From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33047) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XN7Jy-0007xC-Sr for qemu-devel@nongnu.org; Thu, 28 Aug 2014 17:33:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XN7Js-0002py-NY for qemu-devel@nongnu.org; Thu, 28 Aug 2014 17:33:30 -0400 Received: from mail-la0-f49.google.com ([209.85.215.49]:46696) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XN7Js-0002pn-Gm for qemu-devel@nongnu.org; Thu, 28 Aug 2014 17:33:24 -0400 Received: by mail-la0-f49.google.com with SMTP id b17so1706563lan.22 for ; Thu, 28 Aug 2014 14:33:23 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20140828212157.21832.67572@loki> References: <1408407718-10835-1-git-send-email-mdroth@linux.vnet.ibm.com> <1408407718-10835-9-git-send-email-mdroth@linux.vnet.ibm.com> <20140827134751.GA18523@redhat.com> <20140828212157.21832.67572@loki> From: Peter Maydell Date: Thu, 28 Aug 2014 22:33:02 +0100 Message-ID: Content-Type: text/plain; charset=UTF-8 Subject: Re: [Qemu-devel] [PATCH 08/12] pci: allow 0 address for PCI IO regions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Roth Cc: "Michael S. Tsirkin" , Alexey Kardashevskiy , Alexander Graf , QEMU Developers , Mike Day , "qemu-ppc@nongnu.org" , tyreld@linux.vnet.ibm.com, nfont@linux.vnet.ibm.com On 28 August 2014 22:21, Michael Roth wrote: > But I guess there's still a separate issue, where there's a high liklihood that > a 0 address would conflict with some hard-wired IO address? Wouldn't this be a > guest bug though? Even if it's a guest bug, we should act like the hardware does if the guest does this. If that differs between PCI controllers then we need a flag so the host controller model can select the required behaviour. (The versatile PB PCI controller we model does have "address 0 is valid", and we'd need to have this working if we implemented DMA accesses properly.) -- PMM