QDMA Features¶
QDMA Linux Driver supports the following list of features
QDMA Hardware Features¶
SRIOV with 4 Physical Functions(PF) and 252 Virtual Functions(VF)
Memory Mapped(MM) and Stream(ST) interfaces per queue
2048 queue sets
- 2048 H2C (Host-to-Card) descriptor rings
- 2048 C2H (Card-to-Host) descriptor rings
- 2048 completion rings
Supports Legacy and MSI-X Interrupts
- 2048 MSI-X vectors.
- Up to 8 MSI-X per function.
- Interrupt Aggregation
- User Interrupts
- Error Interrupts
- Legacy Interrupts : Supported only for PF0 with single queue
Mailbox communication between PF and VF driver
Interrupt support for Mailbox events
Flexible interrupt allocation between PF/VF
HW Error reporting
Zero byte transfers
Immediate data transfers
Descriptor bypass(8, 16, 32, 64 descriptor sizes) support
Descriptor Prefetching
Streaming C2H completion entry coalescing
Disabling overflow check in completion ring
Streaming H2C to C2H and C2H to H2C loopback support
Dynamic queue configuration
Completion ring descriptors of 8, 16, 32, 64 bytes sizes
Flexible BAR mapping for QDMA configuration register space
ECC support
Completions in memory mapped mode
For details on Hardware Features refer to QDMA_Product_Guide.
QDMA Software Features¶
- Polling and Interrupt Modes
QDMA software provides 2 different drivers. PF driver for Physical functions and and VF driver for Virtual Functions. PF and VF drivers can be inserted in different modes.
- Polling Mode
In Poll Mode, Software polls for the write back completions(Status Descriptor Write Back)
- Direct Interrupt Mode
In Direct Interrupt mode, Each queue is assigned to one of the available interrupt vectors in a round robin fashion to service the requests. Interrupt is raised by the HW upon receiving the completions and software reads the completion status.
- Indirect Interrupt Mode
In Indirect Interrupt mode or Interrupt Aggregation mode, each vector has an associated Interrupt Aggregation Ring. The QID and status of queues requiring service are written into the Interrupt Aggregation Ring. When a PCIe MSI-X interrupt is received by the Host, the software reads the Interrupt Aggregation Ring to determine which queue needs service. Mapping of queues to vectors is programmable
- Auto Mode
Auto mode is mix of Poll and Interrupt Aggregation mode. Driver polls for the write back status updates. Interrupt aggregation is used for processing the completion ring.
- Allows only Privileged Physical Functions to program the contexts and registers
- Dynamic queue configuration
- Dynamic driver configuration
- Driver configuration through sysfs
- Asynchronous and Synchronous IO support
- Display the Version details for SW and HW