Add some words about signals and mention that CTRL-\ will drop the vkernel
[dragonfly.git] / share / man / man7 / vkernel.7
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1e4d9fd9 32.\" $DragonFly: src/share/man/man7/vkernel.7,v 1.6 2007/02/03 11:27:07 swildner Exp $
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03071031 34.Dd January 19, 2007
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35.Dt VKERNEL 7
36.Os
37.Sh NAME
38.Nm vkernel
39.Nd virtual kernel architecture
40.Sh SYNOPSIS
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41.Cd "machine vkernel"
42.Cd "device vkd"
43.Cd "device vke"
44.Pp
4af18995 45.Pa /usr/obj/usr/src/sys/VKERNEL/kernel.debug
03071031 46.Op Fl sUv
09b03fff 47.Op Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
4af18995 48.\".Op Fl i Ar file
09b03fff 49.Op Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
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50.Op Fl m Ar size
51.Op Fl r Ar file
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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"
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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.
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63.\".It Fl i Ar file
64.\"Specify a memory image
65.\".Ar file
66.\"to be used by the kernel.
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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.
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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).
09b03fff 120Lowercase versions of
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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
c8e7d028 130.Sx EXAMPLES
4af18995 131for further information on how to prepare a root image.
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132.It Fl s
133Boot into single-user mode.
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134.It Fl U
135Enable writing to kernel memory and module loading.
136By default, those are disabled for security reasons.
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137.It Fl v
138Turn on verbose booting.
139.El
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140.Sh SIGNALS
141The virtual kernel enables all terminal signals while in
142.Xr ddb 4
143mode but only enables
144.Ql \&^\e
145.Pq Dv SIGQUIT
146while operating as a console which causes the virtual kernel to enter its
147internal
148.Xr ddb 4
149debugger.
c8e7d028 150.Sh EXAMPLES
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151A couple of steps are necessary in order to prepare the system to build and
152run a virtual kernel.
153.Ss Setting up the filesystem
154The
155.Nm
156architecture needs a number of files which reside in
157.Pa /var/vkernel .
158Since these files tend to get rather big and the
159.Pa /var
160partition is usually of limited size, we recommend the directory to be
161created in the
162.Pa /home
163partition with a link to it in
164.Pa /var :
c8e7d028 165.Bd -literal
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166mkdir /home/var.vkernel
167ln -s /home/var.vkernel /var/vkernel
168.Ed
169.Pp
170Next, a filesystem image to be used by the virtual kernel has to be
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171created and populated (assuming world has been built previously):
172.Bd -literal
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173dd if=/dev/zero of=/var/vkernel/rootimg.01 bs=1m count=2048
174vnconfig -c -s labels vn0 /var/vkernel/rootimg.01
175disklabel -r -w vn0 auto
c8e7d028 176disklabel -e vn0 # edit the label to create a vn0a partition
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177newfs /dev/vn0a
178mount /dev/vn0a /mnt
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179cd /usr/src
180make installworld DESTDIR=/mnt
181cd etc
182make distribution DESTDIR=/mnt
6a060312 183echo '/dev/vkd0a / ufs rw 1 1' >/mnt/etc/fstab
c8e7d028 184echo 'console "/usr/libexec/getty Pc" cons25 on secure' >/mnt/etc/ttys
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185umount /mnt
186vnconfig -u vn0
187.Ed
188.Ss Compiling the virtual kernel
189In order to compile a virtual kernel use the
190.Li VKERNEL
191kernel configuration file residing in
192.Pa /usr/src/sys/config
193(or a configuration file derived thereof):
c8e7d028 194.Bd -literal
4af18995 195cd /usr/src
09b03fff 196make -DNO_MODULES buildkernel KERNCONF=VKERNEL
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197.Ed
198.Ss Enabling virtual kernel operation
199A special
200.Xr sysctl 8 ,
201.Va vm.vkernel_enable ,
202must be set to enable
203.Nm
204operation:
c8e7d028 205.Bd -literal
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206sysctl vm.vkernel_enable=1
207.Ed
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208.Ss Configuring the network on the host system
209In order to access a network interface of the host system from the
210.Nm ,
211you must add the interface to a
212.Xr bridge 4
213device which will then be passed to the
214.Fl I
215option:
216.Bd -literal
217kldload if_bridge.ko
218kldload if_tap.ko
219ifconfig bridge0 create
220ifconfig bridge0 addm re0 # assuming re0 is the host's interface
221ifconfig bridge0 up
222.Ed
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223.Ss Running the kernel
224Finally, the virtual kernel can be run:
c8e7d028 225.Bd -literal
4af18995 226cd /usr/obj/usr/src/sys/VKERNEL
09b03fff 227\&./kernel.debug -m 64m -r /var/vkernel/rootimg.01 -I auto:bridge0
4af18995 228.Ed
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229.Pp
230The
231.Xr reboot 8
232command can be used to stop a virtual kernel.
4af18995 233.Sh SEE ALSO
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234.Xr bridge 4 ,
235.Xr tap 4 ,
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236.Xr vn 4 ,
237.Xr build 7 ,
238.Xr disklabel 8 ,
09b03fff 239.Xr ifconfig 8 ,
c8e7d028 240.Xr vnconfig 8
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241.Sh HISTORY
242Virtual kernels were introduced in
243.Dx 1.7 .
244.Sh AUTHORS
245.An -nosplit
246.An Matt Dillon
247thought up and implemented the
248.Nm
249architecture.
250This manual page was written by
251.An Sascha Wildner .