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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
56 .Op Fl n Ar numcpus Ns Op Ar :lbits Ns Oo Ar :cbits 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
193 .It Fl n Ar numcpus Ns Op Ar :lbits Ns Oo Ar :cbits Oc
195 specifies the number of CPUs you wish to emulate.
196 Up to 16 CPUs are supported with 2 being the default unless otherwise
199 specifies the number of bits within APICID(=CPUID) needed for representing
201 Controls the number of threads/core (0bits - 1 thread, 1bit - 2 threads).
202 This parameter is optional (mandatory only if
206 specifies the number of bits within APICID(=CPUID) needed for representing
208 Controls the number of core/package (0bits - 1 core, 1bit - 2 cores).
209 This parameter is optional.
211 Specify a pidfile in which to store the process ID.
212 Scripts can use this file to locate the vkernel pid for the purpose of
213 shutting down or killing it.
215 The vkernel will hold a lock on the pidfile while running.
216 Scripts may test for the lock to determine if the pidfile is valid or
217 stale so as to avoid accidentally killing a random process.
218 Something like '/usr/bin/lockf -ks -t 0 pidfile echo -n' may be used
220 A non-zero exit code indicates that the pidfile represents a running
223 An error is issued and the vkernel exits if this file cannot be opened for
224 writing or if it is already locked by an active vkernel process.
226 Specify a R/W disk image
228 to be used by the kernel, with the first
239 option specified on the command line will be the boot disk.
241 Boot into single-user mode.
243 Enable writing to kernel memory and module loading.
244 By default, those are disabled for security reasons.
246 Turn on verbose booting.
249 A number of virtual device drivers exist to supplement the virtual kernel.
253 driver allows for up to 16
256 The root device will be
260 for further information on how to prepare a root image).
264 driver allows for up to 16 virtual CD-ROM devices.
265 Basically this is a read only
267 device with a block size of 2048.
268 .Ss Network interface
271 driver supports up to 16 virtual network interfaces which are associated with
276 device, the per-interface read only
279 .Va hw.vke Ns Em X Ns Va .tap_unit
280 holds the unit number of the associated
284 The virtual kernel only enables
288 while operating in regular console mode.
292 to the virtual kernel causes the virtual kernel to enter its internal
294 debugger and re-enable all other terminal signals.
297 to the virtual kernel triggers a clean shutdown by passing a
299 to the virtual kernel's
303 It is possible to directly gdb the virtual kernel's process.
304 It is recommended that you do a
305 .Ql handle SIGSEGV noprint
306 to ignore page faults processed by the virtual kernel itself and
307 .Ql handle SIGUSR1 noprint
308 to ignore signals used for simulating inter-processor interrupts.
310 To compile a vkernel with profiling support, the
312 variable needs to be used to pass
318 make -DNO_MODULES CONFIGARGS=-p buildkernel KERNCONF=VKERNEL
321 .Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
322 .It Pa /sys/config/VKERNEL
323 .It Pa /sys/config/VKERNEL64
328 configuration files, for
330 .Sh CONFIGURATION FILES
331 Your virtual kernel is a complete
333 system, but you might not want to run all the services a normal kernel runs.
334 Here is what a typical virtual kernel's
336 file looks like, with some additional possibilities commented out.
339 network_interfaces="lo0 vke0"
345 .Sh DISKLESS OPERATION
348 from a NFS root, a number of tunables need to be set:
349 .Bl -tag -width indent
351 IP address to be set in the vkernel interface.
352 .It Va boot.netif.netmask
353 Netmask for the IP to be set.
354 .It Va boot.netif.name
355 Network interface name inside the vkernel.
356 .It Va boot.nfsroot.server
359 .It Va boot.nfsroot.path
360 Host path where a world and distribution
361 targets are properly installed.
364 See an example on how to boot a diskless
370 A couple of steps are necessary in order to prepare the system to build and
371 run a virtual kernel.
372 .Ss Setting up the filesystem
375 architecture needs a number of files which reside in
377 Since these files tend to get rather big and the
379 partition is usually of limited size, we recommend the directory to be
382 partition with a link to it in
385 mkdir -p /home/var.vkernel/boot
386 ln -s /home/var.vkernel /var/vkernel
389 Next, a filesystem image to be used by the virtual kernel has to be
390 created and populated (assuming world has been built previously).
391 If the image is created on a UFS filesystem you might want to pre-zero it.
392 On a HAMMER filesystem you should just truncate-extend to the image size
393 as HAMMER does not re-use data blocks already present in the file.
395 vnconfig -c -S 2g -T vn0 /var/vkernel/rootimg.01
396 disklabel -r -w vn0s0 auto
397 disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
399 mount /dev/vn0s0a /mnt
401 make installworld DESTDIR=/mnt
403 make distribution DESTDIR=/mnt
404 echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
405 echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
412 entry with the following line and turn off all other gettys.
414 console "/usr/libexec/getty Pc" cons25 on secure
421 if you would like to automatically log in as root.
423 Then, unmount the disk.
428 .Ss Compiling the virtual kernel
429 In order to compile a virtual kernel use the
431 kernel configuration file residing in
433 (or a configuration file derived thereof):
436 make -DNO_MODULES buildkernel KERNCONF=VKERNEL
437 make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
439 .Ss Enabling virtual kernel operation
442 .Va vm.vkernel_enable ,
443 must be set to enable
447 sysctl vm.vkernel_enable=1
449 .Ss Configuring the network on the host system
450 In order to access a network interface of the host system from the
452 you must add the interface to a
454 device which will then be passed to the
460 ifconfig bridge0 create
461 ifconfig bridge0 addm re0 # assuming re0 is the host's interface
464 .Ss Running the kernel
465 Finally, the virtual kernel can be run:
468 \&./boot/kernel/kernel -m 64m -r rootimg.01 -I auto:bridge0
476 commands from inside a virtual kernel.
477 After doing a clean shutdown the
479 command will re-exec the virtual kernel binary while the other two will
480 cause the virtual kernel to exit.
481 .Ss Diskless operation
486 network configuration:
488 \&./boot/kernel/kernel -m 64m -m -i memimg.0000 -I /var/run/vknet
489 -e boot.netif.ip=172.1.0.4
490 -e boot.netif.netmask=255.255.0.0
491 -e boot.netif.name=vke0
492 -e boot.nfsroot.server=172.1.0.1
493 -e boot.nfsroot.path=/home/vkernel/vkdiskless
495 .Sh BUILDING THE WORLD UNDER A VKERNEL
496 The virtual kernel platform does not have all the header files expected
497 by a world build, so the easiest thing to do right now is to specify a
498 pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when
499 building the world under a virtual kernel, like this:
501 vkernel# make MACHINE_PLATFORM=pc32 buildworld
502 vkernel# make MACHINE_PLATFORM=pc32 installworld
517 .%A Aggelos Economopoulos
519 .%T "A Peek at the DragonFly Virtual Kernel"
522 Virtual kernels were introduced in
527 thought up and implemented the
529 architecture and wrote the
536 This manual page was written by