Header files and declarations

The global declarations required for an MDI driver include:

• Appropriate #include lines for header files

• A global module_info(D4str) structure, qinit(D4str) structures for read and write operations, and a global streamtab(D4str) structure declared as <prefix>info; see info(D1str). These are used by the STREAMS subsystem to identify the entry points, high and low water marks, module name, and the minimum and maximum packet sizes for a MDI driver.

• All MDI drivers should declare their version number in the _ndversion(D1str) variable.

• DDI version 8 and later MDI drivers must also populate drvinfo(D4) and drvops(D4) structures for the driver. The drvinfo structure must include a pointer to the driver's streamtab(D4str) structure in the drv_str member.

• Drivers written for DDI versions prior to version 8 must set the devflag(D1) variable to appropriate values.

All externally visible symbols such as entry point routines and global structures should be identified by a driver prefix(D1). For example, the IBM Token-Ring driver, which uses the tok prefix, includes the tokopen( ) and tokintr( ) entry point routines and structures named tokurinit, tokuwinit, tokinfo, and so forth.