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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 Ns Oo Ar =mac Oc
56 .Op Fl n Ar numcpus Ns Op Ar :lbits Ns Oo Ar :cbits Oc
58 .Op Fl r Ar file Ns Op Ar :serno
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 Ns Oo Ar =MAC 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.
155 argument is the MAC address of the
158 If not specified, a pseudo-random one will be generated.
160 When running multiple vkernels it is often more convenient to simply
163 socket and let vknetd deal with the tap and/or bridge.
164 An example of this would be
165 .Pa /var/run/vknet:0.0.0.0:10.2.0.2/16 .
167 Specify which, if any, real CPUs to lock virtual CPUs to.
171 .Cm map Ns Op Ns , Ns Ar startCPU ,
176 does not map virtual CPUs to real CPUs.
179 .Cm map Ns Op Ns , Ns Ar startCPU
180 maps each virtual CPU to a real CPU starting with real CPU 0 or
185 locks all virtual CPUs to the real CPU specified by
188 Specify the amount of memory to be used by the kernel in bytes,
196 Lowercase versions of
201 .It Fl n Ar numcpus Ns Op Ar :lbits Ns Oo Ar :cbits Oc
203 specifies the number of CPUs you wish to emulate.
204 Up to 16 CPUs are supported with 2 being the default unless otherwise
207 specifies the number of bits within APICID(=CPUID) needed for representing
209 Controls the number of threads/core (0bits - 1 thread, 1bit - 2 threads).
210 This parameter is optional (mandatory only if
214 specifies the number of bits within APICID(=CPUID) needed for representing
216 Controls the number of core/package (0bits - 1 core, 1bit - 2 cores).
217 This parameter is optional.
219 Specify a pidfile in which to store the process ID.
220 Scripts can use this file to locate the vkernel pid for the purpose of
221 shutting down or killing it.
223 The vkernel will hold a lock on the pidfile while running.
224 Scripts may test for the lock to determine if the pidfile is valid or
225 stale so as to avoid accidentally killing a random process.
226 Something like '/usr/bin/lockf -ks -t 0 pidfile echo -n' may be used
228 A non-zero exit code indicates that the pidfile represents a running
231 An error is issued and the vkernel exits if this file cannot be opened for
232 writing or if it is already locked by an active vkernel process.
233 .It Fl r Ar file Ns Op Ar :serno
234 Specify a R/W disk image
236 to be used by the kernel, with the first
243 A serial number for the virtual disk can be specified in
250 option specified on the command line will be the boot disk.
252 Boot into single-user mode.
254 Enable writing to kernel memory and module loading.
255 By default, those are disabled for security reasons.
257 Turn on verbose booting.
260 A number of virtual device drivers exist to supplement the virtual kernel.
264 driver allows for up to 16
267 The root device will be
271 for further information on how to prepare a root image).
275 driver allows for up to 16 virtual CD-ROM devices.
276 Basically this is a read only
278 device with a block size of 2048.
279 .Ss Network interface
282 driver supports up to 16 virtual network interfaces which are associated with
287 device, the per-interface read only
290 .Va hw.vke Ns Em X Ns Va .tap_unit
291 holds the unit number of the associated
295 By default, half of the total mbuf clusters available is distributed equally
296 among all the vke devices up to 256.
297 This can be overriden with the tunable
298 .Va hw.vke.max_ringsize .
299 Take into account the number passed will be aligned to the lower power of two.
301 The virtual kernel only enables
305 while operating in regular console mode.
309 to the virtual kernel causes the virtual kernel to enter its internal
311 debugger and re-enable all other terminal signals.
314 to the virtual kernel triggers a clean shutdown by passing a
316 to the virtual kernel's
320 It is possible to directly gdb the virtual kernel's process.
321 It is recommended that you do a
322 .Ql handle SIGSEGV noprint
323 to ignore page faults processed by the virtual kernel itself and
324 .Ql handle SIGUSR1 noprint
325 to ignore signals used for simulating inter-processor interrupts.
