Re: PATCH - InfiniBand Access Layer (IBAL)

From: Roland Dreier (roland_at_topspin.com)
Date: 03/16/04

  • Next message: Greg KH: "Re: [PATCH] i2c driver fixes for 2.6.4"
    To: "Woodruff, Robert J" <woody@co.intel.com>
    Date:	15 Mar 2004 17:41:50 -0800
    
    

    I understand that you've only had a short time to review the code, and
    many of your comments are points well taken. I think most of the
    technical comments can wait to be debated on the openib.org mailing
    lists (which I am assured are coming soon). However, since this is
    being preserved for posterity in the linux-kernel archive, I wanted to
    correct a few inaccuracies.

        Robert> 3.) The code is not compliant with the InfiniBand
        Robert> specification and has proprietary implementations of
        Robert> things like "path records" so it will only work with the
        Robert> TopSpin subnet manager that requires you to buy a topspin
        Robert> switch.

    This is definitely not our intent, and we fix whatever IB compliancy
    bugs we find as soon as we know about them. In addition, I know that
    people have been able to use the Topspin/Mellanox code from OpenIB
    with OpenSM and no Topspin switch (this did require some compliance
    fixes to both OpenSM and the Topspin code).

        Robert> 6.)The VAPI code has extra propietary verbs that are not
        Robert> specified by the InfiniBand Specification.

    True, but I'm not sure why this is a deficiency. We found certain
    things that were required for good performance were not specified by
    the IBTA, and we added them. The Linux way is definitely not to
    follow a spec when the spec is wrong.

        Robert> 9.) The CM does not support reliable datagrams.

    Fair enough but I'm sure we can easily add RD support before any
    hardware supporting RD is ready. We took a pragmatic approach and
    didn't implement "speculative" features.

        Robert> 10) There is no built in support for plug and play events,
        Robert> port up/down, LID change, SM change

    I'm not sure what plug and play events are (certainly they're not part
    of the IB spec). However, we did add extended IB asynchronous events
    for LID/SM changes and P_Key changes (port up and down are already
    part of the IB spec).

    As I said above, the rest of your points are well taken (although of
    course there are two sides to every story) and we can talk about them
    when we get the openib.org mailing lists up.

     - Roland
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  • Next message: Greg KH: "Re: [PATCH] i2c driver fixes for 2.6.4"

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