From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH 0/2] Viridian MSRs Date: Wed, 16 Oct 2013 14:54:04 +0100 Message-ID: <525E9A7C.1070703@citrix.com> References: <1381860730-18191-1-git-send-email-andrew.cooper3@citrix.com> <525E82B302000078000FB665@nat28.tlf.novell.com> <525E72FD.10808@citrix.com> <525E92F702000078000FB6F3@nat28.tlf.novell.com> <525E965E.8000401@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VWRYA-0005Wo-M7 for xen-devel@lists.xenproject.org; Wed, 16 Oct 2013 13:54:10 +0000 In-Reply-To: <525E965E.8000401@citrix.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: Andrew Cooper Cc: xen-devel , Paul Durrant , Keir Fraser , Jan Beulich List-Id: xen-devel@lists.xenproject.org On 16/10/13 14:36, Andrew Cooper wrote: > > I disagree. There is a perfectly good mechanism for advertising which > viridian extensions are available, which was being blindly ignored by > Linux (The specific bug was the HyperV drivers assuming a HyperV timer > without checking that it was actually present, leading to an hang when > waiting for a timer interrupt). > > This is a Linux bug; Xen should not be functionally crippled because a > guest can't enumerate support correctly. > > And anyway - the entire set of viridian extensions is an off-by-default, > opt-in configuration option in the first place. Anyone who decided to > try Linux with viridan can turn it off if it doesn't work. I think Jan is suggesting that you pre-emptively check that it doesn't cause breakage in Linux. So that any Linux bugs (if there are any) can be fixed sooner. David