uses.html 23.2 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
    "http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<head>
   <meta content="text/html; charset=iso-8859-1" http-equiv="Content-Type">
<title>What it's good for</title>
</head>
<body alink="#FF0000" vlink="#55188A" link="#0000EF" bgcolor="#FFFFFF" text="#000099">
<table border="0">
<tr align="left">
<td valign="top">
<table border="0">

<tr align="left"><td valign="top" >
<img src="http://user-mode-linux.sourceforge.net/uml-small.png" height="171" width="120"/> 
</td></tr>

<tr align="left"><td valign="top" bgcolor="#e0e0e0">
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/index.html">Site Home Page</a></font>
<br>
              <font size="-1"><a href="http://uml.harlowhill.com">The UML Wiki</a></font>
<br>
              <font size="-1"><a href="http://usermodelinux.org">UML Community Site</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/roadmap.html">The UML roadmap</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/uses.html">What it's good for</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/case-studies.html">Case Studies</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/kernel.html">Kernel Capabilities</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/dl-sf.html">Downloading it</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/run.html">Running it</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/compile.html">Compiling</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/install.html">Installation</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/skas.html">Skas Mode</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/patches.html">Incremental Patches</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/tests.html">Test Suite</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/devanon.html">Host memory use</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/fs_making.html">Building filesystems</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/faq.html">Troubles</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/contrib.html">User Contributions</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/links.html">Related Links</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/todo.html">The ToDo list</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/projects.html">Projects</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/diary.html">Diary</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/thanks.html">Thanks</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/contacts.html">Contacts</a></font>
</td></tr>

<tr align="left"><td valign="top" bgcolor="#e0e0e0">Tutorials<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/UserModeLinux-HOWTO.html">The HOWTO (html)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/UserModeLinux-HOWTO.txt">The HOWTO (text)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/hostfs.html">Host file access</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/input.html">Device inputs</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/shared_fs.html">Sharing filesystems</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/fs.html">Creating filesystems</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/resize.html">Resizing filesystems</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/networking.html">Virtual Networking</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/mconsole.html">Management Console</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/debugging.html">Kernel Debugging</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/honeypots.html">UML Honeypots</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/gprof.html">gprof and gcov</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/xtut.html">Running X</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/trouble.html">Diagnosing problems</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/config.html">Configuration</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slack_readme.html">Installing Slackware</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/arch-port.html">Porting UML</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/iomem.html">IO memory emulation</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/2G-2G.html">UML on 2G/2G hosts</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/lksct/index.html">Adding a UML system call</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/nesting.html">Running nested UMLs</a></font>
</td></tr>

<tr align="left"><td valign="top" bgcolor="#e0e0e0">How you can help<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/help-gen.html">Overview</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/help-doc.html">Documentation</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/help-userspace.html">Utilities</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/help-kernel-v1.html">Kernel bugs</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/projects.html">Kernel projects</a></font>
</td></tr>

<tr align="left"><td valign="top" bgcolor="#e0e0e0">Screenshots<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/net.html">A virtual network</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/x.html">An X session</a></font>
</td></tr>

<tr align="left"><td valign="top" bgcolor="#e0e0e0">Transcripts<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/login.html">A login session</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/debug-session.html">A debugging session</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slackinst.html">Slackware installation</a></font>
</td></tr>

<tr align="left"><td valign="top" bgcolor="#e0e0e0">Reference<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/switches.html">Kernel switches</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slack_readme.html">Slackware README</a></font>
</td></tr>

<tr align="left"><td valign="top" bgcolor="#e0e0e0">Papers<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2000/index.html">ALS 2000 paper (html)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2000.tex">ALS 2000 paper (TeX)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/als2000/slides.html">ALS 2000 slides</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lca2001/lca.html">LCA 2001 slides</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ols2001/index.html">OLS 2001 paper (html)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/ols2001.tex">OLS 2001 paper (TeX)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2001/index.html">ALS 2001 paper (html)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/als2001.tex">ALS 2001 paper (TeX)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ists2002/umlsec.htm">UML security (html)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lca2002/lca2002.htm">LCA 2002 (html)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/wvu2002/wvu2002.htm">WVU 2002 (html)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ists_rt/ists_rt.htm">Security Roundtable (html)</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/ols2002/ols2002.html">OLS 2002 slides</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/slides/lwe2005/LWE2005.html">LWE 2005 slides</a></font>
</td></tr>

<tr align="left"><td valign="top" bgcolor="#e0e0e0">Fun and Games<br>
<font size="-1"><a href="http://user-mode-linux.sourceforge.net/cgi-bin/hangman">Kernel Hangman</a></font>
<br>
              <font size="-1"><a href="http://user-mode-linux.sourceforge.net/sdotm.html">Disaster of the Month</a></font>
</td></tr>

</table>
</td>
<td valign="top" align="left">

<center>
            <h3>What are people using it for?</h3>
          </center>

<a name="Virtual hosting"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Virtual hosting</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Virtual hosting">
UML can run basically anything that the host can, so it's possible to
split a physical system into a bunch of independent virtual machines.
Some examples:
<ul>
<li>
<a href="http://davidcoulson.net">David Coulson</a> is
running an entire network of UMLs, the public face of which is 
<a href="http://usermodelinux.org">
usermodelinux.org</a>, which is running in one of them.  He has
written an paper on his adventures 
<a href="http://uml.openconsultancy.com/">here</a>.
He also has a nice UML monitoring and control daemon which we intend
to steal and use for umlcoop.org.  Information about that can be found 
<a href="http://uml.openconsultancy.com/umld/client.php">
here</a>.
</li>
<li>
I've mirrored this site and the UML downloads in a 
<a href="http://jdike.stearns.org/uml/index.html">UML</a>
running on a UML server set up by Bill Stearns.
</li>

<li>
There are a number of commercial UML hosting providers now.  These are
the ones that I'm aware of:
<ul>

<li>
<a href="http://www.kspei.com/">kspei.com</a>
</li>

<li>
<a href="http://www.vd-server.de">vd-server.de</a>
</li>

<li>
<a href="http://www.linuxvds.com">LinuxVDS.com</a>
</li>

<li>
<a href="http://www.bytemark-hosting.co.uk/">
Bytemark Hosting
</a>
</li>

<li>
<a href="http://rimuhosting.com">
Rimu Hosting
</a>
</li>

<li>
<a href="http://www.memset.com">
memset
</a>
</li>

<li>
<a href="http://www.linode.com">
Linode.com
</a>
</li>

<li>
<a href="http://hosting.tummy.com">
tummy.com, ltd. Hosting Services
</a>
</li>

<li>
<a href="http://jvds.com">
jvds.com
</a>
</li>

<li>
<a href="http://www.tektonic.net">
TekTonic Network Solutions
</a>
</li>

<li>
<a href="http://vps.pigscanfly.ca">
Pigs Can Fly Computing
</a>
</li>

<li>
<a href="http://www.exodus.ro/?dedicated">
Exodus Internet Services
</a>
</li>

<li>
<a href="http://www.redwoodvirtual.com">
Redwood Virtual
</a>
</li>

<li>
<a href="http://www.virtual-server.net/">
Virtual-Server.NET
</a>
</li>

<li>
<a href="http://www.edis.at/neu/vrs_server.shtml">
Edis
</a>
</li>

<li>
<a href="http://www.usermodelinux.de/">
usermodelinux.de
</a>
</li>

<li>
<a href="http://thelizard.com/uml/">
The Packardt Imaging</a>
</li>

<li>
<a href="http://umlhosting.ch/">meisterwerk</a>
</li>

<li>
<a href="http://www.coherenthosting.com/">
Coherent Hosting
</a>
</li>

<li>
<a href="http://mythic-beasts.com/vds.html">
Mythic Beasts
</a>
</li>

<li>
<a href="http://debian.co.jp">
debian.co.jp
</a>
</li>

<li>
<a href="http://www.easylinehost.net">
Easylinehost
</a>
</li>

<li>
<a href="http://www.server-ranch.ch">
Server-Ranch.ch
</a>
</li>

<li>
<a href="http://www.quantact.com">
Quantact
</a>
</li>

<li>
<a href="http://vpsland.com">
VPSLAND.com
</a>
</li>

<li>
<a href="http://vps.ispbrasil.com.br">
ISPBrasil
</a>
</li>

<li>
<a href="http://eTecc.net/vds.php">
eTecc.net
</a>
</li>

<li>
<a href="http://www.budgetdedicated.com/">
BudgetDedicated.com
</a>
</li>

<li>
<a href="http://www.web-solutions.de/produkte/umlserver.php">
Giga Codes Web-Solutions
</a>
</li>

</ul>
</li>
</ul>

</blockquote>
 
<a name="Kernel development and debugging"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Kernel development and debugging</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Kernel development and debugging">
This kernel allows developers to write and debug
code using the normal process-level tools, like gdb, gprof, and gcov.
Also, developers who are away from their normal environment can carry
on development, using a UML virtual machine as their kernel testing box.
There is more information here on 
<a href="compile.html">building</a> this kernel
from source and <a href="debugging.html">debugging
</a> it, plus a 
<a href="debug-session.html">debugging session
transcript</a>.
<p>
The eXtreme Programming methodology says that testing should be run
frequently, and automatically.  This can be hard to do with kernel
code, but UML makes this just another set of processes. The Linux
FreeSWAN team is using FreeSWAN enabled User-Mode-Linux to do nightly
testing of IPsec and DNSsec code.  This is run nightly, the results of
which is regularly published.
</blockquote>

<a name="Process debugging"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Process debugging</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Process debugging">
Perhaps surprisingly, UML is also occasionally useful for debugging
user-level processes.  Ever get a odd error from a system call and
have no idea why it's happening, either because there are a dozen
reasons that errno could be returned and the documentation doesn't
list the one you're hitting or, according to the documentation, the
errno is completely inexplicable?  Well, fire up UML, set a breakpoint
on the system call in question, run your program, and you'll see very
quickly why it's failing.
</blockquote>

