Date: Mon, 15 May 2006 16:13:42 -0700
From: Grant Grundler <iod00d@hp.com>
To: Roland Dreier <rdreier@cisco.com>
Cc: "Bryan O'Sullivan" <bos@pathscale.com>,
       Segher Boessenkool <segher@kernel.crashing.org>,
       linux-kernel@vger.kernel.org, openib-general@openib.org
Subject: Re: [openib-general] Re: [PATCH 21 of 53] ipath - use phys_to_virt instead of bus_to_virt
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On Mon, May 15, 2006 at 02:28:45PM -0700, Roland Dreier wrote:
>     Bryan> Any ideas?  Should this turn from a one-liner into a
>     Bryan> big-refactor-for-2.6.18 patch?
> 
> I don't think there's a quick way to fix this.  What you really want
> to do is override the DMA mapping functions for your device so that
> you can keep track of the kernel mapping.

Or figure out which openib.org interface has to change so the
original virt addresses that were registered/handed to the ULP
are passed down to the low level interface driver too.
Seems like a more obvious way to fix the problem.
Someone did suggest this already, right?

> (cf the ehca driver), and I think patches to do it on x86-64 are
> floating around as part of the "Calgary IOMMU" work.

parisc has been using dma_ops for several years.
I don't expect dma_ops to become part of generic code.
DMA support is inherently arch specific.
Because of that, I don't look forward to a low level
device driver that is mucking with dma_ops.

hth,
grant
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