NAME
virt-uname - system information for virtual machines
virt-dmesg - print kernel messages for virtual machines
SUMMARY
virt-uname [-options] [domains...]
virt-dmesg [-options] [domains...]
DESCRIPTION
These virtualization tools allow you to inspect the status of virtual
machines running Linux.
The tools all use libvirt so are capable of showing stats across a
variety of different virtualization systems.
COMMON OPTIONS
Each command obeys a common set of options. The general form is:
virt-*program* [-options] [domains...]
where *domains* is a list of guest names to act on. If no domains are
specified then we act on all active domains by default.
A *domain* may be specified either by its name or by its ID. Use *virsh
list* to get a list of active domain names and IDs.
The virt-mem tools do not work on domains which are not active (running
or paused). eg. They do not work on shut down domains.
-c uri, --connect uri
Connect to libvirt URI. The default is to connect to the default
libvirt URI, normally Xen.
--csv
Print the results in CSV format, suitable for importing into a
spreadsheet or database.
This option is only supported if virt-mem was built with CSV
support.
--debug
Emit debugging information on stderr. Please supply this if you
report a bug.
--help
Display usage summary.
-t memoryimage
Test mode. Instead of checking libvirt for domain information, this
runs the virt-mem tool directly on the memory image supplied. You
may specify the -t option multiple times.
--version
Display version and exit.
-E auto|littleendian|bigendian
-T auto|i386|x86-64|*address*
-W auto|32|64
These options force the endianness, text address, and word size for
the subsequent domains listed on the command line (or if no domains
are listed, then for all domains).
These default to *auto* which tries to do automatic detection (using
libvirt, or details from the memory images themselves). You only
need to use these options if virt-mem tools get the automatic
detection wrong.
Endianness (*-E*) sets the memory endianness, for data, pointers and
so on.
Text address (*-T*) sets the base address of the kernel image. *-T
i386* means to try some common addresses for i386-based kernels. *-T
x86-64* means to try some common addresses for x86-64-based kernels.
*-T *address** sets the address specifically (*0x* prefix is allowed
to specify hex addresses).
Word size (*-W*) sets the word size, 32 or 64 bits.
-A auto|i386|x86-64|...
This option sets the architecture to one of a collection of known
architectures. It is equivalent to setting endianness and wordsize
in one go, but not text address.
EXAMPLES
# virt-uname
f9x32kvm: Linux localhost.localdomain 2.6.24-0.155.rc7.git6.fc9 #1
SMP Tue Jan 15 17:52:31 EST 2008 i686 (none)
# virt-dmesg f9x32kvm | tail
<6>Bluetooth: Core ver 2.11
<6>NET: Registered protocol family 31
<6>Bluetooth: HCI device and connection manager initialized
<6>Bluetooth: HCI socket layer initialized
<6>Bluetooth: L2CAP ver 2.9
<6>Bluetooth: L2CAP socket layer initialized
<6>Bluetooth: RFCOMM socket layer initialized
<6>Bluetooth: RFCOMM TTY layer initialized
<6>Bluetooth: RFCOMM ver 1.8
<7>eth0: no IPv6 routers present
SHORTCOMINGS
The virt-mem tools spy on the guest's memory image. There are some
shortcomings to this, described here.
(1) Only works on specific, tested releases of Linux kernels. Support
for arbitrary Linux kernel versions may be patchy because of changes in
the internal structures used. Support for non-Linux kernels is currently
non-existent, and probably impossible for Windows because of lack of an
acceptable source license.
(2) Heuristics are used which may mean in the worst case that the output
is wrong.
(3) Structures which are frequently modified may cause errors. This
could be a problem if, for example, the process table in the guest is
being rapidly updated.
(4) We have to scan memory to find kernel symbols, etc., which can be
quite slow. Optimizing the memory scanner would help, and caching the
base address of the symbol table(s) would make it dramatically faster.
SECURITY
The current code tries hard to be secure against malicious guests, for
example guests which set up malicious kernel memory.
SEE ALSO
uname(1), dmesg(1), virsh(1), xm(1), ,
, ,
AUTHORS
Richard W.M. Jones
COPYRIGHT
(C) Copyright 2008 Red Hat Inc., Richard W.M. Jones http://libvirt.org/
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.
REPORTING BUGS
Bugs can be viewed on the Red Hat Bugzilla page:
.
If you find a bug in virt-mem, please follow these steps to report it:
1. Check for existing bug reports
Go to and search for similar bugs.
Someone may already have reported the same bug, and they may even
have fixed it.
2. Capture debug and error messages
Run
virt-*program* --debug > virt-mem.log 2>&1
and keep *virt-mem.log*. It contains error messages which you should
submit with your bug report.
3. Get version of virt-mem and version of libvirt.
Run
virt-*program* --version
4. Submit a bug report.
Go to 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).
5. Assign the bug to rjones @ redhat.com
Assign or reassign the bug to rjones @ redhat.com (without the
spaces). You can also send me an email with the bug number if you
want a faster response.