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User Contributions
Related Links
The HOWTO (html)
The HOWTO (text)
Host file access
Device inputs
Sharing filesystems
Creating filesystems
Resizing filesystems
Virtual Networking
Management Console
Kernel Debugging
UML Honeypots
gprof and gcov
Running X
Diagnosing problems
Installing Slackware
Porting UML
IO memory emulation
UML on 2G/2G hosts
Adding a UML system call
Running nested UMLs
How you can help
Kernel projects
A virtual network
An X session
A login session
A debugging session
Slackware installation
Kernel switches
Slackware README
ALS 2000 paper (html)
ALS 2000 paper (TeX)
ALS 2000 slides
LCA 2001 slides
OLS 2001 paper (html)
OLS 2001 paper (TeX)
ALS 2001 paper (html)
ALS 2001 paper (TeX)
UML security (html)
LCA 2002 (html)
WVU 2002 (html)
Security Roundtable (html)
OLS 2002 slides
LWE 2005 slides
Fun and Games
Kernel Hangman
Disaster of the Month


UML download mirrors
The UML downloads are available from a number of mirrors:
UML Mirror Location
Sourceforge CA, USA
Dartmouth ISTS Dartmouth College, Hanover, NH, USA Utrecht, The Netherlands PA, USA Cleveland OH, USA
VD-server Dusseldorf, Germany
Pacific Internet Sydney, Australia Dallas, TX, USA
Redwood Virtual Fremont, CA, USA Frankfurt/Main, Germany
Catalyst2 Telehouse Docklands, London, UK
This page will connect you to the mirror.

If you hate this new-fangled download page and want the SourceForge project download page back, click here .
The root filesystem
There are a number of bootable root filesystems available for download. They cover most of the major distributions and a number of more specialized, minor ones. They are compressed filesystem images and typically are downloads of tens of megabytes, uncompressing to several hundred megs.

If this is too large a download for you, the tomsrtbt filesystem is small enough to be reasonable for almost everyone. For its size, it provides an amazing number of tools.

Another possibility is to generate your own filesystem. There are a number of separate projects which will let you create your own filesystems from media. They are listed
here . If you're an absolute rank UML beginner, downloading one of the preinstalled filesystems is the better way to go.

Antoine Martin has made a number of UML filesystems and kernel images available here . These are more up to date than what's listed here, so I'd recommend getting one of his.

This list contains a sample of the most popular filesystem images. To see the full selection, click the the "whole list" link at the bottom of the table.

Filesystems File Type : bzipped ext2 filesystem image
Name Release Date Download Size (bytes)
root_fs_slack8.1.bz2 Apr 4 2003 15844807
Changelog Released by : jdike Mar 24 2002 59981981
Changelog Released by : jdike Mar 24 2002 172424097
Changelog Released by : jdike
root_fs_toms1.7.205.bz2 Mar 18 2002 1488703
Changelog Released by : jdike
root_fs.rh-7.2-full.pristine.20020312.bz2 Mar 12 2002 175597416
Changelog Released by : jdike
root_fs.rh-7.2-server.pristine.20020312.bz2 Mar 12 2002 64164735
Changelog Released by : jdike
root_fs.co60.pristine.bz2 Jul 6 2001 77677468
Changelog Released by : jdike
Debian-3.0r0.ext2.bz2 Mar 27 2003 23106438
Changelog Released by : jdike
The whole list

Jail filesystems
These are filesystems which boot up UML with exactly one service for the purpose of jailing that service (along with any unfriendly outsiders who manage to break into it).

Currently, we have only a DNS filesystem from Chris Reahard. See his
description for what's in it and how to use it. More contributions are welcome.
Jail filesystems File Type : bzipped ext2 filesystem image
Name Release Date Download Size (bytes)
jail_dns-0.3.bz2 Oct 23 2001 4122297
Changelog Released by : jdike
The whole list

UML utilities
If you are going to grab the standalone kernel or patch below, you want to pay attention to this section. Otherwise, if you install the RPM or deb, you can ignore it, since these utilities come with the packages.

This is a tarball of the sources for the UML utilities
Build and install them with
make all
make install DESTDIR=/
from the top level directory.

Ocassionally, a new UML needs a new version of one of the utilities. So, if you don't install one of the packages, you should check the changelog to see if you need anything new, and, if so, grab, build, and install the tools from the tarball.
UML Utilities File Type : bzipped source tarball
Name Release Date Download Size (bytes)
uml_utilities_20040406.tar.bz2 Apr 7 2004 60201
Changelog Released by : jdike
uml_utilities_20040114.tar.bz2 Jan 15 2004 58557
Changelog Released by : jdike
uml_utilities_20030903.tar.bz2 Sep 3 2003 55790
Changelog Released by : jdike
The whole list

The bare kernel
If you don't want to grab one of the packages, you can download the precompiled kernel binary. In this case, it's up to you to make sure you have the userspace tools you'll need, and to make sure that they are up to date with the kernel, since they change occasionally.

