Chapter 7. Proc pseudo file system

The proc pseudo file system provides some useful information about the SCSI subsystem. The kernel configuration option that selects "proc_fs" is CONFIG_PROC_FS and in almost all cases it should be selected. SCSI specific information is found under the directory /proc/scsi. Probably the most commonly accessed entry is cat /proc/scsi/scsi which lists the attached SCSI devices. See Section 8.3 for more details.

The lower level drivers are allocated proc_fs entries of the form:

/proc/scsi/<driver_name>/<scsi_adapter_number>

where the <driver_name> is something like "aic7xxx" or "BusLogic". The <scsi_adapter_number> (also known as the host number) is the same number that was discussed in Section 3.1. Note that one driver may control one or more hosts. What is stored in this file is lower level driver dependent (and in the case of some adapter drivers it is possible to set parameters via this file). When reporting problems to newsgroups or maintainers it is useful to include the output of this file (e.g. cat /proc/scsi/aic7xxx/0 ).

The cdrom driver provides information about attached cdrom devices in the /proc/sys/dev/cdrom directory. This will include both SCSI devices (i.e. those controlled by the sr driver) and IDE devices (i.e. those controlled by the ide-cd driver). See Section 9.2.3.

The sg driver provides information about its state and attached hosts and devices in the /proc/scsi/sg directory. See Section 9.4.3.

More general information on the proc pseudo file system can be found in the kernel source file: /usr/src/linux/Documentation/filesystems/proc.txt.