From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935436AbdCVPlQ (ORCPT ); Wed, 22 Mar 2017 11:41:16 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:39908 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935211AbdCVPlE (ORCPT ); Wed, 22 Mar 2017 11:41:04 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 294D660263 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=okaya@codeaurora.org Subject: Re: [PATCH 17/17] arm64: Do not expose PCI mmap through procfs To: Will Deacon References: <4281f8e01b9fc5628cbf4a5c77abd642801e23c7.1490188942.git.dwmw2@infradead.org> <1490191473.28249.9.camel@infradead.org> <5362b452-8526-1a97-ebf7-7052f1af56f7@codeaurora.org> <20170322141820.GI8026@arm.com> Cc: David Woodhouse , linux-pci@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org From: Sinan Kaya Message-ID: <517f4cc1-df3b-553b-59bf-f60ddd7c32d8@codeaurora.org> Date: Wed, 22 Mar 2017 11:40:52 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170322141820.GI8026@arm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/22/2017 10:18 AM, Will Deacon wrote: > On Wed, Mar 22, 2017 at 10:15:04AM -0400, Sinan Kaya wrote: >> On 3/22/2017 10:04 AM, David Woodhouse wrote: >>> On Wed, 2017-03-22 at 09:54 -0400, Sinan Kaya wrote: >>>> On 3/22/2017 9:25 AM, David Woodhouse wrote: >>>>> >>>>> >>>>> +#ifdef __aarch64__ >>>>> +/* ARM64 wants to be special and not expose this through /proc >>>>> like everyone else */ >>>>> +#undef HAVE_PCI_MMAP >>>>> +#endif >>>>> + >>>> Where is this ARM64 special requirement coming from? >>> >>> The idea is that as a new platform, ARM64 shouldn't need to implement >>> legacy userspace interfaces. >>> >>> http://lists.infradead.org/pipermail/linux-arm-kernel/2016-April/422571.html >>> >> >> Aren't we breaking an ABI for userspace? I know DPDK relies on this feature. > > It relies on the /proc interface? That's the first I've ever heard of that > -- everybody so far has only been interested in the sysfs stuff. > > Nothing's more broken than before, because we've never supported the /proc > interface, but if existing arm64 code out there is failing because of that > then I'm of course open to supporting it. I'm just surprised that nobody > else has come up with that before, since DPDK is in common use. > > Can you point me at the specific code, please? I'm correcting myself. I had to go back my memory from last year. DPDK requires HAVE_PCI_MMAP to be set. We have been carrying some old maillist patch around for DPDK customers internally. When HAVE_PCI_MMAP is set, resource files are created in sysfs and procfs. DPDK is using the files in sysfs directory not procfs directory. Having HAVE_PCI_MMAP defined is the DPDK requirement. > > Will > -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.