Schily's USER COMMANDS SCGCHECK(1)
NAME
scgcheck - check and validate the ABI of libscg
SYNOPSIS
scgcheck [ options ]
DESCRIPTION
Scgcheck is used to check and verify the Application Binary
Interface of libscg.
Device naming
Most users do not need to care about device naming at all,
as in -auto mode, scgcheck implements auto target support
and automagically finds a test drive in case that exactly
one CD-ROM type drive is available in the system.
OPTIONS
-version
Print version information and exit.
-auto
Instead of asking to confirm each test before runing
it, scgcheck tries to do a fully automated test.
dev=target
Set the SCSI target for the device, see notes above. A
typical target device specification is dev=1,6,0 . If
a filename must be provided together with the numerical
target specification, the filename is implementation
specific. The correct filename in this case can be
found in the system specific manuals of the target
operating system. On a FreeBSD system without CAM sup-
port, you need to use the control device (e.g.
/dev/rcd0.ctl). A correct device specification in this
case may be dev=/dev/rcd0.ctl:@ .
General SCSI addressing
The target device to the dev= option refers to
scsibus/target/lun of the device. Communication on
SunOS is done with the SCSI general driver scg. Other
operating systems are using a library simulation of
this driver. Possible syntax is: dev=
scsibus,target,lun or dev= target,lun. In the latter
case, the device has to be connected to the default
SCSI bus of the machine. Scsibus, target and lun are
integer numbers. Some operating systems or SCSI tran-
sport implementations may require to specify a filename
in addition. In this case the correct syntax for the
device is: dev= devicename:scsibus,target, or dev=
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devicename:target,lun. If the name of the device node
that has been specified on such a system refers to
exactly one SCSI device, a shorthand in the form dev=
devicename:@ or dev= devicename:@,lun may be used
instead of dev= devicename:scsibus,target,
Remote SCSI addressing
To access remote SCSI devices, you need to prepend the
SCSI device name by a remote device indicator. The
remote device indicator is either REMOTE:user@host: or
REMOTE:host: A valid remote SCSI device name may be:
REMOTE:user@host: to allow remote SCSI bus scanning or
REMOTE:user@host:1,0,0 to access the SCSI device at
host connected to SCSI bus # 1,target 0, lun 0. In
order to allow remote access to a specific host, the
rscsi(1) program needs to be present and configured on
the host.
Alternate SCSI transports
ATAPI drives are just SCSI drives that inherently use
the ATA packet interface as SCSI command transport
layer build into the IDE (ATA) transport. You may need
to specify an alternate transport layer on the command
line if your OS does not implement a fully integrated
kernel driver subsystem that allows to access any drive
using SCSI commands via a single unique user interface.
To access SCSI devices via alternate transport layers,
you need to prepend the SCSI device name by a transport
layer indicator. The transport layer indicator may be
something like USCSI: or ATAPI:. To get a list of sup-
ported transport layers for your platform, use dev=
HELP:
Portability Background
To make scgcheck portable to all UNIX platforms, the
syntax dev= devicename:scsibus,target, is preferred as
it hides OS specific knowledge about device names from
the user. A specific OS may not necessarily support a
way to specify a real device file name nor a way to
specify scsibus,target,lun.
Scsibus 0 is the default SCSI bus on the machine. Watch
the boot messages for more information or look into
/var/adm/messages for more information about the SCSI
configuration of your machine. If you have problems to
figure out what values for scsibus,target,lun should be
used, try the -scanbus option of scgcheck described
below.
Autotarget Mode
If no dev= option is present, or if it only contains a
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transport specifyer but no address notation, scgcheck
tries to scan the SCSI address space for CD-ROM drives.
If exactly one is found, this is used by default.
timeout=#
Set the default SCSI command timeout value to #
seconds. The default SCSI command timeout is the
minimum timeout used for sending SCSI commands. If a
SCSI command fails due to a timeout, you may try to
raise the default SCSI command timeout above the
timeout value of the failed command. If the command
runs correctly with a raised command timeout, please
report the better timeout value and the corresponding
command to the author of the program. If no timeout
option is present, a default timeout of 40 seconds is
used.
debug=#, -d
Set the misc debug value to # (with debug=#) or incre-
ment the misc debug level by one (with -d). If you
specify -dd, this equals to debug=2. This may help to
find problems while opening a driver for libscg. as
well as with sector sizes and sector types. Using
-debug slows down the process and may be the reason for
a buffer underrun.
kdebug=#, kd=#
Tell the scg-driver to modify the kernel debug value
while SCSI commands are running.
scgopts=list
A comma separated list of SCSI options that are handled
by libscg. The implemented options may be uptated
indepentendly from applications. Currently, one
option: ignore-resid is supported to work around a
Linux kernel bug.
-silent, -s
Do not print out a status report for failed SCSI com-
mands.
-v Increment the level of general verbosity by one. This
is used e.g. to display the progress of the process.
-V Increment the verbose level with respect of SCSI com-
mand transport by one. This helps to debug problems
during the process, that occur in the CD-Recorder. If
you get incomprehensible error messages you should use
this flag to get more detailed output. -VV will show
data buffer content in addition. Using -V or -VV slows
down the process.
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f=file
Specify the log file to be used instead of check.log.
EXAMPLES
FILES
SEE ALSO
cdrecord(1), readcd(1), mkisofs(1), scg(7).
NOTES
When using scgcheck with the broken Linux SCSI generic
driver. You should note that scgcheck uses a hack, that
tries to emulate the functionality of the scg driver.
Unfortunately, the sg driver on Linux has several severe
bugs:
o It cannot see if a SCSI command could not be sent at
all.
o It cannot get the SCSI status byte. Scgcheck for that
reason cannot report failing SCSI commands in some
situations.
o It cannot get real DMA count of transfer. Scgcheck can-
not tell you if there is an DMA residual count.
o It cannot get number of bytes valid in auto sense data.
Scgcheck cannot tell you if device transfers no sense
data at all.
o It fetches to few data in auto request sense
(CCS/SCSI-2/SCSI-3 needs >= 18).
DIAGNOSTICS
A typical error message for a SCSI command looks like:
scgcheck: I/O error. test unit ready: scsi sendcmd: no error
CDB: 00 20 00 00 00 00
status: 0x2 (CHECK CONDITION)
Sense Bytes: 70 00 05 00 00 00 00 0A 00 00 00 00 25 00 00 00 00 00
Sense Key: 0x5 Illegal Request, Segment 0
Sense Code: 0x25 Qual 0x00 (logical unit not supported) Fru 0x0
Sense flags: Blk 0 (not valid)
cmd finished after 0.002s timeout 40s
The first line gives information about the transport of the
command. The text after the first colon gives the error
text for the system call from the view of the kernel. It
usually is: I/O error unless other problems happen. The
next words contain a short description for the SCSI command
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that fails. The rest of the line tells you if there were any
problems for the transport of the command over the SCSI bus.
fatal error means that it was not possible to transport the
command (i.e. no device present at the requested SCSI
address).
The second line prints the SCSI command descriptor block for
the failed command.
The third line gives information on the SCSI status code
returned by the command, if the transport of the command
succeeds. This is error information from the SCSI device.
The fourth line is a hex dump of the auto request sense
information for the command.
The fifth line is the error text for the sense key if avail-
able, followed by the segment number that is only valid if
the command was a copy command. If the error message is not
directly related to the current command, the text deferred
error is appended.
The sixth line is the error text for the sense code and the
sense qualifier if available. If the type of the device is
known, the sense data is decoded from tables in scsierrs.c .
The text is followed by the error value for a field replace-
able unit.
The seventh line prints the block number that is related to
the failed command and text for several error flags. The
block number may not be valid.
The eight line reports the timeout set up for this command
and the time that the command realy needed to complete.
BUGS
CREDITS
MAILING LISTS
AUTHOR
Joerg Schilling
D-13353 Berlin
Germany
Additional information can be found on:
http://cdrecord.org/private/cdrecord.html
If you have support questions, send them to:
cdrtools-support@lists.sourceforge.net
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If you have definitely found a bug, send a mail to:
cdrtools-developers@lists.sourceforge.net
or joerg@schily.net
To subscribe, use:
https://lists.sourceforge.net/lists/listinfo/cdrtools-
developers
or https://lists.sourceforge.net/lists/listinfo/cdrtools-
support
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