From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3CB0DE7717F for ; Thu, 12 Dec 2024 13:48:35 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tLjXX-0001Hp-06; Thu, 12 Dec 2024 08:47:39 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tLjXS-0001H8-EG for qemu-devel@nongnu.org; Thu, 12 Dec 2024 08:47:36 -0500 Received: from mgamail.intel.com ([198.175.65.18]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tLjXO-0003lG-Ul for qemu-devel@nongnu.org; Thu, 12 Dec 2024 08:47:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1734011251; x=1765547251; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=hs9T44JhyRfs29SpkAwD3BjTGPUJVD3Mnkntj/Jfus8=; b=eSlmXovb7stLdhf4uulIDSzwpZ0ZYD0+bJqS5oCtrL7/wM8fmAskhQNK c0EYTHItRq7GSH2O7RH/dJnDchkzYPux+bifTNS/O+ZIZcj5VIbLt8FfY TKf/Luw3+JKX0LZm5r8rR3mzsuuAQhcPwrJ521ZgaCgwIgKY7seCDPV6c 5iBLI7N7cR07i7ezNPevxJmecsdppMkj1TsabiOF5pqph9vEBOvs4UA0/ XDIU6Glc07TXURGMOpyozHpYKfKH5NKepYk8eUC+Yug5NpqOArPtzv92Z A5Yw2A7C/X4WloNr38fZ4v380PzcO1hOkQNyDHWJQb+fHTuD2MPDe2vlS g==; X-CSE-ConnectionGUID: jARFK9VLTvKEwbZqNJw8CQ== X-CSE-MsgGUID: ej0hjxpGSGy+r4AJulAOAQ== X-IronPort-AV: E=McAfee;i="6700,10204,11284"; a="34560716" X-IronPort-AV: E=Sophos;i="6.12,228,1728975600"; d="scan'208";a="34560716" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Dec 2024 05:47:26 -0800 X-CSE-ConnectionGUID: yEX+uZrgQqWgtaay0SYwsw== X-CSE-MsgGUID: V6KOUGRxTomfncA41aSQtQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,228,1728975600"; d="scan'208";a="96306788" Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.36]) by orviesa006.jf.intel.com with ESMTP; 12 Dec 2024 05:47:24 -0800 Date: Thu, 12 Dec 2024 22:05:39 +0800 From: Zhao Liu To: Ani Sinha Cc: Sergio Lopez , Paolo Bonzini , Richard Henderson , Eduardo Habkost , Michael Tsirkin , Marcel Apfelbaum , Igor Mammedov , qemu-devel , Daniel Berrange Subject: Re: [PATCH] hw/i386/cpu: remove default_cpu_version and simplify Message-ID: References: <20241208064810.893451-1-anisinha@redhat.com> <8FE9B724-4233-4D94-AC17-5D6B90F55D7C@redhat.com> <891266A0-3863-48FA-9440-64EB9364E665@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=gb2312 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <891266A0-3863-48FA-9440-64EB9364E665@redhat.com> Received-SPF: pass client-ip=198.175.65.18; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -48 X-Spam_score: -4.9 X-Spam_bar: ---- X-Spam_report: (-4.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.496, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org > Had a conversation with Igor offline. CPU_VERSION_LATEST does not work since it¡¯s a moving target. Therefore for a specific machine, what version of cpu model will be chosen will depend on what is latest and this will change with time. It can break guests that stick to a single cpu model. > > One way to fix this would be to keep a fixed mapping between cpu model and machine versions. However, it will be a nightmare to maintain such mappings. Thanks Ani! The commit ad18392 also mentioned the plan to move to CPU_VERSION_LATEST. Because previsou commits have repeatedly mentioned the plan to move to CPU_VERSION_LATEST (not only the commit dcafd1ef0af227 you referred, but also the commit ad18392), I think it's necessary to include the termination of this plan (i.e., your explanation of why you are no longer attempting to move to CPU_VERSION_LATEST) in the commit message. This way, the history regarding default_cpu_version will be easier to search, and it effectively puts an end to the previous plan. Thanks, Zhao