5 virt-what - detect if we are running in a virtual machine
13 C<virt-what> is a shell script which can be used to detect if the
14 program is running in a virtual machine.
16 The program prints out a list of "facts" about the virtual machine,
17 derived from heuristics. One fact is printed per line.
19 If nothing is printed and the script exits with code 0 (no error),
20 then it can mean I<either> that the program is running on bare-metal
21 I<or> the program is running inside a type of virtual machine which we
22 don't know about or cannot detect.
30 This is Microsoft Hyper-V hypervisor.
32 Status: confirmed by RWMJ
36 This is an IBM SystemZ (or other S/390) hardware partitioning system.
37 Additional facts listed below may also be printed.
39 =item B<ibm_systemz-direct>
41 This is Linux running directly on a IBM SystemZ hardware partitioning
44 This is expected to be a highly unusual configuration - if
45 you see this result you should treat it with suspicion.
49 =item B<ibm_systemz-lpar>
51 This is Linux running directly on an LPAR on an IBM SystemZ
52 hardware partitioning system.
56 =item B<ibm_systemz-zvm>
58 This is a z/VM guest running in an LPAR on an IBM SystemZ
59 hardware partitioning system.
61 Status: confirmed by RWMJ using a Fedora guest running in z/VM
63 =item B<linux_vserver>
65 This process is running in a Linux VServer container.
67 Status: contributed by Barış Metin
71 This guest is running on the KVM hypervisor using hardware
74 Note that if the hypervisor is using software acceleration
75 you should I<not> see this, but should see the C<qemu> fact
78 Status: confirmed by RWMJ.
82 The guest appears to be running inside an OpenVZ or Virtuozzo
85 Status: contributed by Evgeniy Sokolov
89 The guest is running inside Parallels Virtual Platform
90 (Parallels Desktop, Parallels Server).
92 Status: contributed by Justin Clift
96 The guest is running inside IBM PowerVM Lx86 Linux/x86 emulator.
98 Status: data originally supplied by Jeffrey Scheel, confimed by
103 This is QEMU hypervisor using software emulation.
105 Note that for KVM (hardware accelerated) guests you should I<not> see
108 Status: confirmed by RWMJ.
112 This is a User-Mode Linux (UML) guest.
114 Status: contributed by Laurent Léonard
118 Some sort of virtualization appears to be present, but we are not sure
119 what it is. In some very rare corner cases where we know that
120 virtualization is hard to detect, we will try a timing attack to see
121 if certain machine instructions are running much more slowly than they
122 should be, which would indicate virtualization. In this case, the
123 generic fact C<virt> is printed.
127 This is Hitachi Virtualization Manager (HVM) Virtage
128 hardware partitioning system.
130 Status: data supplied by Bhavna Sarathy, not confirmed
134 This is a VirtualBox guest.
136 Status: contributed by Laurent Léonard
140 The guest appears to be running on Microsoft VirtualPC.
142 Status: not confirmed
146 The guest appears to be running on VMware hypervisor.
148 Status: confirmed by RWMJ
152 The guest appears to be running on Xen hypervisor.
154 Status: confirmed by RWMJ
158 This is the Xen dom0 (privileged domain).
160 Status: confirmed by RWMJ
164 This is a Xen domU (paravirtualized guest domain).
166 Status: confirmed by RWMJ
170 This is a Xen guest fully virtualized (HVM).
172 Status: confirmed by RWMJ
178 Programs that use or wrap C<virt-what> should check that the exit
179 status is 0 before they attempt to parse the output of the command.
181 A non-zero exit status indicates some error, for example, an
182 unrecognized command line argument. If the exit status is non-zero
183 then the output "facts" (if any were printed) cannot be guaranteed and
186 The exit status does I<not> have anything to do with whether the
187 program is running on baremetal or under virtualization, nor with
188 whether C<virt-what> managed detection "correctly" (which is basically
189 unknowable given the large variety of virtualization systems out there
190 and that some systems deliberately emulate others).
192 =head1 RUNNING VIRT-WHAT FROM OTHER PROGRAMS
194 C<virt-what> is designed so that you can easily run it from
195 other programs or wrap it up in a library.
197 Your program should check the exit status (see the section above).
199 Some programming languages (notably Python: issue 1652) erroneously
200 mask the C<SIGPIPE> signal and do not restore it when executing
201 subprocesses. C<virt-what> is a shell script and some shell commands
202 do not work correctly when you do this. You may see warnings from
203 C<virt-what> similar to this:
205 echo: write error: Broken pipe
207 The solution is to set the C<SIGPIPE> signal handler back to C<SIG_DFL>
208 before running C<virt-what>.
210 =head1 IMPORTANT NOTE
212 Most of the time, using this program is the I<wrong> thing to do.
213 Instead you should detect the specific features you actually want to
214 use. (As an example, if you wanted to issue Xen hypervisor commands
215 you would look for the C</proc/xen/privcmd> file).
217 However people keep asking for this, so we provide it. There are a
222 =item Bug reporting tool
224 If you think that virtualization could affect how your program runs,
225 then you might use C<virt-what> to report this in a bug reporting
228 =item Status display and monitoring tools
230 You might include this information in status and monitoring programs.
232 =item System tuning (sometimes)
234 You might use this program to tune an operating system so it runs
235 better as a virtual machine of a particular hypervisor. However if
236 installing paravirtualized drivers, it's better to check for the
237 specific features your drivers need (eg. for the presence of PCI devices).
243 L<http://people.redhat.com/~rjones/virt-what/>,
244 L<http://www.vmware.com/>,
245 L<http://www.microsoft.com/windows/products/winfamily/virtualpc>,
246 L<http://xensource.com/>,
247 L<http://bellard.org/qemu/>,
248 L<http://kvm.qumranet.com/>,
249 L<http://openvz.org/>
253 Richard W.M. Jones <rjones @ redhat . com>
257 (C) Copyright 2008-2011 Red Hat Inc.,
258 L<http://people.redhat.com/~rjones/virt-what/>
260 This program is free software; you can redistribute it and/or modify
261 it under the terms of the GNU General Public License as published by
262 the Free Software Foundation; either version 2 of the License, or
263 (at your option) any later version.
265 This program is distributed in the hope that it will be useful,
266 but WITHOUT ANY WARRANTY; without even the implied warranty of
267 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
268 GNU General Public License for more details.
270 You should have received a copy of the GNU General Public License
271 along with this program; if not, write to the Free Software
272 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
274 =head1 REPORTING BUGS
276 Bugs can be viewed on the Red Hat Bugzilla page:
277 L<https://bugzilla.redhat.com/>.
279 If you find a bug in virt-what, please follow these steps to report it:
283 =item 1. Check for existing bug reports
285 Go to L<https://bugzilla.redhat.com/> and search for similar bugs.
286 Someone may already have reported the same bug, and they may even
289 =item 2. Capture debug and error messages
293 virt-what > virt-what.log 2>&1
295 and keep I<virt-what.log>. It may contain error messages which you
296 should submit with your bug report.
298 =item 3. Get version of virt-what.
304 =item 4. Submit a bug report.
306 Go to L<https://bugzilla.redhat.com/> and enter a new bug.
307 Please describe the problem in as much detail as possible.
309 Remember to include the version numbers (step 3) and the debug
310 messages file (step 2) and as much other detail as possible.
312 =item 5. Assign the bug to rjones @ redhat.com
314 Assign or reassign the bug to B<rjones @ redhat.com> (without the
315 spaces). You can also send me an email with the bug number if you
316 want a faster response.