Q:
My application communicates with SCSI Parallel devices like
scanners or printers using the SCSIAction or IOSCSIUserClient
APIs. This worked on all versions of Mac OS X prior to 10.2. On Mac OS X 10.2, when I call
SCSIAction I get an opWrErr (-49). Or, if I call
IOSCSIDeviceInterface->open
I get a kIOReturnExclusiveAccess error (0xE00002C5 or -536870203).
Why does this no longer work?
A:
IOSCSIUserClient and SCSIAction are deprecated APIs in Mac
OS X 10.2. The intention was for these APIs to continue functioning
as on earlier releases until users installed SCSI HBA drivers
written to the new IOSCSIParallelFamily that shipped in Mac
OS X 10.2. These APIs were inadvertently disabled and have been restored in
Mac OS X 10.2.1 (rr. 3006423, 3026125). Until then, calling
open on an IOSCSIDeviceInterface will return
kIOReturnExclusiveAccess.
SCSIAction internally calls that same function and maps the
I/O Kit error kIOReturnExclusiveAccess to the OSErr opWrErr.
SCSITaskUserClient is the API that replaces IOSCSIUserClient
and SCSIAction. Apple recommends that developers wishing
the greatest backward compatibility use both SCSITaskUserClient
and SCSIAction/IOSCSIUserClient to discover their device,
then use the API which found the device to communicate with
it.
[Sep 13 2002]
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