This turns on a logging facility that can be used to debug a number
of SCSI related problems.

If you say Y here, no logging output will appear by default, but you
can enable logging by saying Y to "/proc file system support" and
"Sysctl support" below and executing the command

echo <bitmask> > /proc/sys/dev/scsi/logging_level

where <bitmask> is a four byte value representing the logging type
and logging level for each type of logging selected.

There are a number of logging types and you can find them in the
source at <file:drivers/scsi/scsi_logging.h>. The logging levels
are also described in that file and they determine the verbosity of
the logging for each logging type.

If you say N here, it may be harder to track down some types of SCSI
problems. If you say Y here your kernel will be somewhat larger, but
there should be no noticeable performance impact as long as you have
logging turned off.