SCO OpenServer

cdistributed(D3oddi)

cdistributed -- indicate character driver can have multiprocessor access

Syntax

#include <sys/arch.h>
#include <sys/conf.h>
#include <sys/types.h>

int cdistributed(dev_t dev, int flags);

Description

This function marks a character driver as being capable of multiprocessor access.

Arguments

dev

Device number

flags

Option mask ORed to the current flags defining processor access for the specified device. (The character device switch table is used by the kernel to access a character device driver.)

The following values may be ORed together in flags (defined in <sys/conf.h>) to mark the corresponding driver routines as being multithreaded:

DIST_CDEV_CLOSE: mark a driver's close(D2oddi) routine as multithreaded
DIST_CDEV_IOCTL: mark a driver's ioctl(D2oddi) routine as multithreaded
DIST_CDEV_OPEN: mark a driver's open(D2oddi) routine as multithreaded
DIST_CDEV_READ: mark a driver's read(D2oddi) routine as multithreaded
DIST_CDEV_WRITE: mark a driver's write(D2oddi) routine as multithreaded

Return values

On a multiprocessor system, cdistributed( ) always returns 1. On a uniprocessor system, cdistributed( ) always returns 0.

Usage

Context and synchronization

Initialization context

Hardware applicability

All

Version applicability

oddi: 2mp, 3mp, 4mp, 5mp, 6mp

SVR5 DDI compatibility

DDI does not support this function. See ``Multithreaded drivers'' in HDK Technical Reference for information about how multithreaded drivers are identified in DDI.

References

bdistributed(D3oddi), idistributed(D3oddi), sdistributed(D3oddi),

``Multithreaded drivers'' in HDK Technical Reference

Examples

The following example illustrates how cdistributed( ) is used to register the driver's read(D2oddi) and write(D2oddi) entry points as multithreaded:

   #include "sys/arch.h"
   #include "sys/conf.h"
   xxinit()
   {
          ...
          cdistributed(dev, DIST_CDEV_READ | DIST_CDEV_WRITE );
          ...
   }