Date:	Mon, 18 May 2015 12:47:06 +0300
From:	Or Gerlitz <gerlitz.or@...il.com>
To:	Michael Wang <yun.wang@...fitbricks.com>
Cc:	Roland Dreier <roland@...nel.org>,
	Sean Hefty <sean.hefty@...el.com>,
	Hal Rosenstock <hal@....mellanox.co.il>,
	Doug Ledford <dledford@...hat.com>,
	"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	linux-doc@...r.kernel.org, Or Gerlitz <ogerlitz@...lanox.com>,
	Ira Weiny <ira.weiny@...el.com>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Subject: Re: [PATCH RFC v2] Documentation/infiniband: Add docs for rdma-helpers

On Mon, May 18, 2015 at 11:41 AM, Michael Wang
<yun.wang@...fitbricks.com> wrote:
> Since v1:
>   * Merge the descriptions from Doug:
>     http://www.spinics.net/lists/linux-rdma/msg25172.html
>
> This is the following patch for:
>   https://lkml.org/lkml/2015/5/5/417
> which try to document the settled rdma_cap_XX().
>
> Highlights:
>   There could be many missing/mistakes/misunderstanding, please don't
>   be hesitate to point out the issues, any suggestions to improve or
>   complete the description are very welcomed ;-)

Michael, none of what you wrote above belongs to the change-log which
is going to stay for-ever in the upstream git repo. You should put it
all belong the --- line after your S.O.B and add proper change log
telling what this patch is about

>
> Signed-off-by: Michael Wang <yun.wang@...fitbricks.com>
> ---
>  Documentation/infiniband/rdma_helpers.txt | 79 +++++++++++++++++++++++++++++++
>  1 file changed, 79 insertions(+)
>  create mode 100644 Documentation/infiniband/rdma_helpers.txt
>
> diff --git a/Documentation/infiniband/rdma_helpers.txt b/Documentation/infiniband/rdma_helpers.txt
> new file mode 100644
> index 0000000..be9416d
> --- /dev/null
> +++ b/Documentation/infiniband/rdma_helpers.txt
> @@ -0,0 +1,79 @@
> +RDMA HELPERS
> +
> +  The following helpers are used to check the specific capabilities of a
> +  particular port before utilizing those capabilities.
> +
> +    rdma_cap_ib_mad            - Infiniband Management Datagrams.
> +    rdma_cap_ib_smi            - Infiniband Subnet Management Interface.
> +    rdma_cap_ib_cm             - Infiniband Communication Manager.
> +    rdma_cap_iw_cm             - IWARP Communication Manager.
> +    rdma_cap_ib_sa             - Infiniband Subnet Administration.
> +    rdma_cap_ib_mcast          - Infiniband Multicast Join/Leave Protocol.
> +    rdma_cap_read_multi_sge    - RDMA Read Work Request Support Multiple SGE.
> +    rdma_cap_af_ib             - Native Infiniband Address.
> +    rdma_cap_eth_ah            - InfiniBand Transport With Ethernet Address.
> +
> +USAGE
> +
> +  if (rdma_cap_XX(device, i)) {
> +       /* The port i of device support XX */
> +       ...
> +  } else {
> +       /* The port i of device don't support XX */
> +       ...
> +  }
> +
> +  rdma_cap_ib_mad
> +  ---------------
> +    Management Datagrams (MAD) are a required part of the InfiniBand
> +    specification and are supported on all InfiniBand devices.  A slightly
> +    extended version are also supported on OPA interfaces.
> +
> +  rdma_cap_ib_smi
> +  ---------------
> +    Subnet Management Interface (SMI) will handle SMP packet from SM
> +    in an infiniband fabric.
> +
> +  rdma_cap_ib_cm
> +  ---------------
> +    Communication Manager (CM) service, used to ease the process of connecting
> +    to a remote host.  The IB-CM can be used to connect to remote hosts using
> +    either InfiniBand or RoCE connections, iWARP has its own CM.
> +
> +  rdma_cap_iw_cm
> +  ---------------
> +    iWARP Communication Manager (CM), Similar to the IB-CM, but only used on
> +    iWARP devices.
> +
> +  rdma_cap_ib_sa
> +  ---------------
> +    Subnet Administration (SA) is the database built by SM in an
> +    infiniband fabric.
> +
> +  rdma_cap_ib_mcast
> +  ---------------
> +    InfiniBand (and OPA) use a different multicast mechanism rather than
> +    traditional IP multicast found on Ethernet devices.  If this is true, then
> +    traditional IPv4/IPv6 multicast is handled by the IPoIB layer and direct
> +    multicast joins and leaves are handled per the InfiniBand specifications.
> +
> +  rdma_cap_read_multi_sge
> +  ---------------
> +    Certain devices (iWARP in particular) have restrictions on the number of
> +    scatter gather elements that can be present in an RDMA READ work request,
> +    this is true if the device does not have that restriction.
> +
> +  rdma_cap_af_ib
> +  ---------------
> +    Many code paths for traditional InfiniBand and RoCE links are the same,
> +    but need minor differences to accommodate the different addresses on the
> +    two types of connections.  This helper is true when the address of the
> +    specific connection is of the InfiniBand native variety.
> +
> +  rdma_cap_eth_ah
> +  ---------------
> +    Queue Pair is InfiniBand transport, but uses Ethernet address instead
> +    of native InfiniBand address (aka, this is a RoCE QP, and that means
> +    ethertype 0x8915 + GRH for RoCEv1 and IP/UDP to well known UDP port for
> +    RoCEv2), this is true when the address family of the specific queue pair
> +    is of the Ethernet (RoCE) variety.
> --
> 2.1.0
>
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