Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757855AbZGGNWh (ORCPT ); Tue, 7 Jul 2009 09:22:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757657AbZGGNW1 (ORCPT ); Tue, 7 Jul 2009 09:22:27 -0400 Received: from mx2.redhat.com ([66.187.237.31]:50588 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757650AbZGGNWZ (ORCPT ); Tue, 7 Jul 2009 09:22:25 -0400 Date: Tue, 7 Jul 2009 16:21:36 +0300 From: "Michael S. Tsirkin" To: Gregory Haskins Cc: Avi Kivity , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Davide Libenzi Subject: Re: [KVM PATCH v9 2/2] KVM: add iosignalfd support Message-ID: <20090707132136.GB7578@redhat.com> References: <20090706202742.14222.65548.stgit@dev.haskins.net> <20090706203321.14222.67866.stgit@dev.haskins.net> <20090707112024.GA3647@redhat.com> <4A53372E.6090509@redhat.com> <20090707122250.GC3647@redhat.com> <4A533F45.90609@redhat.com> <20090707125148.GE3647@redhat.com> <4A53460B.8090401@novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A53460B.8090401@novell.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2100 Lines: 71 On Tue, Jul 07, 2009 at 08:56:43AM -0400, Gregory Haskins wrote: > Michael S. Tsirkin wrote: > > On Tue, Jul 07, 2009 at 03:27:49PM +0300, Avi Kivity wrote: > > > >> On 07/07/2009 03:22 PM, Michael S. Tsirkin wrote: > >> > >>> On Tue, Jul 07, 2009 at 02:53:18PM +0300, Avi Kivity wrote: > >>> > >>> > >>>>>> + /* address-range must be precise for a hit */ > >>>>>> > >>>>>> > >>>>>> > >>>>> So there's apparently no way to specify that > >>>>> you want 1,2, or 4 byte writes at address X? > >>>>> > >>>>> > >>>>> > >>>> Why would you want that? > >>>> > >>>> > >>> Donnu. Why would anyone want to catch 8 byte writes at all? > >>> > >>> > >> One of the natural write sizes. > >> > >> > >>> Seriously, why add artificial limitations? > >>> IMO, addr=0,len=1 and addr=0,len=2 should not conflict. > >>> > >>> > >>> > >> They should not conflict, but a two byte write need not hit a one byte > >> registration. > >> > > > > Yes. That's exactly what I'm saying. I think it should be possible to > > create 2 fds: > > > > addr = 0 > > len = 1 > > addr = 0 > > len = 2 > > and at most one will ever trigger. > > > > But current code will not let you create the second one. > > > > > Note that this was by design to keep the code simple since we don't have > a (known) use case for overlap. At the very least, you have to address > how data subsets are handled. But do we really need that functionality? > > -Greg > Hey, forget about overlap. Overlap does not exist as a concept. You now spend a lot of effort to detect it. Kill all that code, and just do this on assignment: list_for_each(...) if (rhs->add == lhs->addr && rhs->len == lhs->len && (rhs->wildcard || lhs->wildcard || rhs->data == lhs->data)) return -EEXIST; -- MST -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/