xref: /dflybsd-src/share/man/man7/vkernel.7 (revision 5dfd06ac148512faf075c4e399e8485fd955578f) 
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32.\" $DragonFly: src/share/man/man7/vkernel.7,v 1.4 2007/01/19 08:13:44 swildner Exp $
33.\"
34.Dd January 19, 2007
35.Dt VKERNEL 7
36.Os
37.Sh NAME
38.Nm vkernel
39.Nd virtual kernel architecture
40.Sh SYNOPSIS
41.Cd "machine vkernel"
42.Cd "device vkd"
43.Cd "device vke"
44.Pp
45.Pa /usr/obj/usr/src/sys/VKERNEL/kernel.debug
46.Op Fl sUv
47.Op Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
48.\".Op Fl i Ar file
49.Op Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
50.Op Fl m Ar size
51.Op Fl r Ar file
52.Sh DESCRIPTION
53The
54.Nm
55architecture allows for running
56.Dx
57kernels in userland.
58.Pp
59The following options are available:
60.Bl -tag -width ".Fl m Ar size"
61.It Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
62Specify an environment to be used by the kernel.
63.\".It Fl i Ar file
64.\"Specify a memory image
65.\".Ar file
66.\"to be used by the kernel.
67.It Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
68Create a virtual network device, with the first
69.Fl I
70option defining
71.Dq Li vke0 ,
72the second one
73.Dq Li vke1 ,
74and so on.
75.Pp
76The
77.Ar interface
78argument is the name of a
79.Xr tap 4
80device node.
81The
82.Pa /dev/
83path prefix does not have to be specified and will be automatically prepended.
84Specifying
85.Cm auto
86will pick the first unused
87.Xr tap 4
88device.
89.Pp
90The
91.Ar address1
92and
93.Ar address2
94arguments are the IP addresses of the
95.Xr tap 4
96and
97.Xr vke 4
98interfaces.
99Optionally,
100.Ar address1
101may be of the form
102.Li bridge Ns Em X
103in which case the
104.Xr tap 4
105interface is added to the specified
106.Xr bridge 4
107interface.
108.Pp
109The
110.Ar netmask
111argument applies to all interfaces for which an address is specified.
112.It Fl m Ar size
113Specify the amount of memory to be used by the kernel in bytes,
114.Cm K
115(kilobytes),
116.Cm M
117(megabytes) or
118.Cm G
119(gigabytes).
120Lowercase versions of
121.Cm K , M ,
122and
123.Cm G
124are allowed.
125.It Fl r Ar file
126Specify the root image
127.Ar file
128to be used by the kernel.
129See
130.Sx EXAMPLES
131for further information on how to prepare a root image.
132.It Fl s
133Boot into single-user mode.
134.It Fl U
135Enable writing to kernel memory and module loading.
136By default, those are disabled for security reasons.
137.It Fl v
138Turn on verbose booting.
139.El
140.Sh EXAMPLES
141A couple of steps are necessary in order to prepare the system to build and
142run a virtual kernel.
143.Ss Setting up the filesystem
144The
145.Nm
146architecture needs a number of files which reside in
147.Pa /var/vkernel .
148Since these files tend to get rather big and the
149.Pa /var
150partition is usually of limited size, we recommend the directory to be
151created in the
152.Pa /home
153partition with a link to it in
154.Pa /var :
155.Bd -literal
156mkdir /home/var.vkernel
157ln -s /home/var.vkernel /var/vkernel
158.Ed
159.Pp
160Next, a filesystem image to be used by the virtual kernel has to be
161created and populated (assuming world has been built previously):
162.Bd -literal
163dd if=/dev/zero of=/var/vkernel/rootimg.01 bs=1m count=2048
164vnconfig -c -s labels vn0 /var/vkernel/rootimg.01
165disklabel -r -w vn0 auto
166disklabel -e vn0	# edit the label to create a vn0a partition
167newfs /dev/vn0a
168mount /dev/vn0a /mnt
169cd /usr/src
170make installworld DESTDIR=/mnt
171cd etc
172make distribution DESTDIR=/mnt
173echo '/dev/vkd0 / ufs rw 1 1' >/mnt/etc/fstab
174echo 'console "/usr/libexec/getty Pc" cons25 on secure' >/mnt/etc/ttys
175umount /mnt
176vnconfig -u vn0
177.Ed
178.Ss Compiling the virtual kernel
179In order to compile a virtual kernel use the
180.Li VKERNEL
181kernel configuration file residing in
182.Pa /usr/src/sys/config
183(or a configuration file derived thereof):
184.Bd -literal
185cd /usr/src
186make -DNO_MODULES buildkernel KERNCONF=VKERNEL
187.Ed
188.Ss Enabling virtual kernel operation
189A special
190.Xr sysctl 8 ,
191.Va vm.vkernel_enable ,
192must be set to enable
193.Nm
194operation:
195.Bd -literal
196sysctl vm.vkernel_enable=1
197.Ed
198.Ss Configuring the network on the host system
199In order to access a network interface of the host system from the
200.Nm ,
201you must add the interface to a
202.Xr bridge 4
203device which will then be passed to the
204.Fl I
205option:
206.Bd -literal
207kldload if_bridge.ko
208kldload if_tap.ko
209ifconfig bridge0 create
210ifconfig bridge0 addm re0	# assuming re0 is the host's interface
211ifconfig bridge0 up
212.Ed
213.Ss Running the kernel
214Finally, the virtual kernel can be run:
215.Bd -literal
216cd /usr/obj/usr/src/sys/VKERNEL
217\&./kernel.debug -m 64m -r /var/vkernel/rootimg.01 -I auto:bridge0
218.Ed
219.Pp
220The
221.Xr reboot 8
222command can be used to stop a virtual kernel.
223.Sh SEE ALSO
224.Xr bridge 4 ,
225.Xr tap 4 ,
226.Xr vn 4 ,
227.Xr build 7 ,
228.Xr disklabel 8 ,
229.Xr ifconfig 8 ,
230.Xr vnconfig 8
231.Sh HISTORY
232Virtual kernels were introduced in
233.Dx 1.7 .
234.Sh AUTHORS
235.An -nosplit
236.An Matt Dillon
237thought up and implemented the
238.Nm
239architecture.
240This manual page was written by
241.An Sascha Wildner .
242