Fedora xen - Aug 2008 - ANNOUNCE: virt-what 1.0 - a shell script to detect if you are running in a virtual machine

I''m pleased to announce the first release of
''virt-what'', which is a
simple shell script that detects if you are running inside a virtual
machine, and prints some "facts" about that virtual machine.  This is
a frequently requested feature.

  Home page:        http://et.redhat.com/~rjones/virt-what/
  Source and RPMs:  http://et.redhat.com/~rjones/virt-what/files/

So far we can detect:

 - Xen
 - QEMU and KVM (but not distinguish between them)
 - VMware
 - Microsoft VirtualPC

I''m hoping that people who run or develop other virtualization
technology will be able to contribute snippets to detect those.

It''s worth saying (before Dan Berrange says it anyway) that although
people often think they need this sort of feature, in most cases using
this script is the WRONG THING.  If you need a specific virtualization
feature, then add code to your application to detect that feature.
eg. If you need to make Xen hypervisor calls, your application should
try to open /proc/xen/privcmd.  As Dan once put it:

  A shell script just printing out ''native'',
''dom0'' or ''domU'' is too
  simplistic to be broadly useful to management applications. The
  concepts are also ill-defined, eg ''native'' as a concept can
be a
  baremetal kernel, or a fully-virtualized guest, or both.
''DomU'' does
  not distinguish full or paravirt. The distinction of ''dom0''
vs
  ''native'' is irrelevant in non-Xen virtualization systems (eg
KVM).

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
virt-top is ''top'' for virtual machines.  Tiny program with
many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top

On Wed, 27 Aug 2008, Richard W.M. Jones wrote:
> I''m pleased to announce the first release of
''virt-what'', which is a
> simple shell script that detects if you are running inside a virtual
> machine, and prints some "facts" about that virtual machine. 
This is
> a frequently requested feature.
> [...]
On dom0 running a xen kernel (CentOS 5.2), I get:

 	xen
 	xen-dom0

whether or not xend is started. On PV guests, I get the same output (they 
have /proc/xen/privcmd too). On HVM guests, I get no output.

Steve
----------------------------------------------------------------------------
Steve Thompson                 E-mail:      smt AT vgersoft DOT com
Voyager Software LLC           Web:         http://www DOT vgersoft DOT com
39 Smugglers Path              VSW Support: support AT vgersoft DOT com
Ithaca, NY 14850
   "186,300 miles per second: it''s not just a good idea,
it''s the law"
----------------------------------------------------------------------------

On Sat, Aug 30, 2008 at 04:21:31PM -0400, Steve Thompson
wrote:
> On Wed, 27 Aug 2008, Richard W.M. Jones wrote:
>
>> I''m pleased to announce the first release of
''virt-what'', which is a
>> simple shell script that detects if you are running inside a virtual
>> machine, and prints some "facts" about that virtual machine. 
This is
>> a frequently requested feature.
>> [...]
>
> On dom0 running a xen kernel (CentOS 5.2), I get:
>
> 	xen
> 	xen-dom0
>
> whether or not xend is started.
> On PV guests, I get the same output (they have /proc/xen/privcmd
> too). On HVM guests, I get no output.
Oh dear, that''s a bug.  Which version of xen are you running?

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
virt-top is ''top'' for virtual machines.  Tiny program with
many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top