User mode programs communicate with the changer driver through a number of ioctls which are described
below. Changer element addresses used in the communication between the kernel and the changer device are
mapped to zero-based logical addresses. Element types are specified as follows:
CHET_MT Medium transport element (picker).
CHET_ST Storage element (slot).
CHET_IE Import/export element (portal).
CHET_DT Data transfer element (drive).
The following ioctl(2) calls apply to the changer. They are defined in the header file <sys/chio.h>.
CHIOMOVE (structchanger_move) Move a medium from one element to another (MOVEMEDIUM) using the
current picker. The source and destination elements are specified in a changer_move
structure, which includes at least the following fields:
u_int cm_fromtype; /* element type to move from */
u_int cm_fromunit; /* logical unit of from element */
u_int cm_totype; /* element type to move to */
u_int cm_tounit; /* logical unit of to element */
u_int cm_flags; /* misc. flags */
If the CM_INVERT in the cm_flags field is set, the medium changer is instructed to flip the
medium while moving it.
CHIOEXCHANGE (structchanger_exchange) Move the medium located in the source element to the first
destination element, and move the medium that had been in the first destination element to
the second destination element. In case of a simple exchange, the source and second
destination elements should be the same. The current picker is used to perform the
operation. The addresses of the affected elements is specified to the ioctl in a
changer_exchange structure which includes at least the following fields:
u_int ce_srctype; /* element type of source */
u_int ce_srcunit; /* logical unit of source */
u_int ce_fdsttype; /* element type of first destination */
u_int ce_fdstunit; /* logical unit of first destination */
u_int ce_sdsttype; /* element type of second destination */
u_int ce_sdstunit; /* logical unit of second destination */
u_int ce_flags; /* misc. flags */
In ce_flags, CM_INVERT1 and/or CM_INVERT2 may be set to flip the first or second medium
during the exchange operation, respectively.
Thisoperationisuntested.
CHIOPOSITION (structchanger_position) Position the current picker in front of the specified element.
The element is specified with a changer_position structure, which includes at least the
following elements:
u_int cp_type; /* element type */
u_int cp_unit; /* logical unit of element */
u_int cp_flags; /* misc. flags */
The cp_flags field may be set to CP_INVERT to invert the picker during the operation.
CHIOGPICKER (int) Return the logical address of the current picker.
CHIOSPICKER (int) Select the picker specified by the given logical address.
CHIOGPARAMS (structchanger_params) Return the configuration parameters for the media changer. This
ioctl fills the changer_params structure passed by the user with at least the following
fields:
u_int cp_npickers; /* number of pickers */
u_int cp_nslots; /* number of slots */
u_int cp_nportals; /* number of import/export portals */
u_int cp_ndrives; /* number of drives */
This call can be used by applications to query the dimensions of the jukebox before using
the CHIGSTATUS ioctl to query the jukebox status.
CHIOIELEM Perform the INITIALIZEELEMENTSTATUS call on the media changer device. This forces the
media changer to update its internal status information with respect to loaded media. It
also scans any barcode labels provided that it has a label reader. The ch driver's status
is not affected by this call.
CHIOGSTATUS (structchanger_element_status_request) Perform the READELEMENTSTATUS call on the media
changer device. This call reads the element status information of the media changer and
converts it to an array of changer_element_status structures.
With each call to CHIOGSTATUS, the status of one or more elements of one type may be
queried.
The application passes a changer_element_status_request structure to the ch driver which
contains the following fields:
u_int cesr_element_type;
u_int cesr_element_base;
u_int cesr_element_count;
u_int cesr_flags;
struct changer_element_status *cesr_element_status;
This structure is read by the driver to determine the type, logical base address and number
of elements for which information is to be returned in the array of changer_element_status
structures pointed to by the cesr_element_status field. The application must allocate
enough memory for cesr_element_count status structures (see below). The cesr_flags can
optionally be set to CESR_VOLTAGS to indicate that volume tag (bar code) information is to
be read from the jukebox and returned.
The cesr_element_base and cesr_element_count fields must be valid with respect to the
physical configuration of the changer. If they are not, the CHIOGSTATUS ioctl returns the
EINVAL error code.
The information about the elements is returned in an array of changer_element_status
structures. This structure include at least the following fields:
u_int ces_addr; /* element address in media changer */
u_char ces_flags; /* see CESTATUS definitions below */
u_char ces_sensecode; /* additional sense code for element */
u_char ces_sensequal; /* additional sense code qualifier */
u_char ces_invert; /* invert bit */
u_char ces_svalid; /* source address (ces_source) valid */
u_short ces_source; /* source address of medium */
changer_voltag_t ces_pvoltag; /* primary volume tag */
changer_voltag_t ces_avoltag; /* alternate volume tag */
u_char ces_idvalid; /* ces_scsi_id is valid */
u_char ces_scsi_id; /* SCSI id of element (if ces_idvalid is nonzero) */
u_char ces_lunvalid; /* ces_scsi_lun is valid */
u_char ces_scsi_lun; /* SCSI lun of element (if ces_lunvalid is nonzero) */
The ces_addr field contains the address of the element in the coordinate system of the
media changer. It is not used by the driver, and should be used for diagnostic purposes
only.
The following flags are defined for the ces_flags field:
CESTATUS_FULL A medium is present.
CESTATUS_IMPEXP The medium has been deposited by the operator (and not by a picker).
CESTATUS_EXCEPT The element is in an exceptional state (e.g. invalid barcode label,
barcode not yet scanned).
CESTATUS_ACCESS The element is accessible by the picker.
CESTATUS_EXENAB The element supports medium export.
CESTATUS_INENAB The element supports medium import.
Note that not all flags are valid for all element types.
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