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
|
<!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>Host file access</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 width="120" height="171" src="uml-small.png">
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">
<font size="-1"><a href="index.html">Site Home Page</a></font>
<br>
<font size="-1"><a href="uses.html">What it's good for</a></font>
<br>
<font size="-1"><a href="case-studies.html">Case Studies</a></font>
<br>
<font size="-1"><a href="kernel.html">Kernel Capabilities</a></font>
<br>
<font size="-1"><a href="dl-sf.html">Downloading it</a></font>
<br>
<font size="-1"><a href="run.html">Running it</a></font>
<br>
<font size="-1"><a href="compile.html">Compiling</a></font>
<br>
<font size="-1"><a href="install.html">Installation</a></font>
<br>
<font size="-1"><a href="fs_making.html">Building filesystems</a></font>
<br>
<font size="-1"><a href="faq.html">Troubles</a></font>
<br>
<font size="-1"><a href="contrib.html">User Contributions</a></font>
<br>
<font size="-1"><a href="links.html">Related Links</a></font>
<br>
<font size="-1"><a href="todo.html">The ToDo list</a></font>
<br>
<font size="-1"><a href="projects.html">Projects</a></font>
<br>
<font size="-1"><a href="diary.html">Diary</a></font>
<br>
<font size="-1"><a href="thanks.html">Thanks</a></font>
<br>
<font size="-1"><a href="contacts.html">Contacts</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Tutorials<br>
<font size="-1"><a href="UserModeLinux-HOWTO.html">The HOWTO (html)</a></font>
<br>
<font size="-1"><a href="UserModeLinux-HOWTO.txt">The HOWTO (text)</a></font>
<br>
<font size="-1"><a href="hostfs.html">Host file access</a></font>
<br>
<font size="-1"><a href="input.html">Device inputs</a></font>
<br>
<font size="-1"><a href="shared_fs.html">Sharing filesystems</a></font>
<br>
<font size="-1"><a href="fs.html">Creating filesystems</a></font>
<br>
<font size="-1"><a href="networking.html">Virtual Networking</a></font>
<br>
<font size="-1"><a href="mconsole.html">Management Console</a></font>
<br>
<font size="-1"><a href="debugging.html">Kernel Debugging</a></font>
<br>
<font size="-1"><a href="gprof.html">gprof and gcov</a></font>
<br>
<font size="-1"><a href="xtut.html">Running X</a></font>
<br>
<font size="-1"><a href="trouble.html">Diagnosing problems</a></font>
<br>
<font size="-1"><a href="config.html">Configuration</a></font>
<br>
<font size="-1"><a href="slack_readme.html">Installing Slackware</a></font>
<br>
<font size="-1"><a href="arch-port.html">Porting UML</a></font>
<br>
<font size="-1"><a href="iomem.html">IO memory emulation</a></font>
<br>
<font size="-1"><a href="2G-2G.html">UML on 2G/2G hosts</a></font>
<br>
<font size="-1"><a href="lksct/index.html">Adding a UML system call</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">How you can help<br>
<font size="-1"><a href="help-gen.html">Overview</a></font>
<br>
<font size="-1"><a href="help-doc.html">Documentation</a></font>
<br>
<font size="-1"><a href="help-userspace.html">Utilities</a></font>
<br>
<font size="-1"><a href="help-kernel-v1.html">Kernel bugs</a></font>
<br>
<font size="-1"><a href="projects.html">Kernel projects</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Screenshots<br>
<font size="-1"><a href="net.html">A virtual network</a></font>
<br>
<font size="-1"><a href="x.html">An X session</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Transcripts<br>
<font size="-1"><a href="login.html">A login session</a></font>
<br>
<font size="-1"><a href="debug-session.html">A debugging session</a></font>
<br>
<font size="-1"><a href="slackinst.html">Slackware installation</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Reference<br>
<font size="-1"><a href="switches.html">Kernel switches</a></font>
<br>
<font size="-1"><a href="slack_readme.html">Slackware README</a></font>
</td></tr>
<tr align="left"><td valign="top" bgcolor="#e0e0e0">Papers<br>
<font size="-1"><a href="als2000/index.html">ALS 2000 paper (html)</a></font>
<br>
<font size="-1"><a href="als2000.tex">ALS 2000 paper (TeX)</a></font>
<br>
<font size="-1"><a href="slides/als2000/slides.html">ALS 2000 slides</a></font>
<br>
<font size="-1"><a href="slides/lca2001/lca.html">LCA 2001 slides</a></font>
<br>
<font size="-1"><a href="slides/ols2001/index.html">OLS 2001 paper (html)</a></font>
<br>
<font size="-1"><a href="ols2001.tex">OLS 2001 paper (TeX)</a></font>
<br>
<font size="-1"><a href="als2001/index.html">ALS 2001 paper (html)</a></font>
<br>
<font size="-1"><a href="als2001.tex">ALS 2001 paper (TeX)</a></font>
<br>
<font size="-1"><a href="slides/ists2002/umlsec.htm">UML security (html)</a></font>
<br>
<font size="-1"><a href="slides/lca2002/lca2002.htm">LCA 2002 (html)</a></font>
<br>
<font size="-1"><a href="slides/wvu2002/wvu2002.htm">WVU 2002 (html)</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="sdotm.html">Disaster of the Month</a></font>
</td></tr>
</table>
</td>
<td valign="top" align="left">
<center>
<h3>Host file access</h3>
</center>
If you want to access files on the host machine from inside UML, you
can treat it as a separate machine and either nfs mount directories
from the host or copy files into the virtual machine with scp or rcp.
