Creating Device-special Files for User-level SCSI Drivers

Creating Device-special Files for User-level SCSI Drivers

If the logical unit for the SCSI device you want to control from a user-level program is some value other than 0, you need to create a device-special file. See the mknod(1) and ds(7) man pages for more information. To create a device-special file, use the mknod command:

% mknod filename type major# minor#

where:

filename: The name of the device special file to create for the device.
type: The type of special file:
c = character special file
b = block special file
major#: The major device number. For a device that will be controlled from a user-level program, this number is 195, which is the major device number of devscsi.
minor#: The 14-bit (decimal) minor device. The bits are defined as shown in Figure 5-1.

Figure 5-1 : Minor Number Bit Definitions Example

% mknod /dev/scsi/sc0d1l1 c 195 17

The minor device number is set to 1710, which is 00100012, thus indicating a device that has logical unit number 1 and a target ID of 1.