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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8AB3DC433E1 for ; Mon, 15 Jun 2020 15:34:04 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5EE9C20857 for ; Mon, 15 Jun 2020 15:34:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5EE9C20857 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jkr7F-00005D-Lb; Mon, 15 Jun 2020 15:33:41 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jkr7E-000057-D5 for xen-devel@lists.xenproject.org; Mon, 15 Jun 2020 15:33:40 +0000 X-Inumbo-ID: 950b0c7d-af1d-11ea-b80e-12813bfff9fa Received: from esa6.hc3370-68.iphmx.com (unknown [216.71.155.175]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 950b0c7d-af1d-11ea-b80e-12813bfff9fa; Mon, 15 Jun 2020 15:33:39 +0000 (UTC) Authentication-Results: esa6.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none IronPort-SDR: 7QT1MsNHvao7+56qherYyjnDUwjmRMJyADuszo0B1FsRffN16rSslb3luoG4+947Gkee50EOks kNCrfj3kJVnCQBbfvRdL5+KU3sd366mAMi6VAtr88hAum3HtAPmm125Kp8HsAsRg4QAwsGU6FR v3BgveZu1BtggJ+antYiwbzrCKaWN+od2KT71OruL4zd9pC6EH/5NPW8yzwT7JiS+bd2WKAQ2y V+lRcsvMIjm0LyGiS16qN91hrdustsNHpLS4Rrh2Yypii31S+MgdLLOlYvuqOvrFakr2OzjNqN rCg= X-SBRS: 2.7 X-MesageID: 20419838 X-Ironport-Server: esa6.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.73,515,1583211600"; d="scan'208";a="20419838" Subject: Re: [PATCH for-4.14 8/8] x86/hvm: enable emulated PIT for PVH dom0 To: Roger Pau Monne , References: <20200612155640.4101-1-roger.pau@citrix.com> <20200612155640.4101-9-roger.pau@citrix.com> From: Andrew Cooper Message-ID: Date: Mon, 15 Jun 2020 16:33:33 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200612155640.4101-9-roger.pau@citrix.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Language: en-GB X-ClientProxiedBy: AMSPEX02CAS02.citrite.net (10.69.22.113) To AMSPEX02CL02.citrite.net (10.69.22.126) X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Wei Liu , Jan Beulich , paul@xen.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 12/06/2020 16:56, Roger Pau Monne wrote: > Some video BIOS require a PIT in order to work properly, hence classic > PV dom0 gets partial access to the physical PIT as long as it's not in > use by Xen. Is this actually true today? I can believe that it may have been necessary on old hardware, but the structure of systems has changed massively over the past 20 years, and the PIT is very legacy these days. We shouldn't be blindly propagating bodges like this forward. ~Andrew