[openib-general] mthca FMR correctness (and memory windows)

[Talpey, Thomas]

At 02:58 PM 3/20/2006, Roland Dreier wrote:
>If you want to invalidate each FMR individually, then there's not much
>point in using FMRs at all.  Just register and unregister memory regions.

Really? The idea of FMR, I thought, was to preallocate the TPT entry
up front (alloc_fmr), and then populate it with the lightweight fmr api
(map_phys_fmr).

If I use ib_reg_phys_mr(), then I incur all the preallocation overhead
each time. Sure the benefit of an FMR isn't merely that the hard work
is deferred, opening a vulnerability while it's pending??

>No chance.  You need to implement MW allocation in mthca.  It's not a
>ton of work but it hasn't reached the top of anyone's list yet.

Rats! :-) Well, I'll maybe try to scope that, if you haven't already?

Tom.