Compatibility of Xilinx QDMA Linux Driver with OpenNIC Shell – "Zero Qs" Issue

[nehalbaganal]

Hello,

I'm currently working with the OpenNIC shell and trying to interface with the QDMA subsystem using Xilinx’s official QDMA Linux driver (dma_ip_drivers/QDMA/linux-kernel). I am encountering issues related to queue configuration and would appreciate your insights on compatibility and expected behavior.

What works
Driver loads successfully (qdma-pf bound to the PFs).
dma-ctl shows the QDMA devices:

./dma-ctl dev list
qdmac1000 0000:c1:00.0 max QP: 0, -~-
qdmac1001 0000:c1:00.1 max QP: 0, -~-

Device capabilities are detected correctly:

./dma-ctl qdmac1000 cap
Total number of queues supported: 512
MM enabled: yes
ST enabled: yes

What Fails

When attempting to add a queue:
./dma-ctl qdmac1000 q add idx 0 mode mm dir c2h
I consistently get the message:
Zero Qs

And listing queues shows none configured:

./dma-ctl qdmac1000 q list 0 1
Zero Qs

Is the official Xilinx QDMA Linux driver (dma_ip_drivers/QDMA/linux-kernel) expected to be compatible with the OpenNIC shell?
If yes, how is this compatibility achieved, and what steps are required on the software side (e.g., driver, device nodes, netdev registration) to ensure queue setup works correctly?

[slahmer97]

Hi,

The Xilinx QDMA Linux driver from dma_ip_drivers/QDMA/linux-kernel is primarily designed as a generic character device abstraction for data movement; but does not provide a network (netdev) abstraction. This means that while it can enumerate the device and report capabilities, it won’t configure or expose network-style queues as expected in a NIC context.

If your goal is to use the OpenNIC shell as a network interface, there are two main options:

OpenNIC driver which a minimal netdev driver designed specifically for the OpenNIC shell. It integrates the QDMA subsystem in MM/ST mode for packet I/O. But it doesn't support all QDMA features (i.e., different rx/tx desc/cmpt size/layout; high number of queues) but is sufficient for networking functionality (e.g., packet TX/RX).

If you look for more high performance userpace networking, you can use QDMA PMD. It builds on the QDMA IP's full (most i can say) feature set that you would need. This would suite you if you want user-space packet processing or need higher performance and more flexibility.

Hope this helps