RE: [Xen-users] amd processors + virtualisation

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: Thomas Harold [mailto:tgh@xxxxxxxxxxxx] 
> Sent: 29 May 2007 15:25
> To: Petersson, Mats
> Cc: Alex Samad; xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] amd processors + virtualisation
> 
> Petersson, Mats wrote:
> >> how can I tell in /proc/cpuinfo weather my amd processor can 
> >> do hardware 
> >> assisted vitalisation
> > 
> > "cat /proc/cpuinfo|grep svm" should give you a line of "flags"
> > containing "svm" if your processor has AMD-V (aka SVM). 
> > 
> > The other pretty easy way is to tell from the type of memory the
> > motherboard uses. If it's got DDR2 memories, then it's got 
> AMD-V with
> > one exception: processors called "Sempron" don't have AMD-V, but all
> > others do (Athlon, Opteron, Turion). 
> 
> I vaguely remember back when I was setting up Xen 3.0.2 on a 
> Gentoo box 
> (in mid-2006), that the "svm" flag didn't show up in that 
> list until I 
> had compiled in support for HVM (i.e. adding in Xen).  Now, I was 
> running a custom kernel on the Gentoo box at that point in time, with 
> the bare minimum of built-in options.  So it was likely an 
> error on my 
> part that cause the "svm" flag to be hidden.

There isn't any compile option to remove/add this flag as such. There is
of course a need to have a new-enough kernel that knows about this flag,
so an older kernel may not recognise the flag itself. 

> 
> On the newer CentOS5 boxes using AM2 Athlon64 X2 and SocketF Opteron 
> CPUs, the default CentOS5 kernel does allow the "svm" flag to peek 
> through.  And I have not installed virtualization support on 
> this box (yet).

Presumably, you have a recent enough kernel now (it's been in there for
quite some time, I spent a few minutes trying to locate the version
where it went in, but I (using google) wasn't able to find it...)

--
Mats
> 
> 
> 
> 



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