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32 .Dd September 28, 2013
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 Disables hardware pagetable for vkernel.
256 Enable writing to kernel memory and module loading.
257 By default, those are disabled for security reasons.
259 Turn on verbose booting.
262 A number of virtual device drivers exist to supplement the virtual kernel.
266 driver allows for up to 16
269 The root device will be
273 for further information on how to prepare a root image).
277 driver allows for up to 16 virtual CD-ROM devices.
278 Basically this is a read only
280 device with a block size of 2048.
281 .Ss Network interface
284 driver supports up to 16 virtual network interfaces which are associated with
289 device, the per-interface read only
292 .Va hw.vke Ns Em X Ns Va .tap_unit
293 holds the unit number of the associated
297 By default, half of the total mbuf clusters available is distributed equally
298 among all the vke devices up to 256.
299 This can be overridden with the tunable
300 .Va hw.vke.max_ringsize .
301 Take into account the number passed will be aligned to the lower power of two.
303 The virtual kernel only enables
307 while operating in regular console mode.
311 to the virtual kernel causes the virtual kernel to enter its internal
313 debugger and re-enable all other terminal signals.
316 to the virtual kernel triggers a clean shutdown by passing a
318 to the virtual kernel's
322 It is possible to directly gdb the virtual kernel's process.
323 It is recommended that you do a
324 .Ql handle SIGSEGV noprint
325 to ignore page faults processed by the virtual kernel itself and
326 .Ql handle SIGUSR1 noprint
327 to ignore signals used for simulating inter-processor interrupts.
329 To compile a vkernel with profiling support, the
331 variable needs to be used to pass
337 make -DNO_MODULES CONFIGARGS=-p buildkernel KERNCONF=VKERNEL
340 .Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
341 .It Pa /sys/config/VKERNEL
342 .It Pa /sys/config/VKERNEL64
347 configuration files, for
349 .Sh CONFIGURATION FILES
350 Your virtual kernel is a complete
352 system, but you might not want to run all the services a normal kernel runs.
353 Here is what a typical virtual kernel's
355 file looks like, with some additional possibilities commented out.
358 network_interfaces="lo0 vke0"
364 .Sh DISKLESS OPERATION
367 from a NFS root, a number of tunables need to be set:
368 .Bl -tag -width indent
370 IP address to be set in the vkernel interface.
371 .It Va boot.netif.netmask
372 Netmask for the IP to be set.
373 .It Va boot.netif.name
374 Network interface name inside the vkernel.
375 .It Va boot.nfsroot.server
378 .It Va boot.nfsroot.path
379 Host path where a world and distribution
380 targets are properly installed.
383 See an example on how to boot a diskless
389 A couple of steps are necessary in order to prepare the system to build and
390 run a virtual kernel.
391 .Ss Setting up the filesystem
394 architecture needs a number of files which reside in
396 Since these files tend to get rather big and the
398 partition is usually of limited size, we recommend the directory to be
401 partition with a link to it in
404 mkdir -p /home/var.vkernel/boot
405 ln -s /home/var.vkernel /var/vkernel
408 Next, a filesystem image to be used by the virtual kernel has to be
409 created and populated (assuming world has been built previously).
410 If the image is created on a UFS filesystem you might want to pre-zero it.
411 On a HAMMER filesystem you should just truncate-extend to the image size
412 as HAMMER does not re-use data blocks already present in the file.
414 vnconfig -c -S 2g -T vn0 /var/vkernel/rootimg.01
415 disklabel -r -w vn0s0 auto
416 disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
418 mount /dev/vn0s0a /mnt
420 make installworld DESTDIR=/mnt
422 make distribution DESTDIR=/mnt
423 echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
424 echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
431 entry with the following line and turn off all other gettys.
433 console "/usr/libexec/getty Pc" cons25 on secure
440 if you would like to automatically log in as root.
442 Then, unmount the disk.
447 .Ss Compiling the virtual kernel
448 In order to compile a virtual kernel use the
450 kernel configuration file residing in
452 (or a configuration file derived thereof):
455 make -DNO_MODULES buildkernel KERNCONF=VKERNEL
456 make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
458 .Ss Enabling virtual kernel operation
461 .Va vm.vkernel_enable ,
462 must be set to enable
466 sysctl vm.vkernel_enable=1
468 .Ss Configuring the network on the host system
469 In order to access a network interface of the host system from the
471 you must add the interface to a
473 device which will then be passed to the
479 ifconfig bridge0 create
480 ifconfig bridge0 addm re0 # assuming re0 is the host's interface
483 .Ss Running the kernel
484 Finally, the virtual kernel can be run:
487 \&./boot/kernel/kernel -m 64m -r rootimg.01 -I auto:bridge0
495 commands from inside a virtual kernel.
496 After doing a clean shutdown the
498 command will re-exec the virtual kernel binary while the other two will
499 cause the virtual kernel to exit.
500 .Ss Diskless operation
505 network configuration:
507 \&./boot/kernel/kernel -m 64m -m -i memimg.0000 -I /var/run/vknet
508 -e boot.netif.ip=172.1.0.4
509 -e boot.netif.netmask=255.255.0.0
510 -e boot.netif.name=vke0
511 -e boot.nfsroot.server=172.1.0.1
512 -e boot.nfsroot.path=/home/vkernel/vkdiskless
514 .Sh BUILDING THE WORLD UNDER A VKERNEL
515 The virtual kernel platform does not have all the header files expected
516 by a world build, so the easiest thing to do right now is to specify a
517 pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when
518 building the world under a virtual kernel, like this:
520 vkernel# make MACHINE_PLATFORM=pc32 buildworld
521 vkernel# make MACHINE_PLATFORM=pc32 installworld
537 .%A Aggelos Economopoulos
539 .%T "A Peek at the DragonFly Virtual Kernel"
542 Virtual kernels were introduced in
547 thought up and implemented the
549 architecture and wrote the
556 This manual page was written by