freebsd-dev/sys/scsi/README

This release consists of the following files 
(relative to the base of the source tree )

share/man/man4/scsi.4 <-useful general info
share/man/man4/uk.4
share/man/man4/su.4
share/man/man4/ch.4
share/man/man4/cd.4
share/man/man4/sd.4
share/man/man4/st.4 <--READ THIS IF YOU USE TAPES!
sbin/scsi/procargs.c
sbin/scsi/scsi.c
sbin/scsi/scsi.1
sbin/scsi/Makefile
sbin/st/Makefile
sbin/st/st.1
sbin/st/st.c
sys/sys/chio.h
sys/sys/cdio.h
sys/sys/mtio.h
sys/sys/scsiio.h
sys/i386/conf/EXAMPLE
sys/i386/isa/ultra14f.c <-runs 14f and 34f
sys/i386/isa/ultra_all.c.beta <-beta version, runs 14f,24f and 34f
sys/i386/isa/bt742a.c
sys/i386/isa/aha1742.c
sys/i386/isa/aha1542.c
sys/scsi/syspatches
sys/scsi/syspatches/conf.c
sys/scsi/syspatches/user_scsi.diffs
sys/scsi/syspatches/MAKEDEV.diff
sys/scsi/syspatches/isa.c.patch
sys/scsi/syspatches/README
sys/scsi/uk.c
sys/scsi/su.c
sys/scsi/st.c
sys/scsi/sd.c
sys/scsi/ch.c
sys/scsi/cd.c
sys/scsi/scsi_ioctl.c
sys/scsi/scsi_base.c
sys/scsi/scsiconf.c
sys/scsi/scsi_tape.h
sys/scsi/scsi_disk.h
sys/scsi/scsi_changer.h
sys/scsi/scsi_cd.h
sys/scsi/scsi_all.h
sys/scsi/scsi_debug.h
sys/scsi/scsiconf.h
sys/scsi/README <--this file

notice sys/scsi/sg.c and sys/sys/sgio.h have been removed


----------------------------------------------------------------
This scsi system is designed to allow the re-use of top end drivers
such as disk and tape drivers, with different scsi adapters.

As of writing this document, There are top end drivers working for:
----------------------------------------------------------------
generic scsi disk
generic scsi tape
cd-rom  (plays music under the xcplayer (?) program)
AEG Character recognition devices *
Calera Character recognition devices *
Generic scsi-II scanners *
Exabyte tape changer device.
GENERIC SCSI DEVICES (user generated scsi commands) 
----------------------------------------------------------------


There are also working bottom end drivers for:
----------------------------------------------------------------
adaptec 1542 (and 1742 in 1542 mode)
bustec 742a (apparently works for VESA version (445S?))(and 747?)
adaptec 174x  (note NOT 27xx)
Ultrastore 14f (works for 34f (VESA version))				
Ultrastore 24f RSN (Beta version included here)
----------------------------------------------------------------


################## Using the scsi system ##################
------------minor numbers---------------
This scsi system does not allocate minor numbers to devices depending
on their SCSI IDs is any way. A devices minor number is dependant
on the order in which it was found.
e.g. the first tape found will become st0 (minor number 0)
	the second found will become st1 (minor number 16)
	the third will become st2 (minor 32) 
	etc.

These devices could be on the same scsi bus or different scsi busses.
That would not change their minor numbers.

THE EXCEPTION  TO THIS IS IN THE GENERIC SCSI DRIVER. in which case
the following mapping applies:

BB TTT LLL  B= scsi bus number, T = target number, L = LUN.

It is possible to run two different TYPES of scsi adapters at the 
same time and have st0 on one and st1 on another. (for example)

There is a scheme supported in which scsi devices can be 'wired in' even
if they are not present or powered on at probe time. (see scsiconf.c)
In addition, the scsi(1) command allows the operator ask for a
reprobe at any time.  Newly found devices will be configured in. Any
device that does not map to a known device type is attached to the
'unknown' (uk) driver.


--------------making devices------------
A changed version of /dev/MAKEDEV is supplied that
can be used to make devices sd[01234] and st[01234]

e.g. 
cd /dev
sh MAKEDEV sd0 sd1 sd2 st0 st1 cd0

see st(1) and st(4) for info on tape devices.

--------------file layout-------------------
Originally I had all scsi definitions in one file: scsi.h
I have since moved definitions of commands so that all
definitions needed for a particular type of device are
found together in the include file of that name.
This approximatly follows the layout of their definition 
in the SCSI-2 spec. 
As such they are:

scsi_all.h  		general commands for all devices --- CHAPTER 7
scsi-disk.h  		commands relevant to disk        --- CHAPTER 8
scsi-tape.h  		commands for scsi tapes          --- CHAPTER 9
scsi-cd.h    		commands for cd-roms (and audio) --- CHAPTER 13
scsi-changer.h    	commands medium changer devices  --- CHAPTER 16

---------ioctl definitions-------------
User accessable structures (e.g. ioctl definitions) have been
placed in sys/cdio, sys/sgio and sys/chio (based after sys/mtio for
the ioctls for mag tapes (including st).
General scsi ioctls are found in sys/scsiio.h.

-----------cd-rom-----------------
The cd rom driver ha been tested by a number of people and
grefen@convex.com has completed the audio play
functions.
(xcdplayer was available from the 'from_ref' directory on agate)

At this time it is possible audio play is broken on cdroms and I will
be unable to fix it until I get one to test.
***IMPORTANT***
Cdrom audio is only suported at all for cdroms that use SCSI2 audio
definitions.

-------------media changer---------------
Once again courtesy of grefen@convex.com (in germany)
I have not tested this but he assures me it's ready for testing.
If anyone has an exabyte tape changer or similar, 
contact the author for information regarding the control interface
and program.

WARNING: This has not been tested for a LONG TIME!


---------recent changes-----------
Removed all bitfields from machine independent sections to make
it possible for them to be used on big-endian architectures.

Removed scsi specific timeouts in favour of system timeout handling.

Many structures (getting more all the time) now dynamically allocated.

Addition of code in the tape driver to recognise models of drive that
have particular problems so they can be handled specially.

many bug-fixes and cleanups.

---------even more recent changes:--------

rewrote almost the entire thing..



------Mon Oct 11 22:20:25 WST 1993------

Code is now all KNF (or close to it).

A new structure has been introduced..
Called scsi_link, one of these exists for every bus/target/lun
that has a driver attached to it.
It has links to the adapter and to the driver, as well as status
information of global interest. (e.g. if the device is in use).
The use of this new structure has allowed the compaction of a
lot of duplicated code into a single copy (now in scsi_base.c)
and makes more simple the USER level scsi implimentation.