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The following routines are used to provide unique identifiers, device IDs, for devices. Specifically, kernel modules use these interfaces to identify and locate devices, independent of the device's physical connection
or its logical device name or number.
ddi_devid_compare() compares two device IDs byte-by-byte and determines both equality and sort order.
ddi_devid_sizeof() returns the number of bytes allocated for the passed in device ID (devid).
ddi_devid_init() allocates memory and initializes the opaque device ID structure. This function does not store the devid. If the device id is not derived from the device's firmware, it is the driver's responsibility to store
the devid on some reliable store. When a devid_type of either DEVID_SCSI3_WWN, DEVID_SCSI_SERIAL, or DEVID_ENCAP is accepted,
an array of bytes (id) must be passed in (nbytes).
When the devid_type DEVID_FAB is used, the array of bytes (id) must be NULL and the length (nbytes) must be zero. The fabricated device ids, DEVID_FAB will be initialized with the machine's host id and a timestamp.
Drivers must free the memory allocated by this function, using the ddi_devid_free() function.
ddi_devid_free() frees the memory allocated for the returned devid by the ddi_devid_init() and devid_str_decode() functions.
ddi_devid_register() registers the device ID address (devid) with the DDI framework, associating it with the dev_info passed in (dip). The drivers
must register device IDs at attach time. See attach(9E).
ddi_devid_unregister() removes the device ID address from the dev_info passed in (dip). Drivers must use this function to unregister the device ID when devices are being
detached. This function does not free the space allocated for the device ID. The driver must free the space allocated for the device ID, using the ddi_devid_free() function. See detach(9E).
ddi_devid_valid() validates the device ID (devid) passed in. The driver must use this function to validate any fabricated device ID that has been stored on a device.
The ddi_devid_str_encode() function encodes a devid and minor_name into a null-terminated ASCII string, returning a pointer to that string. If both a devid and a minor_name are non-null, then a slash (/) is used to separate the devid from the minor_name in the encoded string. If minor_name is null, then only the devid is encoded. If the devid is null, then the special string id0 is returned. Note that you cannot compare the returned string against another string with strcmp() to determine devid equality. The returned string must be freed by calling devid_str_free().
The ddi_devid_str_decode() function takes a string previously produced by the devid_str_encode(3DEVID) or ddi_devid_str_encode() function and decodes the contained device ID and minor_name, allocating and returning pointers to the extracted parts through the retdevid and retminor_name arguments. If the special devidstr id0 was specified
then the returned device ID and minor name will both be null. A non-null returned devid must be freed by the caller through the ddi_devid_free() function. A non-null returned minor name must be freed by calling ddi_devid_str_free().
The ddi_devid_str_free() function is used to free all strings returned by the ddi_devid functions (the ddi_devid_str_encode() function return value and the returned retminor_name argument).
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