From: Keir Fraser <keir.fraser@eu.citrix.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
"kurt.hackel@oracle.com" <kurt.hackel@oracle.com>,
"Dugger, Donald D" <donald.d.dugger@intel.com>,
"Nakajima, Jun" <jun.nakajima@intel.com>,
"Zhang, Xiantao" <xiantao.zhang@intel.com>
Subject: Re: Live migration fails due to c/s 20627
Date: Mon, 14 Dec 2009 23:19:45 +0000 [thread overview]
Message-ID: <C74C7891.46AD%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <7368e0be-f9f9-47fc-9dd3-4cc9a3f5515c@default>
On 14/12/2009 18:02, "Dan Magenheimer" <dan.magenheimer@oracle.com> wrote:
> This may be true in concept, but existing tools (including
> the default xm tools) do NOT check for this... I just
> tested a live migration between a Nehalem (which supports
> rdtscp) and a Conroe (which does not). The live migration
> works fine and the app using rdtscp runs fine on the
> Nehalem and then crashes when the live migration completes
> on the Conroe. I *know* of existing code in Oracle
> that will be broken by this!
This is a general problem for migration between dissimilar processors. The
solution is to 'level' the feature sets, by masking CPUID flags from the
more-featured processor. In this case you would mask out RDTSCP (and perhaps
others too). This does need the RDTSCP flag setting/clearing to be moved to
xc_cpuid_x86.c, as currently the user cannot override the policy wedged into
the hypervisor itself. That's an easy thing to fix.
-- Keir
next prev parent reply other threads:[~2009-12-14 23:19 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-14 18:02 Live migration fails due to c/s 20627 Dan Magenheimer
2009-12-14 23:19 ` Keir Fraser [this message]
2009-12-15 4:40 ` Xu, Dongxiao
2009-12-15 15:56 ` Dan Magenheimer
2009-12-15 16:10 ` Xu, Dongxiao
2009-12-15 16:31 ` Dan Magenheimer
2009-12-15 17:08 ` Dan Magenheimer
2009-12-15 18:04 ` Xu, Dongxiao
2009-12-16 2:07 ` Nakajima, Jun
2009-12-16 2:43 ` Zhang, Xiantao
2009-12-16 4:14 ` Dan Magenheimer
2009-12-16 5:07 ` Zhang, Xiantao
2009-12-16 16:23 ` Dan Magenheimer
2009-12-16 17:38 ` Jeremy Fitzhardinge
2009-12-16 6:19 ` Jeremy Fitzhardinge
2009-12-16 15:20 ` Dan Magenheimer
2009-12-16 17:31 ` Jeremy Fitzhardinge
2009-12-15 17:12 ` Jeremy Fitzhardinge
2009-12-15 17:24 ` Xu, Dongxiao
2009-12-15 18:25 ` Jeremy Fitzhardinge
2009-12-15 19:20 ` Dan Magenheimer
2009-12-15 19:31 ` Keir Fraser
2009-12-15 19:52 ` Keir Fraser
2009-12-16 15:41 ` Andre Przywara
2009-12-16 16:54 ` Dan Magenheimer
2009-12-15 19:25 ` Keir Fraser
2009-12-15 18:05 ` Xu, Dongxiao
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