Cross channel communication capability for connectX-4

Hi, I would like to consult a question regarding to cross channel communication. I am currently using the connectx-4 card. According to the user manual, cards newer than connectx-3 should support cross channel capability for creating managed QP. However, the result of query device(ibv_exp_query_device) returns that the exp_device_cap_flags to be (IBV_EXP_START_FLAG << 30), which doesn’t equal to IBV_EXP_DEVICE_CROSS_CHANNEL as mentioned in the manual. Besides, the ibv_exp_create_cq for creating CQ with flags for cross channel communication cannot work.

Can anyone give me some clues how to enable and use such capability? Is this a reason caused by the new version mallanox OFED driver?

Thanks in advance!

Cross Channel feature supported by v4.9 LTS version of the MOFED. Newer version of MOFED based on rdma-core package and doesn’t use experimental verbs

https://docs.mellanox.com/display/rdmacore50/Cross+Channel

Please, check RDMA programming manual how to use it

https://www.mellanox.com/related-docs/prod_software/RDMA_Aware_Programming_user_manual.pdf