3 virt-uname - system information for virtual machines
5 virt-dmesg - print kernel messages for virtual machines
7 virt-ps - list processes for virtual machines
9 virt-mem - tool with additional information output
13 virt-uname [-options] [domains...]
15 virt-dmesg [-options] [domains...]
17 virt-ps [-options] [domains...]
29 These virtualization tools allow you to inspect the status of virtual
30 machines running Linux.
32 These tools are designed to work like familiar Linux/Unix command line
35 These tools all use libvirt so are capable of showing information
36 across a variety of different virtualization systems.
38 The virt-mem tools do not work on domains which are not active
39 (running or paused). eg. They do not work on shut down domains.
40 However they can (usually) be used on domains which are active but
41 hanging or unresponsive. You also have the option of capturing a
42 memory image of a domain for post-mortem analysis, allowing you to
43 quickly reboot a failed domain and analyze it later at your leisure.
47 Each command obeys a common set of options. The general form is:
49 virt-I<program> [-options] [domains...]
51 where I<program> is a subtool such as C<uname>, C<dmesg> or C<ps>, and
52 I<domains> is a list of guest names to act on. If no domains are
53 specified then we act on all active domains by default.
55 A I<domain> may be specified either by its name, by its ID or by its
56 UUID. Use I<virsh list> to get a list of active domain names and IDs.
58 Equivalently you can use the C<virt-mem> meta-tool with subcommands,
61 virt-mem I<program> [...]
63 The C<virt-mem> program offers additional features, such as the
64 ability to capture VM images for post-mortem analysis (see below).
68 =item B<-c uri>, B<--connect uri>
70 Connect to libvirt URI. The default is to connect to the default
71 libvirt URI, normally Xen.
75 Print the results in CSV format, suitable for importing into a
76 spreadsheet or database.
78 This option is only supported if virt-mem was built with CSV support.
82 Emit debugging information on stderr. Please supply this if you
87 Display usage summary.
89 =item B<--list-kernels>
91 List which guest kernel versions are known/supported, then exit.
93 =item B<-t memoryimage>
95 Post-mortem analysis mode.
97 Instead of checking libvirt for domain information, this runs the tool
98 directly on the memory image supplied. You may specify the B<-t>
99 option multiple times. Use the C<virt-mem capture> command to capture
102 See also the section L</"MEMORY IMAGES"> below.
106 Display version and exit.
108 =item B<-E auto|littleendian|bigendian>
110 =item B<-T auto|i386|x86-64|I<address>|I<address,min,max>>
112 =item B<-W auto|32|64>
114 These options force the endianness, text address, and word size for
115 the subsequent domains listed on the command line (or if no domains
116 are listed, then for all domains).
118 These default to I<auto> which tries to do automatic detection (using
119 libvirt, or details from the memory images themselves). You only need
120 to use these options if virt-mem tools get the automatic detection
123 Endianness (I<-E>) sets the memory endianness, for data, pointers and
124 so on. I<-E littleendian> is the endianness used on Intel i386,
125 x86-64 and (usually) IA64. I<-E bigendian> is the endianness used on
126 many RISC chips such as SPARC and PowerPC.
128 Text address (I<-T>) sets the base address and optionally min and max
129 addresses of the kernel image. I<-T i386> means to try some common
130 addresses for i386-based kernels. I<-T x86-64> means to try some
131 common addresses for x86-64-based kernels.
133 I<-T address> sets the kernel base address specifically (I<0x> prefix
134 is used to specify hex addresses). I<-T address,min,max> sets the
135 kernel base address, minimum address and maximum address.
137 Word size (I<-W>) sets the word size, 32 or 64 bits.
139 =item B<-A auto|i386|x86-64|...>
141 This option sets the architecture to one of a collection of known
142 architectures. It is equivalent to setting endianness and wordsize in
143 one go, but not text address.
149 This prints the latest kernel messages from the virtual machine, as if
150 you were logged into the machine and used L<dmesg(1)>.
154 This prints the contents of the system C<utsname> structure, similar
155 to what is printed by the L<uname(1)> command.
159 C<virt-mem> is a meta-tool which allows you to run all the commands
160 above, and provides some extra features.
162 Instead of the preceeding commands such as C<virt-dmesg> you can
167 Options and other command line arguments work the same.
169 Additional C<virt-mem> subcommands are listed below.
171 =head2 virt-mem capture -o memoryimage [-options] [domains...]
173 Capture the memory image of a virtual machine for later post-mortem
174 analysis. Use the I<-t memoryimage> option for any other virt-mem
175 tool to analyze the memory image later.
