mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 05:04:00 +08:00
5d3f083d8f
This patch fixes typos in various Documentation txts. The patch addresses some misc words. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Adrian Bunk <bunk@stusta.de>
181 lines
6.1 KiB
Plaintext
181 lines
6.1 KiB
Plaintext
|
|
README for the SCSI media changer driver
|
|
========================================
|
|
|
|
This is a driver for SCSI Medium Changer devices, which are listed
|
|
with "Type: Medium Changer" in /proc/scsi/scsi.
|
|
|
|
This is for *real* Jukeboxes. It is *not* supported to work with
|
|
common small CD-ROM changers, neither one-lun-per-slot SCSI changers
|
|
nor IDE drives.
|
|
|
|
Userland tools available from here:
|
|
http://linux.bytesex.org/misc/changer.html
|
|
|
|
|
|
General Information
|
|
-------------------
|
|
|
|
First some words about how changers work: A changer has 2 (possibly
|
|
more) SCSI ID's. One for the changer device which controls the robot,
|
|
and one for the device which actually reads and writes the data. The
|
|
later may be anything, a MOD, a CD-ROM, a tape or whatever. For the
|
|
changer device this is a "don't care", he *only* shuffles around the
|
|
media, nothing else.
|
|
|
|
|
|
The SCSI changer model is complex, compared to - for example - IDE-CD
|
|
changers. But it allows to handle nearly all possible cases. It knows
|
|
4 different types of changer elements:
|
|
|
|
media transport - this one shuffles around the media, i.e. the
|
|
transport arm. Also known as "picker".
|
|
storage - a slot which can hold a media.
|
|
import/export - the same as above, but is accessible from outside,
|
|
i.e. there the operator (you !) can use this to
|
|
fill in and remove media from the changer.
|
|
Sometimes named "mailslot".
|
|
data transfer - this is the device which reads/writes, i.e. the
|
|
CD-ROM / Tape / whatever drive.
|
|
|
|
None of these is limited to one: A huge Jukebox could have slots for
|
|
123 CD-ROM's, 5 CD-ROM readers (and therefore 6 SCSI ID's: the changer
|
|
and each CD-ROM) and 2 transport arms. No problem to handle.
|
|
|
|
|
|
How it is implemented
|
|
---------------------
|
|
|
|
I implemented the driver as character device driver with a NetBSD-like
|
|
ioctl interface. Just grabbed NetBSD's header file and one of the
|
|
other linux SCSI device drivers as starting point. The interface
|
|
should be source code compatible with NetBSD. So if there is any
|
|
software (anybody knows ???) which supports a BSDish changer driver,
|
|
it should work with this driver too.
|
|
|
|
Over time a few more ioctls where added, volume tag support for example
|
|
wasn't covered by the NetBSD ioctl API.
|
|
|
|
|
|
Current State
|
|
-------------
|
|
|
|
Support for more than one transport arm is not implemented yet (and
|
|
nobody asked for it so far...).
|
|
|
|
I test and use the driver myself with a 35 slot cdrom jukebox from
|
|
Grundig. I got some reports telling it works ok with tape autoloaders
|
|
(Exabyte, HP and DEC). Some People use this driver with amanda. It
|
|
works fine with small (11 slots) and a huge (4 MOs, 88 slots)
|
|
magneto-optical Jukebox. Probably with lots of other changers too, most
|
|
(but not all :-) people mail me only if it does *not* work...
|
|
|
|
I don't have any device lists, neither black-list nor white-list. Thus
|
|
it is quite useless to ask me whenever a specific device is supported or
|
|
not. In theory every changer device which supports the SCSI-2 media
|
|
changer command set should work out-of-the-box with this driver. If it
|
|
doesn't, it is a bug. Either within the driver or within the firmware
|
|
of the changer device.
|
|
|
|
|
|
Using it
|
|
--------
|
|
|
|
This is a character device with major number is 86, so use
|
|
"mknod /dev/sch0 c 86 0" to create the special file for the driver.
