size(9P)						   Kernel Properties for Drivers						  size(9P)

NAME

       size, Nblock, blksize, device-nblocks, device-blksize - device size properties

DESCRIPTION

       A driver can communicate size information to the system by the values associated with following properties. Size information falls into two
       categories: device size associated with a dev_info_t node, and minor node size associated with a  ddi_create_minor_node(9F)  dev_t  (parti-
       tion).

       device size property names:

       device-nblocks	 An int64_t property representing device size in device-blksizeblocks.

       device-blksize	 An  integer  property	representing  the  size  in bytes of a block. If defined, the value must be a power of two. If not
			 defined, DEV_BSIZE is implied.

       minor size property names:

       Size	  An int64_t property representing the size in bytes of a character minor device (S_IFCHR spec_type in ddi_create_minor_node).

       Nblocks	  An int64_t property representing the number blocks, in device-blksize units, of a  block  minor  device  (S_IFBLK  spec_type	in
		  ddi_create_minor_node).

       blksize	  An  integer  property  representing  the size in bytes of a block. If defined, the value must be a power of two. If not defined,
		  DEV_BSIZE is implied.

       A driver that implements both block and character minor device nodes should support both "Size" and "Nblocks". Typically, the following	is
       true: Size = Nblocks * blksize.

       A driver where all ddi_create_minor_node(9F) calls for a given instance are associated with the same physical block device should implement
       "device-nblocks". If the device has a fixed block size with a value other than DEV_BSIZE then "device-blksize" should be implemented.

       The driver is responsible for ensuring that property values are updated when device, media, or partition sizes change. For each represented
       item, if its size is know to be zero, the property value should be zero. If its size is unknown, the property should not be defined.

       A  driver  may choose to implement size properties within its prop_op(9E) implementation. This reduces system memory since no space is used
       to store the properties.

       The DDI property interfaces deal in signed numbers. All Size(9P) values should be considered unsigned. It is the responsibility of the code
       dealing with the property value to ensure that an unsigned interpretation occurs.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+

SEE ALSO

       attach(9E), detach(9E), prop_op(9E), ddi_create_minor_node(9F), inquiry-vendor-id(9P)

       Writing Device Drivers

SunOS 5.11							    23 Janl2008 							  size(9P)