From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 026BCC43216 for ; Wed, 28 Jul 2021 05:43:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF8BC600EF for ; Wed, 28 Jul 2021 05:43:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233082AbhG1FnM (ORCPT ); Wed, 28 Jul 2021 01:43:12 -0400 Received: from verein.lst.de ([213.95.11.211]:52388 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229814AbhG1FnL (ORCPT ); Wed, 28 Jul 2021 01:43:11 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id D0E1267357; Wed, 28 Jul 2021 07:43:06 +0200 (CEST) Date: Wed, 28 Jul 2021 07:43:06 +0200 From: Christoph Hellwig To: Jason Gunthorpe Cc: Alex Williamson , Christoph Hellwig , Arnd Bergmann , Yishai Hadas , bhelgaas@google.com, corbet@lwn.net, diana.craciun@oss.nxp.com, kwankhede@nvidia.com, eric.auger@redhat.com, masahiroy@kernel.org, michal.lkml@markovi.net, linux-pci@vger.kernel.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kbuild@vger.kernel.org, mgurtovoy@nvidia.com, maorg@nvidia.com, leonro@nvidia.com Subject: Re: [PATCH 12/12] vfio/pci: Introduce vfio_pci_core.ko Message-ID: <20210728054306.GA3421@lst.de> References: <20210721161609.68223-1-yishaih@nvidia.com> <20210721161609.68223-13-yishaih@nvidia.com> <20210727155440.680ee22e.alex.williamson@redhat.com> <20210727230941.GL1721383@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210727230941.GL1721383@nvidia.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Jul 27, 2021 at 08:09:41PM -0300, Jason Gunthorpe wrote: > On Tue, Jul 27, 2021 at 03:54:40PM -0600, Alex Williamson wrote: > > > I'm still not happy with how this is likely to break users and even > > downstreams when upgrading to a Kconfig with this change. > > I've never heard of Kconfig as stable ABI. Christoph/Arnd, have you > heard of any cases where we want to keep it stable? It isn't an ABI, but we really do try to avoid breaking if we can and I rember Linus shouting at people if they did that for common options. However lately for example the completely silly s/THUNDERBOLT/USB4/ change did slip through and did break my test setup with a vfio passed through external nvme drive :( > Which might reasonably be from an old kernel. 'make oldconfig' prompts: > > VFIO Non-Privileged userspace driver framework (VFIO) [Y/n/m/?] y > VFIO No-IOMMU support (VFIO_NOIOMMU) [Y/n/?] y > VFIO support for PCI devices (VFIO_PCI_CORE) [N/m/y/?] (NEW) > > Which is completely fine, IMHO. Why do we need to have VFIO_PCI_CORE as a user visible option? I'd just select it.