File:  [NetBSD Developer Wiki] / wikisrc / ports / xen / howto.mdwn
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Wed Dec 24 00:04:47 2014 UTC (4 years, 11 months ago) by gdt
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add advice on versions

    1: Introduction
    2: ============
    3: 
    4: [![[Xen
    5: screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](../../gallery/in-Action/hubertf-xen.png)
    6: 
    7: Xen is a virtual machine monitor or hypervisor for x86 hardware
    8: (i686-class or higher), which supports running multiple guest
    9: operating systems on a single physical machine.  With Xen, one uses
   10: the Xen kernel to control the CPU, memory and console, a dom0
   11: operating system which mediates access to other hardware (e.g., disks,
   12: network, USB), and one or more domU operating systems which operate in
   13: an unprivileged virtualized environment.  IO requests from the domU
   14: systems are forwarded by the hypervisor (Xen) to the dom0 to be
   15: fulfilled.
   16: 
   17: Xen supports two styles of guests.  The original is Para-Virtualized
   18: (PV) which means that the guest OS does not attempt to access hardware
   19: directly, but instead makes hypercalls to the hypervisor.  This is
   20: analogous to a user-space program making system calls.  (The dom0
   21: operating system uses PV calls for some functions, such as updating
   22: memory mapping page tables, but has direct hardware access for disk
   23: and network.)   PV guests must be specifically coded for Xen.
   24: 
   25: The more recent style is HVM, which means that the guest does not have
   26: code for Xen and need not be aware that it is running under Xen.
   27: Attempts to access hardware registers are trapped and emulated.  This
   28: style is less efficient but can run unmodified guests.
   29: 
   30: At boot, the dom0 kernel is loaded as module with Xen as the kernel.
   31: The dom0 can start one or more domUs.  (Booting is explained in detail
   32: in the dom0 section.)
   33: 
   34: NetBSD supports Xen in that it can serve as dom0, be used as a domU,
   35: and that Xen kernels and tools are available in pkgsrc.  This HOWTO
   36: attempts to address both the case of running a NetBSD dom0 on hardware
   37: and running NetBSD as a domU in a VPS.
   38: 
   39: Prerequisites
   40: -------------
   41: 
   42: Installing NetBSD/Xen is not extremely difficult, but it is more
   43: complex than a normal installation of NetBSD.
   44: In general, this HOWTO is occasionally overly restrictive about how
   45: things must be done, guiding the reader to stay on the established
   46: path when there are no known good reasons to stray.
   47: 
   48: This HOWTO presumes a basic familiarity with the Xen system
   49: architecture.
   50: 
   51: This HOWTO presumes familiarity with installing NetBSD on i386/amd64
   52: hardware and installing software from pkgsrc.
   53: 
   54: For more details on Xen, see [](http://www.xen.org/).
   55: 
   56: Versions of Xen and NetBSD
   57: ==========================
   58: 
   59: Most of the installation concepts and instructions are independent of
   60: Xen version.  This section gives advice on which version to choose.
   61: Versions not in pkgsrc and older unsupported versions of NetBSD are
   62: inentionally ignored.
   63: 
   64: Xen
   65: ---
   66: 
   67: In NetBSD, xen is provided in pkgsrc, via matching pairs of packages
   68: xenkernel and xentools.  We will refer only to the kernel versions,
   69: but note that both packages must be installed together and must have
   70: matching versions.
   71: 
   72: xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3.  These no longer
   73: receive security patches and should not be used.
   74: 
   75: xenkernel41 provides Xen 4.1.  This is no longer maintained by Xen,
   76: but as of 2014-12 receives backported security patches.  It is a
   77: reasonable although trailing-edge choice.
   78: 
   79: xenkernel42 provides Xen 4.2.  This is maintained by Xen, but old as
   80: of 2014-12.
   81: 
   82: Ideally newer versions of Xen will be added to pkgsrc.
   83: 
   84: NetBSD
   85: ------
   86: 
   87: The netbsd-5, netbsd-6, netbsd-7, and -current branches are all
   88: reasonable choices, with more or less the same considerations for
   89: non-Xen use.  Therefore, netbsd-6 is recommended as the stable version
   90: of the most recent release.
