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Re: [Xen-users] how to configure cpuid in pvm ?

To: Samuel Kvasnica <bugreports@xxxxxxxxxxxxxx>
Subject: Re: [Xen-users] how to configure cpuid in pvm ?
From: Thomas Halinka <lists@xxxxxxxxx>
Date: Mon, 03 Jan 2011 18:11:49 +0100
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its just works fine with pvm. I needed this Feature for running F11-PVM
under XEN 4.01 - pvops and suse-kernel.

Could your post your corresponding line from domu.cfg?



Am Montag, den 03.01.2011, 17:24 +0100 schrieb Samuel Kvasnica:
> Hello,
> I got into troubles with the live migration of a Xen domU pvm running a
> java application.
> There are 2 host systems. One is a newer Xeon3450 system, the other one
> is a 2-core PentiumD.
> Both are running xenified kernel, xen is 4.0.1. If the java
> application was initially started
> when domU is located on weaker node, i.e. PentiumD, it can be
> sucessfully migrated back and forth.
> But if the application was first started when on newer Xeon node, jvm
> will crash with internal invalid instruction
> error while migrating to PentiumD.
> That seems like java jit compiler is performing some
> cpu-code-optimizations which are based
> on cpu model/features determined upon jvm start. (Unfortunately there
> does not seem to be any explicit option
> to disable such optimization or select particular cpu model).
> Given this conclusion, I started to tweak the cpuid settings in domU
> config. I managed to get
> a common subset of cpu features for both nodes. These are visible in
> /proc/cpuinfo on both nodes
> and seem to be correct.
> However, jvm will still crash in course of migration, so it seems like
> the cpuid does not really work
> on low level.
> Indeed, I tried the cpuid utility:
> http://www.etallen.com/cpuid.html
> and it reports real cpu model/features independent what do I set in
> cpuid config !
> Whats wrong here ? Is cpuid not supposed to work in paravirt domain ?
> Are cpuid registers not really emulated ?
> best regards,
> Sam
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