From mboxrd@z Thu Jan 1 00:00:00 1970 From: Don Slutz Subject: Re: [PATCH v3 07/11] hvm/hpet: Init comparator64 like comparator. Date: Fri, 25 Apr 2014 18:00:50 -0400 Message-ID: <535ADB12.8020601@terremark.com> References: <1397756585-27091-1-git-send-email-dslutz@verizon.com> <1397756585-27091-8-git-send-email-dslutz@verizon.com> <5357F719020000780000BA8F@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5357F719020000780000BA8F@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 , Don Slutz Cc: Keir Fraser , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 04/23/14 11:23, Jan Beulich wrote: >>>> On 17.04.14 at 19:43, wrote: >> The software-developers-hpet-spec-1-0a.pdf says that the comparator >> starts as all 1's. Also make the hidden register comparator64 the same. >> >> Since only the hidden register comparator64 is used by hpet_save, it >> needs to start out with the right value. > But the immediately preceding patch arranged for the field to get > suitably updated, so is this change really doing anything but > cosmetics? The preceding patch only makes a difference when the hpet is enabled. A disabled hpet (like when a guest is starting), should start with the value the spec says. Both hpet_save and the guest reading the comparator register use comparator64 to get the value. So instead of just adding the line with comparator64, I could also delete the setting of .cmp. I picked the simpler one (just add the init). So either way, not doing this change and for example using xen-hvmctx on a guest that was started paused, you see all 0 not all 1. -Don Slutz > Jan >