177 The I<-o memoryimage> option is required, and is used to name the
178 output file. If a single guest is captured, then the output is saved
179 in the I<memoryimage> file. However, if multiple guests are captured,
180 then their images are saved in I<memoryimage.ID> where I<ID> is
181 replaced with the domain ID.
183 See also the section L</"MEMORY IMAGES"> below.
188 f9x32kvm: Linux localhost.localdomain 2.6.24-0.155.rc7.git6.fc9 #1
189 SMP Tue Jan 15 17:52:31 EST 2008 i686 (none)
191 # virt-dmesg f9x32kvm | tail
192 <6>Bluetooth: Core ver 2.11
193 <6>NET: Registered protocol family 31
194 <6>Bluetooth: HCI device and connection manager initialized
195 <6>Bluetooth: HCI socket layer initialized
196 <6>Bluetooth: L2CAP ver 2.9
197 <6>Bluetooth: L2CAP socket layer initialized
198 <6>Bluetooth: RFCOMM socket layer initialized
199 <6>Bluetooth: RFCOMM TTY layer initialized
200 <6>Bluetooth: RFCOMM ver 1.8
201 <7>eth0: no IPv6 routers present
205 All the tools can read dumped kernel images, using the common
206 I<-t memoryimage> option. In addition you can capture memory
207 images from domains for post-mortem analysis using the
208 C<virt-mem capture> command (see above).
210 The memory images which are saved by C<virt-mem capture> contain a
211 header and some additional information about the kernel image, such as
212 architecture, original text address, and so forth. Thus these images
213 can be reanalysed just using the I<-t memoryimage> option.
215 We also support analyzing raw kernel dumps, eg. produced using the
216 L<qemu(1)> monitor's C<memsave> command. In this case however you
217 usually need to specify the original architecture, text address and
218 perhaps other details using the I<-A>, I<-T> and other command line
223 The virt-mem tools spy on the guest's memory image. There are some
224 shortcomings to this, described here.
230 Only works on specific, tested releases of Linux kernels. Support
231 for arbitrary Linux kernel versions may be patchy because of changes
232 in the internal structures used. Support for non-Linux kernels is
233 currently non-existent, and probably impossible for Windows because of
234 lack of an acceptable source license.
238 Heuristics are used which may mean in the worst case that the
243 Structures which are frequently modified may cause errors. This
244 could be a problem if, for example, the process table in the guest is
245 being rapidly updated.
249 We have to scan memory to find kernel symbols, etc., which can be
250 quite slow. Optimizing the memory scanner would help, and caching the
251 base address of the symbol table(s) would make it dramatically faster.
257 The current code tries hard to be secure against malicious guests, for
258 example guests which set up malicious kernel memory.
269 L<http://www.libvirt.org/ocaml/>,
270 L<http://www.libvirt.org/>,
271 L<http://et.redhat.com/~rjones/>,
272 L<http://caml.inria.fr/>
276 Richard W.M. Jones <rjones @ redhat . com>
280 (C) Copyright 2008 Red Hat Inc., Richard W.M. Jones
283 This program is free software; you can redistribute it and/or modify
284 it under the terms of the GNU General Public License as published by
285 the Free Software Foundation; either version 2 of the License, or
286 (at your option) any later version.
288 This program is distributed in the hope that it will be useful,
289 but WITHOUT ANY WARRANTY; without even the implied warranty of
290 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
291 GNU General Public License for more details.
293 You should have received a copy of the GNU General Public License
294 along with this program; if not, write to the Free Software
295 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
297 =head1 REPORTING BUGS
299 Bugs can be viewed on the Red Hat Bugzilla page:
300 L<https://bugzilla.redhat.com/>.
302 If you find a bug in virt-mem, please follow these steps to report it:
306 =item 1. Check for existing bug reports
308 Go to L<https://bugzilla.redhat.com/> and search for similar bugs.
309 Someone may already have reported the same bug, and they may even
312 =item 2. Capture debug and error messages
316 virt-I<program> --debug > virt-mem.log 2>&1
318 and keep I<virt-mem.log>. It contains error messages which you should
319 submit with your bug report.
321 =item 3. Get version of virt-mem and version of libvirt.
325 virt-I<program> --version
327 =item 4. Submit a bug report.
329 Go to L<https://bugzilla.redhat.com/> and enter a new bug.
330 Please describe the problem in as much detail as possible.
332 Remember to include the version numbers (step 3) and the debug
333 messages file (step 2).
335 =item 5. Assign the bug to rjones @ redhat.com
337 Assign or reassign the bug to B<rjones @ redhat.com> (without the
338 spaces). You can also send me an email with the bug number if you
339 want a faster response.