From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1N5IOw-0002G8-9Y for qemu-devel@nongnu.org; Tue, 03 Nov 2009 07:22:18 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1N5IOq-0002FX-Lw for qemu-devel@nongnu.org; Tue, 03 Nov 2009 07:22:16 -0500 Received: from [199.232.76.173] (port=46217 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1N5IOq-0002FU-ER for qemu-devel@nongnu.org; Tue, 03 Nov 2009 07:22:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:65484) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1N5IOq-0004A7-2g for qemu-devel@nongnu.org; Tue, 03 Nov 2009 07:22:12 -0500 Message-ID: <4AF0206F.7080004@redhat.com> Date: Tue, 03 Nov 2009 14:22:07 +0200 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH V6 17/32] pci: 64bit bar support. References: <1256905286-25435-1-git-send-email-yamahata@valinux.co.jp> <1256905286-25435-18-git-send-email-yamahata@valinux.co.jp> <20091101160730.GA21894@redhat.com> <20091103035210.GA28390%yamahata@valinux.co.jp> <20091103114756.GC3375@redhat.com> In-Reply-To: <20091103114756.GC3375@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Isaku Yamahata , qemu-devel@nongnu.org On 11/03/2009 01:47 PM, Michael S. Tsirkin wrote: > > If qemu is compiled with target phys address size 32 bit, emulated > devices can not support a 64 bit BAR. Therefore, according to PCI spec, > such devices should declare all BARs as 32 bit. > > What happens if you take a PCI card that supports 64-bit BARs and stick it into a machine that has a 32-bit physical address space? The firmware/OS will configure the BARs to below 4G. > I think you are right that guests on such systems really do not have a > way to address PCI devices if BAR is set beyond 4G. But pci emulation is > better off not relying on this, IMO. Makes sense? > No. Device emulation shouldn't change with the machine type. -- error compiling committee.c: too many arguments to function