STREAMS-UX Programmer's Guide (February 2007)

Modules and Drivers

Data Structures

Chapter 4

SQLVL_DEFAULT Default level synchronization. It is the same as

SQLVL_QUEUEPAIR.

SQLVL_MODULE Module level synchronization. All the instances of

modules/drivers are synchronized.

SQLVL_ELSEWHERE Synchronize with respect to the group of co-operating

modules/drivers which access each others data. The

group name is specified in the inst_sync_info.

SQLVL_GLOBAL Provides Global synchronization. No more than one

thread of execution can access modules/drivers under

this level.

inst_sync_info

Used to provide the name of the driver/module/group in case of SQLVL_ELSEWHERE

synchronization. If not used, set NULL string.

The drv_info_t Structure

All STREAMS drivers must define drv_info_t structure and must be allocated statically. This structure is

not applicable for STREAMS modules. The structure is defined in <sys/conf.h>.

The drv_info_t has the following fields:

char *name; /* Name of driver */

char *class; /* Device class ("disk","tape", etc.) */

ubit32 flags; /* Device flags (see below) */

int b_major; /* Block device major number */

int c_major; /* Character device major number */

cdio_t *cdio; /* Pointer to cdio(CDIO4) structure */

void *gio_private; /* Additional GIO information */

void *cdio_private; /* Additional CDIO information */

name Points to a string containing name of the driver. This should match the name specified in

module metadata.

class Pointer to a string containing the name of the class that the driver is in. For interface

drivers, instances of a card are counted within each class when they are identified at kernel

boot time. Instance numbers are unique within a device class.

flags Contains the bitmask of flags that describe the module/driver.

DRV_CHAR Character device driver.

DRV_BLOCK Block device driver.

DRV_SCAN Driver supports bus scanning.

DRV_MP_SAFE MP aware driver and provides its own multi-processing

protection.

DRV_SAVE_CONF Save configuration information to /etc/ioconfig. This

file retains potentially volatile information such as

dynamic major numbers and card instance numbers

across reboots.

b_major Set this field to -1. STREAMS drivers or modules are not block device drivers.