Date: Thu, 16 Jul 2015 10:13:02 -0600
From: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
To: "'Christoph Hellwig'" <hch@infradead.org>
Cc: Steve Wise <swise@opengridcomputing.com>,
        "'Sagi Grimberg'" <sagig@dev.mellanox.co.il>,
        "'Steve Wise'" <swise@ogc.us>, "'Tom Talpey'" <tom@talpey.com>,
        "'Doug Ledford'" <dledford@redhat.com>, sagig@mellanox.com,
        ogerlitz@mellanox.com, roid@mellanox.com, linux-rdma@vger.kernel.org,
        eli@mellanox.com, target-devel@vger.kernel.org,
        linux-nfs@vger.kernel.org, trond.myklebust@primarydata.com,
        bfields@fieldses.org, "'Oren Duer'" <oren@mellanox.com>
Subject: Re: [PATCH V3 1/5] RDMA/core: Transport-independent access flags
Message-ID: <20150716161302.GA3680@obsidianresearch.com>
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On Thu, Jul 16, 2015 at 01:04:02AM -0700, 'Christoph Hellwig' wrote:
> On Wed, Jul 15, 2015 at 01:12:57PM -0600, Jason Gunthorpe wrote:
> > > This looks perfect to me.  After this we can get rid of the
> > > ib_get_dma_mr calls outside of ib_alloc_pd, and eventuall move
> > > setting up ->local_dma_lkey into the HW driver and kill of
> > > ib_get_dma_mr, IB_DEVICE_LOCAL_DMA_LKEY and device->local_dma_lkey.
> > 
> > Just for clarity, again, we can never do this.
> > 
> > device->local_dma_lkey requires dedicated hardware support. We cannot
> > create it in software on old hardware. The only option I see is the
> > different-for-every-PD solution in my patch.
> 
> I don't see how my sentence above contradicts this.
> 
> One we use pd->local_dma_lkey everywhere, we can kill of
> device->local_dma_lkey as an API - drivers either stick it straight
> into pd->local_dma_lkey or do the internal equivalent of
> ib_get_dma_mr.

Right, I misread your message

Thanks,
Jason