From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Wise Subject: Re: RDMA/cxgb4: Support on-chip SQs Date: Wed, 30 Jan 2013 15:51:24 -0600 Message-ID: <510995DC.4020602@opengridcomputing.com> References: <20130130210006.GA22134@elgon.mountain> <51099270.5070406@opengridcomputing.com> <20130130214425.GA5674@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130130214425.GA5674-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jason Gunthorpe Cc: Dan Carpenter , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Roland Dreier List-Id: linux-rdma@vger.kernel.org On 1/30/2013 3:44 PM, Jason Gunthorpe wrote: > On Wed, Jan 30, 2013 at 03:36:48PM -0600, Steve Wise wrote: >> I wonder, then, what the correct service is to get the cpu physical >> address from a kernel virtual address returned from >> dma_alloc_coherent()? I think this is correct as-is, since I think >> dma_alloc_coherent() falls under the "directly mapped" addresses in >> the virt_to_phys() prototype comment. > DMA-API.txt says: > > This routine allocates a region of bytes of consistent memory. > It also returns a which may be cast to an unsigned > integer the same width as the bus and used as the physical address > base of the region. > > So instead of virt_to_phys you should use dma_addr?? I don't think so. The result of virt_to_phys() is used in remap_pfn_range() to map this memory into user space... The dma_addr is give to HW for DMA operations. > I think the note about 'directly mapped' refers to things the arch > setups during early boot, not dma_alloc stuff. > > Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html