Add a note that dntpd can be started at boot time even if the network
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4af18995 1.\"
98b2ba80 2.\" Copyright (c) 2006, 2007
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a8cc122d 32.\" $DragonFly: src/share/man/man7/vkernel.7,v 1.30 2007/08/18 16:09:57 swildner Exp $
4af18995 33.\"
98b2ba80 34.Dd August 18, 2007
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35.Dt VKERNEL 7
36.Os
37.Sh NAME
0592e24d 38.Nm vkernel ,
98b2ba80 39.Nm vcd ,
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40.Nm vkd ,
41.Nm vke
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42.Nd virtual kernel architecture
43.Sh SYNOPSIS
65d7306b 44.Cd "platform vkernel"
98b2ba80 45.Cd "device vcd"
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46.Cd "device vkd"
47.Cd "device vke"
48.Pp
4af18995 49.Pa /usr/obj/usr/src/sys/VKERNEL/kernel.debug
03071031 50.Op Fl sUv
a72d8a9f 51.Op Fl c Ar file
09b03fff 52.Op Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
dd54cb3a 53.Op Fl i Ar file
09b03fff 54.Op Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
702acf06 55.Op Fl l Ar cpulock
4af18995 56.Op Fl m Ar size
c5b0b0ba 57.Op Fl n Ar numcpus
b02b4170 58.Op Fl p Ar file
4af18995 59.Op Fl r Ar file
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60.Sh DESCRIPTION
61The
62.Nm
63architecture allows for running
64.Dx
65kernels in userland.
66.Pp
67The following options are available:
68.Bl -tag -width ".Fl m Ar size"
a72d8a9f 69.It Fl c Ar file
7834fbcc 70Specify a readonly CD-ROM image
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71.Ar file
72to be used by the kernel, with the first
73.Fl c
74option defining
75.Li vcd0 ,
76the second one
77.Li vcd1 ,
78and so on. The first
79.Fl r
80or
81.Fl c
82option specified on the command line will be the boot disk.
7834fbcc 83The CD9660 filesystem is assumed when booting from this media.
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84.It Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
85Specify an environment to be used by the kernel.
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86.It Fl i Ar file
87Specify a memory image
88.Ar file
89to be used by the virtual kernel.
90If no
91.Fl i
92option is given, the kernel will generate a name of the form
93.Pa /var/vkernel/memimg.XXXXXX ,
94with the trailing
95.Ql X Ns s
96being replaced by a sequential number, e.g.\&
97.Pa memimg.000001 .
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98.It Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
99Create a virtual network device, with the first
100.Fl I
101option defining
0592e24d 102.Li vke0 ,
09b03fff 103the second one
0592e24d 104.Li vke1 ,
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105and so on.
106.Pp
107The
108.Ar interface
109argument is the name of a
110.Xr tap 4
111device node.
112The
113.Pa /dev/
114path prefix does not have to be specified and will be automatically prepended.
115Specifying
116.Cm auto
117will pick the first unused
118.Xr tap 4
119device.
120.Pp
121The
122.Ar address1
123and
124.Ar address2
125arguments are the IP addresses of the
126.Xr tap 4
127and
0592e24d 128.Nm vke
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129interfaces.
130Optionally,
131.Ar address1
132may be of the form
133.Li bridge Ns Em X
134in which case the
135.Xr tap 4
136interface is added to the specified
137.Xr bridge 4
138interface.
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139The
140.Nm vke
141address is not assigned until the interface is brought up in the guest.
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142.Pp
143The
144.Ar netmask
145argument applies to all interfaces for which an address is specified.
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146.It Fl l Ar cpulock
147Specify which, if any, real CPUs to lock virtual CPUs to.
148.Ar cpulock
149is one of
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150.Cm any ,
151.Cm map Ns Op Ns , Ns Ar startCPU ,
152or
153.Ar CPU .
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154.Pp
155.Cm any
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156does not map virtual CPUs to real CPUs.
157This is the default.
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158.Pp
159.Cm map Ns Op Ns , Ns Ar startCPU
160maps each virtual CPU to a real CPU starting with real CPU 0 or
161.Ar startCPU
162if specified.
