| 摘要 |
A system for sending large Command Descriptor Block (CDB) structures in a serial attached SCSI (SAS) controller includes a CDB Transmit Block, a CDB Memory, a Context Memory, a Direct Memory Access (DMA) Queue, a Transmit DMA Engine, and a SAS Interface. The CDB Transmit Block receives one or more Message Frames. If the CDB is small (32 bytes or less), the CDB Transmit Block reads data from the Message Frame and transmits a SAS Command Frame over the SAS interface. If the CDB is large (33 bytes or more), the CDB Transmit Block places a large CDB entry into the DMA Queue. The Transmit DMA Engine receives the large CDB entry from the DMA queue, utilizes an address pointer from the Message Frame to the CDB Memory to fetch large CDB information into a DMA buffer, and transmits a SAS Command Frame over the SAS interface. |
