From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59205) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d3Pdb-0004I3-1R for qemu-devel@nongnu.org; Wed, 26 Apr 2017 12:17:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d3PdX-00025M-RA for qemu-devel@nongnu.org; Wed, 26 Apr 2017 12:17:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56904) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d3PdX-00024L-KH for qemu-devel@nongnu.org; Wed, 26 Apr 2017 12:17:51 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E333B6198F for ; Wed, 26 Apr 2017 16:17:49 +0000 (UTC) Date: Wed, 26 Apr 2017 18:17:43 +0200 From: Igor Mammedov Message-ID: <20170426181743.33a547fa@nial.brq.redhat.com> In-Reply-To: <20170426143404.GX3482@thinpad.lan.raisama.net> References: <20170425153750.43322-1-imammedo@redhat.com> <20170426143404.GX3482@thinpad.lan.raisama.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3] pc/fwcfg: unbreak migration from qemu-2.5 and qemu-2.6 during firmware boot List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, mst@redhat.com, dgilbert@redhat.com, lersek@redhat.com, Marcel Apfelbaum On Wed, 26 Apr 2017 11:34:04 -0300 Eduardo Habkost wrote: > On Tue, Apr 25, 2017 at 05:37:50PM +0200, Igor Mammedov wrote: > > Since 2.7 commit (b2a575a Add optionrom compatible with fw_cfg DMA version) > > regressed migration during firmware exection time by > > abusing fwcfg.dma_enabled property to decide loading > > dma version of option rom AND by mistake disabling DMA > > for 2.6 and earlier globally instead of only for option rom. > > > > so 2.6 machine type guest is broken when it already runs > > firmware in DMA mode but migrated to qemu-2.7(pc-2.6) > > at that time; > > > > a) qemu-2.6:pc2.6 (fwcfg.dma=on,firmware=dma,oprom=ioport) > > b) qemu-2.7:pc2.6 (fwcfg.dma=off,firmware=ioport,oprom=ioport) > > > > to: a b > > from > > a OK FAIL > > b OK OK > > > > So we currently have broken forward migration from > > qemu-2.6 to qemu-2.[789] that however could be fixed > > for 2.10 by re-enabling DMA for 2.[56] machine types > > and allowing dma capable option rom only since 2.7. > > As result qemu should end up with: > > > > c) qemu-2.10:pc2.6 (fwcfg.dma=on,firmware=dma,oprom=ioport) > > > > to: a b c > > from > > a OK FAIL OK > > b OK OK OK > > c OK FAIL OK > > > > where forward migration from qemu-2.6 to qemu-2.10 should > > work again leaving only qemu-2.[789]:pc-2.6 broken. > > > > Reported-by: Eduardo Habkost > > Analyzed-by: Laszlo Ersek > > Signed-off-by: Igor Mammedov > > Reviewed-by: Laszlo Ersek > > Reviewed-by: Eduardo Habkost Marcel or Michael, could you pick up and merge the patch through your tree?