.\" @(#)scgcheck.1	1.8 03/06/21 Copyright 2000 J. Schilling
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.TH SCGCHECK 1 "Version 2.0" "J\*org Schilling" "Schily\'s USER COMMANDS"
.SH NAME
scgcheck \- check and validate the ABI of libscg
.SH SYNOPSIS
.B scgcheck
[
.I options
]

.SH DESCRIPTION
.B Scgcheck
is used to check and verify the Application Binary Interface of libscg.

.PP
The
.I device
refers to
.IR scsibus / target / lun
of the drive. Communication on 
.I SunOS
is done with the SCSI general driver
.B scg.
Other operating systems are using a library simulation of this driver.
Possible syntax is:
.B dev=
.IR scsibus , target , lun
or
.B dev=
.IR target , lun .
In the latter case, the drive has to be connected to the default 
SCSI bus of the machine.
.IR Scsibus ,
.I target 
and 
.I lun
are integer numbers. 
Some operating systems or SCSI transport implementations may require to
specify a filename in addition.
In this case the correct syntax for the device is:
.B dev=
.IR devicename : scsibus , target , lun
or
.B dev=
.IR 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
.B dev=
.IR devicename : @
or
.B dev=
.IR devicename : @ , lun
may be used instead of
.B dev=
.IR devicename : scsibus , target , lun .

.PP
To access remote SCSI devices, you need to prepend the SCSI device name by
a remote device indicator. The remote device indicator is either
.BI REMOTE: user@host:
or
.BR
.BI REMOTE: host:
.br
A valid remote SCSI device name may be:
.BI REMOTE: user@host:
to allow remote SCSI bus scanning or
.BI REMOTE: user@host:1,0,0
to access the SCSI device at 
.I host
connected to SCSI bus # 1,target 0 lun 0.

.PP
To make 
.B readcd
portable to all \s-2UNIX\s0 platforms, the syntax
.B dev=
.IR devicename : scsibus , target , lun
is preferred as is hides OS specific knowledge about device names from the user.
A specific OS must not necessarily support a way to specify a real device file name nor a
way to specify 
.IR scsibus , target , lun .

.PP
.I Scsibus 
0 is the default SCSI bus on the machine. Watch the boot messages for more 
information or look into 
.B /var/run/dmesg.boot 
for more information about the SCSI configuration of your machine.
If you have problems to figure out what values for 
.IR scsibus , target , lun
should be used, try the 
.B \-scanbus
option of 
.BR cdrecord .

.SH OPTIONS
.TP
.B \-version
Print version information and exit.
.TP
.BI dev= target
Sets the SCSI target default for SCSI Bus scanning test, see notes above.
This allows e.g. to specify to use Solaris USCSI or remote SCSI 
for the bus scanning case.

For the non bus scanning case, a typical device specification is
.BI dev= 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 
.I FreeBSD
system without 
.I CAM
support, you need to use the control device (e.g.
.IR /dev/rcd0.ctl ).
A correct device specification in this case may be
.BI dev= /dev/rcd0.ctl:@
\&.
.sp
On Linux, drives connected to a parallel port adapter are mapped
to a virtual SCSI bus. Different adapters are mapped to different
targets on this virtual SCSI bus.
.sp
If no 
.I dev
option is present, 
.B cdrecord
will try to get the device from the 
.B CDR_DEVICE
environment.
.sp
If the argument to the
.B dev=
option does not contain the characters ',', '/', '@' or ':',
it is interpreted as an label name that may be found in the file
/usr/local/etc/cdrecord (see FILES section).
.TP
.BI timeout= #
Set the default SCSI command timeout value to 
.IR # " 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 
.I timeout 
option is present, a default timeout of 40 seconds is used.
.TP
.BI debug= "#, " -d
Set the misc debug value to # (with debug=#) or increment
the misc debug level by one (with -d). If you specify
.I -dd,
this equals to 
.BI debug= 2.
This may help to find problems while opening a driver for libscg.
as well as with sector sizes and sector types.
Using
.B \-debug
slows down the process and may be the reason for a buffer underrun.
.TP
.BR kdebug= "#, " kd= #
Tell the 
.BR scg -driver
to modify the kernel debug value while SCSI commands are running.
.TP
.BR \-silent ", " \-s
Do not print out a status report for failed SCSI commands.
.TP
.B \-v
Increment the level of general verbosity by one.
This is used e.g. to display the progress of the process.
.TP
.B \-V
Increment the verbose level with respect of SCSI command 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.
.B \-VV
will show data buffer content in addition.
Using
.B \-V
or
.B \-VV
slows down the process.
.TP
.BI f= file
Specify the log file to be used instead of 
.IR check.log .

.SH EXAMPLES

.SH FILES
.SH SEE ALSO
.BR cdrecord (1),
.BR readcd (1),
.BR mkisofs (8).

.SH NOTES
.PP
When using 
.B scgckeck
with the broken 
.B "Linux SCSI generic driver."
You should note that 
.B scgcheck
uses a hack, that tries to emulate the functionality of the scg driver.
Unfortunately, the sg driver on 
.B Linux
has several severe bugs:
.TP
\(bu
It cannot see if a SCSI command could not be sent at all.
.TP
\(bu
It cannot get the SCSI status byte. 
.B Scgcheck
for that reason cannot report failing SCSI commands in some
situations.
.TP
\(bu
It cannot get real DMA count of transfer. 
.B Scgcheck
cannot tell you if there is an DMA residual count.
.TP
\(bu
It cannot get number of bytes valid in auto sense data.
.B Scgcheck
cannot tell you if device transfers no sense data at all.
.TP
\(bu
It fetches to few data in auto request sense (CCS/SCSI-2/SCSI-3 needs >= 18).

.SH DIAGNOSTICS
.PP
.PP
A typical error message for a SCSI command looks like:
.sp
.RS
.nf
readcd: 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
.fi
.sp
.RE
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:
.B "I/O error
unless other problems happen. The next words contain a short description for
the SCSI command that fails. The rest of the line tells you if there were
any problems for the transport of the command over the SCSI bus.
.B "fatal error
means that it was not possible to transport the command (i.e. no device present
at the requested SCSI address).
.PP
The second line prints the SCSI command descriptor block for the failed command.
.PP
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.
.PP
The fourth line is a hex dump of the auto request sense information for the 
command.
.PP
The fifth line is the error text for the sense key if available, followed
by the segment number that is only valid if the command was a
.I copy
command. If the error message is not directly related to the current command,
the text
.I deferred error
is appended.
.PP
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
.IR scsierrs.c " .
The text is followed by the error value for a field replaceable unit.
.PP
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.
.PP
The eight line reports the timeout set up for this command and the time
that the command realy needed to complete.

.SH BUGS

.SH CREDITS

.SH "MAILING LISTS

.SH AUTHOR
.nf
J\*org Schilling
Seestr. 110
D-13353 Berlin
Germany
.fi
.PP
Additional information can be found on:
.br
http://www.fokus.fhg.de/usr/schilling/cdrecord.html
.PP
If you have support questions, send them to:
.PP
.B
cdrecord-support@berlios.de
.br
or
.B
other-cdwrite@lists.debian.org
.PP
If you have definitely found a bug, send a mail to:
.PP
.B
cdrecord-developers@berlios.de
.br
or
.B
schilling@fokus.fhg.de
.PP
To subscribe, use:
.PP
.B
http://lists.berlios.de/mailman/listinfo/cdrecord-developers 
.br
or
.B
http://lists.berlios.de/mailman/listinfo/cdrecord-support