From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH] x86/HVM: tie RTC emulation mode to enabling of Viridian emulation Date: Tue, 2 Jul 2013 10:19:12 -0400 Message-ID: <20130702141912.GA4416@phenom.dumpdata.com> References: <51D2973102000078000E21A5@nat28.tlf.novell.com> <20130702091130.GA13934@ocelot.phlegethon.org> <51D2B92E02000078000E22D9@nat28.tlf.novell.com> <20130702095115.GB13934@ocelot.phlegethon.org> <51D2C5FD02000078000E2334@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <51D2C5FD02000078000E2334@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: George Dunlap , Keir Fraser , paul.durrant@citrix.com, Tim Deegan , xen-devel List-Id: xen-devel@lists.xenproject.org On Tue, Jul 02, 2013 at 11:22:21AM +0100, Jan Beulich wrote: > >>> On 02.07.13 at 11:51, Tim Deegan wrote: > > At 10:27 +0100 on 02 Jul (1372760862), Jan Beulich wrote: > >> >>> On 02.07.13 at 11:11, Tim Deegan wrote: > >> > At 08:02 +0100 on 02 Jul (1372752161), Jan Beulich wrote: > >> >> As the mode not conforming to the hardware specification (by allowing > >> >> the guest to skip the REG C reads in its interrupt handler) is a > >> >> Viridian invention, it seems logical to tie this mode to that extension > >> >> being enabled. If the extension is disabled, proper hardware emulation > >> >> will be done instead. > >> >> > >> >> The main thing necessary here is the synchronization of the RTC > >> >> emulation code and the setting of the respective flag in hvmloader's > >> >> creation of the ACPI WAET table. > >> >> > >> >> Signed-off-by: Jan Beulich > >> > > >> > Wasn't this going to have its own param, defaulting to off on create and > >> > to on on migrate? I suspect most people just leave the viridian flag on > >> > for all domains. > >> > >> In which case there would be no behavioral difference to what > >> we're going to release with 4.3. (That's leaving aside the fact that > >> I think people doing so is not the best practice.) > > > > Why not? The Viridian interfaces is pretty well essential for running > > recent Windows, and shouldn't be harmful for other OSes. > > Shouldn't. But as we learned it occasionally is - Linux when built > without CONFIG_XEN_PVHVM detects the HyperV functionality, > and tried using HyperV functionality that Xen doesn't really emulate > (see commits 32068f65 ["x86: Hyper-V: register clocksource only if > its advertised"] and db34bbb7 ["X86: Add a check to catch Xen > emulation of Hyper-V"]). Shouldn't those patches be in stable tree by now? > > Jan > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel