An excerpt from the net ... Didn't ever personally try it though. ------------------------------------------------------- Description of new logging facility
The logging facility will make it much easier to troubleshoot problems in the field. The basic idea is that it is possible to request debugging information be enabled at any given instant in time, which will be placed into the kernel log file. The general idea is that there are a number of different facilities within the kernel, each of which can generate messages at varying levels of verbosity. When you have specific problems in one area, you can turn on highly verbose logging for the messages in that subsystem, and leave the rest off, or put some of the others at lower levels of verbosity. Each of the different facilities have names. The valid names are: all, none, timeout, scan, mlqueue, mlcomplete, llqueue, llcomplete, hlqueue, hlcomplete, and ioctl. Each facility can have a verbosity level from 0 to 7, where 0 indicates completely quiet, and 7 represents maximum verbosity. There are two fundamental ways of turning this on - one is via the LILO command line: scsi_logging=N where N is a number that represents the logging mask. There isn't a really good symbolic way of describing what you are really turning on from the kernel command line - you are essentially specifying a 32 bit quantity that has all of the logging levels stored in it. The easiest way to find the number you actually want is by setting the desired logging level from the /proc filesystem, and then recording the logging mask that is reported. The other way to turn on logging is via the /proc filesystem. A shell command like: # echo "scsi log timeout 5" > /proc/scsi/scsi will set the verbosity level to 5 for events related to timeout handling. If you are lazy and unsure where the problem is, you can set all of the facilities to the maximum verbosity level with the following command: # echo "scsi log all" > /proc/scsi/scsi Similarly, it is possible to turn off all logging with the following command: # echo "scsi log none" > /proc/scsi/scsi Note - there is a kernel configuration option (CONFIG_SCSI_LOGGING) that can be used to enable/disable logging. The presence of the logging code shouldn't present any noticeable run-time overhead, as the testing to see whether a given facility is at a sufficiently high logging level is all done inline without any function calls. The only noticeable effect of having the logging enabled is that the kernel will be slightly larger, as a number of printk() and other statements will need to be present. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dupuis, Chad Sent: Friday, February 04, 2005 1:58 AM To: [email protected] Subject: Debug out from SCSI layers Hi, Is there a way to make the SCSI layers (midlayer, sd, etc.) print out a some debug output to /var/log/messages so that one can see what's going on in those driver real time? Thanks, Chad - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
