Well Known ioctl Interfaces
Many ioctl(9E) operations are common to a class of device drivers. For example,
most disk drivers implement many of the dkio(7I) family of ioctls. Many of these
interfaces copy in or copy out data structures from the kernel, and some
of these data structures have changed size in the LP64 data model. The
following section lists the ioctlsthat now require explicit conversion in 64-bit driver ioctl
routines for the dkio, fdio(7I), fbio(7I), cdio(7I), and mtio(7I) families of ioctls.
The nblocks property is exported by each slice of a block device driver.
This property contains the number of 512-byte blocks that each slice of the
device can support. The nblocks property is defined as a signed 32-bit
quantity, which limits the maximum size of a slice to 1 Tbyte.
Disk devices that provide more than 1 Tbyte of storage per disk
must define the Nblocks property, which should still contain the number of 512 byte
blocks that the device can support. However, Nblocks is a signed 64-bit
quantity, which removes any practical limit on disk space.
The nblocks property is now deprecated. All disk devices should provide the Nblocks