From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] VFIO driver: Non-privileged user level PCI drivers Date: Wed, 02 Jun 2010 15:25:11 +0300 Message-ID: <4C064DA7.6060504@redhat.com> References: <4C04C085.1030107@redhat.com> <20100601095532.GA9178@redhat.com> <20100602094201.GC964@8bytes.org> <20100602095312.GA25335@redhat.com> <20100602101940.GG964@8bytes.org> <20100602102144.GD29023@redhat.com> <20100602103516.GI964@8bytes.org> <20100602103828.GF29023@redhat.com> <20100602111224.GA11033@8bytes.org> <20100602112100.GA29697@redhat.com> <20100602121927.GA11162@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Michael S. Tsirkin" , Tom Lyon , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, chrisw@sous-sol.org, hjk@linutronix.de, gregkh@suse.de, aafabbri@cisco.com, scofeldm@cisco.com To: Joerg Roedel Return-path: Received: from mx1.redhat.com ([209.132.183.28]:42690 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752341Ab0FBMZ1 (ORCPT ); Wed, 2 Jun 2010 08:25:27 -0400 In-Reply-To: <20100602121927.GA11162@8bytes.org> Sender: kvm-owner@vger.kernel.org List-ID: On 06/02/2010 03:19 PM, Joerg Roedel wrote: > >> Yes. so you do: >> iommu = open >> ioctl(dev1, BIND, iommu) >> ioctl(dev2, BIND, iommu) >> ioctl(dev3, BIND, iommu) >> ioctl(dev4, BIND, iommu) >> >> No need to add a SHARE ioctl. >> > In my proposal this looks like: > > > dev1 = open(); > ioctl(dev2, SHARE, dev1); > ioctl(dev3, SHARE, dev1); > ioctl(dev4, SHARE, dev1); > > So we actually save an ioctl. > The problem with this is that it is assymetric, dev1 is treated differently from dev[234]. It's an unintuitive API. -- error compiling committee.c: too many arguments to function