   91: 
   92: As of NetBSD 6, a NetBSD domU will support multiple vcpus.  There is
   93: no SMP support for NetBSD as dom0.  (The dom0 itself doesn't really
   94: need SMP; the lack of support is really a problem when using a dom0 as
   95: a normal computer.)
   96: 
   97: Recommendation
   98: --------------
   99: 
  100: Therefore, this HOWTO recommends running xenkernel42 (and xentools42)
  101: and NetBSD 6 stable branch.
  102: 
  103: NetBSD as a dom0
  104: ================
  105: 
  106: NetBSD can be used as a dom0 and works very well.  The following
  107: sections address installation, updating NetBSD, and updating Xen.
  108: 
  109: Styles of dom0 operation
  110: ------------------------
  111: 
  112: There are two basic ways to use Xen.  The traditional method is for
  113: the dom0 to do absolutely nothing other than providing support to some
  114: number of domUs.  Such a system was probably installed for the sole
  115: purpose of hosting domUs, and sits in a server room on a UPS.
  116: 
  117: The other way is to put Xen under a normal-usage computer, so that the
  118: dom0 is what the computer would have been without Xen, perhaps a
  119: desktop or laptop.  Then, one can run domUs at will.  Purists will
  120: deride this as less secure than the previous approach, and for a
  121: computer whose purpose is to run domUs, they are right.  But Xen and a
  122: dom0 (without domUs) is not meaingfully less secure than the same
  123: things running without Xen.  One can boot Xen or boot regular NetBSD
  124: alternately with little problems, simply refraining from starting the
  125: Xen daemons when not running Xen.
  126: 
  127: Note that NetBSD as dom0 does not support multiple CPUs.  This will
  128: limit the performance of the Xen/dom0 workstation approach.
  129: 
  130: Installation of NetBSD and Xen
  131: ------------------------------
  132: 
  133: Note that it doesn't make sense to talk about installing a dom0 OS
  134: without also installing Xen itself.
  135: 
  136: First do a NetBSD/i386 or NetBSD/amd64
  137: [installation](../../docs/guide/en/chap-inst.html) of the 5.1 release
  138: (or newer) as you usually do on x86 hardware. The binary releases are
  139: available from [](ftp://ftp.NetBSD.org/pub/NetBSD/). Binary snapshots
  140: for current and the stable branches are available on daily autobuilds.
  141: If you plan to use the `grub` boot loader, when partitioning the disk
  142: you have to make the root partition smaller than 512Mb, and formatted as
  143: FFSv1 with 8k block/1k fragments. If the partition is larger than this,
  144: uses FFSv2 or has different block/fragment sizes, grub may fail to load
  145: some files. Also keep in mind that you'll probably want to provide
  146: virtual disks to other domains, so reserve some partitions for these
  147: virtual disks. Alternatively, you can create large files in the file
  148: system, map them to vnd(4) devices and export theses vnd devices to
  149: other domains.
