[ofa-general] [PATCH] infiniband: add userspace support for invalidate stag

[Steve Wise]

On Fri, 2007-05-04 at 14:50 -0700, Roland Dreier wrote:
> A few general things:
>  - please always submit patches with a changelog entry and
>    Signed-off-by: line
>  - please send patches in logical chunks.  Usually I'm complaining
>    about people combining unrelated things into one patch, but in this
>    case I think you divided the patch up too much -- rather than 5
>    patches, this should probably be one kernel patch and one userspace
>    patch.
>  - please make libibverbs patches apply to the libibverbs git tree
>    with -p1.  You seem to have generated patches against an OFED package.
> 
> OK, with that out of the way, I think there are still some issues to
> sort out with how to handle send with invalidate from userspace.
> These patches don't address the case of new userspace with
> send-with-invalidate support talking to an unpatched kernel -- it
> seems that send-with-invalidate would be silently turned into a plain
> send request, which is not a very good failure mode.
> 
> I don't know what the right solution is yet -- a kernel ABI bump for
> this one case (send with invalidate support for userspace drivers that
> don't do kernel bypass == amso1100) is ugly.  Maybe we also need a
> device capabilities bit that says whether send-with-invalidate is
> supported?
> 

There already exists a SEND-INV capabilities flag.

<snip>
        IB_DEVICE_SEND_W_INV            = (1<<16),

I think with the capabilities flag, we shouldn't worry about changing
the ABI.  But the drivers will need to set this flag.  Amso currently
does...

Steve.