From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751892AbbJLQbQ (ORCPT ); Mon, 12 Oct 2015 12:31:16 -0400 Received: from mail-wi0-f180.google.com ([209.85.212.180]:33878 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751073AbbJLQbP (ORCPT ); Mon, 12 Oct 2015 12:31:15 -0400 Subject: Re: [RFC PATCH 2/2] vfio: Include no-iommu mode To: Alex Williamson , Stephen Hemminger References: <20151009182228.14752.99700.stgit@gimli.home> <20151009184110.14752.53531.stgit@gimli.home> <20151012085607.2c64f98f@urahara> <1444666999.4059.362.camel@redhat.com> Cc: avi@cloudius-systems.com, gleb@scylladb.com, corbet@lwn.net, bruce.richardson@intel.com, mst@redhat.com, linux-kernel@vger.kernel.org, alexander.duyck@gmail.com, gleb@cloudius-systems.com, vladz@cloudius-systems.com, iommu@lists.linux-foundation.org, hjk@hansjkoch.de, gregkh@linuxfoundation.org From: Avi Kivity Message-ID: <561BE04E.4030108@scylladb.com> Date: Mon, 12 Oct 2015 19:31:10 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <1444666999.4059.362.camel@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/12/2015 07:23 PM, Alex Williamson wrote: >> Also, although you think the long option will set the bar high >> enough it probably will not satisfy anyone. It is annoying enough, that >> I would just carry a patch to remove it the silly requirement. >> And the the people who believe >> all user mode DMA is evil won't be satisfied either. > I find that many users blindly follow howtos and only sometimes do they > question the options if they sound scary enough. So yeah, I would > intend to make the option upstream sound scary enough for people to > think twice about using it and maybe even read the description. That > still doesn't prevent pasting it into modprobe.d and forgetting about > it. I think we need to allow for packages to work with this. I.e. drop files into config directories rather than require editing of config files. I think this is mostly workable via modprobe.d. (for our own use case, we don't require the extreme performance of many L2/L3 dpdk apps so we'll work with regular iommued vfio for bare-metal installations and ship prebuilt virtual machine images for clouds, so it doesn't matter that much to me).