Microsoft KB Archive/140610

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BUG: SCSI Miniport Parms Not Parsed on Multi PCI Bus Systems

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Q140610

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The information in this article applies to:


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

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SYMPTOMS
On systems with more than one PCI bus, the SCSI miniport might not receive the adapter-specific parameters specified in the registry for the adapters on the non-primary PCI bus. This affects the SCSIPORT parameters like DisableTaggedQueuing, DisableSynchronousTransfers, and DisableDisconnects as well as others.

For information on setting parameters for SCSI miniport drivers, please see the Windows NT DDK documentation.

STATUS
This is a limitation on the Scsiport.sys driver when used on a system with multiple PCI busses and there are no plans to modify the driver. As a work- around, set the registry as follows:

For the first PCI adapter, use Device0. If the second PCI adapter is on the same PCI bus as the first adapter, use Device1. If the second PCI adapter is on the next PCI bus scanned, use Device2 for the second adapter. Everytime a new PCI bus is scanned, increment the DeviceX string by two rather than one.

MORE INFORMATION
SCSIPORT does not correctly handle the SCSI miniport parameters if a system has more than one PCI bus and there is an adapter on the primary PCI bus and an adapter on the non-primary PCI bus.

For example, if you want to disable tagged command queuing on the second SCSI adapter (Device1). A key similar to the following would be added to the registry with the value: DisableTaggedQueuing : REG_DWORD : 0x1:

HKEY_LOCAL_MACHINE SYSTEM CurrentControlSet Services aic78xx Parameters Device1

The problem is that SCSIPORT never correctly uses the registry parameter string, so tagged queuing isn't disabled for the second adapter. Note that if all the SCSI adapters are on the primary PCI bus, the registry parameters are parsed correctly. Also, the generic key "Device" can still be used to pass parameters to all the adapters supported by the specified miniport.

Additional query words: 3.50

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Issue type :

Technology : kbAudDeveloper kbWinDDKSearch kbWin32sSearch kbWin32DDKSearch kbWin32DDKNT350 kbWin32DDKNTSearch