Sending large command descriptor block (CDB) structures in serial attached SCSI (SAS) controller

A computer program product for sending large command descriptor block (CDB) structures in a serial attached SCSI (small computer system interface) (SAS) controller, the computer program product comprising:

• a non-transitory computer usable medium having computer usable code tangibly embodied therewith, the computer usable program code comprising:
• computer usable program code configured to read data from a message frame utilizing a CDB Transmit Block;
• computer usable program code configured to determining whether a size of a CDB of the message frame is larger than thirty-three bytes;
• computer usable program code configured to place a large CDB entry for a message frame having a CDB larger than thirty-three bytes into a direct memory access (DMA) queue;
• computer usable program code configured to send the large CDB entry from the DMA queue to a transmit DMA engine;
• computer usable program code configured to utilize an address pointer to CDB memory contained in the large CDB entry to load large CDB information for the message frame into a DMA buffer;
• computer usable program code configured to transmit a SAS command frame for the message frame having a CDB larger than thirty-three bytes over a SAS interface utilizing the transmit DMA engine;
• and
• computer usable program code configured to transmit a SAS command frame for the message frame having a CDB smaller than thirty-three bytes over the SAS interface utilizing the CDB transmit block.

A system, comprising:

• a direct memory access (DMA) queue;
• a command descriptor block (CDB) transmit block configured to:
• receive a message frame;
• determine whether a size of a CDB of the message frame is larger than thirty-three bytes;
• place a large CDB entry for a message frame having a CDB larger than thirty-three bytes into the DMA queue;
• and
• transmit a SAS command frame for a message frame having a CDB smaller than thirty-three bytes over the SAS interface utilizing the CDB transmit block;
• and
• a transmit DMA engine configured to receive the large CDB entry from the DMA queue,
• wherein the transmit DMA engine is configured to utilize an address pointer to a CDB memory contained in the large CDB entry to load large CDB information for the message frame having a CDB larger than thirty-three bytes into a DMA buffer and transmit a serial attached SCSI (small computer system interface) (SAS) frame for the message frame having a CDB larger than thirty-three bytes over a SAS interface.

A serial attached SCSI (small computer system interface) (SAS) controller, comprising:

• a direct memory access (DMA) queue;
• a command descriptor block (CDB) transmit block, communicatively coupled to the DMA queue, wherein the CDB Transmit Block is configured to:
• receive a message frame;
• determine whether a size of a CDB of the message frame is larger than thirty-three bytes;
• place a large CDB entry for a message frame having a CDB larger than thirty-three bytes into the DMA queue;
• and
• transmit a SAS command frame for a message frame having a CDB smaller than thirty-three bytes over the SAS interface utilizing the CDB transmit block;
• and
• a transmit DMA engine communicatively coupled to the DMA queue, wherein the transmit DMA engine is configured to receive the large CDB from the DMA queue;
• a SAS interface, communicatively coupled to the CDB Transmit Block and the transmit DMA engine,
• wherein the transmit DMA engine is configured to utilize an address pointer to a CDB memory contained in the large CDB entry to load large CDB information for the message frame having a CDB larger than thirty-three bytes into a DMA buffer and transmit a SAS frame for the message frame having a CDB larger than thirty-three bytes over the SAS interface.