[openib-general] SRP & Infiniband

[Roland Dreier]

    Mohit> I am not clear about the functionalities of the user level
    Mohit> HCA driver?  Are there any specifications for it or it is
    Mohit> totally vendor based?

The userspace interface is based on the "verbs" described in chapter
11 of the IB spec, but there is no formal API spec.

    Mohit> It is also said it is used in speed path operations? Does
    Mohit> anyone has any ideas how does it do accomplishes it?

The kernel sets up a mapping of HCA registers into userspace, and then
userspace can talk directly to the IB hardware without going through
the kernel.

    Mohit> If I have SCSI storage devices in a SAN then can I use SRP
    Mohit> module to send some request and User mode HCA library for
    Mohit> some speed path operation? Basically I wanted to know that
    Mohit> for SCSI devices can User mode HCA library be used for
    Mohit> speed path operations . If yes the how they can be
    Mohit> used(Only theoretical details rest I wil try)

It would be theoretically possible to implement a userspace process
that connects to an SRP target and implement SRP in userspace.
However, I don't think this would be any better than using a kernel
SRP driver along with direct IO from userspace.

 - R.