From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [RFC PATCH 00/28] Removing struct page from P2PDMA Date: Mon, 24 Jun 2019 15:16:32 -0300 Message-ID: <20190624181632.GC8268@ziepe.ca> References: <20190620161240.22738-1-logang@deltatee.com> <20190620193353.GF19891@ziepe.ca> <20190624073126.GB3954@lst.de> <20190624134641.GA8268@ziepe.ca> <20190624135024.GA11248@lst.de> <20190624135550.GB8268@ziepe.ca> <7210ba39-c923-79ca-57bb-7cf9afe21d54@deltatee.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <7210ba39-c923-79ca-57bb-7cf9afe21d54@deltatee.com> Sender: linux-kernel-owner@vger.kernel.org To: Logan Gunthorpe Cc: Christoph Hellwig , Dan Williams , Linux Kernel Mailing List , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, linux-rdma , Jens Axboe , Bjorn Helgaas , Sagi Grimberg , Keith Busch , Stephen Bates List-Id: linux-rdma@vger.kernel.org On Mon, Jun 24, 2019 at 10:53:38AM -0600, Logan Gunthorpe wrote: > > It is only a very narrow case where you can take shortcuts with > > dma_addr_t, and I don't think shortcuts like are are appropriate for > > the mainline kernel.. > > I don't think it's that narrow and it opens up a lot of avenues for > system design that people are wanting to go. If your high speed data > path can avoid the root complex and CPU, you can design a system which a > much smaller CPU and fewer lanes directed at the CPU. I mean the shortcut that something generates dma_addr_t for Device A and then passes it to Device B - that is too hacky for mainline. Sounded like this series does generate the dma_addr for the correct device.. Jason