Porting drivers to SCO OpenServer 5 from earlier SCO releases

New SCO OpenServer 5 features

The following list highlights new SCO OpenServer 5 Release 5 features that you may want to incorporate into drive being ported from earlier SCO systems. These features have been implemented so that older drivers that do not use them will run on SCO OpenServer 5 Release 5 without modification.

distributed interrupts
SCO OpenServer 5 Release 5 supports distributed interrupts on multiprocessor systems. Use the idistributed(D3oddi) or Sharegister(D3osdi) function (SCSI host adapter drivers only) to register a driver that supports distributed interrupts. Multithreaded drivers do not need to be modified to support distributed interrupts but their performance may be enhanced on some MP platforms by making these modifications.

PCI support
Kernel functions to support devices connected to a PCI bus. See ``PCI''.

Multithreaded STREAMS
Use the sdistributed(D3oddi) kernel function to register the base level routines of STREAMS drivers as multithreaded; use the idistributed(D3oddi) kernel function to register the interrupt level of any driver as multithreaded. Multithreading STREAMS drivers enhances performance for network adapter drivers on multiprocessor platforms. SCO OpenServer 5 Release 5 STREAMS are SVID/3 compatible and have been enhanced to support many of the features provided in the SVR4 STREAMS implementation. Note, however, that the kernel interface for SCO OpenServer 5 Release 5 STREAMS are based on the SVR3 STREAMS implementation. For more information, see ``SCO OpenServer 5 Release 5 STREAMS interface''.

Device Query Interface (DQI)
provides a consistent and reliable mechanism for user-level programs to determine which devices are attached to the system. Existing non-SCSI disk and tape drivers should be modified to support the DQI. Drivers that are not modified will still run on SCO OpenServer 5 but ScoAdmin and other utilities that use DQI will not be able to access your device unless the driver is modified. See ``DQI''.

Note that all SCSI peripheral and host adapter drivers automatically have DQI support on SCO OpenServer 5 Release 5. The generic SCSI configuration driver, Scfg, provides the DQI information so SCSI drivers do not require special coding to get DQI support.

SCSI multi-channel support
The mscsi(F) file, the bootstring, and the SCSI request block structure used in SCSI drivers support an additional parameter, bus, for each SCSI device. If a SCSI host adapter has multiple channels, its driver should take advantage of this parameter to allow selection of the channel where a particular device is attached.

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