Re: [PATCH V3 1/5] RDMA/core: Transport-independent access flags

'Christoph Hellwig'
2015-07-16T08:04:02Z

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.
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