From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.tuxdriver.com (charlotte.tuxdriver.com [70.61.120.58]) by dpdk.org (Postfix) with ESMTP id C69E336E for ; Wed, 30 Sep 2015 16:52:12 +0200 (CEST) Received: from hmsreliant.think-freely.org ([2001:470:8:a08:7aac:c0ff:fec2:933b] helo=localhost) by smtp.tuxdriver.com with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.63) (envelope-from ) id 1ZhIjo-0006gl-3L; Wed, 30 Sep 2015 10:52:10 -0400 Date: Wed, 30 Sep 2015 10:52:02 -0400 From: Neil Horman To: David Marchand Message-ID: <20150930145202.GE32524@hmsreliant.think-freely.org> References: <1425912999-13118-1-git-send-email-david.marchand@6wind.com> <1425912999-13118-3-git-send-email-david.marchand@6wind.com> <20150310131428.GB7873@hmsreliant.think-freely.org> <20150929122542.419781cc@urahara> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-Spam-Score: -1.0 (-) X-Spam-Status: No Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH 2/2] virtio: change io privilege level as early as possible X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Sep 2015 14:52:14 -0000 On Wed, Sep 30, 2015 at 10:28:53AM +0200, David Marchand wrote: > On Tue, Sep 29, 2015 at 9:25 PM, Stephen Hemminger < > stephen@networkplumber.org> wrote: > > > On Tue, 10 Mar 2015 09:14:28 -0400 > > Neil Horman wrote: > > > > > > > > I don't see how this works for all cases. The constructor is called > > once when > > > the library is first loaded. What if you have multiple independent > > (i.e. not > > > forked children) processes that are using the dpdk in parallel? Only the > > > process that triggered the library load will have io permissions set > > > appropriately. I think what you need is to have every application that > > expects > > > to call through the transmit path or poll the receive path call iopl, > > which I > > > think speaks to having this requirement documented, so each application > > can call > > > iopl prior to calling fork/daemonize/etc. > > > > > > > I am still seeing this problem with DPDK 2.0 and 2.1. > > It seems to me that doing the iopl init in eal_init is the only safe way. > > Other workaround is to have application calling iopl_init before eal_init > > but that kind of violates the current method of all things being > > initialized > > by eal_init > > > > Putting it in the virtio pmd constructor is my preferred solution and we > don't need to pollute the eal for virtio (specific to x86, btw). > Preferred solution or not, you can't just call iopl from the constructor, because not all process will get appropriate permissions. It needs to be called by every process. What Stephen is saying is that your solution has use cases for which it doesn't work, and that needs to be solved. Neil > > -- > David Marchand