8.23. SCSI_IOCTL_GET_IDLUN

SCSI_IOCTL_GET_IDLUN 0x5382. This ioctl takes a pointer to a "struct scsi_idlun" object as its third argument. The "struct scsi_idlun" is not visible to user applications. To use this, that structure needs to be replicated in the user's program. Something like:

typedef struct my_scsi_idlun { int four_in_one; /* 4 separate bytes of info compacted into 1 int */ int host_unique_id; /* distinguishes adapter cards from same supplier */ } My_scsi_idlun;

"four_in_one" is made up as follows:

(scsi_device_id | (lun << 8) | (channel << 16) | (host_no << 24))

These 4 components are assumed (or masked) to be 1 byte each. These are the four numbers that the SCSI subsystem uses to index devices, often written as "<host_no, channel, scsi_id, lun>". The 'host_unique_id' assigns a different number to each controller from the same manufacturer/low-level device driver. Most of the information provided by this command is more easily obtained from SG_GET_SCSI_ID.