Hi DPDK Community,

I'm currently working with dpdk-22.11 ( also tried current 24.07) and facing an issue when initializing 2×25G Mellanox NICs (MT27800 Family [ConnectX-5]) on ARM based system.

During device probing, I see the following errors:

EAL: Probe PCI driver: mlx5_pci (15b3:1017) device: 0001:01:00.0 (socket -1)

mlx5_common: Failed to allocate DevX UAR (BF/NC)

mlx5_common: Failed to allocate UAR.

mlx5_net: Failed to prepare Tx DevX UAR.

mlx5_net: probe of PCI device 0001:01:00.0 aborted after encountering an error: Operation not permitted

Interestingly, the same setup works fine with 2×100G MT28800 Family [ConnectX-5 Ex] NICs.

Also this 2x25G cards work well with Linux kernel.  The issue is only with DPDK binding.

When I enable kernel prints, UAR allocation appears successful, suggesting the issue may be DevX-specific on MT27800.

I'd appreciate any guidance on:

• Known limitations or configuration differences between MT27800 and MT28800
• Whether DevX should be disabled explicitly for MT27800 (e.g., MLX5_DEVX=0)
• Any firmware or kernel dependencies that might affect DevX support

Thanks in advance for your help.

Best Regards,

Prashant Gupta