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    SubjectRe: [PATCH 2.6.13 5/14] sas-class: sas_discover.c Discover process (end devices)
    On 09/13/05 18:25, Patrick Mansfield wrote:
    > On Tue, Sep 13, 2005 at 05:02:36PM -0400, Luben Tuikov wrote:
    >>On 09/13/05 16:36, Matthew Wilcox wrote:
    >>>On Tue, Sep 13, 2005 at 04:23:42PM -0400, Luben Tuikov wrote:
    >>>>A SCSI LUN is not "u64 lun", it has never been and it will
    >>>>never be.
    >>>>A SCSI LUN is "u8 LUN[8]" -- it is this from the Application
    >>>>Layer down to the _transport layer_ (if you cared to look at
    >>>>_any_ LL transport).
    > Not all HBA drivers implement a mapping to a SCSI transport, we have
    > raid drivers and even an FC driver that has its own lun definition that
    > does not fit any SAM or SCSI spec.

    Us too. Especially RAID.

    > I think the only HBA's today that can handle an 8 byte lun are lpfc and
    > iscsi (plus new SAS ones).
    > So, we can't have one "LUN" that fits all, and it makes no sense to call
    > it a LUN when it is really a wtf.

    "u64 lun" is a lot worse than "u8 LUN[8]". you can work with
    the latter but the former raises questions like
    "How was this translated from the "u8 LUN[8]" which I use
    in the application client and in the transport?"

    Then, if your lun is 16 bits, there is no question where it is
    in "u8 LUN[8]" -- SAM is _clear_ on that.

    Second, as I said before a Logical Unit Number _is_ "u8 LUN[8]",
    there is _no_ MSB or LSB, and there will never be. Thus, you cannot
    stuff it into "u64".

    Yes, we _can_ have _one_ LUN that fits all, _because_
    we would copy it _as_ is from the LLDD, be it 16 bits or
    32 bits or whatever, in SCSI order format: Big endian.

    Again, SAM is clear on that.


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