  150: 
  151: Next step is to install the Xen packages via pkgsrc or from binary
  152: packages. See [the pkgsrc
  153: documentation](http://www.NetBSD.org/docs/pkgsrc/) if you are unfamiliar
  154: with pkgsrc and/or handling of binary packages. Xen 3.1, 3.3, 4.1 and
  155: 4.2 are available. 3.1 supports PCI pass-through while other versions do
  156: not. You'll need either `sysutils/xentools3` and `sysutils/xenkernel3`
  157: for Xen 3.1, `sysutils/xentools33` and `sysutils/xenkernel33` for Xen
  158: 3.3, `sysutils/xentools41` and `sysutils/xenkernel41` for Xen 4.1. or
  159: `sysutils/xentools42` and `sysutils/xenkernel42` for Xen 4.2. You'll
  160: also need `sysutils/grub` if you plan do use the grub boot loader. If
  161: using Xen 3.1, you may also want to install `sysutils/xentools3-hvm`
  162: which contains the utilities to run unmodified guests OSes using the
  163: *HVM* support (for later versions this is included in
  164: `sysutils/xentools`). Note that your CPU needs to support this. Intel
  165: CPUs must have the 'VT' instruction, AMD CPUs the 'SVM' instruction. You
  166: can easily find out if your CPU support HVM by using NetBSD's cpuctl
  167: command:
  168: 
  169:     # cpuctl identify 0
  170:     cpu0: Intel Core 2 (Merom) (686-class), id 0x6f6
  171:     cpu0: features 0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
  172:     cpu0: features 0xbfebfbff<PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX>
  173:     cpu0: features 0xbfebfbff<FXSR,SSE,SSE2,SS,HTT,TM,SBF>
  174:     cpu0: features2 0x4e33d<SSE3,DTES64,MONITOR,DS-CPL,,TM2,SSSE3,CX16,xTPR,PDCM,DCA>
  175:     cpu0: features3 0x20100800<SYSCALL/SYSRET,XD,EM64T>
  176:     cpu0: "Intel(R) Xeon(R) CPU            5130  @ 2.00GHz"
  177:     cpu0: I-cache 32KB 64B/line 8-way, D-cache 32KB 64B/line 8-way
  178:     cpu0: L2 cache 4MB 64B/line 16-way
  179:     cpu0: ITLB 128 4KB entries 4-way
  180:     cpu0: DTLB 256 4KB entries 4-way, 32 4MB entries 4-way
  181:     cpu0: Initial APIC ID 0
  182:     cpu0: Cluster/Package ID 0
  183:     cpu0: Core ID 0
  184:     cpu0: family 06 model 0f extfamily 00 extmodel 00
  185: 
  186: Depending on your CPU, the feature you are looking for is called HVM,
  187: SVM or VMX.
  188: 
  189: Next you need to copy the selected Xen kernel itself. pkgsrc installed
  190: them under `/usr/pkg/xen*-kernel/`. The file you're looking for is
  191: `xen.gz`. Copy it to your root file system. `xen-debug.gz` is a kernel
  192: with more consistency checks and more details printed on the serial
  193: console. It is useful for debugging crashing guests if you use a serial
  194: console. It is not useful with a VGA console.
  195: 
  196: You'll then need a NetBSD/Xen kernel for *domain0* on your root file
  197: system. The XEN3PAE\_DOM0 kernel or XEN3\_DOM0 provided as part of the
  198: i386 or amd64 binaries is suitable for this, but you may want to
  199: customize it. Keep your native kernel around, as it can be useful for
  200: recovery. *Note:* the *domain0* kernel must support KERNFS and `/kern`
  201: must be mounted because *xend* needs access to `/kern/xen/privcmd`.
  202: 
  203: Next you need to get a bootloader to load the `xen.gz` kernel, and the
  204: NetBSD *domain0* kernel as a module. This can be `grub` or NetBSD's boot
  205: loader. Below is a detailled example for grub, see the boot.cfg(5)
  206: manual page for an example using the latter.
  207: 
  208: This is also where you'll specify the memory allocated to *domain0*, the
  209: console to use, etc ...
  210: 
  211: Here is a commented `/grub/menu.lst` file:
  212: 
  213:     #Grub config file for NetBSD/xen. Copy as /grub/menu.lst and run
  214:     # grub-install /dev/rwd0d (assuming your boot device is wd0).
  215:     #
  216:     # The default entry to load will be the first one
  217:     default=0
  218: 
  219:     # boot the default entry after 10s if the user didn't hit keyboard
  220:     timeout=10
  221: 
  222:     # Configure serial port to use as console. Ignore if you'll use VGA only
  223:     serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
  224: 
  225:     # Let the user select which console to use (serial or VGA), default
  226:     # to serial after 10s
  227:     terminal --timeout=10 serial console
  228: 
  229:     # An entry for NetBSD/xen, using /netbsd as the domain0 kernel, and serial
  230:     # console. Domain0 will have 64MB RAM allocated.
  231:     # Assume NetBSD is installed in the first MBR partition.
