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Inside Macintosh: Devices /

Chapter 4 - SCSI Manager 4.3 / SCSI Manager 4.3 Reference

SCSI Manager 4.3 Functions / SIM Support Functions

MakeCallback

You use the MakeCallback function to signal the XPT to call a completion routine.

void MakeCallback(SCSI_IO *scsiPB);

scsiPB

A pointer to a SCSI I/O parameter block, which is described on page 4-23.

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scsiCompletion

CallbackProc

A pointer to a completion routine.

DESCRIPTION

The MakeCallback function instructs the XPT to execute the completion routine in the SCSI I/O parameter block. The XPT restores the client's A5 world and then calls the completion routine. A SIM should always use this function rather than calling completion routines directly because the XPT may chose to defer the actual execution of the routine until page faults are safe.

You should surround a call to MakeCallback with calls to ExitingSIM and EnteringSIM so that the Virtual Memory Manager can properly handle any page faults caused by the completion routine.

SPECIAL CONSIDERATIONS

You get the address of this function from the MakeCallback field of the SIM initialization record.

SEE ALSO

See "Writing a SCSI Interface Module," beginning on page 4-15, for more information about using this function.