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32 .\" $DragonFly: src/share/man/man7/vkernel.7,v 1.43 2008/09/02 22:41:19 thomas Exp $
42 .Nd virtual kernel architecture
44 .Cd "platform vkernel"
49 .Pa /var/vkernel/boot/kernel
52 .Op Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
54 .Op Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
63 architecture allows for running
67 The following options are available:
68 .Bl -tag -width ".Fl m Ar size"
70 Specify a readonly CD-ROM image
72 to be used by the kernel, with the first
83 option specified on the command line will be the boot disk.
84 The CD9660 filesystem is assumed when booting from this media.
85 .It Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
86 Specify an environment to be used by the kernel.
88 Specify a memory image
90 to be used by the virtual kernel.
93 option is given, the kernel will generate a name of the form
94 .Pa /var/vkernel/memimg.XXXXXX ,
97 being replaced by a sequential number, e.g.\&
99 .It Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
100 Create a virtual network device, with the first
110 argument is the name of a
115 path prefix does not have to be specified and will be automatically prepended.
118 will pick the first unused
126 arguments are the IP addresses of the
137 interface is added to the specified
142 address is not assigned until the interface is brought up in the guest.
146 argument applies to all interfaces for which an address is specified.
148 Specify which, if any, real CPUs to lock virtual CPUs to.
152 .Cm map Ns Op Ns , Ns Ar startCPU ,
157 does not map virtual CPUs to real CPUs.
160 .Cm map Ns Op Ns , Ns Ar startCPU
161 maps each virtual CPU to a real CPU starting with real CPU 0 or
166 locks all virtual CPUs to the real CPU specified by
169 Specify the amount of memory to be used by the kernel in bytes,
177 Lowercase versions of
183 Specify the number of CPUs you wish to emulate.
184 Up to 16 CPUs are supported.
185 The virtual kernel must be built with
187 to use this option and will default to 2 CPUs unless otherwise specified.
189 Specify a file in which to store the process ID.
190 A warning is issued if this file cannot be opened for writing.
192 Specify a R/W disk image
194 to be used by the kernel, with the first
205 option specified on the command line will be the boot disk.
207 Boot into single-user mode.
209 Enable writing to kernel memory and module loading.
210 By default, those are disabled for security reasons.
212 Turn on verbose booting.
215 A number of virtual device drivers exist to supplement the virtual kernel.
219 driver allows for up to 16
222 The root device will be
226 for further information on how to prepare a root image).
230 driver allows for up to 16 virtual CD-ROM devices.
231 Basically this is a read only
233 device with a block size of 2048.
234 .Ss Network interface
237 driver supports up to 16 virtual network interfaces which are associated with
242 device, the per-interface read only
245 .Va hw.vke Ns Em X Ns Va .tap_unit
246 holds the unit number of the associated
250 The virtual kernel only enables
254 while operating in regular console mode.
258 to the virtual kernel causes the virtual kernel to enter its internal
260 debugger and re-enable all other terminal signals.
263 to the virtual kernel triggers a clean shutdown by passing a
265 to the virtual kernel's
269 It is possible to directly gdb the virtual kernel's process.
270 It is recommended that you do a
271 .Ql handle SIGSEGV noprint
272 to ignore page faults processed by the virtual kernel itself and
273 .Ql handle SIGUSR1 noprint
274 to ignore signals used for simulating inter-processor interrupts (SMP build
277 .Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
278 .It Pa /sys/config/VKERNEL
281 configuration file, for
285 A couple of steps are necessary in order to prepare the system to build and
286 run a virtual kernel.
287 .Ss Setting up the filesystem
290 architecture needs a number of files which reside in
292 Since these files tend to get rather big and the
294 partition is usually of limited size, we recommend the directory to be
297 partition with a link to it in
300 mkdir -p /home/var.vkernel/boot
301 ln -s /home/var.vkernel /var/vkernel
304 Next, a filesystem image to be used by the virtual kernel has to be
305 created and populated (assuming world has been built previously).
306 If the image is created on a UFS filesystem you might want to pre-zero it.
307 On a HAMMER filesystem you should just truncate-extend to the image size
308 as HAMMER does not re-use data blocks already present in the file.
310 vnconfig -c -s labels -S 2g -T vn0 /var/vkernel/rootimg.01
311 disklabel -r -w vn0s0 auto
312 disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
314 mount /dev/vn0s0a /mnt
316 make installworld DESTDIR=/mnt
318 make distribution DESTDIR=/mnt
319 echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
320 echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
327 entry with the following line and turn off all other gettys.
329 console "/usr/libexec/getty Pc" cons25 on secure
336 if you would like to automatically log in as root.
338 Then, unmount the disk.
343 .Ss Compiling the virtual kernel
344 In order to compile a virtual kernel use the
346 kernel configuration file residing in
348 (or a configuration file derived thereof):
351 make -DNO_MODULES buildkernel KERNCONF=VKERNEL
352 make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
354 .Ss Enabling virtual kernel operation
357 .Va vm.vkernel_enable ,
358 must be set to enable
362 sysctl vm.vkernel_enable=1
364 .Ss Configuring the network on the host system
365 In order to access a network interface of the host system from the
367 you must add the interface to a
369 device which will then be passed to the
375 ifconfig bridge0 create
376 ifconfig bridge0 addm re0 # assuming re0 is the host's interface
379 .Ss Running the kernel
380 Finally, the virtual kernel can be run:
383 \&./boot/kernel -m 64m -r rootimg.01 -I auto:bridge0
391 commands from inside a virtual kernel.
392 After doing a clean shutdown the
394 command will re-exec the virtual kernel binary while the other two will
395 cause the virtual kernel to exit.
396 .Sh BUILDING THE WORLD UNDER A VKERNEL
397 The virtual kernel platform does not have all the header files expected
398 by a world build, so the easiest thing to do right now is to specify a
399 pc32 target when building the world under a virtual kernel, like this:
401 vkernel# make MACHINE_PLATFORM=pc32 buildworld
402 vkernel# make MACHINE_PLATFORM=pc32 installworld
404 .Sh CONFIGURATION FILES
405 Your virtual kernel is a complete
407 system, but you might not want to run all the services a normal kernel runs.
408 Here is what a typical virtual kernel's
410 file looks like, with some additional possibilities commented out.
413 network_interfaces="lo0 vke0"
431 .%A Aggelos Economopoulos
433 .%T "A Peek at the DragonFly Virtual Kernel"
436 Virtual kernels were introduced in
441 thought up and implemented the
443 architecture and wrote the
450 This manual page was written by