From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: Xen 4.3 development update Date: Wed, 8 May 2013 10:00:16 +0100 Message-ID: <518A1420.3080305@eu.citrix.com> References: <515B186F02000078000CA1A7@nat28.tlf.novell.com> <20130402163440.GB17022@ocelot.phlegethon.org> <515BF5F102000078000CA39C@nat28.tlf.novell.com> <515C0A0D.6020007@eu.citrix.com> <4691AE88-FA92-4826-BF5E-50175BACA5D9@gmail.com> <20130404152321.GI42936@ocelot.phlegethon.org> <20130404170507.GJ42936@ocelot.phlegethon.org> <517E73DE.7090803@brockmann-consult.de> <20130502154856.GO65547@ocelot.phlegethon.org> <5183E8BF.7030706@eu.citrix.com> <20130504104714.GY11427@reaktio.net> <518915E9.9070500@eu.citrix.com> <6035A0D088A63A46850C3988ED045A4B57B42EC7@BITCOM1.int.sbss.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <6035A0D088A63A46850C3988ED045A4B57B42EC7@BITCOM1.int.sbss.com.au> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: James Harper Cc: "suravee.suthikulpanit@amd.com" , "Tim (Xen.org)" , "xen-devel@lists.xen.org" , Jan Beulich , Andres Lagar-Cavilla , Peter Maloney List-Id: xen-devel@lists.xenproject.org On 07/05/13 23:23, James Harper wrote: >>> A couple of questions: >>> >>> - Does Citrix XenServer Windows PV driver work with vanilla Xen 4.2.x? I >> remember someone complaining on the list that it doesn't work.. (but I'm >> not sure about that). >> >> I did a quick test of the XS 6.0.2 drivers on unstable and they didn't >> work. Didn't do any debugging, however. >> >>> - Does GPLPV do the lazy patching for WinXP on AMD? >> I highly doubt it, but you'd have to ask James Harper. >> > GPLPV does do some TPR patching. You need to add the /PATCHTPR option to your boot.ini. It works for 2000 as well (and 2003 before MS stopped using TPR at all in sp2), if anyone cares :) > > For AMD, TPR access is changed to a LOCK MOVE CR8 instruction which enables setting of TPR without a VMEXIT. For Intel, TPR writes are only done if it would change the value of TPR, and reads are always done from a cached value. I guess this is what you mean by 'lazy'. > > I think xen itself does TPR optimisation for Intel these days so this may be unnecessary. > > It certainly makes a big difference for XP. Well the context of this thread is a set of changes that makes the non-lazy TPR exits *much much* more expensive on AMD hardware. The existence of a widely-available set of drivers as a work-round would be a pretty important factor in how we decide to proceed. So if I just download your latest drivers and add /PATCHTPR on the boot.ini, the AMD TPR patching should work? -George