From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: mx.groups.io; dkim=missing; spf=pass (domain: citrix.com, ip: 216.71.145.142, mailfrom: anthony.perard@citrix.com) Received: from esa1.hc3370-68.iphmx.com (esa1.hc3370-68.iphmx.com [216.71.145.142]) by groups.io with SMTP; Thu, 08 Aug 2019 07:27:48 -0700 Authentication-Results: esa1.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none; spf=None smtp.pra=anthony.perard@citrix.com; spf=Pass smtp.mailfrom=anthony.perard@citrix.com; spf=None smtp.helo=postmaster@mail.citrix.com Received-SPF: None (esa1.hc3370-68.iphmx.com: no sender authenticity information available from domain of anthony.perard@citrix.com) identity=pra; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="anthony.perard@citrix.com"; x-sender="anthony.perard@citrix.com"; x-conformance=sidf_compatible Received-SPF: Pass (esa1.hc3370-68.iphmx.com: domain of anthony.perard@citrix.com designates 162.221.158.21 as permitted sender) identity=mailfrom; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="anthony.perard@citrix.com"; x-sender="anthony.perard@citrix.com"; x-conformance=sidf_compatible; x-record-type="v=spf1"; x-record-text="v=spf1 ip4:209.167.231.154 ip4:178.63.86.133 ip4:195.66.111.40/30 ip4:85.115.9.32/28 ip4:199.102.83.4 ip4:192.28.146.160 ip4:192.28.146.107 ip4:216.52.6.88 ip4:216.52.6.188 ip4:162.221.158.21 ip4:162.221.156.83 ~all" Received-SPF: None (esa1.hc3370-68.iphmx.com: no sender authenticity information available from domain of postmaster@mail.citrix.com) identity=helo; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="anthony.perard@citrix.com"; x-sender="postmaster@mail.citrix.com"; x-conformance=sidf_compatible IronPort-SDR: o7Hyn1uQJw+4YzxQGj+Hr9iVVX+AHTV8qzanfYpS5c56Q4CLbG21V7USZSG/xwSZ7TdTPaZrVF jY8HMqJuHEJAheem4t1Wl2CsaZ3MTuG87QyzPtP/kaFnRokpMEUTUak1SZ+yvHSrtDcKovmlfU Q5dbxGcEtmMa0rewe2xKXLSPd2/82B3BYyQgtNRzgP971MyjlCgZ6Y0c9kZjJjdW1ZMm5psj6P oQfpdVBSaQhUcJ706/sCOUrdeq7Xes0m+ebC7UKsZY6v+HYEZyzi77l0HsmmSINF5/nudvnZO3 qes= X-SBRS: 2.7 X-MesageID: 4074016 X-Ironport-Server: esa1.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.64,361,1559534400"; d="scan'208";a="4074016" Date: Thu, 8 Aug 2019 15:03:48 +0100 From: "Anthony PERARD" To: Roger Pau =?iso-8859-1?Q?Monn=E9?= CC: , Julien Grall , , Jordan Justen , Ard Biesheuvel , Laszlo Ersek Subject: Re: [edk2-devel] [PATCH v4 35/35] OvmfPkg/OvmfXen: use RealTimeClockRuntimeDxe from EmbeddedPkg Message-ID: <20190808140348.GW1242@perard.uk.xensource.com> References: <20190729153944.24239-1-anthony.perard@citrix.com> <20190729153944.24239-36-anthony.perard@citrix.com> <20190807160957.csgyplb6cqfen5ix@Air-de-Roger> MIME-Version: 1.0 In-Reply-To: <20190807160957.csgyplb6cqfen5ix@Air-de-Roger> User-Agent: Mutt/1.12.1 (2019-06-15) Return-Path: anthony.perard@citrix.com Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit On Wed, Aug 07, 2019 at 06:09:57PM +0200, Roger Pau Monné wrote: > On Mon, Jul 29, 2019 at 04:39:44PM +0100, Anthony PERARD wrote: > > A Xen PVH guest doesn't have a RTC that OVMF would expect, so > > PcatRealTimeClockRuntimeDxe fails to initialize and prevent the > > firmware from finish to boot. To prevent that, we will use > > XenRealTimeClockLib which simply always return the same time. > > This will work on both Xen PVH and HVM guests. > > Not that this is not correct, but what's the point in requiring a > clock if it can be faked by always returning the same value? It's not a clock that is required, it is a library that implements RealTimeClockLib. Something needs it, so it is provided, even if it is only to display the "current time". > It seems like it's usage is not really required, and could indeed be > dropped altogether? Way to much work to drop it. Also, I don't work to fork OVMF. The ARM implementation of OVMF for Xen does the same thing and simply always return the same value. > Alternatively, there's the PV clock which is available to PVH guests > and will return a proper time. We might need to do that one day I guess, but right now it is just a nice to have. Thanks, -- Anthony PERARD