可装入驱动程序接口

设备驱动程序必须是可动态装入的。驱动程序还应是可卸载的，以帮助节省内存资源。可卸载驱动程序还应易于测试、调试和修补。

每个设备驱动程序都需要实现 _init(9E)、_fini(9E) 和 _info(9E) 入口点以支持驱动程序的装入和卸载。以下示例显示了可装入驱动程序接口的典型实现。

static void *statep;                /* for soft state routines */
static struct cb_ops xx_cb_ops;     /* forward reference */
static struct dev_ops xx_ops = {
    DEVO_REV,
    0,
    xxgetinfo,
    nulldev,
    xxprobe,
    xxattach,
    xxdetach,
    xxreset,
    nodev,
    &xx_cb_ops,
    NULL,
    xxpower,
    ddi_quiesce_not_needed,
};

static struct modldrv modldrv = {
    &mod_driverops,
    "xx driver v1.0",
    &xx_ops
};

static struct modlinkage modlinkage = {
    MODREV_1,
    &modldrv,
    NULL
};

int
_init(void)
{
    int error;
    ddi_soft_state_init(&statep, sizeof (struct xxstate),
        estimated_number_of_instances);
    /* further per-module initialization if necessary */
    error = mod_install(&modlinkage);
    if (error != 0) {
        /* undo any per-module initialization done earlier */
        ddi_soft_state_fini(&statep);
    }
    return (error);
}

int
_fini(void)
{
    int error;
    error = mod_remove(&modlinkage);
    if (error == 0) {
        /* release per-module resources if any were allocated */
        ddi_soft_state_fini(&statep);
    }
    return (error);
}

int
_info(struct modinfo *modinfop)
{
    return (mod_info(&modlinkage, modinfop));
}