Does ConnectX-5 / ConnectX-7 / BlueField-3 SuperNIC support disabling RDMA ICRC validation?

Infrastructure & Networking Adapters and Cables InfiniBand/VPI Adapter Cards
1

We would like to know whether disabling RDMA ICRC validation on the receiving NIC is supported on the following SKUs.

Per this forum thread, the recommended method is to set the rx_icrc_chk_dis field in the PCMR register via mlxreg. However, querying PCMR on our cards returns the standard 17 fields without rx_icrc_chk_dis_cap or rx_icrc_chk_dis, even after upgrading to the latest firmware.

Hardware tested

Device OPN PSID FW (latest tested) rx_icrc_chk_dis present?
ConnectX-5 MCX516A-CCAT MT_0000000012 16.34.1002 No
ConnectX-7 MCX75310AAS-NEAT MT_0000000838 28.47.2682 No
ConnectX-7 (engineering sample) MCX715105AS-WEAT MT_0000000856 28.41.1000 (no upgrade available) No
BlueField-3 SuperNIC 900-9D3B4-00PN-EA0 MT_0000001011 32.43.1014 No

Tools: mlxup 4.30.0 / 4.34.0, MFT 4.26.1-6, mlxreg / flint.

Questions

  1. Is rx_icrc_chk_dis available on these SKUs in any firmware version, or only on specific SKUs (e.g. BlueField-3 DPU SKU MT_0000000883)?
  2. If rx_icrc_chk_dis is not available on our SKUs, is there an alternative method to disable RDMA ICRC validation?
  3. Is a debug or special firmware build available that exposes ICRC disable for our SKUs?

System info

  • Host: Ubuntu 20.04.6 LTS, kernel 5.15.0-52-generic
  • mlx5_core: MLNX_OFED 23.10-3.2.2
2

Hello,

The two readings related to icrc are exposed by MFT, please upgrade MFT to the latest version and check if that helps. In case the issue persists after the upgrade, please open a support case with us for further investigation.

3

Hi, thanks for the suggestion.

We tried both MFT 4.34.1-18 LTS (2025 LTS U2) and the latest
MFT 4.36.0-147 on the same host (Ubuntu 20.04, MLNX_OFED 23.10-3.2.2),
upgraded from MFT 4.26.1-6.

After each upgrade we re-queried PCMR on all four cards. PCMR exposes
23 fields on both 4.34 and 4.36 (was 17 on 4.26), so the upgrades did
expand visibility. However rx_icrc_chk_dis_cap and rx_icrc_chk_dis
are still absent on all four PSIDs:

Device PSID FW
ConnectX-5 MT_0000000012 16.35.8008
ConnectX-7 MT_0000000838 28.47.2682
ConnectX-7 (ES) MT_0000000856 28.41.1000
BlueField-3 SuperNIC MT_0000001011 32.43.1014

mlxreg --show_regs enumerated the full register inventory — no register
name contains icrc or crc on either MFT version, and ROCE_ACCL only
carries congestion-control fields.

We’ll proceed to open a support case as suggested. Thanks.