|
|
|
|
If the module finds the changer, it prints some messages about the
|
|
device [ try "dmesg" if you don't see anything ] and should show up in
|
|
/proc/devices. If not.... some changers use ID ? / LUN 0 for the
|
|
device and ID ? / LUN 1 for the robot mechanism. But Linux does *not*
|
|
look for LUNs other than 0 as default, because there are too many
|
|
broken devices. So you can try:
|
|
|
|
1) echo "scsi add-single-device 0 0 ID 1" > /proc/scsi/scsi
|
|
(replace ID with the SCSI-ID of the device)
|
|
2) boot the kernel with "max_scsi_luns=1" on the command line
|
|
(append="max_scsi_luns=1" in lilo.conf should do the trick)
|
|
|
|
|
|
Trouble?
|
|
--------
|
|
|
|
If you insmod the driver with "insmod debug=1", it will be verbose and
|
|
prints a lot of stuff to the syslog. Compiling the kernel with
|
|
CONFIG_SCSI_CONSTANTS=y improves the quality of the error messages alot
|
|
because the kernel will translate the error codes into human-readable
|
|
strings then.
|
|
|
|
You can display these messages with the dmesg command (or check the
|
|
logfiles). If you email me some question because of a problem with the
|
|
driver, please include these messages.
|
|
|
|
|
|
Insmod options
|
|
--------------
|
|
|
|
debug=0/1
|
|
Enable debug messages (see above, default: 0).
|
|
|
|
verbose=0/1
|
|
Be verbose (default: 1).
|
|
|
|
init=0/1
|
|
Send INITIALIZE ELEMENT STATUS command to the changer
|
|
at insmod time (default: 1).
|
|
|
|
timeout_init=<seconds>
|
|
timeout for the INITIALIZE ELEMENT STATUS command
|
|
(default: 3600).
|
|
|
|
timeout_move=<seconds>
|
|
timeout for all other commands (default: 120).
|
|
|
|
dt_id=<id1>,<id2>,...
|
|
dt_lun=<lun1>,<lun2>,...
|
|
These two allow to specify the SCSI ID and LUN for the data
|
|
transfer elements. You likely don't need this as the jukebox
|
|
should provide this information. But some devices don't ...
|
|
|
|
vendor_firsts=
|
|
vendor_counts=
|
|
vendor_labels=
|
|
These insmod options can be used to tell the driver that there
|
|
are some vendor-specific element types. Grundig for example
|
|
does this. Some jukeboxes have a printer to label fresh burned
|
|
CDs, which is addressed as element 0xc000 (type 5). To tell the
|
|
driver about this vendor-specific element, use this:
|
|
$ insmod ch \
|
|
vendor_firsts=0xc000 \
|
|
vendor_counts=1 \
|
|
vendor_labels=printer
|
|
All three insmod options accept up to four comma-separated
|
|
values, this way you can configure the element types 5-8.
|
|
You likely need the SCSI specs for the device in question to
|
|
find the correct values as they are not covered by the SCSI-2
|
|
standard.
|
|
|
|
|
|
Credits
|
|
-------
|
|
|
|
I wrote this driver using the famous mailing-patches-around-the-world
|
|
method. With (more or less) help from:
|
|
|
|
Daniel Moehwald <moehwald@hdg.de>
|
|
Dane Jasper <dane@sonic.net>
|
|
R. Scott Bailey <sbailey@dsddi.eds.com>
|
|
Jonathan Corbet <corbet@lwn.net>
|
|
|
|
Special thanks go to
|
|
Martin Kuehne <martin.kuehne@bnbt.de>
|
|
for a old, second-hand (but full functional) cdrom jukebox which I use
|
|
to develop/test driver and tools now.
|
|
|
|
Have fun,
|
|
|
|
Gerd
|
|
|
|
--
|
|
Gerd Knorr <kraxel@bytesex.org>
|