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    SubjectRe: [PATCH 0/7] IB/hfi1: Remove write() and use ioctl() for user access
    On Mon, Apr 18, 2016 at 11:24:11AM -0700, Christoph Hellwig wrote:
    > On Mon, Apr 18, 2016 at 11:40:47AM -0600, Jason Gunthorpe wrote:
    > > I wasn't arguing this should integrate into verbs in some way, only
    > > that the way to access the driver-specific uAPI of a RDMA device should
    > > be through the RDMA common uAPI and not through a random char dev.
    >
    > Well, it's stuff not related to our RDMA userspace API (which _is_
    > Verbs, not counting for the complete crackpot abuse in usnic), but
    > very device specific.

    It is weakly related, it uses the same device discovery and security
    model.

    > The stuff the intel driver are doing isn't pretty, but unfortunately
    > not unusual either - lots of SCSI or network driver have ioctls
    > like that. Now we could argue if the ioctls should be one the
    > main node (uverbs) or the a driver private chardev, or not exist
    > at all and people will have to patch the driver with some vendor
    > version if they really need it. Examples for either of these
    > choices exist in the tree.

    Right - and the RDMA uAPI has always had an integrated driver-bypass
    channel as part of the verb uAPI calls, extending that to allow for
    new-driver-specific calls seems very natural.

    Jason

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