From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: kvm PCI assignment & VFIO ramblings Date: Fri, 26 Aug 2011 14:20:00 +1000 Message-ID: <20110826042000.GE2308@yookeroo.fritz.box> References: <20110823110431.GK2079@amd.com> <20110824091425.GE2079@amd.com> <20110824093300.GI30097@yookeroo.fritz.box> <20110824110332.GH2079@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: aafabbri , Alexey Kardashevskiy , "kvm@vger.kernel.org" , Paul Mackerras , "linux-pci@vger.kernel.org" , qemu-devel , chrisw , iommu , Avi Kivity , Anthony Liguori , linuxppc-dev , "benve@cisco.com" To: "Roedel, Joerg" Return-path: Received: from e23smtp09.au.ibm.com ([202.81.31.142]:40742 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750843Ab1HZEYm (ORCPT ); Fri, 26 Aug 2011 00:24:42 -0400 Received: from /spool/local by au.ibm.com with XMail ESMTP for from ; Fri, 26 Aug 2011 05:21:33 +1000 Content-Disposition: inline In-Reply-To: <20110824110332.GH2079@amd.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Aug 24, 2011 at 01:03:32PM +0200, Roedel, Joerg wrote: > On Wed, Aug 24, 2011 at 05:33:00AM -0400, David Gibson wrote: > > On Wed, Aug 24, 2011 at 11:14:26AM +0200, Roedel, Joerg wrote: > > > > I don't see a reason to make this meta-grouping static. It would harm > > > flexibility on x86. I think it makes things easier on power but there > > > are options on that platform to get the dynamic solution too. > > > > I think several people are misreading what Ben means by "static". I > > would prefer to say 'persistent', in that the meta-groups lifetime is > > not tied to an fd, but they can be freely created, altered and removed > > during runtime. > > Even if it can be altered at runtime, from a usability perspective it is > certainly the best to handle these groups directly in qemu. Or are there > strong reasons to do it somewhere else? Funny, Ben and I think usability demands it be the other way around. If the meta-groups are transient - that is lifetime tied to an fd - then any program that wants to use meta-groups *must* know the interfaces for creating one, whatever they are. But if they're persistent, the admin can use other tools to create the meta-group then just hand it to a program to use, since the interfaces for _using_ a meta-group are identical to those for an atomic group. This doesn't preclude a program from being meta-group aware, and creating its own if it wants to, of course. My guess is that qemu would not want to build its own meta-groups, but libvirt probably would. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson