=encoding utf8

=head1 NAME

virt-what - detect if we are running in a virtual machine

=head1 SUMMARY

virt-what [options]

=head1 DESCRIPTION

C<virt-what> is a shell script which can be used to detect if the
program is running in a virtual machine.

The program prints out a list of "facts" about the virtual machine,
derived from heuristics.  One fact is printed per line.

If nothing is printed and the script exits with code 0 (no error),
then it can mean I<either> that the program is running on bare-metal
I<or> the program is running inside a type of virtual machine which we
don't know about or cannot detect.

=head1 FACTS

=over 4

=item B<hyperv>

This is Microsoft Hyper-V hypervisor.

Status: confirmed by RWMJ

=item B<ibm_systemz>

This is an IBM SystemZ (or other S/390) hardware partitioning system.
Additional facts listed below may also be printed.

=item B<ibm_systemz-direct>

This is Linux running directly on a IBM SystemZ hardware partitioning
system.

This is expected to be a highly unusual configuration - if
you see this result you should treat it with suspicion.

Status: not confirmed

=item B<ibm_systemz-lpar>

This is Linux running directly on an LPAR on an IBM SystemZ
hardware partitioning system.

Status: not confirmed

=item B<ibm_systemz-zvm>

This is a z/VM guest running in an LPAR on an IBM SystemZ
hardware partitioning system.

Status: confirmed by RWMJ using a Fedora guest running in z/VM

=item B<linux_vserver>

This process is running in a Linux VServer container.

Status: contributed by Barış Metin

=item B<kvm>

This guest is running on the KVM hypervisor using hardware
acceleration.

Note that if the hypervisor is using software acceleration
you should I<not> see this, but should see the C<qemu> fact
instead.

Status: confirmed by RWMJ.

=item B<openvz>

The guest appears to be running inside an OpenVZ or Virtuozzo
container.

Status: contributed by Evgeniy Sokolov

=item B<parallels>

The guest is running inside Parallels Virtual Platform
(Parallels Desktop, Parallels Server).

Status: contributed by Justin Clift

=item B<powervm_lx86>

The guest is running inside IBM PowerVM Lx86 Linux/x86 emulator.

Status: data originally supplied by Jeffrey Scheel, confimed by
Yufang Zhang and RWMJ

=item B<qemu>

This is QEMU hypervisor using software emulation.

Note that for KVM (hardware accelerated) guests you should I<not> see
this.

Status: confirmed by RWMJ.

=item B<uml>

This is a User-Mode Linux (UML) guest.

Status: contributed by Laurent Léonard

=item B<virt>

Some sort of virtualization appears to be present, but we are not sure
what it is.  In some very rare corner cases where we know that
virtualization is hard to detect, we will try a timing attack to see
if certain machine instructions are running much more slowly than they
should be, which would indicate virtualization.  In this case, the
generic fact C<virt> is printed.

=item B<virtage>

This is Hitachi Virtualization Manager (HVM) Virtage
hardware partitioning system.

Status: data supplied by Bhavna Sarathy, not confirmed

=item B<virtualbox>

This is a VirtualBox guest.

Status: contributed by Laurent Léonard

=item B<virtualpc>

The guest appears to be running on Microsoft VirtualPC.

Status: not confirmed

=item B<vmware>

The guest appears to be running on VMware hypervisor.

Status: confirmed by RWMJ

=item B<xen>

The guest appears to be running on Xen hypervisor.

Status: confirmed by RWMJ

=item B<xen-dom0>

This is the Xen dom0 (privileged domain).

Status: confirmed by RWMJ

=item B<xen-domU>

This is a Xen domU (paravirtualized guest domain).

Status: confirmed by RWMJ

=item B<xen-hvm>

This is a Xen guest fully virtualized (HVM).

Status: confirmed by RWMJ

=back

=head1 EXIT STATUS

Programs that use or wrap C<virt-what> should check that the exit
status is 0 before they attempt to parse the output of the command.

A non-zero exit status indicates some error, for example, an
unrecognized command line argument.  If the exit status is non-zero
then the output "facts" (if any were printed) cannot be guaranteed and
should be ignored.

The exit status does I<not> have anything to do with whether the
program is running on baremetal or under virtualization, nor with
whether C<virt-what> managed detection "correctly" (which is basically
unknowable given the large variety of virtualization systems out there
and that some systems deliberately emulate others).

=head1 RUNNING VIRT-WHAT FROM OTHER PROGRAMS

C<virt-what> is designed so that you can easily run it from
other programs or wrap it up in a library.

Your program should check the exit status (see the section above).

Some programming languages (notably Python: issue 1652) erroneously
mask the C<SIGPIPE> signal and do not restore it when executing
subprocesses.  C<virt-what> is a shell script and some shell commands
do not work correctly when you do this.  You may see warnings from
C<virt-what> similar to this:

 echo: write error: Broken pipe

The solution is to set the C<SIGPIPE> signal handler back to C<SIG_DFL>
before running C<virt-what>.

=head1 IMPORTANT NOTE

Most of the time, using this program is the I<wrong> thing to do.
Instead you should detect the specific features you actually want to
use.  (As an example, if you wanted to issue Xen hypervisor commands
you would look for the C</proc/xen/privcmd> file).

However people keep asking for this, so we provide it.  There are a
few legitimate uses:

=over 4

=item Bug reporting tool

If you think that virtualization could affect how your program runs,
then you might use C<virt-what> to report this in a bug reporting
tool.

=item Status display and monitoring tools

You might include this information in status and monitoring programs.

=back

=head1 SEE ALSO

L<http://people.redhat.com/~rjones/virt-what/>,
L<http://www.vmware.com/>,
L<http://www.microsoft.com/windows/products/winfamily/virtualpc>,
L<http://xensource.com/>,
L<http://bellard.org/qemu/>,
L<http://kvm.qumranet.com/>,
L<http://openvz.org/>

=head1 AUTHORS

Richard W.M. Jones <rjones @ redhat . com>

=head1 COPYRIGHT

(C) Copyright 2008-2011 Red Hat Inc.,
L<http://people.redhat.com/~rjones/virt-what/>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

=head1 REPORTING BUGS

Bugs can be viewed on the Red Hat Bugzilla page:
L<https://bugzilla.redhat.com/>.

If you find a bug in virt-what, please follow these steps to report it:

=over 4

=item 1. Check for existing bug reports

Go to L<https://bugzilla.redhat.com/> and search for similar bugs.
Someone may already have reported the same bug, and they may even
have fixed it.

=item 2. Capture debug and error messages

Run

 virt-what > virt-what.log 2>&1

and keep I<virt-what.log>.  It may contain error messages which you
should submit with your bug report.

=item 3. Get version of virt-what.

Run

 virt-what --version

=item 4. Submit a bug report.

Go to L<https://bugzilla.redhat.com/> and enter a new bug.
Please describe the problem in as much detail as possible.

Remember to include the version numbers (step 3) and the debug
messages file (step 2) and as much other detail as possible.

=item 5. Assign the bug to rjones @ redhat.com

Assign or reassign the bug to B<rjones @ redhat.com> (without the
spaces).  You can also send me an email with the bug number if you
want a faster response.

=back