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 May 17, 2012 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 PROFILING 300To compile a vkernel with profiling support, the 301.Va CONFIGARGS 302variable needs to be used to pass 303.Fl p 304to 305.Xr config 8 . 306.Bd -literal 307cd /usr/src 308make -DNO_MODULES CONFIGARGS=-p buildkernel KERNCONF=VKERNEL 309.Ed 310.Sh FILES 311.Bl -tag -width ".It Pa /sys/config/VKERNEL" -compact 312.It Pa /sys/config/VKERNEL 313.It Pa /sys/config/VKERNEL64 314.El 315.Pp 316Per architecture 317.Nm 318configuration files, for 319.Xr config 8 . 320.Sh CONFIGURATION FILES 321Your virtual kernel is a complete 322.Dx 323system, but you might not want to run all the services a normal kernel runs. 324Here is what a typical virtual kernel's 325.Pa /etc/rc.conf 326file looks like, with some additional possibilities commented out. 327.Bd -literal 328hostname="vkernel" 329network_interfaces="lo0 vke0" 330ifconfig_vke0="DHCP" 331sendmail_enable="NO" 332#syslog_enable="NO" 333blanktime="NO" 334.Ed 335.Sh DISKLESS OPERATION 336To boot a 337.Nm 338from a NFS root, a number of tunables need to be set: 339.Bl -tag -width indent 340.It Va boot.netif.ip 341IP address to be set in the vkernel interface. 342.It Va boot.netif.netmask 343Netmask for the IP to be set. 344.It Va boot.netif.name 345Network interface name inside the vkernel. 346.It Va boot.nfsroot.server 347Host running 348.Xr nfsd 8 . 349.It Va boot.nfsroot.path 350Host path where a world and distribution 351targets are properly installed. 352.El 353.Pp 354See an example on how to boot a diskless 355.Nm 356in the 357.Sx EXAMPLES 358section. 359.Sh EXAMPLES 360A couple of steps are necessary in order to prepare the system to build and 361run a virtual kernel. 362.Ss Setting up the filesystem 363The 364.Nm 365architecture needs a number of files which reside in 366.Pa /var/vkernel . 367Since these files tend to get rather big and the 368.Pa /var 369partition is usually of limited size, we recommend the directory to be 370created in the 371.Pa /home 372partition with a link to it in 373.Pa /var : 374.Bd -literal 375mkdir -p /home/var.vkernel/boot 376ln -s /home/var.vkernel /var/vkernel 377.Ed 378.Pp 379Next, a filesystem image to be used by the virtual kernel has to be 380created and populated (assuming world has been built previously). 381If the image is created on a UFS filesystem you might want to pre-zero it. 382On a HAMMER filesystem you should just truncate-extend to the image size 383as HAMMER does not re-use data blocks already present in the file. 384.Bd -literal 385vnconfig -c -S 2g -T vn0 /var/vkernel/rootimg.01 386disklabel -r -w vn0s0 auto 387disklabel -e vn0s0 # add `a' partition with fstype `4.2BSD' 388newfs /dev/vn0s0a 389mount /dev/vn0s0a /mnt 390cd /usr/src 391make installworld DESTDIR=/mnt 392cd etc 393make distribution DESTDIR=/mnt 394echo '/dev/vkd0s0a / ufs rw 1 1' >/mnt/etc/fstab 395echo 'proc /proc procfs rw 0 0' >>/mnt/etc/fstab 396.Ed 397.Pp 398Edit 399.Pa /mnt/etc/ttys 400and replace the 401.Li console 402entry with the following line and turn off all other gettys. 403.Bd -literal 404console "/usr/libexec/getty Pc" cons25 on secure 405.Ed 406.Pp 407Replace 408.Li \&Pc 409with 410.Li al.Pc 411if you would like to automatically log in as root. 412.Pp 413Then, unmount the disk. 414.Bd -literal 415umount /mnt 416vnconfig -u vn0 417.Ed 418.Ss Compiling the virtual kernel 419In order to compile a virtual kernel use the 420.Li VKERNEL 421kernel configuration file residing in 422.Pa /sys/config 423(or a configuration file derived thereof): 424.Bd -literal 425cd /usr/src 426make -DNO_MODULES buildkernel KERNCONF=VKERNEL 427make -DNO_MODULES installkernel KERNCONF=VKERNEL DESTDIR=/var/vkernel 428.Ed 429.Ss Enabling virtual kernel operation 430A special 431.Xr sysctl 8 , 432.Va vm.vkernel_enable , 433must be set to enable 434.Nm 435operation: 436.Bd -literal 437sysctl vm.vkernel_enable=1 438.Ed 439.Ss Configuring the network on the host system 440In order to access a network interface of the host system from the 441.Nm , 442you must add the interface to a 443.Xr bridge 4 444device which will then be passed to the 445.Fl I 446option: 447.Bd -literal 448kldload if_bridge.ko 449kldload if_tap.ko 450ifconfig bridge0 create 451ifconfig bridge0 addm re0 # assuming re0 is the host's interface 452ifconfig bridge0 up 453.Ed 454.Ss Running the kernel 455Finally, the virtual kernel can be run: 456.Bd -literal 457cd /var/vkernel 458\&./boot/kernel/kernel -m 64m -r rootimg.01 -I auto:bridge0 459.Ed 460.Pp 461You can issue the 462.Xr reboot 8 , 463.Xr halt 8 , 464or 465.Xr shutdown 8 466commands from inside a virtual kernel. 467After doing a clean shutdown the 468.Xr reboot 8 469command will re-exec the virtual kernel binary while the other two will 470cause the virtual kernel to exit. 471.Ss Diskless operation 472Booting a 473.Nm 474with a 475.Xr vknetd 8 476network configuration: 477.Bd -literal 478\&./boot/kernel/kernel -m 64m -m -i memimg.0000 -I /var/run/vknet 479 -e boot.netif.ip=172.1.0.4 480 -e boot.netif.netmask=255.255.0.0 481 -e boot.netif.name=vke0 482 -e boot.nfsroot.server=172.1.0.1 483 -e boot.nfsroot.path=/home/vkernel/vkdiskless 484.Ed 485.Sh BUILDING THE WORLD UNDER A VKERNEL 486The virtual kernel platform does not have all the header files expected 487by a world build, so the easiest thing to do right now is to specify a 488pc32 (in a 32 bit vkernel) or pc64 (in a 64 bit vkernel) target when 489building the world under a virtual kernel, like this: 490.Bd -literal 491vkernel# make MACHINE_PLATFORM=pc32 buildworld 492vkernel# make MACHINE_PLATFORM=pc32 installworld 493.Ed 494.Sh SEE ALSO 495.Xr vknet 1 , 496.Xr bridge 4 , 497.Xr tap 4 , 498.Xr vn 4 , 499.Xr sysctl.conf 5 , 500.Xr build 7 , 501.Xr config 8 , 502.Xr disklabel 8 , 503.Xr ifconfig 8 , 504.Xr vknetd 8 , 505.Xr vnconfig 8 506.Rs 507.%A Aggelos Economopoulos 508.%D March 2007 509.%T "A Peek at the DragonFly Virtual Kernel" 510.Re 511.Sh HISTORY 512Virtual kernels were introduced in 513.Dx 1.7 . 514.Sh AUTHORS 515.An -nosplit 516.An Matt Dillon 517thought up and implemented the 518.Nm 519architecture and wrote the 520.Nm vkd 521device driver. 522.An Sepherosa Ziehau 523wrote the 524.Nm vke 525device driver. 526This manual page was written by 527.An Sascha Wildner . 528