Step 1: Minidriver Initialization

There are three stages of minidriver initialization:

When the minidriver is first loaded into memory by the kernel.
When GDI calls Enable to get the GDIINFO table.
When GDI calls Enable to initialize the video hardware.

Note that the parameters passed to the Enable DDI indicate whether the driver should initialize the GDIINFO structure or the video hardware. Drivers should not rely on the order of the Enable calls.

Init Routine (Before GDI)

The kernel calls the display driver's initialization routine when it first loads the driver. At this point, neither GDI nor USER have been loaded, so no graphics operations are required. Instead, you can carry out initialization procedures that do not affect the display adapter. For an example of init code, see the INIT.ASM file in the display driver samples.

Enable GDIINFO

GDI calls Enable twice whenever it creates or restores a display DC. One of the calls is to get the GDIINFO block from your minidriver. For a code example, see the ENABLE.ASM file in the display driver samples.

You must set the following fields in the GDIINFO structure for your adapter. Do this after using the DIB_Enable function to get the information from the DIB engine:

dpVersion	dpNumBrushes
dpHorzRes	dpNumPens
dpVertRes	dpNumFonts
dpBitsPixel	dpNumColors
dpPlanes

Note that the DIB engine may set capability bits in GDIINFO in addition to those set by the display minidriver. The driver should not modify the bits set by the engine. To achieve this, the driver should use the logical OR operator when setting bits. Minidrivers that do not have an accessible frame buffer should set the NOT_FRAMEBUFFER bit in the deFlags member of the DIBENGINE structure.

If your adapter does not provide a hardware graphics accelerator, set the C1_SLOW_CARD bit in the dpCaps1 member.

When your minidriver has completed initializing the GDIINFO structure, return it to GDI.

Initializing the Hardware

Minidrivers initialize the video hardware and create their PDEVICE structure on one of the calls to Enable. Use the following steps to initialize your hardware:

Initialize the graphics adapter to be in the correct graphics mode. This should include setting the refresh rate based on the current monitor. For more information on refresh rates, see About Refresh Rate Support.
A minidriver should not call FatalExit if it is not possible to enable the hardware. Instead, the Enable function should return zero, indicating failure. This causes the system to reboot into clean Windows with the default VGA driver.
Create the driver's PDEVICE structure by calling the CreateDIBPDevice entry point in the DIB engine with a BITMAPINFO definition of its display surface. The DIB engine will create a PDEVICE structure.
If display memory is banked switched, the driver should call VFLATD to register the frame buffer. The driver must provide a code template that performs bank switching to VFLATD so that the virtual display will work properly. VFLATD will return a selector for accessing the screen. This value is stored in the deBits field of the PDEVICE structure. If the display memory is linear, this step is not necessary. Instead, the driver must create a selector to its linear display memory and store it into the PDEVICE structure. The driver should use MS-DOS protected mode interface (DPMI) services to create the linear selector. Using VFLATD, the driver can ignore the system-memory limitations and obtain an address to a logical frame buffer that is large enough to store the color data for an entire screen.
If the display adapter registers itself as requiring bank switching, whenever a page fault occurs during a drawing operation, the VxD maps the required block of memory from the logical frame buffer to A000:0000. By calling the VxD's Create_Virtual_Frame_Buffer function, a driver registers its bank-switching procedure and obtains a selector identifying the logical frame buffer. For more information about the VFLATD, see About Virtual Flat-Frame Buffer Device.
Route all GDI calls to the DIB engine by including DIBLINK.ASM and DIBENG.LIB in your driver build environment. Note that the Enable call is not routed. Also note that cursor-related calls are handled by the DIB engine.

You now have a generic display minidriver. You need to follow the remaining steps in order to customize your minidriver for your display adapter.