Re: ib_types.h moving [was: Re: [ofa-general] [RFC] 3/5: IB ACM: libibacm]

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Wed, Sep 30, 2009 at 06:31:26PM -0700, Ira Weiny wrote:

> > Now I likely would agree with Ira that moving ib_types.h to libibumad
> > is a least painful option. Do we have a better ideas?
> 
> So far I can only think of 2 "correct" options.
> 
>    1) Make ib_types.h into a new library and have libibverbs, libibmad,
>       opensm, and MPI's use the constants and helper functions there.  This of
>       course would force some dependencies.

You are going the wrong way.. libibverbs is the 'fundamental' lowest
level library. Everything should build on it, not re-invent its stuff.

libibumad should not have device discovery and handling functions!
It should use ibv_device and ibv_context identifiers from libibverbs.

It should not duplicate constants and functions from libibverbs.

>    2) split up and spread ib_types.h around to appropriate places.  This will
>       likely include libibmad and libibverbs (others?) I don't think libibumad
>       is appropriate really.  At first, I suggested this mainly out of
>       convenience because WinOF uses it.  However, I don't think it is
>       architecturally correct.  libibumad looks to have a sound interface and
>       should not be messed with.

It has a horrid interface, it should be destoyed :P

It needs exactly 4 functions:
1) open QP0/QP1 special FD based on ibv_device/ibv_context
2) read/write MADs from the special FD into user buffers. Maybe some
   higher level helper functions (ie send/recv with retry, timeout, etc)
3) Do some basic parsing and whatever of the user buffers (if
   necessary, probably not anymore)
4) Do any special control functions on the QP0/QP1/port
   (ie set control bits, etc, etc)

libibmad should do all the hard core mad processing, structure
definitions, parsing helpers, redirection and other special function
logic, etc. It should be able to ride either on the QP0/QP1 special FD
or directly on a UD QP from libibverbs.

Two libraries are probably not needed, one library containing both
layers (with architectural purity), or putting the umad access layer
in libibverbs would be best. We have too many libraries.

Jason
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