Microsoft KB Archive/138697

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DOC: Incomplete Definition of VideoDebugPrint

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Q138697

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The information in this article applies to:


 * Microsoft Win32 Device Driver Kit (DDK) for Windows NT, versions 3.5, 3.51

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The definition of VideoDebugPrint is incomplete. It should be as follows:

Usage:

  VOID VideoDebugPrint((ULONG Level, PCHAR DebugMessage, ...)); "VideoDebugPrint writes a debug string to the WinDbg KD Command window." Parameters:

Level - the debug print level of the message between 0 and 3, with 3

"being the most verbose. This parameter is compared by the VideoPort driver to a global debugging variable set in the registry. If the parameter 'Level' is equal to or less than the global debugging variable, the message is printed." "DebugMessage - The printf formatted string to be printed." Comments:

"The VideoPort driver looks for the following variable at startup in the Registry:"      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DriverName\DeviceN \VideoDebugLevel:REG_DWORD:n Where:


 * DriverName is the video miniport's installed name.
 * DeviceN is the installed device number (for example, Device0).
 * n is the VideoPort's global debug level setting from 0 to 3 for this miniport driver.

If the VideoDebugLevel variable does not exist in the registry, the VideoPort driver uses a default value of zero. Thus, when VideoDebugPrint is called with a Level parameter greater than zero, nothing is printed.

Only kernel-mode video miniport drivers can call VideoDebugPrint.

When you run a free build of the VideoPort and video miniport, all references to this call are eliminated by the compiler.

See any of the sample video miniports in the DDK for an example. This documentation error was fixed in the Windows NT DDK version 4.0.

Additional query words: 3.50 3.51

Keywords : kbdocfix

Issue type :

Technology : kbAudDeveloper kbWinDDKSearch kbWin32sSearch kbWin32DDKSearch kbWin32DDKNT350 kbWin32DDKNT351 kbWin32DDKNTSearch