From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47565) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V8wdQ-0002qS-Bz for qemu-devel@nongnu.org; Mon, 12 Aug 2013 14:14:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V8wdK-0000hS-Cj for qemu-devel@nongnu.org; Mon, 12 Aug 2013 14:14:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7974) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V8wdK-0000hE-45 for qemu-devel@nongnu.org; Mon, 12 Aug 2013 14:14:22 -0400 Date: Mon, 12 Aug 2013 21:15:55 +0300 From: "Michael S. Tsirkin" Message-ID: <1376310634-20778-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [Qemu-devel] [PATCH v2 for-1.6 0/2] future proof rom loading for cross versiom migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Laszlo Ersek , Gerd Hoffmann , pbonzini@redhat.com Changes from v1: address comments by Peter Maydell - drop useless data=data line - rename target_page_size to migration_page_size to make use clear Peter, you also suggested somehow hiding this within memory core. I don't see a clean way to do this without lots of code changes, I think what I propose here is acceptable for 1.6 and we can rework APIs in time for 1.7. Please review, and consider for 1.6. Original cover letter below. ROM files that are put in FW CFG are copied to guest ram, by BIOS, but they are not backed by RAM so they don't get migrated. Each time we'll change at least two bytes in such a ROM this will break cross-version migration: since we can migrate after BIOS has read the first byte but before it has read the second one, getting an inconsistent state. This patchset makes QEMU future-proof against such changes. Naturally, this only helps for -M 1.6 and up, older machine types will still have the cross-version migration bug. I think this should be applied for 1.6, this way we won't have this problem from 1.7 and on. Michael S. Tsirkin (2): memory: export migration page size loader: put FW CFG ROM files into RAM arch_init.c | 3 +++ hw/core/loader.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++--- hw/i386/pc_piix.c | 2 ++ hw/i386/pc_q35.c | 2 ++ include/exec/memory.h | 1 + include/hw/loader.h | 1 + 6 files changed, 59 insertions(+), 3 deletions(-) -- MST