Allocates device driver resources and ensures exclusive access to a device.
The dd_open low function terminal (LFT) device driver interface allocates resources needed by a device driver and can be used to ensure exclusive access to a device if necessary.
| Item | Description |
|---|---|
| DevNo | Specifies the major and minor device numbers. |
| Flag | Specifies the open file control flags. |
| Chan | Specifies the channel number (multiplexed devices only). |
| Ext | Specifies the extension parameter for device-dependent functions. |
If successful, the dd_open device driver interface returns a value of 0. Otherwise, a value of 1 is returned and the errno global variable is set to indicate the error.