I/O routines

The following sections summarize the entry point modifications required for I/O operations when porting drivers from earlier DDI versions or SCO OpenServer 5 to run on DDI 8:

• Modify the syntax of the open(D2) routine. For DDI 8 drivers, STREAMS and non-STREAMS drivers use the same syntax for the open( ) routine. open( ) also takes an idata, channel argument pair to identify the logical device instead of the *devp argument used for earlier DDI versions and SCO OpenServer 5 drivers. The otyp parameter used for earlier drivers is dropped. See the open(D2) manual page for details about some subtle behavioral changes for open( ).

• Replace the read(D2), write(D2), and strategy(D2) routines in non-STREAMS drivers with the biostart(D2) routine. The biostart( ) routine is structure much like the old strategy(D2) and strategy(D2oddi) routines. Much of the code from the old routines can be used in biostart( ), but note that calls to buf_breakup(D3) should be removed because the operating system automatically calls this function beginning with DDI 8.

• Modify the syntax of the chpoll(D2), ioctl(D2), mmap(D2), and close(D2) routines to use the idata, channel pair instead of the dev_t parameter.

• All DDI 8 drivers must include a devinfo(D2) entry point routine, even if there are no useful parameters (which is the case for most software drivers and STREAMS modules) and the entry point routine may just return.

  For drivers being ported from earlier DDI versions, note that the syntax of the devinfo( ) routine has changed and a different set of parameters are supported. See the manual page for details.