1.\" 2.\" Copyright (c) 2006, 2007 3.\" The DragonFly Project. All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in 13.\" the documentation and/or other materials provided with the 14.\" distribution. 15.\" 3. Neither the name of The DragonFly Project nor the names of its 16.\" contributors may be used to endorse or promote products derived 17.\" from this software without specific, prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 22.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 23.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 24.\" INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 25.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 26.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 27.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 28.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 29.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.Dd August 10, 2011 33.Dt VKERNEL 7 34.Os 35.Sh NAME 36.Nm vkernel , 37.Nm vcd , 38.Nm vkd , 39.Nm vke 40.Nd virtual kernel architecture 41.Sh SYNOPSIS 42.Cd "platform vkernel # for 32 bit vkernels" 43.Cd "platform vkernel64 # for 64 bit vkernels" 44.Cd "device vcd" 45.Cd "device vkd" 46.Cd "device vke" 47.Pp 48.Pa /var/vkernel/boot/kernel/kernel 49.Op Fl hsUv 50.Op Fl c Ar file 51.Op Fl e Ar name Ns = Ns Li value : Ns Ar name Ns = Ns Li value : Ns ... 52.Op Fl i Ar file 53.Op Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc 54.Op Fl l Ar cpulock 55.Op Fl m Ar size 56.Op Fl n Ar numcpus 57.Op Fl p Ar pidfile 58.Op Fl r Ar file 59.Sh DESCRIPTION 60The 61.Nm 62architecture allows for running 63.Dx 64kernels in userland. 65.Pp 66The following options are available: 67.Bl -tag -width ".Fl m Ar size" 68.It Fl c Ar file 69Specify a readonly CD-ROM image 70.Ar file 71to be used by the kernel, with the first 72.Fl c 73option defining 74.Li vcd0 , 75the second one 76.Li vcd1 , 77and so on. 78The first 79.Fl r 80or 81.Fl c 82option specified on the command line will be the boot disk. 83The 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 ... 85Specify an environment to be used by the kernel. 86This option can be specified more than once. 87.It Fl h 88Shows a list of available options, each with a short description. 89.It Fl i Ar file 90Specify a memory image 91.Ar file 92to be used by the virtual kernel. 93If no 94.Fl i 95option is given, the kernel will generate a name of the form 96.Pa /var/vkernel/memimg.XXXXXX , 97with the trailing 98.Ql X Ns s 99being replaced by a sequential number, e.g.\& 100.Pa memimg.000001 . 101.It Fl I Ar interface Ns Op Ar :address1 Ns Oo Ar :address2 Oc Ns Oo Ar /netmask Oc 102Create a virtual network device, with the first 103.Fl I 104option defining 105.Li vke0 , 106the second one 107.Li vke1 , 108and so on. 109.Pp 110The 111.Ar interface 112argument is the name of a 113.Xr tap 4 114device node or the path to a 115.Xr vknetd 8 116socket. 117The 118.Pa /dev/ 119path prefix does not have to be specified and will be automatically prepended 120for a device node. 121Specifying 122.Cm auto 123will pick the first unused 124.Xr tap 4 125device. 126.Pp 127The 128.Ar address1 129and 130.Ar address2 131arguments are the IP addresses of the 132.Xr tap 4 133and 134.Nm vke 135interfaces. 136Optionally, 137.Ar address1 138may be of the form 139.Li bridge Ns Em X 140in which case the 141.Xr tap 4 142interface is added to the specified 143.Xr bridge 4 144interface. 145The 146.Nm vke 147address is not assigned until the interface is brought up in the guest. 148.Pp 149The 150.Ar netmask 151argument applies to all interfaces for which an address is specified. 152.Pp 153When running multiple vkernels it is often more convenient to simply 154connect to a 155.Xr vknetd 8 156socket and let vknetd deal with the tap and/or bridge. An example of 157this would be '/var/run/vknet:0.0.0.0:10.2.0.2/16'. 158.It Fl l Ar cpulock 159Specify which, if any, real CPUs to lock virtual CPUs to. 160.Ar cpulock 161is one of 162.Cm any , 163.Cm map Ns Op Ns , Ns Ar startCPU , 164or 165.Ar CPU . 166.Pp 167.Cm any 168does not map virtual CPUs to real CPUs. 169This is the default. 170.Pp 171.Cm map Ns Op Ns , Ns Ar startCPU 172maps each virtual CPU to a real CPU starting with real CPU 0 or 173.Ar startCPU 174if specified. 175.Pp 176.Ar CPU 177locks all virtual CPUs to the real CPU specified by 178.Ar CPU . 179.It Fl m Ar size 180Specify the amount of memory to be used by the kernel in bytes, 181.Cm K 182.Pq kilobytes , 183.Cm M 184.Pq megabytes 185or 186.Cm G 187.Pq gigabytes . 