From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37409) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XrLen-0003aj-NP for qemu-devel@nongnu.org; Thu, 20 Nov 2014 01:56:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XrLef-0007w5-1S for qemu-devel@nongnu.org; Thu, 20 Nov 2014 01:55:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51978) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XrLee-0007vx-Ow for qemu-devel@nongnu.org; Thu, 20 Nov 2014 01:55:48 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sAK6tmsR011966 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Thu, 20 Nov 2014 01:55:48 -0500 Date: Thu, 20 Nov 2014 08:55:45 +0200 From: "Michael S. Tsirkin" Message-ID: <20141120065545.GC30994@redhat.com> References: <1412607364-14141-1-git-send-email-pbonzini@redhat.com> <5462439F.6080401@redhat.com> <546D8491.2010000@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <546D8491.2010000@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 0/3] Migration-safe ACPI table sizing algorithm List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org On Thu, Nov 20, 2014 at 07:05:05AM +0100, Paolo Bonzini wrote: > > > On 11/11/2014 18:13, Paolo Bonzini wrote: > > > > > > On 06/10/2014 16:56, Paolo Bonzini wrote: > >> In the emergency last-minute patches of QEMU 2.1 we did two things: > >> > >> - fixed migration problems from 1.7 or 2.0 to 2.1 due to changes in > >> ACPI table sizes > >> > >> - ensured that future versions will not break migration compatibility > >> with 2.2 for reasonable configurations (with ACPI tables smaller > >> than a hundred kilobytes, roughly) > >> > >> However, this came at the cost of wasting 128 KB unconditionally on > >> even the smaller configuration, and we didn't provide a mechanism to > >> ensure compatibility with larger configurations. > >> > >> This series provides this mechanism. As mentioned early, the design > >> is to consider the SSDT immutable and versioned (together with other > >> non-AML tables such as HPET, TPMA and MADT, SRAT, MCFG, DMAR). > >> The DSDT instead can change more or less arbitrarily. To do this, > >> we add padding after the DSDT to allow for future growth (patch 1). > >> > >> Once we do this, the size of the ACPI table fw_cfg "file" is constant > >> given a machine type and a command-line, so we do not need anymore the > >> larger 128KB padding (patch 2). > >> > >> Patch 3 is just cleanups. > >> > >> Paolo > >> > >> v1->v2: drop linuxboot changes, instead modify the option ROM > >> in a separate patch > >> > >> Paolo Bonzini (3): > >> pc: introduce new ACPI table sizing algorithm > >> pc: go back to smaller ACPI tables > >> pc: clean up pre-2.1 compatibility code > >> > >> hw/i386/acpi-build.c | 20 +++++++++++--------- > >> hw/i386/pc_piix.c | 20 +++++++++++++++++++- > >> hw/i386/pc_q35.c | 6 ++++-- > >> include/hw/i386/pc.h | 2 ++ > >> 4 files changed, 36 insertions(+), 12 deletions(-) > >> > > > > Ping? > > Ping?? > > Paolo I thought we agreed we'll consider alternate approaches after 2.2? I would prefer not to have yet another mode to support if we can help it. -- MST