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40 .Nd virtual kernel architecture
42 .Cd "platform vkernel # for 32 bit vkernels"
43 .Cd "platform vkernel64 # for 64 bit vkernels"
48 .Pa /var/vkernel/boot/kernel/kernel
51 .Op Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ...
53 .Op Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
62 architecture allows for running
66 The following options are available:
67 .Bl -tag -width ".Fl m Ar size"
69 Specify a readonly CD-ROM image
71 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 Shows a list of available options, each with a short description.
89 Specify a memory image
91 to be used by the virtual kernel.
94 option is given, the kernel will generate a name of the form
95 .Pa /var/vkernel/memimg.XXXXXX ,
98 being replaced by a sequential number, e.g.\&
100 .It Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
101 Create a virtual network device, with the first
111 argument is the name of a
113 device node or the path to a
118 path prefix does not have to be specified and will be automatically prepended
122 will pick the first unused
130 arguments are the IP addresses of the
141 interface is added to the specified
146 address is not assigned until the interface is brought up in the guest.
150 argument applies to all interfaces for which an address is specified.
152 When running multiple vkernels it is often more convenient to simply
155 socket and let vknetd deal with the tap and/or bridge. An example of
156 this would be '/var/run/vknet:0.0.0.0:10.2.0.2/16'.
158 Specify which, if any, real CPUs to lock virtual CPUs to.
162 .Cm map Ns Op Ns , Ns Ar startCPU ,
167 does not map virtual CPUs to real CPUs.
170 .Cm map Ns Op Ns , Ns Ar startCPU
171 maps each virtual CPU to a real CPU starting with real CPU 0 or
176 locks all virtual CPUs to the real CPU specified by
179 Specify the amount of memory to be used by the kernel in bytes,
187 Lowercase versions of
193 Specify the number of CPUs you wish to emulate.
194 Up to 16 CPUs are supported.
195 The virtual kernel must be built with
197 to use this option and will default to 2 CPUs unless otherwise specified.
199 Specify a pidfile in which to store the process ID.
200 Scripts can use this file to locate the vkernel pid for the purpose of
201 shutting down or killing it.
203 The vkernel will hold a lock on the pidfile while running.
204 Scripts may test for the lock to determine if the pidfile is valid or
205 stale so as to avoid accidently killing a random process.
206 Something like '/usr/bin/lockf -ks -t 0 pidfile echo -n' may be used
208 A non-zero exit code indicates that the pidfile represents a running
211 An error is issued and the vkernel exits if this file cannot be opened for
212 writing or if it is already locked by an active vkernel process.
214 Specify a R/W disk image
216 to be used by the kernel, with the first
227 option specified on the command line will be the boot disk.
229 Boot into single-user mode.
231 Enable writing to kernel memory and module loading.
232 By default, those are disabled for security reasons.
234 Turn on verbose booting.
237 A number of virtual device drivers exist to supplement the virtual kernel.
241 driver allows for up to 16
244 The root device will be
248 for further information on how to prepare a root image).
252 driver allows for up to 16 virtual CD-ROM devices.
253 Basically this is a read only
255 device with a block size of 2048.
256 .Ss Network interface
259 driver supports up to 16 virtual network interfaces which are associated with
264 device, the per-interface read only
267 .Va hw.vke Ns Em X Ns Va .tap_unit
268 holds the unit number of the associated
272 The virtual kernel only enables
276 while operating in regular console mode.
280 to the virtual kernel causes the virtual kernel to enter its internal
282 debugger and re-enable all other terminal signals.
285 to the virtual kernel triggers a clean shutdown by passing a
287 to the virtual kernel's
291 It is possible to directly gdb the virtual kernel's process.
292 It is recommended that you do a
293 .Ql handle SIGSEGV noprint
294 to ignore page faults processed by the virtual kernel itself and
295 .Ql handle SIGUSR1 noprint
296 to ignore signals used for simulating inter-processor interrupts (SMP build
299 .Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
300 .It Pa /sys/config/VKERNEL
303 configuration file, for
306 .Sh CONFIGURATION FILES
307 Your virtual kernel is a complete
309 system, but you might not want to run all the services a normal kernel runs.
310 Here is what a typical virtual kernel's
312 file looks like, with some additional possibilities commented out.
315 network_interfaces="lo0 vke0"
322 A couple of steps are necessary in order to prepare the system to build and
323 run a virtual kernel.
324 .Ss Setting up the filesystem
327 architecture needs a number of files which reside in
329 Since these files tend to get rather big and the
331 partition is usually of limited size, we recommend the directory to be
334 partition with a link to it in
337 mkdir -p /home/var.vkernel/boot
338 ln -s /home/var.vkernel /var/vkernel
341 Next, a filesystem image to be used by the virtual kernel has to be
342 created and populated (assuming world has been built previously).
343 If the image is created on a UFS filesystem you might want to pre-zero it.
344 On a HAMMER filesystem you should just truncate-extend to the image size
345 as HAMMER does not re-use data blocks already present in the file.
347 vnconfig -c -S 2g -T vn0 /var/vkernel/rootimg.01
348 disklabel -r -w vn0s0 auto
349 disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
351 mount /dev/vn0s0a /mnt
353 make installworld DESTDIR=/mnt
355 make distribution DESTDIR=/mnt
356 echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
357 echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
364 entry with the following line and turn off all other gettys.
366 console "/usr/libexec/getty Pc" cons25 on secure
373 if you would like to automatically log in as root.
375 Then, unmount the disk.
380 .Ss Compiling the virtual kernel
381 In order to compile a virtual kernel use the
383 kernel configuration file residing in
385 (or a configuration file derived thereof):
388 make -DNO_MODULES buildkernel KERNCONF=VKERNEL
389 make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
391 .Ss Enabling virtual kernel operation
394 .Va vm.vkernel_enable ,
395 must be set to enable
399 sysctl vm.vkernel_enable=1
401 .Ss Configuring the network on the host system
402 In order to access a network interface of the host system from the
404 you must add the interface to a
406 device which will then be passed to the
412 ifconfig bridge0 create
413 ifconfig bridge0 addm re0 # assuming re0 is the host's interface
416 .Ss Running the kernel
417 Finally, the virtual kernel can be run:
420 \&./boot/kernel/kernel -m 64m -r rootimg.01 -I auto:bridge0
428 commands from inside a virtual kernel.
429 After doing a clean shutdown the
431 command will re-exec the virtual kernel binary while the other two will
432 cause the virtual kernel to exit.
433 .Sh BUILDING THE WORLD UNDER A VKERNEL
434 The virtual kernel platform does not have all the header files expected
435 by a world build, so the easiest thing to do right now is to specify a
436 pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when
437 building the world under a virtual kernel, like this:
439 vkernel# make MACHINE_PLATFORM=pc32 buildworld
440 vkernel# make MACHINE_PLATFORM=pc32 installworld
454 .%A Aggelos Economopoulos
456 .%T "A Peek at the DragonFly Virtual Kernel"
459 Virtual kernels were introduced in
464 thought up and implemented the
466 architecture and wrote the
473 This manual page was written by