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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
82 option specified on the command line will be the boot disk.
83 The CD9660 filesystem is assumed when booting from this media.
84 .It Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
85 Specify an environment to be used by the kernel.
87 Specify a memory image
89 to be used by the virtual kernel.
92 option is given, the kernel will generate a name of the form
93 .Pa /var/vkernel/memimg.XXXXXX ,
96 being replaced by a sequential number, e.g.\&
98 .It Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
99 Create a virtual network device, with the first
109 argument is the name of a
114 path prefix does not have to be specified and will be automatically prepended.
117 will pick the first unused
125 arguments are the IP addresses of the
136 interface is added to the specified
141 address is not assigned until the interface is brought up in the guest.
145 argument applies to all interfaces for which an address is specified.
147 Specify which, if any, real CPUs to lock virtual CPUs to.
151 .Cm map Ns Op Ns , Ns Ar startCPU ,
156 does not map virtual CPUs to real CPUs.
159 .Cm map Ns Op Ns , Ns Ar startCPU
160 maps each virtual CPU to a real CPU starting with real CPU 0 or
165 locks all virtual CPUs to the real CPU specified by
168 Specify the amount of memory to be used by the kernel in bytes,
176 Lowercase versions of
182 Specify the number of CPUs you wish to emulate.
183 Up to 16 CPUs are supported.
184 The virtual kernel must be built with
186 to use this option and will default to 2 CPUs unless otherwise specified.
188 Specify a file in which to store the process ID.
189 A warning is issued if this file cannot be opened for writing.
191 Specify a R/W disk image
193 to be used by the kernel, with the first
203 option specified on the command line will be the boot disk.
205 Boot into single-user mode.
207 Enable writing to kernel memory and module loading.
208 By default, those are disabled for security reasons.
210 Turn on verbose booting.
213 A number of virtual device drivers exist to supplement the virtual kernel.
217 driver allows for up to 16
220 The root device will be
224 for further information on how to prepare a root image).
228 driver allows for up to 16 virtual CD-ROM devices.
229 Basically this is a read only
231 device with a block size of 2048.
232 .Ss Network interface
235 driver supports up to 16 virtual network interfaces which are associated with
240 device, the per-interface read only
243 .Va hw.vke Ns Em X Ns Va .tap_unit
244 holds the unit number of the associated
248 The virtual kernel only enables
252 while operating in regular console mode.
256 to the virtual kernel causes the virtual kernel to enter its internal
258 debugger and re-enable all other terminal signals.
261 to the virtual kernel triggers a clean shutdown by passing a
263 to the virtual kernel's
267 It is possible to directly gdb the virtual kernel's process.
268 It is recommended that you do a
269 .Ql handle SIGSEGV noprint
270 to ignore page faults processed by the virtual kernel itself and
271 .Ql handle SIGUSR1 noprint
272 to ignore signals used for simulating inter-processor interrupts (SMP build
275 .Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
276 .It Pa /sys/config/VKERNEL
279 configuration file, for
283 A couple of steps are necessary in order to prepare the system to build and
284 run a virtual kernel.
285 .Ss Setting up the filesystem
288 architecture needs a number of files which reside in
290 Since these files tend to get rather big and the
292 partition is usually of limited size, we recommend the directory to be
295 partition with a link to it in
298 mkdir -p /home/var.vkernel/boot
299 ln -s /home/var.vkernel /var/vkernel
302 Next, a filesystem image to be used by the virtual kernel has to be
303 created and populated (assuming world has been built previously). If
304 the image is created on a UFS filesystem you might want to pre-zero it.
305 On a HAMMER filesystem you should just truncate-extend to the image size
306 as HAMMER does not re-use data blocks already present in the file.
308 vnconfig -c -s labels -S 2g -T vn0 /var/vkernel/rootimg.01
309 disklabel -r -w vn0s0 auto
310 disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
312 mount /dev/vn0s0a /mnt
314 make installworld DESTDIR=/mnt
316 make distribution DESTDIR=/mnt
317 echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
318 echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
325 entry with the following line and turn off all other gettys.
327 console "/usr/libexec/getty Pc" cons25 on secure
334 if you would like to automatically log in as root.
336 Then, unmount the disk.
341 .Ss Compiling the virtual kernel
342 In order to compile a virtual kernel use the
344 kernel configuration file residing in
346 (or a configuration file derived thereof):
349 make -DNO_MODULES buildkernel KERNCONF=VKERNEL
350 make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
352 .Ss Enabling virtual kernel operation
355 .Va vm.vkernel_enable ,
356 must be set to enable
360 sysctl vm.vkernel_enable=1
362 .Ss Configuring the network on the host system
363 In order to access a network interface of the host system from the
365 you must add the interface to a
367 device which will then be passed to the
373 ifconfig bridge0 create
374 ifconfig bridge0 addm re0 # assuming re0 is the host's interface
377 .Ss Running the kernel
378 Finally, the virtual kernel can be run:
381 \&./boot/kernel -m 64m -r rootimg.01 -I auto:bridge0
389 commands from inside a virtual kernel.
390 After doing a clean shutdown the
392 command will re-exec the virtual kernel binary while the other two will
393 cause the virtual kernel to exit.
394 .Sh BUILDING THE WORLD UNDER A VKERNEL
395 The virtual kernel platform does not have all the header files expected
396 by a world build, so the easiest thing to do right now is to specify a
397 pc32 target when building the world under a virtual kernel, like this:
399 vkernel# make MACHINE_PLATFORM=pc32 buildworld
400 vkernel# make MACHINE_PLATFORM=pc32 installworld
402 .Sh CONFIGURATION FILES
403 Your virtual kernel is a complete
405 system, but you might not want to run all the services a normal kernel runs.
406 Here is what a typical virtual kernel's
408 file looks like, with some additional possibilities commented out.
411 network_interfaces="lo0 vke0"
429 .%A Aggelos Economopoulos
431 .%T "A Peek at the DragonFly Virtual Kernel"
434 Virtual kernels were introduced in
439 thought up and implemented the
441 architecture and wrote the
448 This manual page was written by