Re: struct rdma_conn_param uses u8 for responder_resources, initiator_depth and private_data_len

[Stefan Metzmacher <metze@xxxxxxxxx>]

Am 21.08.25 um 23:04 schrieb Stefan Metzmacher via samba-technical:
> Hi,
>
> this mail is triggered by the discussion in this thread on
> linux-cifs:
> https://lore.kernel.org/linux-cifs/f551bf7f-697a-4298-a62c-74da18992204@xxxxxxxxx/T/#t
>
> In include/rdma/rdma_cm.h we have this:
>
> struct rdma_conn_param {
>          const void *private_data;
>          u8 private_data_len;
>          u8 responder_resources;
>          u8 initiator_depth;
>          u8 flow_control;
>          u8 retry_count;         /* ignored when accepting */
>          u8 rnr_retry_count;
>          /* Fields below ignored if a QP is created on the rdma_cm_id. */
>          u8 srq;
>          u32 qp_num;
>          u32 qkey;
> };

struct iw_cm_event {
        enum iw_cm_event_type event;
        int                      status;
        struct sockaddr_storage local_addr;
        struct sockaddr_storage remote_addr;
        void *private_data;
        void *provider_data;
        u8 private_data_len;
        u8 ord;
        u8 ird;
};

Also has them as u8...

> The iwarp MPA v2 negotiation can handle values up to
> 0x3fff for responder_resources and initiator_depth.
> And private_data_len can be 0xffff for MPA v1 and
> 0xffff - 4 for MPA v2.
>
> I just found that ROCE only supports u8 in the CM ConnectRequest
> (and I guess it's ROCE v1 and v2 as well as Infiniband,
> but I've only every seen ROCE v2 captures).
>
> BTW: does ROCE also support private data and if how much?
>
> So is it desired to limit iwarp to u8 values too?
>
> Thanks!
> metze