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98b2ba80 2.\" Copyright (c) 2006, 2007
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b6a66df5 32.Dd March 28, 2010
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33.Dt VKERNEL 7
34.Os
35.Sh NAME
0592e24d 36.Nm vkernel ,
98b2ba80 37.Nm vcd ,
0592e24d
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38.Nm vkd ,
39.Nm vke
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40.Nd virtual kernel architecture
41.Sh SYNOPSIS
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42.Cd "platform vkernel # for 32 bit vkernels"
43.Cd "platform vkernel64 # for 64 bit vkernels"
98b2ba80 44.Cd "device vcd"
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45.Cd "device vkd"
46.Cd "device vke"
47.Pp
c009fcfa 48.Pa /var/vkernel/boot/kernel
03071031 49.Op Fl sUv
a72d8a9f 50.Op Fl c Ar file
09b03fff 51.Op Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
dd54cb3a 52.Op Fl i Ar file
09b03fff 53.Op Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
702acf06 54.Op Fl l Ar cpulock
4af18995 55.Op Fl m Ar size
c5b0b0ba 56.Op Fl n Ar numcpus
b02b4170 57.Op Fl p Ar file
4af18995 58.Op Fl r Ar file
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59.Sh DESCRIPTION
60The
61.Nm
62architecture allows for running
63.Dx
64kernels in userland.
65.Pp
66The following options are available:
67.Bl -tag -width ".Fl m Ar size"
a72d8a9f 68.It Fl c Ar file
7834fbcc 69Specify a readonly CD-ROM image
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70.Ar file
71to be used by the kernel, with the first
72.Fl c
73option defining
74.Li vcd0 ,
75the second one
76.Li vcd1 ,
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77and so on.
78The first
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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.
43cfb771 183Up to 16 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.
200The first
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201.Fl r
202or
203.Fl c
204option specified on the command line will be the boot disk.
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205.It Fl s
206Boot into single-user mode.
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207.It Fl U
208Enable writing to kernel memory and module loading.
209By default, those are disabled for security reasons.
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210.It Fl v
211Turn on verbose booting.
212.El
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213.Sh DEVICES
214A number of virtual device drivers exist to supplement the virtual kernel.
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215.Ss Disk device
216The
217.Nm vkd
218driver allows for up to 16
219.Xr vn 4
220based disk devices.
221The root device will be
222.Li vkd0
223(see
224.Sx EXAMPLES
225for further information on how to prepare a root image).
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226.Ss CD-ROM device
227The
228.Nm vcd
229driver allows for up to 16 virtual CD-ROM devices.
230Basically this is a read only
231.Nm vkd
232device with a block size of 2048.
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233.Ss Network interface
234The
235.Nm vke
236driver supports up to 16 virtual network interfaces which are associated with
237.Xr tap 4
238devices on the host.
239For each
240.Nm vke
241device, the per-interface read only
242.Xr sysctl 3
243variable
244.Va hw.vke Ns Em X Ns Va .tap_unit
245holds the unit number of the associated
246.Xr tap 4
247device.
1e4d9fd9 248.Sh SIGNALS
dec8c72c 249The virtual kernel only enables
bb195a01 250.Dv SIGQUIT
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251and
252.Dv SIGTERM
253while operating in regular console mode.
254Sending
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255.Ql \&^\e
256.Pq Dv SIGQUIT
bb195a01 257to the virtual kernel causes the virtual kernel to enter its internal
1e4d9fd9 258.Xr ddb 4
dec8c72c 259debugger and re-enable all other terminal signals.
bb195a01 260Sending
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261.Dv SIGTERM
262to the virtual kernel triggers a clean shutdown by passing a
263.Dv SIGUSR2
264to the virtual kernel's
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265.Xr init 8
266process.
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267.Sh DEBUGGING
268It is possible to directly gdb the virtual kernel's process.
269It is recommended that you do a
270.Ql handle SIGSEGV noprint
4010bf94 271to ignore page faults processed by the virtual kernel itself and
e7c2f376 272.Ql handle SIGUSR1 noprint
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273to ignore signals used for simulating inter-processor interrupts (SMP build
274only).
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275.Sh FILES
276.Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
277.It Pa /sys/config/VKERNEL
278default
279.Nm
280configuration file, for
281.Xr config 8 .
282.El
c8e7d028 283.Sh EXAMPLES
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284A couple of steps are necessary in order to prepare the system to build and
285run a virtual kernel.
286.Ss Setting up the filesystem
287The
288.Nm
289architecture needs a number of files which reside in
290.Pa /var/vkernel .
291Since these files tend to get rather big and the
292.Pa /var
293partition is usually of limited size, we recommend the directory to be
294created in the
295.Pa /home
296partition with a link to it in
297.Pa /var :
c8e7d028 298.Bd -literal
c009fcfa 299mkdir -p /home/var.vkernel/boot
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300ln -s /home/var.vkernel /var/vkernel
301.Ed
302.Pp
303Next, a filesystem image to be used by the virtual kernel has to be
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304created and populated (assuming world has been built previously).
305If the image is created on a UFS filesystem you might want to pre-zero it.