188Lowercase versions of 189.Cm K , M , 190and 191.Cm G 192are allowed. 193.It Fl n Ar numcpus 194Specify the number of CPUs you wish to emulate. 195Up to 16 CPUs are supported. 196The virtual kernel must be built with 197.Cd options SMP 198to use this option and will default to 2 CPUs unless otherwise specified. 199.It Fl p Ar pidfile 200Specify a pidfile in which to store the process ID. 201Scripts can use this file to locate the vkernel pid for the purpose of 202shutting down or killing it. 203.Pp 204The vkernel will hold a lock on the pidfile while running. 205Scripts may test for the lock to determine if the pidfile is valid or 206stale so as to avoid accidentally killing a random process. 207Something like '/usr/bin/lockf -ks -t 0 pidfile echo -n' may be used 208to test the lock. 209A non-zero exit code indicates that the pidfile represents a running 210vkernel. 211.Pp 212An error is issued and the vkernel exits if this file cannot be opened for 213writing or if it is already locked by an active vkernel process. 214.It Fl r Ar file 215Specify a R/W disk image 216.Ar file 217to be used by the kernel, with the first 218.Fl r 219option defining 220.Li vkd0 , 221the second one 222.Li vkd1 , 223and so on. 224The first 225.Fl r 226or 227.Fl c 228option specified on the command line will be the boot disk. 229.It Fl s 230Boot into single-user mode. 231.It Fl U 232Enable writing to kernel memory and module loading. 233By default, those are disabled for security reasons. 234.It Fl v 235Turn on verbose booting. 236.El 237.Sh DEVICES 238A number of virtual device drivers exist to supplement the virtual kernel. 239.Ss Disk device 240The 241.Nm vkd 242driver allows for up to 16 243.Xr vn 4 244based disk devices. 245The root device will be 246.Li vkd0 247(see 248.Sx EXAMPLES 249for further information on how to prepare a root image). 250.Ss CD-ROM device 251The 252.Nm vcd 253driver allows for up to 16 virtual CD-ROM devices. 254Basically this is a read only 255.Nm vkd 256device with a block size of 2048. 257.Ss Network interface 258The 259.Nm vke 260driver supports up to 16 virtual network interfaces which are associated with 261.Xr tap 4 262devices on the host. 263For each 264.Nm vke 265device, the per-interface read only 266.Xr sysctl 3 267variable 268.Va hw.vke Ns Em X Ns Va .tap_unit 269holds the unit number of the associated 270.Xr tap 4 271device. 272.Sh SIGNALS 273The virtual kernel only enables 274.Dv SIGQUIT 275and 276.Dv SIGTERM 277while operating in regular console mode. 278Sending 279.Ql \&^\e 280.Pq Dv SIGQUIT 281to the virtual kernel causes the virtual kernel to enter its internal 282.Xr ddb 4 283debugger and re-enable all other terminal signals. 284Sending 285.Dv SIGTERM 286to the virtual kernel triggers a clean shutdown by passing a 287.Dv SIGUSR2 288to the virtual kernel's 289.Xr init 8 290process. 291.Sh DEBUGGING 292It is possible to directly gdb the virtual kernel's process. 293It is recommended that you do a 294.Ql handle SIGSEGV noprint 295to ignore page faults processed by the virtual kernel itself and 296.Ql handle SIGUSR1 noprint 297to ignore signals used for simulating inter-processor interrupts (SMP build 298only). 299.Sh FILES 300.Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact 301.It Pa /sys/config/VKERNEL 302.It Pa /sys/config/VKERNEL64 303.El 304.Pp 305Per architecture 306.Nm 307configuration files, for 308.Xr config 8 . 309.Sh CONFIGURATION FILES 310Your virtual kernel is a complete 311.Dx 312system, but you might not want to run all the services a normal kernel runs. 313Here is what a typical virtual kernel's 314.Pa /etc/rc.conf 315file looks like, with some additional possibilities commented out. 316.Bd -literal 317hostname="vkernel" 318network_interfaces="lo0 vke0" 319ifconfig_vke0="DHCP" 320sendmail_enable="NO" 321#syslog_enable="NO" 322blanktime="NO" 323.Ed 324.Sh DISKLESS OPERATION 325To boot a 326.Nm 327from a NFS root, a number of tunables need to be set: 328.Bl -tag -width indent 329.It Va boot.netif.ip 330IP address to be set in the vkernel interface. 331.It Va boot.netif.netmask 332Netmask for the IP to be set. 333.It Va boot.netif.name 334Network interface name inside the vkernel. 335.It Va boot.nfsroot.server 336Host running 337.Xr nfsd 8 . 338.It Va boot.nfsroot.path 339Host path where a world and distribution 340targets are properly installed. 341.El 342.Pp 343See an example on how to boot a diskless 344.Nm 345in the 346.Sx EXAMPLES 347section. 348.Sh EXAMPLES 349A couple of steps are necessary in order to prepare the system to build and 350run a virtual kernel. 