From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47524) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VB3Cj-0001aY-AP for qemu-devel@nongnu.org; Sun, 18 Aug 2013 09:39:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VB3Cd-0005TY-As for qemu-devel@nongnu.org; Sun, 18 Aug 2013 09:39:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4453) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VB3Cd-0005TL-3Y for qemu-devel@nongnu.org; Sun, 18 Aug 2013 09:39:31 -0400 Date: Sun, 18 Aug 2013 16:41:13 +0300 From: "Michael S. Tsirkin" Message-ID: <20130818134113.GA5129@redhat.com> References: <1376347400-21035-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1376347400-21035-1-git-send-email-mst@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3 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 , lersek@redhat.com, kraxel@redhat.com, Anthony Liguori , pbonzini@redhat.com On Tue, Aug 13, 2013 at 01:43:29AM +0300, Michael S. Tsirkin wrote: > Changes from v2: address comments on v2 by Peter Maydell > - switch from global constant to function > - use memory_region_init_ram instead of _ram_ptr > - disable for 1.6 > > 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 now > and we can always rework APIs without wire format changes. > > Please review, and consider for merging. Ping. Any more comments? Also - which tree can this go in through? Mine? > 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 | 6 ++++++ > hw/core/loader.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++--- > 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, 63 insertions(+), 3 deletions(-) > > -- > MST >