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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.
86 This option can be specified more than once.
88 Shows a list of available options, each with a short description.
90 Specify a memory image
92 to be used by the virtual kernel.
95 option is given, the kernel will generate a name of the form
96 .Pa /var/vkernel/memimg.XXXXXX ,
99 being replaced by a sequential number, e.g.\&
101 .It Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc
102 Create a virtual network device, with the first
112 argument is the name of a
114 device node or the path to a
119 path prefix does not have to be specified and will be automatically prepended
123 will pick the first unused
131 arguments are the IP addresses of the
142 interface is added to the specified
147 address is not assigned until the interface is brought up in the guest.
151 argument applies to all interfaces for which an address is specified.
153 When running multiple vkernels it is often more convenient to simply
156 socket and let vknetd deal with the tap and/or bridge. An example of
157 this would be '/var/run/vknet:0.0.0.0:10.2.0.2/16'.
159 Specify which, if any, real CPUs to lock virtual CPUs to.
163 .Cm map Ns Op Ns , Ns Ar startCPU ,
168 does not map virtual CPUs to real CPUs.
171 .Cm map Ns Op Ns , Ns Ar startCPU
172 maps each virtual CPU to a real CPU starting with real CPU 0 or
177 locks all virtual CPUs to the real CPU specified by
180 Specify the amount of memory to be used by the kernel in bytes,
188 Lowercase versions of
194 Specify the number of CPUs you wish to emulate.
195 Up to 16 CPUs are supported.
196 The virtual kernel must be built with
198 to use this option and will default to 2 CPUs unless otherwise specified.
200 Specify a pidfile in which to store the process ID.
201 Scripts can use this file to locate the vkernel pid for the purpose of
202 shutting down or killing it.
204 The vkernel will hold a lock on the pidfile while running.
205 Scripts may test for the lock to determine if the pidfile is valid or
206 stale so as to avoid accidentally killing a random process.
207 Something like '/usr/bin/lockf -ks -t 0 pidfile echo -n' may be used
209 A non-zero exit code indicates that the pidfile represents a running
212 An error is issued and the vkernel exits if this file cannot be opened for
213 writing or if it is already locked by an active vkernel process.
215 Specify a R/W disk image
217 to be used by the kernel, with the first
228 option specified on the command line will be the boot disk.
230 Boot into single-user mode.
232 Enable writing to kernel memory and module loading.
233 By default, those are disabled for security reasons.
235 Turn on verbose booting.
238 A number of virtual device drivers exist to supplement the virtual kernel.
242 driver allows for up to 16
245 The root device will be
249 for further information on how to prepare a root image).
253 driver allows for up to 16 virtual CD-ROM devices.
254 Basically this is a read only
256 device with a block size of 2048.
257 .Ss Network interface
260 driver supports up to 16 virtual network interfaces which are associated with
265 device, the per-interface read only
268 .Va hw.vke Ns Em X Ns Va .tap_unit
269 holds the unit number of the associated
273 The virtual kernel only enables
277 while operating in regular console mode.
281 to the virtual kernel causes the virtual kernel to enter its internal
283 debugger and re-enable all other terminal signals.
286 to the virtual kernel triggers a clean shutdown by passing a
288 to the virtual kernel's
292 It is possible to directly gdb the virtual kernel's process.
293 It is recommended that you do a
294 .Ql handle SIGSEGV noprint
295 to ignore page faults processed by the virtual kernel itself and
296 .Ql handle SIGUSR1 noprint
297 to ignore signals used for simulating inter-processor interrupts (SMP build
300 To compile a vkernel with profiling support, the
302 variable needs to be used to pass
308 make -DNO_MODULES CONFIGARGS=-p buildkernel KERNCONF=VKERNEL
311 .Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
312 .It Pa /sys/config/VKERNEL
313 .It Pa /sys/config/VKERNEL64
318 configuration files, for
320 .Sh CONFIGURATION FILES
321 Your virtual kernel is a complete
323 system, but you might not want to run all the services a normal kernel runs.