163.Pp
164.Ar CPU
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165locks all virtual CPUs to the real CPU specified by
166.Ar CPU .
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167.It Fl m Ar size
168Specify the amount of memory to be used by the kernel in bytes,
169.Cm K
3cea05a4 170.Pq kilobytes ,
4af18995 171.Cm M
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172.Pq megabytes
173or
4af18995 174.Cm G
3cea05a4 175.Pq gigabytes .
09b03fff 176Lowercase versions of
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177.Cm K , M ,
178and
179.Cm G
180are allowed.
c5b0b0ba 181.It Fl n Ar numcpus
8cf87c92 182Specify the number of CPUs you wish to emulate.
3217a401 183Up to 31 CPUs are supported.
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184The virtual kernel must be built with
185.Cd options SMP
186to use this option and will default to 2 CPUs unless otherwise specified.
b02b4170 187.It Fl p Ar file
dec8c72c 188Specify a file in which to store the process ID.
b02b4170 189A warning is issued if this file cannot be opened for writing.
4af18995 190.It Fl r Ar file
a72d8a9f 191Specify a R/W disk image
4af18995 192.Ar file
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193to be used by the kernel, with the first
194.Fl r
195option defining
0592e24d 196.Li vkd0 ,
ec1a8a4d 197the second one
0592e24d 198.Li vkd1 ,
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199and so on. The first
200.Fl r
201or
202.Fl c
203option specified on the command line will be the boot disk.
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204.It Fl s
205Boot into single-user mode.
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206.It Fl U
207Enable writing to kernel memory and module loading.
208By default, those are disabled for security reasons.
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209.It Fl v
210Turn on verbose booting.
211.El
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212.Sh DEVICES
213A number of virtual device drivers exist to supplement the virtual kernel.
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214.Ss Disk device
215The
216.Nm vkd
217driver allows for up to 16
218.Xr vn 4
219based disk devices.
220The root device will be
221.Li vkd0
222(see
223.Sx EXAMPLES
224for further information on how to prepare a root image).
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225.Ss CD-ROM device
226The
227.Nm vcd
228driver allows for up to 16 virtual CD-ROM devices.
229Basically this is a read only
230.Nm vkd
231device with a block size of 2048.
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232.Ss Network interface
233The
234.Nm vke
235driver supports up to 16 virtual network interfaces which are associated with
236.Xr tap 4
237devices on the host.
238For each
239.Nm vke
240device, the per-interface read only
241.Xr sysctl 3
242variable
243.Va hw.vke Ns Em X Ns Va .tap_unit
244holds the unit number of the associated
245.Xr tap 4
246device.
1e4d9fd9 247.Sh SIGNALS
dec8c72c 248The virtual kernel only enables
bb195a01 249.Dv SIGQUIT
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250and
251.Dv SIGTERM
252while operating in regular console mode.
253Sending
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254.Ql \&^\e
255.Pq Dv SIGQUIT
bb195a01 256to the virtual kernel causes the virtual kernel to enter its internal
1e4d9fd9 257.Xr ddb 4
dec8c72c 258debugger and re-enable all other terminal signals.
bb195a01 259Sending
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260.Dv SIGTERM
261to the virtual kernel triggers a clean shutdown by passing a
262.Dv SIGUSR2
263to the virtual kernel's
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264.Xr init 8
265process.
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266.Sh DEBUGGING
267It is possible to directly gdb the virtual kernel's process.
268It is recommended that you do a
269.Ql handle SIGSEGV noprint
270to ignore page faults processed by the virtual kernel itself.
c8e7d028 271.Sh EXAMPLES
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272A couple of steps are necessary in order to prepare the system to build and
273run a virtual kernel.
274.Ss Setting up the filesystem
275The
276.Nm
277architecture needs a number of files which reside in
278.Pa /var/vkernel .
