scsi_ad(D4I) scsi_ad(D4I)
NAME
scsi_ad - PDI device address structure
SYNOPSIS
#include <sys/sdi.h>
DESCRIPTION
The PDI device address structure, scsi_ad, is used by every
scb(D4I) or sfb(D4I) structure with the appropriate PDI
device. PDI interprets the external major and minor numbers,
the logical unit number, and the extended logical unit number
to send the scb or sfb to the correct device.
USAGE
The major number is decoded by PDI to determine the host
adapter and target controller. The minor number typically is
used only by the target driver to determine the logical unit
and any other device specific information (partition of a disk
or density of a tape). PDI determines the logical unit from
sa_lun. This member may have the values 0 to 7, except when
extended unit numbering is used. In this case, the EXLUN
value is set in the sa_lun member, and the sa_exlun member is
set the appropriate value.
For example, if the target controller wanted to access
extended logical unit 0x021a, then sa_lun would equal 0x82,
and sa_exlun would equal 0x1a.
Structure Members
The scdi_ad structure is defined as follows:
long sa_major; /* Major number */
long sa_minor; /* Minor number */
unsigned char sa_lun; /* logical unit number */
unsigned char sa_exlun; /* extended logical unit number */
short sa_fill; /* Fill word */
This structure consists of the device number, which is passed
to the target driver by the kernel, and the logical unit
number. The sa_major and sa_minor members (external major and
minor numbers) are long integers to allow for future expansion
of the major and minor numbers.
REFERENCES
scb(D4I), sfb(D4I)
Copyright 1994 Novell, Inc. Page 1