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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.
197 The virtual kernel must be built with
199 to use this option and will default to 2 CPUs unless otherwise specified.
201 specifies the number of bits within APICID(=CPUID) needed for representing
203 Controls the number of threads/core (0bits - 1 thread, 1bit - 2 threads).
204 This parameter is optional (mandatory only if
208 specifies the number of bits within APICID(=CPUID) needed for representing
210 Controls the number of core/package (0bits - 1 core, 1bit - 2 cores).
211 This parameter is optional.
213 Specify a pidfile in which to store the process ID.
214 Scripts can use this file to locate the vkernel pid for the purpose of
215 shutting down or killing it.
217 The vkernel will hold a lock on the pidfile while running.
218 Scripts may test for the lock to determine if the pidfile is valid or
219 stale so as to avoid accidentally killing a random process.
220 Something like '/usr/bin/lockf -ks -t 0 pidfile echo -n' may be used
222 A non-zero exit code indicates that the pidfile represents a running
225 An error is issued and the vkernel exits if this file cannot be opened for
226 writing or if it is already locked by an active vkernel process.
228 Specify a R/W disk image
230 to be used by the kernel, with the first
241 option specified on the command line will be the boot disk.
243 Boot into single-user mode.
245 Enable writing to kernel memory and module loading.
246 By default, those are disabled for security reasons.
248 Turn on verbose booting.
251 A number of virtual device drivers exist to supplement the virtual kernel.
255 driver allows for up to 16
258 The root device will be
262 for further information on how to prepare a root image).
266 driver allows for up to 16 virtual CD-ROM devices.
267 Basically this is a read only
269 device with a block size of 2048.
270 .Ss Network interface
273 driver supports up to 16 virtual network interfaces which are associated with
278 device, the per-interface read only
281 .Va hw.vke Ns Em X Ns Va .tap_unit
282 holds the unit number of the associated
286 The virtual kernel only enables
290 while operating in regular console mode.
294 to the virtual kernel causes the virtual kernel to enter its internal
296 debugger and re-enable all other terminal signals.
299 to the virtual kernel triggers a clean shutdown by passing a
301 to the virtual kernel's
305 It is possible to directly gdb the virtual kernel's process.
306 It is recommended that you do a
307 .Ql handle SIGSEGV noprint
308 to ignore page faults processed by the virtual kernel itself and
309 .Ql handle SIGUSR1 noprint
310 to ignore signals used for simulating inter-processor interrupts (SMP build
313 To compile a vkernel with profiling support, the
315 variable needs to be used to pass
321 make -DNO_MODULES CONFIGARGS=-p buildkernel KERNCONF=VKERNEL
324 .Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact
325 .It Pa /sys/config/VKERNEL
326 .It Pa /sys/config/VKERNEL64
331 configuration files, for
333 .Sh CONFIGURATION FILES
334 Your virtual kernel is a complete
336 system, but you might not want to run all the services a normal kernel runs.
337 Here is what a typical virtual kernel's
339 file looks like, with some additional possibilities commented out.
342 network_interfaces="lo0 vke0"
348 .Sh DISKLESS OPERATION
351 from a NFS root, a number of tunables need to be set:
352 .Bl -tag -width indent
354 IP address to be set in the vkernel interface.
355 .It Va boot.netif.netmask
356 Netmask for the IP to be set.
357 .It Va boot.netif.name
358 Network interface name inside the vkernel.
359 .It Va boot.nfsroot.server
362 .It Va boot.nfsroot.path
363 Host path where a world and distribution
364 targets are properly installed.
367 See an example on how to boot a diskless
373 A couple of steps are necessary in order to prepare the system to build and
374 run a virtual kernel.
375 .Ss Setting up the filesystem
378 architecture needs a number of files which reside in
380 Since these files tend to get rather big and the
382 partition is usually of limited size, we recommend the directory to be
385 partition with a link to it in
388 mkdir -p /home/var.vkernel/boot
389 ln -s /home/var.vkernel /var/vkernel
392 Next, a filesystem image to be used by the virtual kernel has to be
393 created and populated (assuming world has been built previously).
394 If the image is created on a UFS filesystem you might want to pre-zero it.
395 On a HAMMER filesystem you should just truncate-extend to the image size
396 as HAMMER does not re-use data blocks already present in the file.
398 vnconfig -c -S 2g -T vn0 /var/vkernel/rootimg.01
399 disklabel -r -w vn0s0 auto
400 disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD'
402 mount /dev/vn0s0a /mnt
404 make installworld DESTDIR=/mnt
406 make distribution DESTDIR=/mnt
407 echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab
408 echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab
415 entry with the following line and turn off all other gettys.
417 console "/usr/libexec/getty Pc" cons25 on secure
424 if you would like to automatically log in as root.
426 Then, unmount the disk.
431 .Ss Compiling the virtual kernel
432 In order to compile a virtual kernel use the
434 kernel configuration file residing in
436 (or a configuration file derived thereof):
439 make -DNO_MODULES buildkernel KERNCONF=VKERNEL
440 make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel
442 .Ss Enabling virtual kernel operation
445 .Va vm.vkernel_enable ,
446 must be set to enable
450 sysctl vm.vkernel_enable=1
452 .Ss Configuring the network on the host system
453 In order to access a network interface of the host system from the
455 you must add the interface to a
457 device which will then be passed to the
463 ifconfig bridge0 create
464 ifconfig bridge0 addm re0 # assuming re0 is the host's interface
467 .Ss Running the kernel
468 Finally, the virtual kernel can be run:
471 \&./boot/kernel/kernel -m 64m -r rootimg.01 -I auto:bridge0
479 commands from inside a virtual kernel.
480 After doing a clean shutdown the
482 command will re-exec the virtual kernel binary while the other two will
483 cause the virtual kernel to exit.
484 .Ss Diskless operation
489 network configuration:
491 \&./boot/kernel/kernel -m 64m -m -i memimg.0000 -I /var/run/vknet
492 -e boot.netif.ip=172.1.0.4
493 -e boot.netif.netmask=255.255.0.0
494 -e boot.netif.name=vke0
495 -e boot.nfsroot.server=172.1.0.1
496 -e boot.nfsroot.path=/home/vkernel/vkdiskless
498 .Sh BUILDING THE WORLD UNDER A VKERNEL
499 The virtual kernel platform does not have all the header files expected
500 by a world build, so the easiest thing to do right now is to specify a
501 pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when
502 building the world under a virtual kernel, like this:
504 vkernel# make MACHINE_PLATFORM=pc32 buildworld
505 vkernel# make MACHINE_PLATFORM=pc32 installworld
520 .%A Aggelos Economopoulos
522 .%T "A Peek at the DragonFly Virtual Kernel"
525 Virtual kernels were introduced in
530 thought up and implemented the
532 architecture and wrote the
539 This manual page was written by