279Since these files tend to get rather big and the
280.Pa /var
281partition is usually of limited size, we recommend the directory to be
282created in the
283.Pa /home
284partition with a link to it in
285.Pa /var :
c8e7d028 286.Bd -literal
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287mkdir /home/var.vkernel
288ln -s /home/var.vkernel /var/vkernel
289.Ed
290.Pp
291Next, a filesystem image to be used by the virtual kernel has to be
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292created and populated (assuming world has been built previously):
293.Bd -literal
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294dd if=/dev/zero of=/var/vkernel/rootimg.01 bs=1m count=2048
295vnconfig -c -s labels vn0 /var/vkernel/rootimg.01
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296disklabel -r -w vn0s0 auto
297disklabel -e vn0s0 # edit the label to create a vn0s0a partition
298newfs /dev/vn0s0a
299mount /dev/vn0s0a /mnt
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300cd /usr/src
301make installworld DESTDIR=/mnt
302cd etc
303make distribution DESTDIR=/mnt
7a3238b8 304echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
98b2ba80 305echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
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306.Ed
307.Pp
308Edit
309.Pa /mnt/etc/ttys
310and replace the
311.Li console
312entry with the following line and turn off all other gettys.
313.Bd -literal
314console "/usr/libexec/getty Pc" cons25 on secure
315.Ed
316.Pp
317Then, unmount the disk.
318.Bd -literal
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319umount /mnt
320vnconfig -u vn0
321.Ed
322.Ss Compiling the virtual kernel
323In order to compile a virtual kernel use the
324.Li VKERNEL
325kernel configuration file residing in
326.Pa /usr/src/sys/config
327(or a configuration file derived thereof):
c8e7d028 328.Bd -literal
4af18995 329cd /usr/src
09b03fff 330make -DNO_MODULES buildkernel KERNCONF=VKERNEL
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331.Ed
332.Ss Enabling virtual kernel operation
333A special
334.Xr sysctl 8 ,
335.Va vm.vkernel_enable ,
336must be set to enable
337.Nm
338operation:
c8e7d028 339.Bd -literal
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340sysctl vm.vkernel_enable=1
341.Ed
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342.Ss Configuring the network on the host system
343In order to access a network interface of the host system from the
344.Nm ,
345you must add the interface to a
346.Xr bridge 4
347device which will then be passed to the
348.Fl I
349option:
350.Bd -literal
351kldload if_bridge.ko
352kldload if_tap.ko
353ifconfig bridge0 create
354ifconfig bridge0 addm re0 # assuming re0 is the host's interface
355ifconfig bridge0 up
356.Ed
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357.Ss Running the kernel
358Finally, the virtual kernel can be run:
c8e7d028 359.Bd -literal
4af18995 360cd /usr/obj/usr/src/sys/VKERNEL
09b03fff 361\&./kernel.debug -m 64m -r /var/vkernel/rootimg.01 -I auto:bridge0
4af18995 362.Ed
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363.Pp
364The
365.Xr reboot 8
366command can be used to stop a virtual kernel.
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367.Sh BUILDING THE WORLD UNDER A VKERNEL
368The virtual kernel platform does not have all the header files expected
369by a world build, so the easiest thing to do right now is to specify a
370pc32 target when building the world under a virtual kernel, like this:
371.Bd -literal
372vkernel# make MACHINE_PLATFORM=pc32 buildworld
373vkernel# make MACHINE_PLATFORM=pc32 installworld
374.Ed
4af18995 375.Sh SEE ALSO
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376.Xr bridge 4 ,
377.Xr tap 4 ,
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378.Xr vn 4 ,
379.Xr build 7 ,
380.Xr disklabel 8 ,
09b03fff 381.Xr ifconfig 8 ,
c8e7d028 382.Xr vnconfig 8
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383.Sh HISTORY
384Virtual kernels were introduced in
385.Dx 1.7 .
386.Sh AUTHORS
387.An -nosplit
388.An Matt Dillon
389thought up and implemented the
390.Nm
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391architecture and wrote the
392.Nm vkd
393device driver.
394.An Sepherosa Ziehau
395wrote the
396.Nm vke
397device driver.
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398This manual page was written by
399.An Sascha Wildner .