SG(4) BSD Programmer's Manual SG(4)NAMEsg - machine-independent SCSI generic driver
SYNOPSIS
sg0 at tg? unit 0
sg* at tg? unit ?
DESCRIPTION
The sg driver is used to communicate with devices on the Small Computer
System Interface (ANSI X3.131-1992) bus which are not supported any other
driver. Most devices are supported by the st(4) SCSI tape or sd(4) SCSI
disk drivers. If neither the st(4) or sd(4) driver claim a particular
device the the sg driver will claim the device. The sg driver is a ma-
chine-independent driver which employs machine-dependent drivers for in-
dividual host bus adapters (see hba(4)) to send commands to the SCSI de-
vice. The sg driver takes care of opening the device, locking out other
users and serializing I/O. The sg driver knows nothing about the physical
devices it is communicating with. All real I/O is done by the appropriate
user process passing raw SCSI commands to the sg driver which is forwards
to the device.
The clone entry sg* should be listed last; this will automatically match
any otherwise unmatched SCSI devices. Additional instances of sg devices
can be ``wired'' to particular targets as described in tg(4).
FILES
/dev/sg[0-n] Device nodes through which the device is accessed.
SEE ALSOhba(4), sd(4), st(4)BSDI BSD/OS September 5, 1996 1