Message-ID: <555A04C8.10802@profitbricks.com>
Date:	Mon, 18 May 2015 17:27:04 +0200
From:	Michael Wang <yun.wang@...fitbricks.com>
To:	Doug Ledford <dledford@...hat.com>
CC:	Or Gerlitz <gerlitz.or@...il.com>,
	Roland Dreier <roland@...nel.org>,
	Sean Hefty <sean.hefty@...el.com>,
	Hal Rosenstock <hal@....mellanox.co.il>,
	"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 05/18/2015 05:21 PM, Doug Ledford wrote:
[snip]
>>
>> I'll put the highlights and changelog under '---' in next version, is it
>> looks like this?
> 
> We're still missing Jason's feedback request though.  Specifically, he
> pointed out that kdocs are usually not done in Documentation/*, they are
> done in the .c files where the function is (or the .h file if the
> function is an inline, which these all are).  So, you included some
> limited documentation for each of these items in your original patches
> that added them.  His request was that you put this expanded information
> not in Documentation/infiniband where someone has to go looking for it,
> but as part of the kdoc header for each of the various helpers in
> ib_verbs.h itself.

I see :-) I've not work with the kdoc yet, not sure if there is any
guidelines on how to write the header of inline func for kdoc?

> 
> Just because I want to move this along versus waiting for another
> respin, I'm going to copy and paste these into those locations and clean
> up the changelog when I integrate this patch.

Got it, if there is anything I could help, please let me know ;-)

Regards,
Michael Wang

> 
>>
>> Subject: [PATCH RFC v3] Documentation/infiniband: Add docs for rdma-helpers
>>
>> This is the following patch for:
>>   https://lkml.org/lkml/2015/5/5/417
>> which try to document the settled rdma_cap_XX().
>>
>> Signed-off-by: Michael Wang <yun.wang@...fitbricks.com>
>> ---
>> 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 ;-)
>>
>> v2:
>>   * Merge the descriptions from Doug:
>>     http://www.spinics.net/lists/linux-rdma/msg25172.html
>>
>> v3:
>>   ...
>>
>>  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
>>
>> Regards,
>> Michael Wang
>>
>>>
>>>>
>>>> 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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> 
> 
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