From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:35062) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qxf8P-0004rV-Mt for qemu-devel@nongnu.org; Sun, 28 Aug 2011 09:10:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Qxf8O-0000si-J9 for qemu-devel@nongnu.org; Sun, 28 Aug 2011 09:10:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3045) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qxf8O-0000se-Ai for qemu-devel@nongnu.org; Sun, 28 Aug 2011 09:10:44 -0400 Message-ID: <4E5A3E36.4010709@redhat.com> Date: Sun, 28 Aug 2011 16:10:14 +0300 From: Avi Kivity MIME-Version: 1.0 References: <20110704094358.GA10960@redhat.com> <4E4B7DE1.3050405@cn.fujitsu.com> <4E4C8577.5000608@cn.fujitsu.com> <4E4D2C9F.6040805@redhat.com> <20110826094254.GA6520@redhat.com> <4E59F359.9040506@redhat.com> <20110828114142.GC4875@redhat.com> In-Reply-To: <20110828114142.GC4875@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] pci: add standard bridge device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Kevin Wolf , Isaku Yamahata , qemu-devel@nongnu.org On 08/28/2011 02:41 PM, Michael S. Tsirkin wrote: > > > > If it really matters, you can add a prefetchability attribute to > > MemoryRegions. Does it though? > > Well, its another one of these things that > guests *probably* won't in practice use. > But I don't see a way to be sure. > > If the guest puts a prefetcheable memory BAR behind > a non-prefetcheable range in the bridge, it won't > be able to access that BAR, and it should. Not sure I understand - on real hardware, does it see the BAR or not? > > Prefetcheable BARs on devices are less common than > non-prefetcheable, but they do exist: > I have a system with 2 devices: a VGA controller from Matrox > and an ethernet card from Mellanox have > prefetcheable BARs. > > I'm not sure how prefetcheability attribute will help. > Could you explain pls? > Have an attribute for a region "does not allow prefetchable memory" in subregions Have an attribute for a region "prefetchable memory" When rendering the memory map, ignore any "prefetchable memory" regions that are subregions of a "does not allow prefetchable memory" region. (if I understood correctly - not sure) -- error compiling committee.c: too many arguments to function