From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH V2] net: ethernet: mellanox: correct page conversion Date: Mon, 18 Apr 2016 06:10:58 -0700 Message-ID: <20160418131058.GA25421@infradead.org> References: <1460845412-13120-1-git-send-email-okaya@codeaurora.org> <20160418121247.GA25387@infradead.org> <0c6a430c5f0ec64f51d7c594ef9751dd@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , linux-rdma@vger.kernel.org, timur@codeaurora.org, cov@codeaurora.org, Yishai Hadas , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: okaya@codeaurora.org Return-path: Content-Disposition: inline In-Reply-To: <0c6a430c5f0ec64f51d7c594ef9751dd@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, Apr 18, 2016 at 09:06:18AM -0400, okaya@codeaurora.org wrote: > On 2016-04-18 08:12, Christoph Hellwig wrote: > >On Sat, Apr 16, 2016 at 06:23:32PM -0400, Sinan Kaya wrote: > >>Current code is assuming that the address returned by dma_alloc_coherent > >>is a logical address. This is not true on ARM/ARM64 systems. > > > >Can you explain what you mean with a 'logical address' and what actual > >issue you're trying to solve? > > Vmap call is failing on arm64 systems because dma alloc api already returns > an address mapped with vmap. Please state your problem clearly. What I'm reverse engineering from your posts is: because dma_alloc_coherent uses vmap-like mappings on arm64 (all, some systems?) a driver using a lot of them might run into limits of the vmap pool size. Is this correct? > > Please see arch/arm64/mm directory. ---end quoted text---