hpdd(7)              INTERACTIVE UNIX System              hpdd(7)



          NAME
               hpdd - High Performance Disk Driver

          DESCRIPTION
               The hpdd module contains initialization procedures and low-
               level primitives for driver modules that run as part of the
               High Performance Disk Driver (HPDD) subsystem.  Such drivers
               provide for improved system throughput, increased ease of
               maintenance, and quick implementation by making use of
               structures and code provided by the HPDD.

               There are two types of modules associated with the HPDD:
               driver modules and low-level controller modules.  Driver
               modules provide traditional UNIX System block and character
               device entry points and generate request queues in terms of
               HPDD-specific data elements and a generic set of commands
               common to most low-level hardware controllers.  Currently,
               disk and tape drivers are supported by the hpdd subsystem
               (see disk(7) and tape(7)).  It is anticipated that the list
               of supported drivers will grow fairly slowly.  Low-level
               controller modules exist for each type of actual hardware
               interface supported by the HPDD.  These determine whether
               boards configured are in fact present, translate the generic
               command set to actual hardware commands, and process
               hardware interrupts.  A low-level module may be used by more
               than one driver (as is the case with a SCSI adapter used to
               communicate with both disk and tape drives) and may support
               more than one actual hardware controller.  For example, the
               athd module is used to communicate with all AT-compatible
               fixed disk adapters (ST-506, RLL, or ESDI) that exist within
               a system.

             Configuration
               The file /etc/conf/pack.d/gendev/space.c contains a table
               called gdev_init_routines, which contains the names of the
               driver initialization routines for each HPDD driver module.
               The file /etc/conf/sdevice.d/gendev should indicate all
               interrupt levels to be handled by the HPDD low-level
               modules, as the control and scheduling of this activity is
               the responsibility of the HPDD module itself.  Note that all
               devices supported by the HPDD must be at the same interrupt
               priority level.  In addition, each driver will normally have
               a space.c file associated with it.  Tables in these files
               describe the actual hardware expected to be present in a
               given system configuration.  Note also that the names of the
               low-level controller modules configured must also be present
               in the modules list of the file /etc/conf/cf.d/mdevice.

          SEE ALSO
               disk(7), tape(7).





          Rev. 1.2                                                   Page 1

          hpdd(7)              INTERACTIVE UNIX System              hpdd(7)



          ADDED VALUE
               This entry, supplied by INTERACTIVE Systems Corporation, is
               an extension of UNIX System V.




















































          Rev. 1.2                                                   Page 2