tapes(1M) considers all devices with the node type DDI_NT_TAPE to be tape devices; these devices must have their minor name created with a specific format. The minor name encodes operational modes for the tape device and consists of an ASCII string of the form [ l,m,h,c,u ][ b ][ n ].

The first character set is used to specify the tape density of the device, and are named low (l), medium (m), high (h), compressed (c), and ultra (u). These specifiers only express a relative density; it is up to the driver to assign specific meanings as needed. For example, 9 track tape devices interpret these as actual bits-per-inch densities, where l means 800 BPI, m means 1600 BPI , and h means 6250 BPI, whereas 4mm DAT tapes defines l as standard format, and m, h, c and u as compressed format. Drivers may choose to implement any or all of these format types.

During normal tape operation (non-BSD behavior), once an EOF mark has been reached, subsequent reads from the tape device return an error. An explicit IOCTL must be issued to space over the EOF mark before the next file can be read. b instructs the device to observe BSD behavior, where reading at EOF will cause the tape device to automatically space over the EOF mark and begin reading from the next file.

n or no-rewind-on-close instructs the driver to not rewind to the beginning of tape when the device is closed. Normal behavior for tape devices is to reposition to BOT when closing. See mtio(7I).

The minor number for tape devices should be created by encoding the device's instance number using the tape macro MTMINOR and ORing in the proper combination of density, BSD behavior, and no-rewind flags. See mtio(7I).

To prevent tapes from attempting to automatically generate links for a device, drivers must specify a private node type and refrain from using the node type string DDI_NT_TAPE when callingddi_create_minor_node(9F).

This example demonstrates creating tape device nodes from within the xktape driver's attach(9E) function.

#include <sys/mtio.h> struct tape_minor_info { char *minor_name; int minor_mode; }; /* * create all combinations of logical tapes */ static struct tape_minor_info example_tape[] = { {"", 0}, /* default tape */ {"l", MT_DENSITY1}, {"lb", MT_DENSITY1 | MT_BSD}, {"lbn", MT_DENSITY1 | MT_BSD | MT_NOREWIND}, {"m", MT_DENSITY2}, {"mb", MT_DENSITY2 | MT_BSD}, {"mbn", MT_DENSITY2 | MT_BSD | MT_NOREWIND}, {"h", MT_DENSITY3}, {"hb", MT_DENSITY3 | MT_BSD}, {"hbn", MT_DENSITY3 | MT_BSD | MT_NOREWIND}, {"c", MT_DENSITY4}, {"cb", MT_DENSITY4 | MT_BSD}, {"cbn", MT_DENSITY4| MT_BSD | MT_NOREWIND}, {NULL, 0}, }; int xktapeattach(dev_info_t *dip, ddi_attach_cmd_t cmd) { int instance; struct tape_minor_info *mdp; /* other stuff in attach... */ instance = ddi_get_instance(dip); for (mdp = example_tape; mdp->minor_name != NULL; mdp++) { ddi_create_minor_node(dip, mdp->minor_name, S_IFCHR, (MTMINOR(instance) | mdp->minor_mode), DDI_NT_TAPE, 0); }

Installing the xktape driver on a SPARCstation 20, with the driver controlling a SCSI tape (target 4 attached to an esp(7D) SCSI HBA) and performing a reconfiguration-boot creates the following special files in /devices.

# ls -l /devices/iommu@f,e0000000/sbus@f,e0001000/espdma@f,400000/esp@f,800000/ crw-rw-rw- 1 root sys 33,136 Aug 29 00:02 xktape@4,0: crw-rw-rw- 1 root sys 33,200 Aug 29 00:02 xktape@4,0:b crw-rw-rw- 1 root sys 33,204 Aug 29 00:02 xktape@4,0:bn crw-rw-rw- 1 root sys 33,152 Aug 29 00:02 xktape@4,0:c crw-rw-rw- 1 root sys 33,216 Aug 29 00:02 xktape@4,0:cb crw-rw-rw- 1 root sys 33,220 Aug 29 00:02 xktape@4,0:cbn crw-rw-rw- 1 root sys 33,156 Aug 29 00:02 xktape@4,0:cn crw-rw-rw- 1 root sys 33,144 Aug 29 00:02 xktape@4,0:h crw-rw-rw- 1 root sys 33,208 Aug 29 00:02 xktape@4,0:hb crw-rw-rw- 1 root sys 33,212 Aug 29 00:02 xktape@4,0:hbn crw-rw-rw- 1 root sys 33,148 Aug 29 00:02 xktape@4,0:hn crw-rw-rw- 1 root sys 33,128 Aug 29 00:02 xktape@4,0:l crw-rw-rw- 1 root sys 33,192 Aug 29 00:02 xktape@4,0:lb crw-rw-rw- 1 root sys 33,196 Aug 29 00:02 xktape@4,0:lbn crw-rw-rw- 1 root sys 33,132 Aug 29 00:02 xktape@4,0:ln crw-rw-rw- 1 root sys 33,136 Aug 29 00:02 xktape@4,0:m crw-rw-rw- 1 root sys 33,200 Aug 29 00:02 xktape@4,0:mb crw-rw-rw- 1 root sys 33,204 Aug 29 00:02 xktape@4,0:mbn crw-rw-rw- 1 root sys 33,140 Aug 29 00:02 xktape@4,0:mn crw-rw-rw- 1 root sys 33,140 Aug 29 00:02 xktape@4,0:n

/dev/rmt will contain the logical tape devices (symbolic links to tape devices in /devices).

# ls -l /dev/dsk /dev/rmt/0 -> ../../devices/[....]/xktape@4,0: /dev/rmt/0b -> ../../devices/[....]/xktape@4,0:b /dev/rmt/0bn -> ../../devices/[....]/xktape@4,0:bn /dev/rmt/0c -> ../../devices/[....]/xktape@4,0:c /dev/rmt/0cb -> ../../devices/[....]/xktape@4,0:cb /dev/rmt/0cbn -> ../../devices/[....]/xktape@4,0:cbn /dev/rmt/0cn -> ../../devices/[....]/xktape@4,0:cn /dev/rmt/0h -> ../../devices/[....]/xktape@4,0:h /dev/rmt/0hb -> ../../devices/[....]/xktape@4,0:hb /dev/rmt/0hbn -> ../../devices/[....]/xktape@4,0:hbn /dev/rmt/0hn -> ../../devices/[....]/xktape@4,0:hn /dev/rmt/0l -> ../../devices/[....]/xktape@4,0:l /dev/rmt/0lb -> ../../devices/[....]/xktape@4,0:lb /dev/rmt/0lbn -> ../../devices/[....]/xktape@4,0:lbn /dev/rmt/0ln -> ../../devices/[....]/xktape@4,0:ln /dev/rmt/0m -> ../../devices/[....]/xktape@4,0:m /dev/rmt/0mb -> ../../devices/[....]/xktape@4,0:mb /dev/rmt/0mbn -> ../../devices/[....]/xktape@4,0:mbn /dev/rmt/0mn -> ../../devices/[....]/xktape@4,0:mn /dev/rmt/0n -> ../../devices/[....]/xktape@4,0:n