Also, see where Bill Stearns is putting the UML kernels that he builds, along with their map files.
Kernels File Type : bzipped ELF binary
Name Release Date Download Size (bytes)
linux-2.4.19-5.bz2 Sep 16 2002 802781
Changelog Released by : jdike
The whole list

The UML test suite
This is the brand-new UML test suite. The main driver is, which uses the Perl modules and UML/*.pm. The tests themselves are located under tests. Configuration is done in And that's all the documentation which exists at the moment.
Test Suite File Type : bzipped tarball
Name Release Date Download Size (bytes)
uml_tests_20040726.tar.bz2 Jul 27 2004 19896
Changelog Released by : jdike
uml_tests_20020821.tar.bz2 Aug 21 2002 19647
Changelog Released by : jdike
uml_tests_20020805.tar.bz2 Aug 5 2002 19770
Changelog Released by : jdike
The whole list

Building from source
If you want to build UML from source, you can get the patch here; you could also download the 2.4 ac tree, which has UML in it already, but now it's no more up-to-date. The patch that's available from here applies against the appropriate Linus pool. It will also likely apply against nearby kernels, including his pre-patches, but there are no guarantees. See this page for more detailed instructions for building UML from source.

Again, if you go this route, you need to make sure that you have the tools you'll need to fully use UML.

The patch is updated most frequently. I will release a patch for every CVS update. These patches are named uml-patch-2.4.x-y.bz2. If you want the latest UML, the latest of these patches is what you should get.

Here are the 2.4 patches. If you're using the 2.4 kernel because you think it's more stable, then this is the list you want.
Patches File Type : bzipped patch
Name Release Date Download Size (bytes)
uml-patch-2.4.27-1.bz2 Nov 10 2004 206975
Changelog Released by : jdike
uml-patch-2.4.26-3.bz2 Aug 12 2004 206477
Changelog Released by : jdike
uml-patch-2.4.26-2.bz2 Jul 16 2004 205440
Changelog Released by : jdike
uml-patch-2.4.26-1.bz2 May 13 2004 204818
Changelog Released by : jdike
uml-patch-2.4.25-1.bz2 May 13 2004 205023
Changelog Released by : jdike
The whole list

These are the 2.6 patches, for 2.6 kernels earlier than 2.6.9; starting from that version, an up-to-date UML is included in the kernel itself, so you might probably use an unpatched 2.6 kernel to build UML.

Also, these days, probably UML for Linux/2.6 is updated more frequently and is stabler than UML for Linux/2.4 (it may be different for you, it can depend a lot on your setup).

However, you can always use the 2.4 patches.

If you need to get some later bugfixes / UML patches for 2.6.9 and later kernels, you can check out on the home page of Paolo Giarrusso, also known as Blaisorblade:
Patches File Type : bzipped patch
Name Release Date Download Size (bytes)
uml-patch- Aug 19 2004 142306
Changelog Released by : jdike
uml-patch-2.6.7-2.bz2 Aug 18 2004 126499
Changelog Released by : jdike
uml-patch-2.6.7-1.bz2 Jul 27 2004 127048
Changelog Released by : jdike
uml-patch-2.6.6-1.bz2 May 22 2004 104357
Changelog Released by : jdike
uml-patch-x86-64-2.6.4.bz2 May 1 2004 64090
Changelog Released by : jdike
The whole list

Host skas patches
These are the patches that need to be applied to the host in order for UML's new skas mode to work. A given version of UML will look for a specific skas patch and fall back to tt mode if it's not there. The bootup message will tell you which version it's looking for in case you're not sure.

These are all against stock 2.4.19, except for the RH one, which is against the stock RH8 kernel. They are fairly non-intrusive, so they apply fairly cleanly to any related kernels, and especially to stock kernels until release 2.4.24.

As of 2.4.25, this patch revision does not apply any more to the Linux kernel. Also, you need a different patch for 2.6. You can find both ones on the home page of Paolo Giarrusso, also known as Blaisorblade:
Host SKAS Patches File Type : patch
Name Release Date Download Size (bytes)
host-skas3-2.6.7-v1.patch Jun 17 2004 15957
Changelog Released by : blaisorb
host-skas3-2.6.6-v1.patch May 11 2004 16182
Changelog Released by : blaisorb
host-skas3-2.4.25.patch Apr 30 2004 15721
Changelog Released by : blaisorb
host-skas3-2.6.3-v1.patch Feb 29 2004 16126
Changelog Released by : blaisorb
host-skas3a-RH8.patch Sep 4 2003 18424
Changelog Released by : jdike
The whole list

Host devanon patches
This patches implement /dev/anon in the host. /dev/anon is a driver from which UML can map its physical memory and which has some advantages over tmpfs or other filesystems because it can free host memory when it's not needed. However, currently this patch is not well supported, and has shown to cause some stability problems. It will be revived in the future, however.
/dev/anon patches File Type : patch
Name Release Date Download Size (bytes)
devanon-2.4.23.patch Jan 12 2004 8071
Changelog Released by : jdike
devanon-RH8.patch Jan 12 2004 7991
Changelog Released by : jdike
The whole list

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