  232:     title Xen 3 / NetBSD (hda0, serial)
  233:       root(hd0,0)
  234:       kernel (hd0,a)/xen.gz dom0_mem=65536 com1=115200,8n1
  235:       module (hd0,a)/netbsd bootdev=wd0a ro console=ttyS0
  236: 
  237:     # Same as above, but using VGA console
  238:     # We can use console=tty0 (Linux syntax) or console=pc (NetBSD syntax)
  239:     title Xen 3 / NetBSD (hda0, vga)
  240:       root(hd0,0)
  241:       kernel (hd0,a)/xen.gz dom0_mem=65536
  242:       module (hd0,a)/netbsd bootdev=wd0a ro console=tty0
  243: 
  244:     # NetBSD/xen using a backup domain0 kernel (in case you installed a
  245:     # nonworking kernel as /netbsd
  246:     title Xen 3 / NetBSD (hda0, backup, serial)
  247:       root(hd0,0)
  248:       kernel (hd0,a)/xen.gz dom0_mem=65536 com1=115200,8n1
  249:       module (hd0,a)/netbsd.backup bootdev=wd0a ro console=ttyS0
  250:     title Xen 3 / NetBSD (hda0, backup, VGA)
  251:       root(hd0,0)
  252:       kernel (hd0,a)/xen.gz dom0_mem=65536
  253:       module (hd0,a)/netbsd.backup bootdev=wd0a ro console=tty0
  254: 
  255:     #Load a regular NetBSD/i386 kernel. Can be useful if you end up with a
  256:     #nonworking /xen.gz
  257:     title NetBSD 5.1
  258:       root (hd0,a)
  259:       kernel --type=netbsd /netbsd-GENERIC
  260: 
  261:     #Load the NetBSD bootloader, letting it load the NetBSD/i386 kernel.
  262:     #May be better than the above, as grub can't pass all required infos
  263:     #to the NetBSD/i386 kernel (e.g. console, root device, ...)
  264:     title NetBSD chain
  265:       root        (hd0,0)
  266:       chainloader +1
  267: 
  268:     ## end of grub config file.
  269:           
  270: 
  271: Install grub with the following command:
  272: 
  273:     # grub --no-floppy
  274: 
  275:     grub> root (hd0,a)
  276:      Filesystem type is ffs, partition type 0xa9
  277: 
  278:     grub> setup (hd0)
  279:      Checking if "/boot/grub/stage1" exists... no
  280:      Checking if "/grub/stage1" exists... yes
  281:      Checking if "/grub/stage2" exists... yes
  282:      Checking if "/grub/ffs_stage1_5" exists... yes
  283:      Running "embed /grub/ffs_stage1_5 (hd0)"...  14 sectors are embedded.
  284:     succeeded
  285:      Running "install /grub/stage1 (hd0) (hd0)1+14 p (hd0,0,a)/grub/stage2 /grub/menu.lst"...
  286:      succeeded
  287:     Done.
  288:           
  289: 
  290: Updating NetBSD in a dom0
  291: -------------------------
  292: 
  293: This is just like updating NetBSD on bare hardware, assuming the new
  294: version supports the version of Xen you are running.  Generally, one
  295: replaces the kernel and reboots, and then overlays userland binaries
  296: and adjusts /etc.
  297: 
  298: Note that one must update both the non-Xen kernel typically used for
  299: rescue purposes and the DOM0 kernel used with Xen.
  300: 
  301: Updating Xen versions
  302: ---------------------
  303: 
  304: TODO: write
  305: 
  306: Creating unprivileged domains (domU)
  307: ====================================
  308: 
  309: Creating domUs is almost entirely independent of operating system.  We
  310: first explain NetBSD, and then differences for Linux and Solaris.
  311: 
  312: Creating an unprivileged NetBSD domain (domU)
  313: ---------------------------------------------
  314: 
  315: Once you have *domain0* running, you need to start the xen tool daemon
  316: (`/usr/pkg/share/examples/rc.d/xend start`) and the xen backend daemon
  317: (`/usr/pkg/share/examples/rc.d/xenbackendd start` for Xen3\*,
  318: `/usr/pkg/share/examples/rc.d/xencommons start` for Xen4.\*). Make sure
  319: that `/dev/xencons` and `/dev/xenevt` exist before starting `xend`. You
  320: can create them with this command:
  321: 
  322:     # cd /dev && sh MAKEDEV xen
  323: 
  324: xend will write logs to `/var/log/xend.log` and
  325: `/var/log/xend-debug.log`. You can then control xen with the xm tool.
  326: 'xm list' will show something like:
  327: 
  328:     # xm list
  329:     Name              Id  Mem(MB)  CPU  State  Time(s)  Console
  330:     Domain-0           0       64    0  r----     58.1
  331: 
  332: 'xm create' allows you to create a new domain. It uses a config file in
  333: PKG\_SYSCONFDIR for its parameters. By default, this file will be in
  334: `/usr/pkg/etc/xen/`. On creation, a kernel has to be specified, which
  335: will be executed in the new domain (this kernel is in the *domain0* file
  336: system, not on the new domain virtual disk; but please note, you should
  337: install the same kernel into *domainU* as `/netbsd` in order to make
  338: your system tools, like MAN.SAVECORE.8, work). A suitable kernel is
  339: provided as part of the i386 and amd64 binary sets: XEN3\_DOMU.
  340: 
  341: Here is an /usr/pkg/etc/xen/nbsd example config file:
  342: 
  343:     #  -*- mode: python; -*-
  344:     #============================================================================
  345:     # Python defaults setup for 'xm create'.
  346:     # Edit this file to reflect the configuration of your system.
  347:     #============================================================================
  348: 
  349:     #----------------------------------------------------------------------------
  350:     # Kernel image file. This kernel will be loaded in the new domain.
  351:     kernel = "/home/bouyer/netbsd-XEN3_DOMU"
  352:     #kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
  353: 
  354:     # Memory allocation (in megabytes) for the new domain.
  355:     memory = 128
  356: 
  357:     # A handy name for your new domain. This will appear in 'xm list',
  358:     # and you can use this as parameters for xm in place of the domain
  359:     # number. All domains must have different names.
  360:     #
  361:     name = "nbsd"
  362: 
  363:     # The number of virtual CPUs this domain has.
  364:     #
  365:     vcpus = 1
  366: 
  367:     #----------------------------------------------------------------------------
  368:     # Define network interfaces for the new domain.
  369: 
  370:     # Number of network interfaces (must be at least 1). Default is 1.
  371:     nics = 1
  372: 
  373:     # Define MAC and/or bridge for the network interfaces.
  374:     #
  375:     # The MAC address specified in ``mac'' is the one used for the interface
  376:     # in the new domain. The interface in domain0 will use this address XOR'd
  377:     # with 00:00:00:01:00:00 (i.e. aa:00:00:51:02:f0 in our example). Random
  378:     # MACs are assigned if not given.
  379:     #
  380:     # ``bridge'' is a required parameter, which will be passed to the
  381:     # vif-script called by xend(8) when a new domain is created to configure
  382:     # the new xvif interface in domain0.
  383:     #
  384:     # In this example, the xvif is added to bridge0, which should have been
  385:     # set up prior to the new domain being created -- either in the
  386:     # ``network'' script or using a /etc/ifconfig.bridge0 file.
  387:     #
  388:     vif = [ 'mac=aa:00:00:50:02:f0, bridge=bridge0' ]
  389: 
  390:     #----------------------------------------------------------------------------
  391:     # Define the disk devices you want the domain to have access to, and
  392:     # what you want them accessible as.
  393:     #
  394:     # Each disk entry is of the form:
  395:     #
  396:     #   phy:DEV,VDEV,MODE
  397:     #
  398:     # where DEV is the device, VDEV is the device name the domain will see,
  399:     # and MODE is r for read-only, w for read-write.  You can also create
  400:     # file-backed domains using disk entries of the form:
  401:     #
  402:     #   file:PATH,VDEV,MODE
  403:     #
  404:     # where PATH is the path to the file used as the virtual disk, and VDEV
  405:     # and MODE have the same meaning as for ``phy'' devices.
  406:     #
  407:     # VDEV doesn't really matter for a NetBSD guest OS (it's just used as an index),
  408:     # but it does for Linux.
  409:     # Worse, the device has to exist in /dev/ of domain0, because xm will
  410:     # try to stat() it. This means that in order to load a Linux guest OS
  411:     # from a NetBSD domain0, you'll have to create /dev/hda1, /dev/hda2, ...
  412:     # on domain0, with the major/minor from Linux :(
  413:     # Alternatively it's possible to specify the device number in hex,
  414:     # e.g. 0x301 for /dev/hda1, 0x302 for /dev/hda2, etc ...
  415: 
  416:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
  417:     #disk = [ 'file:/var/xen/nbsd-disk,0x01,w' ]
  418:     #disk = [ 'file:/var/xen/nbsd-disk,0x301,w' ]
  419: 
  420:     #----------------------------------------------------------------------------
  421:     # Set the kernel command line for the new domain.
  422: 
  423:     # Set root device. This one does matter for NetBSD
  424:     root = "xbd0"
  425:     # extra parameters passed to the kernel
  426:     # this is where you can set boot flags like -s, -a, etc ...
  427:     #extra = ""
  428: 
  429:     #----------------------------------------------------------------------------
  430:     # Set according to whether you want the domain restarted when it exits.
  431:     # The default is False.
  432:     #autorestart = True
  433: 
  434:     # end of nbsd config file ====================================================
  435: 
  436: When a new domain is created, xen calls the
  437: `/usr/pkg/etc/xen/vif-bridge` script for each virtual network interface
  438: created in *domain0*. This can be used to automatically configure the
  439: xvif?.? interfaces in *domain0*. In our example, these will be bridged
  440: with the bridge0 device in *domain0*, but the bridge has to exist first.
  441: To do this, create the file `/etc/ifconfig.bridge0` and make it look
  442: like this:
  443: 
  444:     create
  445:     !brconfig $int add ex0 up
  446: 
  447: (replace `ex0` with the name of your physical interface). Then bridge0
  448: will be created on boot. See the MAN.BRIDGE.4 man page for details.
  449: 
  450: So, here is a suitable `/usr/pkg/etc/xen/vif-bridge` for xvif?.? (a
  451: working vif-bridge is also provided with xentools20) configuring:
  452: 
  453:     #!/bin/sh
  454:     #============================================================================
  455:     # $NetBSD: howto.mdwn,v 1.15 2014/12/24 00:04:47 gdt Exp $
  456:     #
  457:     # /usr/pkg/etc/xen/vif-bridge
  458:     #
  459:     # Script for configuring a vif in bridged mode with a dom0 interface.
  460:     # The xend(8) daemon calls a vif script when bringing a vif up or down.
  461:     # The script name to use is defined in /usr/pkg/etc/xen/xend-config.sxp
  462:     # in the ``vif-script'' field.
  463:     #
  464:     # Usage: vif-bridge up|down [var=value ...]
  465:     #
  466:     # Actions:
  467:     #    up     Adds the vif interface to the bridge.
  468:     #    down   Removes the vif interface from the bridge.
  469:     #
  470:     # Variables:
  471:     #    domain name of the domain the interface is on (required).
  472:     #    vifq   vif interface name (required).
  473:     #    mac    vif MAC address (required).
  474:     #    bridge bridge to add the vif to (required).
  475:     #
  476:     # Example invocation:
  477:     #
  478:     # vif-bridge up domain=VM1 vif=xvif1.0 mac="ee:14:01:d0:ec:af" bridge=bridge0
  479:     #
  480:     #============================================================================
  481: 
  482:     # Exit if anything goes wrong
  483:     set -e
  484: 
  485:     echo "vif-bridge $*"
  486: 
  487:     # Operation name.
  488:     OP=$1; shift
  489: 
  490:     # Pull variables in args into environment
  491:     for arg ; do export "${arg}" ; done
  492: 
  493:     # Required parameters. Fail if not set.
  494:     domain=${domain:?}
  495:     vif=${vif:?}
  496:     mac=${mac:?}
  497:     bridge=${bridge:?}
  498: 
  499:     # Optional parameters. Set defaults.
  500:     ip=${ip:-''}   # default to null (do nothing)
  501: 
  502:     # Are we going up or down?
  503:     case $OP in
  504:     up) brcmd='add' ;;
  505:     down)   brcmd='delete' ;;
  506:     *)
  507:         echo 'Invalid command: ' $OP
  508:         echo 'Valid commands are: up, down'
  509:         exit 1
  510:         ;;
  511:     esac
  512: 
  513:     # Don't do anything if the bridge is "null".
  514:     if [ "${bridge}" = "null" ] ; then
  515:         exit
  516:     fi
  517: 
  518:     # Don't do anything if the bridge doesn't exist.
  519:     if ! ifconfig -l | grep "${bridge}" >/dev/null; then
  520:         exit
  521:     fi
  522: 
  523:     # Add/remove vif to/from bridge.
  524:     ifconfig x${vif} $OP
  525:     brconfig ${bridge} ${brcmd} x${vif}
  526: 
  527: Now, running
  528: 
  529:     xm create -c /usr/pkg/etc/xen/nbsd
  530: 
  531: should create a domain and load a NetBSD kernel in it. (Note: `-c`
  532: causes xm to connect to the domain's console once created.) The kernel
  533: will try to find its root file system on xbd0 (i.e., wd0e) which hasn't
  534: been created yet. wd0e will be seen as a disk device in the new domain,
  535: so it will be 'sub-partitioned'. We could attach a ccd to wd0e in
  536: *domain0* and partition it, newfs and extract the NetBSD/i386 or amd64
  537: tarballs there, but there's an easier way: load the
  538: `netbsd-INSTALL_XEN3_DOMU` kernel provided in the NetBSD binary sets.
  539: Like other install kernels, it contains a ramdisk with sysinst, so you
  540: can install NetBSD using sysinst on your new domain.
  541: 
  542: If you want to install NetBSD/Xen with a CDROM image, the following line
  543: should be used in the `/usr/pkg/etc/xen/nbsd` file:
  544: 
  545:     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
  546: 
  547: After booting the domain, the option to install via CDROM may be
  548: selected. The CDROM device should be changed to `xbd1d`.
  549: 
  550: Once done installing, `halt -p` the new domain (don't reboot or halt, it
  551: would reload the INSTALL\_XEN3\_DOMU kernel even if you changed the
  552: config file), switch the config file back to the XEN3\_DOMU kernel, and
  553: start the new domain again. Now it should be able to use `root on xbd0a`
  554: and you should have a second, functional NetBSD system on your xen
  555: installation.
  556: 
  557: When the new domain is booting you'll see some warnings about *wscons*
  558: and the pseudo-terminals. These can be fixed by editing the files
  559: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
  560: `/etc/ttys`, except *console*, like this:
  561: 
  562:     console "/usr/libexec/getty Pc"         vt100   on secure
  563:     ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
  564:     ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
  565:     ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
  566:     ttyE3   "/usr/libexec/getty Pc"         vt220   off secure
  567: 
  568: Finally, all screens must be commented out from `/etc/wscons.conf`.
  569: 
  570: It is also desirable to add
  571: 
  572:     powerd=YES
  573: 
  574: in rc.conf. This way, the domain will be properly shut down if
  575: `xm shutdown -R` or `xm shutdown -H` is used on the domain0.
  576: 
  577: Your domain should be now ready to work, enjoy.
  578: 
  579: Creating an unprivileged Linux domain (domU)
  580: --------------------------------------------
  581: 
  582: Creating unprivileged Linux domains isn't much different from
  583: unprivileged NetBSD domains, but there are some details to know.
  584: 
  585: First, the second parameter passed to the disk declaration (the '0x1' in
  586: the example below)
  587: 
  588:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
  589: 
  590: does matter to Linux. It wants a Linux device number here (e.g. 0x300
  591: for hda). Linux builds device numbers as: (major \<\< 8 + minor). So,
  592: hda1 which has major 3 and minor 1 on a Linux system will have device
  593: number 0x301. Alternatively, devices names can be used (hda, hdb, ...)
