The
scsi driver is the top, machine-independent layer of the two-layer software system that provides an interface for the implementation of drivers to control various SCSI or ATAPI bus devices, and to use different SCSI bus host adapters or EIDE controllers. SCSI bus is capable of supporting a wide variety of peripherals, including hard disks, removable disks, CD-ROMs, scanners, tape drives, and other miscellaneous high-speed devices.
The bottom layer is composed of the drivers for individual EIDE or SCSI bus controller chips (e.g. NCR 5380), accessed through various host bus interfaces, including, but not limited to PCI, ISA, Sbus, TURBOchannel, and NuBus. These individual devices are referred to as “host adaptors” in SCSI terminology, because they connect the SCSI bus to the host computer.
When
NetBSD probes the SCSI busses, it “attaches” any devices it finds to the appropriate drivers.
If no specific driver matches the device, then
scsi attaches the device to the
uk(4) driver so that user level SCSI
ioctl(2) calls may still be performed against the device. Currently, only
sd(4),
cd(4),
st(4) and
uk(4) can attach to an atapi bus.
Please see the
intro(4) manual page to see which SCSI bus host adaptors are supported by
NetBSD on your computer system.