.ToDesktop' to 0x0. Otherwise your driver will
invoked again at boot up time. There are also other Default.Settings values saved under
this key, use ChangeDisplaySettings() with dwFlags=CDS_UPDATEREGISTRY to properly save
them.

To create a DC, device managed bitmap, etc. using the mirrored surface, use the
ordinary GDI APIs. To create the DC specify, use the following:

HDC hdc = CreateDC("DISPLAY", // driver name
                                    deviceName, // example 'mirror' device name
                                    NULL,
                                    NULL);

See DDK sample for a working demonstration.

Minimum requirements for barebones mirrored display driver:

DrvEnableDriver [exported]
DrvEnablePDEV
DrvCompletePDEV
DrvDisablePDEV
DrvEnableSurface
DrvDisableSurface
DrvBitBlt
DrvCopyBits
DrvCreateDeviceBitmap
DrvDeleteDeviceBitmap
DrvTextOut

Minimum requirements for barebones mirrored miniport driver:

DriverEntry [exported]
HwFindAdapter
HwInitialize
HwStartIO

Since there is no physical display device associated with a mirrored surface, these routines
can return positive results.