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306On a HAMMER filesystem you should just truncate-extend to the image size
307as HAMMER does not re-use data blocks already present in the file.
c8e7d028 308.Bd -literal
49802d4e 309vnconfig -c -s labels -S 2g -T vn0 /var/vkernel/rootimg.01
58c55700 310disklabel -r -w vn0s0 auto
c009fcfa 311disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
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312newfs /dev/vn0s0a
313mount /dev/vn0s0a /mnt
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314cd /usr/src
315make installworld DESTDIR=/mnt
316cd etc
317make distribution DESTDIR=/mnt
7a3238b8 318echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
98b2ba80 319echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
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320.Ed
321.Pp
322Edit
323.Pa /mnt/etc/ttys
324and replace the
325.Li console
326entry with the following line and turn off all other gettys.
327.Bd -literal
328console "/usr/libexec/getty Pc" cons25 on secure
329.Ed
330.Pp
eed435dd
SK
331Replace
332.Li \&Pc
333with
334.Li al.Pc
335if you would like to automatically log in as root.
336.Pp
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337Then, unmount the disk.
338.Bd -literal
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339umount /mnt
340vnconfig -u vn0
341.Ed
342.Ss Compiling the virtual kernel
343In order to compile a virtual kernel use the
344.Li VKERNEL
345kernel configuration file residing in
a154d422 346.Pa /sys/config
4af18995 347(or a configuration file derived thereof):
c8e7d028 348.Bd -literal
4af18995 349cd /usr/src
09b03fff 350make -DNO_MODULES buildkernel KERNCONF=VKERNEL
79b58aae 351make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
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352.Ed
353.Ss Enabling virtual kernel operation
354A special
355.Xr sysctl 8 ,
356.Va vm.vkernel_enable ,
357must be set to enable
358.Nm
359operation:
c8e7d028 360.Bd -literal
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361sysctl vm.vkernel_enable=1
362.Ed
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363.Ss Configuring the network on the host system
364In order to access a network interface of the host system from the
365.Nm ,
366you must add the interface to a
367.Xr bridge 4
368device which will then be passed to the
369.Fl I
370option:
371.Bd -literal
372kldload if_bridge.ko
373kldload if_tap.ko
374ifconfig bridge0 create
375ifconfig bridge0 addm re0 # assuming re0 is the host's interface
376ifconfig bridge0 up
377.Ed
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378.Ss Running the kernel
379Finally, the virtual kernel can be run:
c8e7d028 380.Bd -literal
79b58aae 381cd /var/vkernel
c009fcfa 382\&./boot/kernel -m 64m -r rootimg.01 -I auto:bridge0
4af18995 383.Ed
c8e7d028 384.Pp
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385You can issue the
386.Xr reboot 8 ,
387.Xr halt 8 ,
388or
389.Xr shutdown 8
390commands from inside a virtual kernel.
391After doing a clean shutdown the
c8e7d028 392.Xr reboot 8
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393command will re-exec the virtual kernel binary while the other two will
394cause the virtual kernel to exit.
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395.Sh BUILDING THE WORLD UNDER A VKERNEL
396The virtual kernel platform does not have all the header files expected
397by a world build, so the easiest thing to do right now is to specify a
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398pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when
399building the world under a virtual kernel, like this:
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400.Bd -literal
401vkernel# make MACHINE_PLATFORM=pc32 buildworld
402vkernel# make MACHINE_PLATFORM=pc32 installworld
403.Ed
79b58aae 404.Sh CONFIGURATION FILES
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405Your virtual kernel is a complete
406.Dx
407system, but you might not want to run all the services a normal kernel runs.
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408Here is what a typical virtual kernel's
409.Pa /etc/rc.conf
410file looks like, with some additional possibilities commented out.
411.Bd -literal
412hostname="vkernel"
413network_interfaces="lo0 vke0"
414ifconfig_vke0="DHCP"
415sendmail_enable="NO"
416#syslog_enable="NO"
66931b32 417blanktime="NO"
79b58aae 418.Ed
4af18995 419.Sh SEE ALSO
666855ca 420.Xr vknet 1 ,
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421.Xr bridge 4 ,
422.Xr tap 4 ,
c8e7d028 423.Xr vn 4 ,
a154d422 424.Xr sysctl.conf 5 ,
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425.Xr build 7 ,
426.Xr disklabel 8 ,
09b03fff 427.Xr ifconfig 8 ,
dbfd168b 428.Xr vknetd 8 ,
c8e7d028 429.Xr vnconfig 8
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430.Rs
431.%A Aggelos Economopoulos
432.%D March 2007
433.%T "A Peek at the DragonFly Virtual Kernel"
434.Re
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435.Sh HISTORY
436Virtual kernels were introduced in
437.Dx 1.7 .
438.Sh AUTHORS
439.An -nosplit
440.An Matt Dillon
441thought up and implemented the
442.Nm
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443architecture and wrote the
444.Nm vkd
445device driver.
446.An Sepherosa Ziehau
447wrote the
448.Nm vke
449device driver.
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450This manual page was written by
451.An Sascha Wildner .