cb_ops Structure

static struct cb_ops xx_cb_ops = {
    xxopen,         /* open(9E) */
    xxclose,        /* close(9E) */
    xxstrategy,     /* strategy(9E) */
    xxprint,        /* print(9E) */
    xxdump,         /* dump(9E) */
    xxread,         /* read(9E) */
    xxwrite,        /* write(9E) */
    xxioctl,        /* ioctl(9E) */
    xxdevmap,       /* devmap(9E) */
    nodev,          /* mmap(9E) */
    xxsegmap,       /* segmap(9E) */
    xxchpoll,       /* chpoll(9E) */
    xxprop_op,      /* prop_op(9E) */
    NULL,           /* streamtab(9S) */
    D_MP | D_64BIT, /* cb_flag */
    CB_REV,         /* cb_rev */
    xxaread,        /* aread(9E) */
    xxawrite        /* awrite(9E) */
};

The cb_ops(9S) structure contains the entry points for the character operations and block operations of the device driver. Any entry points that the driver does not support should be initialized to nodev(9F). For example, character device drivers should set all the block-only fields, such as cb_stategy, to nodev(9F). Note that the mmap(9E) entry point is maintained for compatibility with previous releases. Drivers should use the devmap(9E) entry point for device memory mapping. If devmap(9E) is supported, set mmap(9E) to nodev(9F).

The streamtab field indicates whether the driver is STREAMS-based. Only the network device drivers that are discussed in Chapter 19, Drivers for Network Devices are STREAMS-based. All non-STREAMS-based drivers must set the streamtab field to NULL.

The cb_flag member contains the following flags:

• The D_MP flag indicates that the driver is safe for multithreading. The Oracle Solaris OS supports only thread-safe drivers so D_MP must be set.

• The D_64BIT flag causes the driver to use the uio_loffset field of the uio(9S) structure. The driver should set the D_64BIT flag in the cb_flag field to handle 64-bit offsets properly.

• The D_DEVMAP flag supports the devmap(9E) entry point. For information on devmap(9E), see Chapter 10, Mapping Device and Kernel Memory.

cb_rev is the cb_ops structure revision number. This field must be set to CB_REV.