cd* at scsibus?
ch* at scsibus?
safte* at scsibus?
sd* at scsibus?
ses* at scsibus?
st* at scsibus?
uk* at scsibus?
# multipath support
emc* at scsibus?
hds* at scsibus?
rdac* at scsibus?
sym* at scsibus?
system provides a uniform and modular
system for the implementation of drivers to control various SCSI devices, and
to utilize different SCSI host adapters through host adapter drivers. When the
system probes the SCSI
buses, it attaches any
devices it finds to the appropriate drivers. If no driver seems appropriate,
then it attaches the device to the uk (unknown) driver so that user level SCSI
ioctls may still be performed against the device.
The option SCSIDEBUG enables the debug ioctl.
All devices and the SCSI buses support boot time allocation so that an upper
number of devices and controllers does not need to be configured;
sd* at scsibus?
will suffice for any number of
The devices are either wired
so they appear as a
particular device unit or counted
so that they
appear as the next available unused unit.
To configure a driver in the kernel without wiring down the device use a config
line similar to ch* at scsibus?
to include the
To wire down a unit use a config line similar to ch1 at
scsibus0 target 4 lun 0
to assign changer 1 as the changer with SCSI ID 4,
SCSI logical unit 0 on SCSI bus 0. Individual scsibuses can be wired down to
specific controllers with a config line similar to
scsibus0 at ahc0
which assigns SCSI bus 0 to the
first unit using the ahc driver. For controllers supporting more than one bus,
the particular bus can be specified as in scsibus3 at
ahc1 bus 1
which assigns scsibus 1 to the second bus probed on the ahc1
When there is a mixture of wired down and counted devices then the counting
begins with the first non-wired down unit for a particular type. That is, if a
disk is wired down as sd1 at scsibus?
, then the
first non-wired disk shall come on line as sd2
There are a number of ioctls that work on any SCSI
device. They are defined in
and can be applied against any SCSI device that permits them. For the tape, it
must be applied against the control device. See the manual page for each
device type for more information about how generic SCSI ioctls may be applied
to a specific device.
- Reset a device.
- Turn on debugging. All SCSI operations originating from
this device's driver will be traced to the console, along with other
information. Debugging is controlled by four bits, described in the header
file. If no debugging is configured into the kernel, debugging will have
no effect. SCSI debugging is controlled by
the configuration option SCSIDEBUG.
- Take a SCSI command and data from a user process and apply
them to the SCSI device. Return all status information and return data to
the process. The ioctl will return a successful status even if the device
rejected the command. As all status is returned to the user, it is up to
the user process to examine this information to decide the success of the
- Ask the driver what its bus, target and lun are. In
addition, the device type, ATAPI or SCSI, is returned.
The system allows common device drivers to work through many different types of
adapters. The adapters take requests from the upper layers and do all I/O
between the SCSI
bus and the system. The maximum
size of a transfer is governed by the adapter. Most adapters can transfer 64KB
in a single operation, and many can transfer larger amounts.
When the kernel is compiled with option SCSIDEBUG, the SCIOCDEBUG ioctl can be
used to enable various amounts of tracing information on any specific device.
Devices not being traced will not produce trace information. The four bits
that make up the debug level each control certain types of debugging
- shows all SCSI bus operations including SCSI commands,
error information and the first 48 bytes of any data transferred.
- shows routines called.
- shows information about what branches are taken and often
some of the return values of functions.
- shows more detailed information including DMA
system appeared in MACH 2.5 at TRW.