Configuring HP-UX For Peripherals

Appendix C 271
Major and Minor Numbers
Understanding how the Kernel Associates Drivers to Device
tables — bdevsw, the block device switch table and cdevsw, the character
device switch table.
Drivers that support both block and character I/O (such as SCSI disk
driver and optical auto changer) have both a block major number and a
character major number. Devices that support only character-mode
access have only a character major number.
The core-hpux file in /usr/conf/master.d contains a Driver install
table, which lists major numbers for reference only.
To identify valid major numbers for devices configured on your system,
you can execute the lsdev command.
lsdev reads the driver headers and lists the drivers configured into the
kernel with their block and character major numbers. If the driver is
designed to use a dynamically assigned major number, lsdev displays
the assigned major number.
Major numbers are displayed in decimal form. The -1 designation in
either character or block major number field of lsdev output can mean:
• The device might be a module that is not a driver.
• No driver is configured.
• Driver is not supported in that block or character mode.
Minor Numbers
Minor numbers represent two kinds of information: the location of the
interface to which a device is attached and driver-dependent
characteristics. This information is organized by specific bit
assignments.
The tables later in this Appendix show the bit assignments for many
HP-UX device drivers. You can also consult the device driver manpage in
section 7 of the HP-UX Reference. For non-HP drivers, consult the
documentation provided with the driver.