From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753837AbbJFP2V (ORCPT ); Tue, 6 Oct 2015 11:28:21 -0400 Received: from mail-wi0-f177.google.com ([209.85.212.177]:35840 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752571AbbJFP2T (ORCPT ); Tue, 6 Oct 2015 11:28:19 -0400 Subject: Re: [PATCH v3 2/3] uio_pci_generic: add MSI/MSI-X support To: "Michael S. Tsirkin" References: <1443991398-23761-1-git-send-email-vladz@cloudius-systems.com> <1443991398-23761-3-git-send-email-vladz@cloudius-systems.com> <20151005031159.GB27303@kroah.com> <56123493.9000602@scylladb.com> <20151005094932.GA5236@kroah.com> <56124EDB.3070701@scylladb.com> <20151006143821.GA11541@redhat.com> <5613DE26.1090202@cloudius-systems.com> <20151006174648-mutt-send-email-mst@redhat.com> Cc: Avi Kivity , Greg KH , linux-kernel@vger.kernel.org, hjk@hansjkoch.de, corbet@lwn.net, bruce.richardson@intel.com, avi@cloudius-systems.com, gleb@cloudius-systems.com, stephen@networkplumber.org, alexander.duyck@gmail.com From: Vlad Zolotarov Message-ID: <5613E88F.8040107@cloudius-systems.com> Date: Tue, 6 Oct 2015 18:28:15 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <20151006174648-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/06/15 17:56, Michael S. Tsirkin wrote: > On Tue, Oct 06, 2015 at 05:43:50PM +0300, Vlad Zolotarov wrote: >> The only "like VFIO" behavior we implement here is binding the MSI-X >> interrupt notification to eventfd descriptor. > There will be more if you add some basic memory protections. I've already explained that there is no need for any additional memory protections since it won't be able to protect anything. > > Besides, that's not true. > Your patch queries MSI capability, sets # of vectors. My patch doesn't set # of vectors. > You even hinted you want to add BAR mapping down the road. > > VFIO does all of that. > >> This doesn't justifies the >> hassle of implementing IOMMU-less VFIO mode. > This applies to both VFIO and UIO really. I'm not sure the hassle of > maintaining this functionality in tree is justified. It remains to be > seen whether there are any users that won't taint the kernel. > Apparently not in the current form of the patch, but who knows. Again, uio_pci_generic with my patch simply follows the UIO design and in addition allows mapping MSI-X interrupts to eventfd's and it does it much more laconically compared to VFIO. Therefore these two modules won't be more related than they are today. thanks, vlad >