MDI driver initialization, configuration, and closing

Section D2mdi manual pages lists the entry point routines that can be used in an MDI driver and describes special practices used for MDI.

The entry point routines used for initialization, configuration, and closing in an MDI driver are:

• All SVR5 MDI drivers must be coded as dynamically-loaded kernel modules and so use the _load(D2mdi) entry point routine for initialization.

• DDI 8 drivers must also include the config(D2mdi) entry point routine with the CFG_ADD and CFG_REMOVE subfunctions coded. MDI drivers should fully implement the CFG_SUSPEND and CFG_RESUME subfunctions; at a minimum, they must code the CFG_SUSPEND subfunction to turn off interrupts if the driver is used on a bus architecture that supports shared interrupts, such as PCI. Other subfunctions can be coded as required.

• DDI 7 and SCO OpenServer 5 MDI drivers must implement a halt(D2mdi) routine to disable interrupts for adapters that may support shared interrupts such as PCI.

• DDI 8 ISA devices must also code the CFG_VERIFY subfunction to the config(D2mdi) entry point routine. Drivers written for DDI versions prior to version 8 use the _verify(D2mdi) entry point routine for this purpose. mdi_AT_verify(D3mdi) is available to SVR5 drivers that support both DDI 8 and prior versions.

• SCO OpenServer 5 MDI drivers (MDI version 1) code all initialization functionality in their init(D2) entry point routines. This includes all functionality that is coded into DDI drivers' _load( ), config( ), and _verify( ) routines.

• MDI drivers must display configuration information as part of their initialization. DDI drivers do this by calling the mdi_printcfg(D3mdi) function in their config(D2mdi) entry point routines (DDI 8) or _load(D2mdi) entry point routines (pre-DDI 8). SCO OpenServer 5 ODDI drivers call the printcfg(D3oddi) function from their init(D2mdi) routines..

• Initialization that is required only when the driver is opened can be coded in the driver's open(D2mdi) entry point routine. MDI drivers are exclusive-open devices, so MDI drivers must prevent multiple opens.

• The _unload(D2mdi) entry point routine defines actions to be taken when the driver is unloaded from the kernel. All resources that are allocated in the driver's _load(D2mdi) entry point routine must be freed in the driver's _unload( ) entry point routine. The _unload( ) routine must also cancel pending callouts such as itimeout(D3) and bufcall(D3str) and free memory and locks that were allocated in the _load( ) entry point routine.