X-Git-Url: http://git.annexia.org/?p=virt-mem.git;a=blobdiff_plain;f=virt-mem.txt;h=119ede4c19ccc2e98f6961ec384de2636b6ce3aa;hp=a8ab3dc82e3194c01322028111ec54307adb541a;hb=e4a9a58795f30b85fd965e6584ca73d7b0a812f8;hpb=9414deeb6210c5f2c5219c6e99eb329b4bb1be26 diff --git a/virt-mem.txt b/virt-mem.txt index a8ab3dc..119ede4 100644 --- a/virt-mem.txt +++ b/virt-mem.txt @@ -1,20 +1,21 @@ NAME - virt-df - 'df'-like utility for virtualization stats + virt-uname - system information for virtual machines + + virt-dmesg - print kernel messages for virtual machines SUMMARY - virt-df [-options] + virt-uname [-options] [domains...] -DESCRIPTION - virt-df is a df(1)-like utility for showing the actual disk usage of - guests. Many command line options are the same as for ordinary *df*. + virt-dmesg [-options] [domains...] - It uses libvirt so it is capable of showing stats across a variety of - different virtualization systems. +DESCRIPTION + These virtualization tools allow you to inspect the status of virtual + machines running Linux. -OPTIONS - -a, --all - Show all domains. The default is show only running (active) domains. + The tools all use libvirt so are capable of showing stats across a + variety of different virtualization systems. +COMMON OPTIONS -c uri, --connect uri Connect to libvirt URI. The default is to connect to the default libvirt URI, normally Xen. @@ -23,72 +24,96 @@ OPTIONS Print the results in CSV format, suitable for importing into a spreadsheet or database. - This option is only supported if virt-df was built with CSV support. + 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. - -h, --human-readable - Display human-readable sizes (eg. "10GiB" instead of large numbers). - - -i, --inodes - Display inode information. - - This option only works for Unix-like filesystems. - --help Display usage summary. - -t diskimage + -t memoryimage Test mode. Instead of checking libvirt for domain information, this - runs virt-df directly on the disk image (or device) supplied. You + runs the virt-mem tool directly on the memory image supplied. You may specify the -t option multiple times. --version Display version and exit. -EXAMPLE - # virt-df - Filesystem 1K-blocks Used Available Type - f9x32kvm:hda1 190740 24817 165923 Linux ext2/3 - f9x32kvm:VolGroup/LogVol00 6568348 3401656 3166692 Linux ext2/3 - f9x32kvm:VolGroup/LogVol01 1015808 Linux swap + -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 - virt-df spies on the guest's disk image to try to work out how much disk - space it is actually using. There are some shortcomings to this, - described here. - - (1) It only understands a limited set of partition types. Assuming that - the files and partitions that we get back from libvirt / Xen correspond - to block devices in the guests, we can go some way towards manually - parsing those partitions to find out what they contain. We can read the - MBR, LVM, superblocks and so on. However that's a lot of parsing work, - and currently there is no library which understands a wide range of - partition schemes and filesystem types (not even libparted which doesn't - support LVM yet). The Linux kernel does support that, but there's not - really any good way to access that work. - - The current implementation uses a hand-coded parser which understands - some formats (MBR, LVM2, ext2/3, DOS FAT, Windows NTFS, Linux swap and - Linux suspend partitions). - - (2) The statistics you get are delayed. The real state of, for example, - an ext2 filesystem is only stored in the memory of the guest's kernel. - The ext2 superblock contains some meta-information about blocks used and - free, but this superblock is not up to date. In fact the guest kernel - may not update it even on a 'sync', not until the filesystem is - unmounted. Some operations do appear to write the superblock, for - example fsync(2) [that is my reading of the ext2/3 source code at - least]. + 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 disk partitions. + example guests which set up malicious kernel memory. SEE ALSO - df(1), virsh(1), xm(1), , + uname(1),dmesg(1), virsh(1), xm(1), , , , @@ -96,8 +121,7 @@ AUTHORS Richard W.M. Jones COPYRIGHT - (C) Copyright 2007-2008 Red Hat Inc., Richard W.M. Jones - http://libvirt.org/ + (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 @@ -117,7 +141,7 @@ REPORTING BUGS Bugs can be viewed on the Red Hat Bugzilla page: . - If you find a bug in virt-df, please follow these steps to report it: + 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. @@ -127,15 +151,15 @@ REPORTING BUGS 2. Capture debug and error messages Run - virt-df --debug > virt-df.log 2>&1 + virt-[program] --debug > virt-mem.log 2>&1 - and keep *virt-df.log*. It contains error messages which you should + and keep *virt-mem.log*. It contains error messages which you should submit with your bug report. - 3. Get version of virt-df and version of libvirt. + 3. Get version of virt-mem and version of libvirt. Run - virt-df --version + virt-[program] --version 4. Submit a bug report. Go to and enter a new bug. Please