351.Ss Setting up the filesystem 352The 353.Nm 354architecture needs a number of files which reside in 355.Pa /var/vkernel . 356Since these files tend to get rather big and the 357.Pa /var 358partition is usually of limited size, we recommend the directory to be 359created in the 360.Pa /home 361partition with a link to it in 362.Pa /var : 363.Bd -literal 364mkdir -p /home/var.vkernel/boot 365ln -s /home/var.vkernel /var/vkernel 366.Ed 367.Pp 368Next, a filesystem image to be used by the virtual kernel has to be 369created and populated (assuming world has been built previously). 370If the image is created on a UFS filesystem you might want to pre-zero it. 371On a HAMMER filesystem you should just truncate-extend to the image size 372as HAMMER does not re-use data blocks already present in the file. 373.Bd -literal 374vnconfig -c -S 2g -T vn0 /var/vkernel/rootimg.01 375disklabel -r -w vn0s0 auto 376disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD' 377newfs /dev/vn0s0a 378mount /dev/vn0s0a /mnt 379cd /usr/src 380make installworld DESTDIR=/mnt 381cd etc 382make distribution DESTDIR=/mnt 383echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab 384echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab 385.Ed 386.Pp 387Edit 388.Pa /mnt/etc/ttys 389and replace the 390.Li console 391entry with the following line and turn off all other gettys. 392.Bd -literal 393console "/usr/libexec/getty Pc" cons25 on secure 394.Ed 395.Pp 396Replace 397.Li \&Pc 398with 399.Li al.Pc 400if you would like to automatically log in as root. 401.Pp 402Then, unmount the disk. 403.Bd -literal 404umount /mnt 405vnconfig -u vn0 406.Ed 407.Ss Compiling the virtual kernel 408In order to compile a virtual kernel use the 409.Li VKERNEL 410kernel configuration file residing in 411.Pa /sys/config 412(or a configuration file derived thereof): 413.Bd -literal 414cd /usr/src 415make -DNO_MODULES buildkernel KERNCONF=VKERNEL 416make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel 417.Ed 418.Ss Enabling virtual kernel operation 419A special 420.Xr sysctl 8 , 421.Va vm.vkernel_enable , 422must be set to enable 423.Nm 424operation: 425.Bd -literal 426sysctl vm.vkernel_enable=1 427.Ed 428.Ss Configuring the network on the host system 429In order to access a network interface of the host system from the 430.Nm , 431you must add the interface to a 432.Xr bridge 4 433device which will then be passed to the 434.Fl I 435option: 436.Bd -literal 437kldload if_bridge.ko 438kldload if_tap.ko 439ifconfig bridge0 create 440ifconfig bridge0 addm re0 # assuming re0 is the host's interface 441ifconfig bridge0 up 442.Ed 443.Ss Running the kernel 444Finally, the virtual kernel can be run: 445.Bd -literal 446cd /var/vkernel 447\&./boot/kernel/kernel -m 64m -r rootimg.01 -I auto:bridge0 448.Ed 449.Pp 450You can issue the 451.Xr reboot 8 , 452.Xr halt 8 , 453or 454.Xr shutdown 8 455commands from inside a virtual kernel. 456After doing a clean shutdown the 457.Xr reboot 8 458command will re-exec the virtual kernel binary while the other two will 459cause the virtual kernel to exit. 460.Ss Diskless operation 461Booting a 462.Nm 463with a 464.Xr vknetd 8 465network configuration: 466.Bd -literal 467\&./boot/kernel/kernel -m 64m -m -i memimg.0000 -I /var/run/vknet 468 -e boot.netif.ip=172.1.0.4 469 -e boot.netif.netmask=255.255.0.0 470 -e boot.netif.name=vke0 471 -e boot.nfsroot.server=172.1.0.1 472 -e boot.nfsroot.path=/home/vkernel/vkdiskless 473.Ed 474.Sh BUILDING THE WORLD UNDER A VKERNEL 475The virtual kernel platform does not have all the header files expected 476by a world build, so the easiest thing to do right now is to specify a 477pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when 478building the world under a virtual kernel, like this: 479.Bd -literal 480vkernel# make MACHINE_PLATFORM=pc32 buildworld 481vkernel# make MACHINE_PLATFORM=pc32 installworld 482.Ed 483.Sh SEE ALSO 484.Xr vknet 1 , 485.Xr bridge 4 , 486.Xr tap 4 , 487.Xr vn 4 , 488.Xr sysctl.conf 5 , 489.Xr build 7 , 490.Xr disklabel 8 , 491.Xr ifconfig 8 , 492.Xr vknetd 8 , 493.Xr vnconfig 8 494.Rs 495.%A Aggelos Economopoulos 496.%D March 2007 497.%T "A Peek at the DragonFly Virtual Kernel" 498.Re 499.Sh HISTORY 500Virtual kernels were introduced in 501.Dx 1.7 . 502.Sh AUTHORS 503.An -nosplit 504.An Matt Dillon 505thought up and implemented the 506.Nm 507architecture and wrote the 508.Nm vkd 509device driver. 510.An Sepherosa Ziehau 511wrote the 512.Nm vke 513device driver. 514This manual page was written by 515.An Sascha Wildner . 516