324 Here is what a typical virtual kernel's
326 file looks like, with some additional possibilities commented out.
329 network_interfaces="lo0 vke0"
335 .Sh DISKLESS OPERATION
338 from a NFS root, a number of tunables need to be set:
339 .Bl -tag -width indent
341 IP address to be set in the vkernel interface.
342 .It Va boot.netif.netmask
343 Netmask for the IP to be set.
344 .It Va boot.netif.name
345 Network interface name inside the vkernel.
346 .It Va boot.nfsroot.server
349 .It Va boot.nfsroot.path
350 Host path where a world and distribution
351 targets are properly installed.
354 See an example on how to boot a diskless
360 A couple of steps are necessary in order to prepare the system to build and
361 run a virtual kernel.
362 .Ss Setting up the filesystem
365 architecture needs a number of files which reside in
367 Since these files tend to get rather big and the
369 partition is usually of limited size, we recommend the directory to be
372 partition with a link to it in
375 mkdir -p /home/var.vkernel/boot
376 ln -s /home/var.vkernel /var/vkernel
379 Next, a filesystem image to be used by the virtual kernel has to be
380 created and populated (assuming world has been built previously).
381 If the image is created on a UFS filesystem you might want to pre-zero it.
382 On a HAMMER filesystem you should just truncate-extend to the image size
383 as HAMMER does not re-use data blocks already present in the file.
385 vnconfig -c -S 2g -T vn0 /var/vkernel/rootimg.01
386 disklabel -r -w vn0s0 auto
387 disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
389 mount /dev/vn0s0a /mnt
391 make installworld DESTDIR=/mnt
393 make distribution DESTDIR=/mnt
394 echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
395 echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
402 entry with the following line and turn off all other gettys.
404 console "/usr/libexec/getty Pc" cons25 on secure
411 if you would like to automatically log in as root.
413 Then, unmount the disk.
418 .Ss Compiling the virtual kernel
419 In order to compile a virtual kernel use the
421 kernel configuration file residing in
423 (or a configuration file derived thereof):
426 make -DNO_MODULES buildkernel KERNCONF=VKERNEL
427 make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
429 .Ss Enabling virtual kernel operation
432 .Va vm.vkernel_enable ,
433 must be set to enable
437 sysctl vm.vkernel_enable=1
439 .Ss Configuring the network on the host system
440 In order to access a network interface of the host system from the
442 you must add the interface to a
444 device which will then be passed to the
450 ifconfig bridge0 create
451 ifconfig bridge0 addm re0 # assuming re0 is the host's interface
454 .Ss Running the kernel
455 Finally, the virtual kernel can be run:
458 \&./boot/kernel/kernel -m 64m -r rootimg.01 -I auto:bridge0
466 commands from inside a virtual kernel.
467 After doing a clean shutdown the
469 command will re-exec the virtual kernel binary while the other two will
470 cause the virtual kernel to exit.
471 .Ss Diskless operation
476 network configuration:
478 \&./boot/kernel/kernel -m 64m -m -i memimg.0000 -I /var/run/vknet
479 -e boot.netif.ip=172.1.0.4
480 -e boot.netif.netmask=255.255.0.0
481 -e boot.netif.name=vke0
482 -e boot.nfsroot.server=172.1.0.1
483 -e boot.nfsroot.path=/home/vkernel/vkdiskless
485 .Sh BUILDING THE WORLD UNDER A VKERNEL
486 The virtual kernel platform does not have all the header files expected
487 by a world build, so the easiest thing to do right now is to specify a
488 pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when
489 building the world under a virtual kernel, like this:
491 vkernel# make MACHINE_PLATFORM=pc32 buildworld
492 vkernel# make MACHINE_PLATFORM=pc32 installworld
507 .%A Aggelos Economopoulos
509 .%T "A Peek at the DragonFly Virtual Kernel"
512 Virtual kernels were introduced in
517 thought up and implemented the
519 architecture and wrote the
526 This manual page was written by