From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45793) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT7rk-0005YU-Fo for qemu-devel@nongnu.org; Wed, 04 Mar 2015 06:53:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YT7rh-0000bv-Mt for qemu-devel@nongnu.org; Wed, 04 Mar 2015 06:53:28 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53529) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT7rh-0000bo-Dj for qemu-devel@nongnu.org; Wed, 04 Mar 2015 06:53:25 -0500 Date: Wed, 4 Mar 2015 11:53:19 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20150304115318.GB2530@work-vm> References: <1424696203-76895-1-git-send-email-agraf@suse.de> <1424696203-76895-4-git-send-email-agraf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1424696203-76895-4-git-send-email-agraf@suse.de> Subject: Re: [Qemu-devel] [PATCH v2 3/3] pc: Disable vmdesc submission for old machines List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: lmr@redhat.com, amit.shah@redhat.com, qemu-devel@nongnu.org, quintela@redhat.com * Alexander Graf (agraf@suse.de) wrote: > Older PC machine types might by accident be backwards live migration compatible, > but with the new vmdesc self-describing blob in our live migration stream we > would break that compatibility. > > Also users wouldn't expect massive behaviorial differences when updating to a > new version of QEMU while retaining their old machine type, especially not > potential breakage in tooling around live migration. > > So disable vmdesc submission for old PC machine types. > > Signed-off-by: Alexander Graf Reviewed-by: Dr. David Alan Gilbert (I'm leaving 2/3 for someone more familiar with -machine) Dave > --- > hw/i386/pc_piix.c | 1 + > hw/i386/pc_q35.c | 1 + > 2 files changed, 2 insertions(+) > > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c > index 38b42b0..35bc377 100644 > --- a/hw/i386/pc_piix.c > +++ b/hw/i386/pc_piix.c > @@ -332,6 +332,7 @@ static void pc_compat_2_2(MachineState *machine) > CPUID_7_0_EBX_HLE | CPUID_7_0_EBX_RTM, 0); > x86_cpu_compat_set_features("Broadwell", FEAT_7_0_EBX, > CPUID_7_0_EBX_HLE | CPUID_7_0_EBX_RTM, 0); > + machine->suppress_vmdesc = true; > } > > static void pc_compat_2_1(MachineState *machine) > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c > index 63027ee..1305eb0 100644 > --- a/hw/i386/pc_q35.c > +++ b/hw/i386/pc_q35.c > @@ -311,6 +311,7 @@ static void pc_compat_2_2(MachineState *machine) > CPUID_7_0_EBX_HLE | CPUID_7_0_EBX_RTM, 0); > x86_cpu_compat_set_features("Broadwell", FEAT_7_0_EBX, > CPUID_7_0_EBX_HLE | CPUID_7_0_EBX_RTM, 0); > + machine->suppress_vmdesc = true; > } > > static void pc_compat_2_1(MachineState *machine) > -- > 1.7.12.4 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK