Provides access to each of the hardware buses by way of the machine I/O device driver.
The bus special files consist of a pseudo-driver in the kernel that allows a privileged user to access each hardware I/O bus. This is done indirectly by using the ioctl subroutine. The calling process, however, must have the appropriate system privilege to open the bus special files.
For additional information on bus special files, see device configuration documentation in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts and machine device driver documentation in AIX 5L Version 5.2 Technical Reference: Kernel and Subsystems Volume 1.
This capability should be used only by device initialization and configuration programs. Programs that depend upon the bus device interface may not be portable to machines with different hardware.
There is at least one bus special file, usually the /dev/pci0 or the /dev/bus0 special file. This file accesses the primary hardware bus. One bus special file exists for each hardware bus on the machine. Each bus special file gains access to the corresponding hardware bus, and exists only if the hardware bus is present or was present at one time. Run the following command to generate a list of all the defined bus special files for a machine:
lsdev -C -c bus -F name | xargs -i echo
/dev/{}
The ioctl subroutine.
Device Configuration Subsystem Programming Introduction, Machine Device Driver, Understanding Device Driver Classes, in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.