ib_detach_mcast(9)

💅 NAME 💅

okay bestie, gather round — this is ib_detach_mcast(9) from the Kernel API Manual, and it does exactly what it says on the tin: it detaches the specified QP from a multicast group. that's it. that's the vibe. 🎀

✨ SYNOPSIS ✨

int ib_detach_mcast (struct ib_qp *qp , union ib_gid *gid , u16 lid );

literally the whole signature, no cap. three args, one int, slay.

🦋 ARGUMENTS 🦋

• qp — the QP you're detaching from the multicast group. the main character of this operation, honestly.
• gid — the multicast group GID. it's a union ib_gid *, so pointer energy 💫
• lid — the multicast group LID, and bestie listen — this one's in host byte order. not network order. host. write that down 🫶

🌸 SEE ALSO 🌸

the kernel file ./include/rdma/ib_verbs.h is where all this lives, and the cross-refs are giving encyclopaedia. buckle up, we're listing every single one because we don't skip entries in this house 💅

• struct rdma_stat_desc(9), struct rdma_hw_stats(9), ib_rate_to_mult(9), ib_rate_to_mbps(9), ib_port_attr_to_speed_info(9), enum ib_mr_type(9), struct ib_mr_status(9), mult_to_ib_rate(9), struct ib_udata(9), struct rdma_netdev(9), struct ib_device_ops(9), ib_get_client_data(9), ib_modify_qp_is_ok(9)
• rdma_cap_ib_switch(9), rdma_start_port(9), rdma_for_each_port(9), rdma_end_port(9), rdma_cap_ib_mad(9), rdma_cap_opa_mad(9), rdma_cap_ib_smi(9), rdma_cap_ib_cm(9), rdma_cap_iw_cm(9), rdma_cap_ib_sa(9), rdma_cap_ib_mcast(9), rdma_cap_af_ib(9), rdma_cap_eth_ah(9), rdma_cap_opa_ah(9), rdma_max_mad_size(9), rdma_cap_roce_gid_table(9), rdma_core_cap_opa_port(9), rdma_mtu_enum_to_int(9), rdma_mtu_from_attr(9)
• ib_alloc_pd(9), ib_dealloc_pd(9), rdma_create_ah(9), rdma_create_user_ah(9), ib_get_gids_from_rdma_hdr(9), ib_get_rdma_header_version(9), ib_init_ah_attr_from_wc(9), ib_create_ah_from_wc(9), rdma_modify_ah(9), rdma_query_ah(9), rdma_destroy_ah_user(9), rdma_destroy_ah(9)
• ib_modify_srq(9), ib_query_srq(9), ib_destroy_srq_user(9), ib_destroy_srq(9), ib_post_srq_recv(9), ib_create_qp(9), ib_modify_qp_with_udata(9), ib_modify_qp(9), ib_query_qp(9), ib_destroy_qp(9), ib_open_qp(9), ib_close_qp(9), ib_post_send(9), ib_post_recv(9)
• ib_alloc_cq_any(9), rdma_set_cq_moderation(9), ib_destroy_cq_user(9), ib_destroy_cq(9), ib_poll_cq(9), ib_req_notify_cq(9)
• ib_virt_dma_to_ptr(9), ib_virt_dma_to_page(9), ib_dma_mapping_error(9), ib_dma_map_single(9), ib_dma_unmap_single(9), ib_dma_map_page(9), ib_dma_unmap_page(9), ib_dma_map_bvec(9), ib_dma_unmap_bvec(9), ib_dma_map_sgtable_attrs(9), ib_dma_map_sg(9), ib_dma_unmap_sg(9), ib_dma_max_seg_size(9), ib_dma_sync_single_for_cpu(9), ib_dma_sync_single_for_device(9)
• ib_dereg_mr_user(9), ib_dereg_mr(9), ib_update_fast_reg_key(9), ib_inc_rkey(9), ib_attach_mcast(9), ib_check_mr_status(9), ib_device_try_get(9)
• rdma_ah_find_type(9), ib_lid_cpu16(9), ib_lid_be16(9), rdma_roce_rescan_device(9), rdma_device_to_ibdev(9), ibdev_to_node(9), rdma_device_to_drv_device(9), rdma_flow_label_to_udp_sport(9), rdma_calc_flow_label(9), rdma_get_udp_sport(9)

and yeah, ib_attach_mcast(9) is right there in the list — the attach to this detach, the prequel, the origin story 😭

ngl bestie, the page keeps it lowkey about return values and error codes — the synopsis gives you int and that's all the lore we get. no invented tea on this blog 🙈

okay that's the whole page, mwah 💖 it shipped from ./include/rdma back in October 2026, and yes — you just read ib_detach_mcast(9) cover to cover. go detach something (respectfully). 🧚‍♀️⭐🌈