<a name="Safely playing with the latest kernels"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Safely playing with the latest kernels</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Safely playing with the latest kernels">
Since the user-mode kernel is not running directly
on the hardware, it has no access to it unless you provide it.  So,
if the kernel contains any nasty bugs, like file corruption bugs, it
can't hurt any data that you care about.
</blockquote>

<a name="Trying out new distributions"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Trying out new distributions</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Trying out new distributions">
Its filesystems are contained in files in the underlying filesystem,
so any time you want to boot a new distribution, you only need to
dedicate a file to it, not an entire disk partition.  The 
 <a href="http://sourceforge.net/project/showfiles.php?group_id=429 ">project download page</a>  has a number of
ready-to-go root filesystems loaded with various distributions,
including SuSE, Slackware, Debian, and Red Hat. 
</blockquote>

<a name="Education"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Education</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Education">
UML is a great teaching tool, especially in courses where students
need a dedicated machine in order to get the most out of it.  I know
that UML is being used to teach OS development, network
administration, and more general system administration.  These are all
cases where having a virtual machine to practice on is far more
convenient for everyone than using physical boxes.
<p>
I know of a number of universities which are running courses on OS
internals and networking using UMLs.  There is also a company 
<a href="http://www.useractive.com/demo">offering</a> 
Linux system administration courses inside UMLs.  Also see the
<a href="http://linux.oreilly.com/news/useractive_0502.html">O'Reilly</a> 
and 
<a href="http://usermodelinux.org/modules.php?name=News&file=article&sid=13&mode=&order=0&thold=0">
usermodelinux.org</a> stories on this.
</blockquote>

<a name="Experimental development"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Experimental development</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Experimental development">
The kernel runs in a virtual machine that can be configured in ways
that your physical machine can't. It can have more memory, more
devices, and, soon, more processors. So you can do development and
testing of hardware capabilities even when you don't have the relevant
hardware. 
</blockquote>

<a name="Poking around inside a running system"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Poking around inside a running system</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Poking around inside a running system">
Since you have a full OS running outside UML, it's pretty easy for the
terminally curious to find ways of looking inside this kernel that are
impossible for a native kernel. 
</blockquote>

<a name="As a secure sandbox or jail"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">As a secure sandbox or jail</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="As a secure sandbox or jail">
Processes inside the user-mode kernel have no access to the hosting
machine or to the outside world that's not explicitly provided.  So, a
malicious application running inside it can do no harm to anything
that matters.
</blockquote>

<a name="Virtual networking"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Virtual networking</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Virtual networking">
UML virtual machines are networkable, to each other, to the host, and
to other physical machines.  So, UML can be used to set up a virtual
network that allows setting up and testing of experimental services.
See the <a href="networking.html">networking</a> 
tutorial and <a href="net.html">virtual network 
screenshot</a> for more information. 
</blockquote>

<a name="As a test environment"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">As a test environment</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="As a test environment">
Testing of some types of software requires booting up a machine.  With
UML, this can be very easily automated.  There is a small test harness
 <a href="http://sourceforge.net/project/showfiles.php?group_id=429 ">available</a> , consisting of a small perl module 
implementing a UML object which provides methods to boot a virtual
machine, log in to it, run commands, and shut it down.
</blockquote>

<a name="Disaster recovery practice"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">Disaster recovery practice</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="Disaster recovery practice">
Do you know what you would do if your machine suddenly didn't boot one
day?  With UML, you can set up virtual disasters and practice
recovering from them.  This doesn't have to be serious business - it
can also be fun.  Ever wonder what happens when you run 
<blockquote>
              <tt>
                <font color="#000000" where="UML">UML# rm -rf /</font>
              </tt>
            </blockquote> 
but been afraid to try it?  Now you can with impunity.
</blockquote>

<a name="A Linux environment for other operating systems"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">A Linux environment for other operating systems</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="A Linux environment for other operating systems">
This is more a potential use, since UML only runs on Linux right now.
But once it's ported to another OS, it is a completely authentic Linux
environment - it will run any Linux executable.  This would be an
interesting shortcut for an OS vendor looking for Linux binary compatibility.
<br>
See the <a href="projects.html">projects</a> page for more information on
porting UML to other operating systems.
</blockquote>

<a name="It doesn't need to be good for anything.  It's fun!"/><table width="100%" bgcolor="#e0e0e0">
            <tr>
              <td>
                <b>
                  <font color="black">It doesn't need to be good for anything.  It's fun!</font>
                </b>
              </td>
            </tr>
          </table>
          <blockquote head="It doesn't need to be good for anything.  It's fun!"></blockquote>


</td>
</tr>
</table>

<center>
<font size="-1">Hosted at </font>
    <a href="http://sourceforge.net">
    <img src="http://sourceforge.net/sflogo.php?group_id=429" width="88" height="31" border="0" alt="SourceForge Logo">
    </a>
</center>
</body>
</html>