From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60068) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZIPCk-000264-6i for qemu-devel@nongnu.org; Thu, 23 Jul 2015 18:43:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZIPCg-0001wX-KY for qemu-devel@nongnu.org; Thu, 23 Jul 2015 18:43:06 -0400 Date: Fri, 24 Jul 2015 01:42:56 +0300 From: "Michael S. Tsirkin" Message-ID: <20150724014004-mutt-send-email-mst@redhat.com> References: <1437566099-10004-1-git-send-email-lvivier@redhat.com> <1437675858-14070-1-git-send-email-lvivier@redhat.com> <1437684406.7562.62.camel@kernel.crashing.org> <1437688015.7562.68.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437688015.7562.68.camel@kernel.crashing.org> Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH v2] pci: allow 0 address for PCI IO/MEM regions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Benjamin Herrenschmidt Cc: Laurent Vivier , Peter Maydell , Michael Roth , QEMU Developers , "qemu-ppc@nongnu.org" , David Gibson On Fri, Jul 24, 2015 at 07:46:55AM +1000, Benjamin Herrenschmidt wrote: > On Thu, 2015-07-23 at 22:00 +0100, Peter Maydell wrote: > > (Also, none of our PCI device models actually try to do > > the "BAR at zero means I won't respond" behaviour, which > > presumably they might do in real life.) > > Devices aren't supposed to do that ... In fact, I don't see HW designers > adding a comparator if they don't have to :-) > > Cheers, > Ben. > You never can tell with HW designers. For example, maybe they used this as a trick to avoid implementing memory/io enable properly. -- MST