Writing Device Drivers

scsi_device Structure

The host bus adapter driver allocates and initializes a scsi_device(9S) structure for the target driver before either the probe(9E) or attach(9E) routine is called. This structure stores information about each SCSI logical unit, including pointers to information areas that contain both generic and device-specific information. One scsi_device(9S) structure exists for each logical unit that is attached to the system. The target driver can retrieve a pointer to this structure by calling ddi_get_driver_private(9F).

Caution – Caution –

Because the host bus adapter driver uses the private field in the target device's dev_info structure, target drivers must not use ddi_set_driver_private(9F).

The scsi_device(9S) structure contains the following fields:

struct scsi_device {
    struct scsi_address           sd_address;    /* opaque address */
    dev_info_t                    *sd_dev;       /* device node */
    kmutex_t                      sd_mutex;
    void                          *sd_reserved;
    struct scsi_inquiry           *sd_inq;
    struct scsi_extended_sense    *sd_sense;
    caddr_t                       sd_private;



Data structure that is passed to the routines for SCSI resource allocation.


Pointer to the target's dev_info structure.


Mutex for use by the target driver. This mutex is initialized by the host bus adapter driver and can be used by the target driver as a per-device mutex. Do not hold this mutex across a call to scsi_transport(9F) or scsi_poll(9F). See Chapter 3, Multithreading for more information on mutexes.


Pointer for the target device's SCSI inquiry data. The scsi_probe(9F) routine allocates a buffer, fills the buffer in with inquiry data, and attaches the buffer to this field.


Pointer to a buffer to contain SCSI request sense data from the device. The target driver must allocate and manage this buffer. See attach() Entry Point (SCSI Target Drivers).


Pointer field for use by the target driver. This field is commonly used to store a pointer to a private target driver state structure.