327 To compile a vkernel with profiling support, the
329 variable needs to be used to pass
335 make -DNO_MODULES CONFIGARGS=-p buildkernel KERNCONF=VKERNEL
338 .Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
339 .It Pa /sys/config/VKERNEL
340 .It Pa /sys/config/VKERNEL64
345 configuration files, for
347 .Sh CONFIGURATION FILES
348 Your virtual kernel is a complete
350 system, but you might not want to run all the services a normal kernel runs.
351 Here is what a typical virtual kernel's
353 file looks like, with some additional possibilities commented out.
356 network_interfaces="lo0 vke0"
362 .Sh DISKLESS OPERATION
365 from a NFS root, a number of tunables need to be set:
366 .Bl -tag -width indent
368 IP address to be set in the vkernel interface.
369 .It Va boot.netif.netmask
370 Netmask for the IP to be set.
371 .It Va boot.netif.name
372 Network interface name inside the vkernel.
373 .It Va boot.nfsroot.server
376 .It Va boot.nfsroot.path
377 Host path where a world and distribution
378 targets are properly installed.
381 See an example on how to boot a diskless
387 A couple of steps are necessary in order to prepare the system to build and
388 run a virtual kernel.
389 .Ss Setting up the filesystem
392 architecture needs a number of files which reside in
394 Since these files tend to get rather big and the
396 partition is usually of limited size, we recommend the directory to be
399 partition with a link to it in
402 mkdir -p /home/var.vkernel/boot
403 ln -s /home/var.vkernel /var/vkernel
406 Next, a filesystem image to be used by the virtual kernel has to be
407 created and populated (assuming world has been built previously).
408 If the image is created on a UFS filesystem you might want to pre-zero it.
409 On a HAMMER filesystem you should just truncate-extend to the image size
410 as HAMMER does not re-use data blocks already present in the file.
412 vnconfig -c -S 2g -T vn0 /var/vkernel/rootimg.01
413 disklabel -r -w vn0s0 auto
414 disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
416 mount /dev/vn0s0a /mnt
418 make installworld DESTDIR=/mnt
420 make distribution DESTDIR=/mnt
421 echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
422 echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
429 entry with the following line and turn off all other gettys.
431 console "/usr/libexec/getty Pc" cons25 on secure
438 if you would like to automatically log in as root.
440 Then, unmount the disk.
445 .Ss Compiling the virtual kernel
446 In order to compile a virtual kernel use the
448 kernel configuration file residing in
450 (or a configuration file derived thereof):
453 make -DNO_MODULES buildkernel KERNCONF=VKERNEL
454 make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
456 .Ss Enabling virtual kernel operation
459 .Va vm.vkernel_enable ,
460 must be set to enable
464 sysctl vm.vkernel_enable=1
466 .Ss Configuring the network on the host system
467 In order to access a network interface of the host system from the
469 you must add the interface to a
471 device which will then be passed to the
477 ifconfig bridge0 create
478 ifconfig bridge0 addm re0 # assuming re0 is the host's interface
481 .Ss Running the kernel
482 Finally, the virtual kernel can be run:
485 \&./boot/kernel/kernel -m 64m -r rootimg.01 -I auto:bridge0
493 commands from inside a virtual kernel.
494 After doing a clean shutdown the
496 command will re-exec the virtual kernel binary while the other two will
497 cause the virtual kernel to exit.
498 .Ss Diskless operation
503 network configuration:
505 \&./boot/kernel/kernel -m 64m -m -i memimg.0000 -I /var/run/vknet
506 -e boot.netif.ip=172.1.0.4
507 -e boot.netif.netmask=255.255.0.0
508 -e boot.netif.name=vke0
509 -e boot.nfsroot.server=172.1.0.1
510 -e boot.nfsroot.path=/home/vkernel/vkdiskless
512 .Sh BUILDING THE WORLD UNDER A VKERNEL
513 The virtual kernel platform does not have all the header files expected
514 by a world build, so the easiest thing to do right now is to specify a
515 pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when
516 building the world under a virtual kernel, like this:
518 vkernel# make MACHINE_PLATFORM=pc32 buildworld
519 vkernel# make MACHINE_PLATFORM=pc32 installworld
534 .%A Aggelos Economopoulos
536 .%T "A Peek at the DragonFly Virtual Kernel"
539 Virtual kernels were introduced in
544 thought up and implemented the
546 architecture and wrote the
553 This manual page was written by