However, since UML is running on the the host, it can access those
files just like any other process and make them available inside the
virtual machine without needing to use the network.
<p>
This is now possible with the hostfs virtual filesystem. With it, you
can mount a host directory into the UML filesystem and access the
files contained in it just as you would on the host.
<a name="Using hostfs"/><table width="100%" bgcolor="#e0e0e0">
<tr>
<td>
<b>
<font color="black">Using hostfs</font>
</b>
</td>
</tr>
</table>
<blockquote head="Using hostfs">
To begin with, make sure that hostfs is available inside the virtual
machine with <blockquote>
<tt>
<font color="#000000">cat /proc/filesystems</font>
</tt>
</blockquote> hostfs should
be listed. If it's not, either rebuild the kernel with hostfs
configured into it or make sure that hostfs is built as a module and
available inside the virtual machine, and insmod it.
<p>
Now all you need to do is run mount:
<blockquote>
<tt>
<font color="#000000">mount none /mnt/host -t hostfs</font>
</tt>
</blockquote>
will mount the host's / on the virtual machine's /mnt/host.
<p>
If you don't want to mount the host root directory, then you can
specify a subdirectory to mount with the -o switch to mount:
<blockquote>
<tt>
<font color="#000000">mount none /mnt/home -t hostfs -o /home</font>
</tt>
</blockquote>
will mount the hosts's /home on the virtual machine's /mnt/home.
</blockquote>
<a name="hostfs as the root filesystem"/><table width="100%" bgcolor="#e0e0e0">
<tr>
<td>
<b>
<font color="black">hostfs as the root filesystem</font>
</b>
</td>
</tr>
</table>
<blockquote head="hostfs as the root filesystem">
It's possible to boot from a directory hierarchy on the host using hostfs
rather than using the standard filesystem in a file.
<p>To start, you need that hierarchy. The easiest way is to loop mount an
existing root_fs file:
<blockquote>
<tt>
<font color="#000000"># mount root_fs uml_root_dir -o loop</font>
</tt>
</blockquote>
You need to change the filesystem type of / in etc/fstab to be 'hostfs', so
that line looks like this:
<tt>
<pre>
<font size="-1">/dev/ubd/0 / hostfs defaults 1 1
</font>
</pre>
</tt>
Then you need to chown to yourself all the files in that directory that are
owned by root. This worked for me:
<blockquote>
<tt>
<font color="#000000"># find . -uid 0 -exec chown jdike {} \;</font>
</tt>
</blockquote>
Next, make sure that your UML kernel has hostfs compiled in, not as a
module. Then run UML with the boot device pointing at that directory:
<blockquote>
<tt>
<font color="#000000">ubd0=/path/to/uml/root/directory</font>
</tt>
</blockquote>
UML should then boot as it does normally.
</blockquote>
<a name="Building hostfs"/><table width="100%" bgcolor="#e0e0e0">
<tr>
<td>
<b>
<font color="black">Building hostfs</font>
</b>
</td>
</tr>
</table>
<blockquote head="Building hostfs">
If you need to build hostfs because it's not in your kernel, you have
two choices:
<p>
<ul>
<li>Compiling hostfs into the kernel:<p>
Reconfigure the kernel and set the 'Host filesystem' option under
'Processor features' to 'Y'. Recompile the kernel and reboot it.
</li>
<li>Compiling hostfs as a module:<p>
Reconfigure the kernel and set the 'Host filesystem' option under
'Processor features' to 'M'. Rebuild the kernel modules. hostfs will
be in arch/um/fs/hostfs/hostfs.o. Install that in /lib/modules/`uname -r`/fs
in the virtual machine, boot it up, and <blockquote>
<tt>
<font color="#000000">insmod hostfs</font>
</tt>
</blockquote>
</li>
</ul>
</blockquote>
</td>
</tr>
</table>
<center>
<font size="-1">
Hosted at </font>
<a href="http://sourceforge.net">
<IMG alt="SourceForge Logo" border="0" height="31" width="88" src="http://sourceforge.net/sflogo.php?group_id=429">
</a>
</center>
</body>
</html>
|
