Microsoft KB Archive/282873

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INFO: Use and Importance of DMA32BitAddresses

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Q282873

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The information in this article applies to:


 * Microsoft Windows 95 Driver Development Kit (DDK)
 * Microsoft Windows 98 Driver Development Kit (DDK)
 * Microsoft Windows ME Driver Development Kit (DDK)

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SUMMARY
This articles discusses the use and importance of DMA32BitAddresses.

MORE INFORMATION
SCSI MiniPort (ScsiPort) drivers, written for disk controllers, use the PORT_CONFIGURATION_INFORMATION structure to fill in adapter specific information in response to a HwFindAdapter routine call back.

The HwFindAdapter call back function is called when a driver calls ScsiPortInitialize.

It is very important for a ScsiPort driver to set the Dma32BitAddresses flag to TRUE. Failing to do so results in the Bigmem.vxd file being loaded and inserted in the call down stack.

The Bigmem.vxd file is provided by the system to help some legacy ISA controllers that can not handle memory above 16 megabytes. The Bigmem.vxd file performs a lot of memory mapping and degrades overall system performance.

Additional query words: BIGMEM.VXD ScsiPort Dma32BitAddresses PORT_CONFIGRATION_INFORMATION

Keywords : kbDDK kbOSWin95 kbOSWin98 kbDSupport kbOSWinME

Issue type : kbinfo

Technology : kbWinMEsearch kbAudDeveloper kbWin95search kbWin98search kbWin95DDKSearch kbWinDDKSearch kbWin98DDKSearch kbWinMEDDK kbWin95DDK kbWin98DDK