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.