  594: as xentools has a table to map these names to devices numbers. To export
  595: a partition to a Linux guest we can use:
  596: 
  597:     disk = [ 'phy:/dev/wd0e,0x300,w' ]
  598:     root = "/dev/hda1 ro"
  599: 
  600: and it will appear as /dev/hda on the Linux system, and be used as root
  601: partition.
  602: 
  603: To install the Linux system on the partition to be exported to the guest
  604: domain, the following method can be used: install sysutils/e2fsprogs
  605: from pkgsrc. Use mke2fs to format the partition that will be the root
  606: partition of your Linux domain, and mount it. Then copy the files from a
  607: working Linux system, make adjustments in `/etc` (fstab, network
  608: config). It should also be possible to extract binary packages such as
  609: .rpm or .deb directly to the mounted partition using the appropriate
  610: tool, possibly running under NetBSD's Linux emulation. Once the
  611: filesystem has been populated, umount it. If desirable, the filesystem
  612: can be converted to ext3 using tune2fs -j. It should now be possible to
  613: boot the Linux guest domain, using one of the vmlinuz-\*-xenU kernels
  614: available in the Xen binary distribution.
  615: 
  616: To get the linux console right, you need to add:
  617: 
  618:     extra = "xencons=tty1"
  619: 
  620: to your configuration since not all linux distributions auto-attach a
  621: tty to the xen console.
  622: 
  623: Creating an unprivileged Solaris domain (domU)
  624: ----------------------------------------------
  625: 
  626: Download an Opensolaris [release](http://opensolaris.org/os/downloads/)
  627: or [development snapshot](http://genunix.org/) DVD image. Attach the DVD
  628: image to a MAN.VND.4 device. Copy the kernel and ramdisk filesystem
  629: image to your dom0 filesystem.
  630: 
  631:     dom0# mkdir /root/solaris
  632:     dom0# vnconfig vnd0 osol-1002-124-x86.iso
  633:     dom0# mount /dev/vnd0a /mnt
  634: 
  635:     ## for a 64-bit guest
  636:     dom0# cp /mnt/boot/amd64/x86.microroot /root/solaris
  637:     dom0# cp /mnt/platform/i86xpv/kernel/amd64/unix /root/solaris
  638: 
  639:     ## for a 32-bit guest
  640:     dom0# cp /mnt/boot/x86.microroot /root/solaris
  641:     dom0# cp /mnt/platform/i86xpv/kernel/unix /root/solaris
  642: 
  643:     dom0# umount /mnt
  644:           
  645: 
  646: Keep the MAN.VND.4 configured. For some reason the boot process stalls
  647: unless the DVD image is attached to the guest as a "phy" device. Create
  648: an initial configuration file with the following contents. Substitute
  649: */dev/wd0k* with an empty partition at least 8 GB large.
  650: 
  651:     memory = 640
  652:     name = 'solaris'
  653:     disk = [ 'phy:/dev/wd0k,0,w' ]
  654:     disk += [ 'phy:/dev/vnd0d,6:cdrom,r' ]
  655:     vif = [ 'bridge=bridge0' ]
  656:     kernel = '/root/solaris/unix'
  657:     ramdisk = '/root/solaris/x86.microroot'
  658:     # for a 64-bit guest
  659:     extra = '/platform/i86xpv/kernel/amd64/unix - nowin -B install_media=cdrom'
  660:     # for a 32-bit guest
  661:     #extra = '/platform/i86xpv/kernel/unix - nowin -B install_media=cdrom'
  662:           
  663: 
  664: Start the guest.
  665: 
  666:     dom0# xm create -c solaris.cfg
  667:     Started domain solaris
  668:                           v3.3.2 chgset 'unavailable'
  669:     SunOS Release 5.11 Version snv_124 64-bit
  670:     Copyright 1983-2009 Sun Microsystems, Inc.  All rights reserved.
  671:     Use is subject to license terms.
  672:     Hostname: opensolaris
  673:     Remounting root read/write
  674:     Probing for device nodes ...
  675:     WARNING: emlxs: ddi_modopen drv/fct failed: err 2
  676:     Preparing live image for use
  677:     Done mounting Live image
  678:           
  679: 
  680: Make sure the network is configured. Note that it can take a minute for
  681: the xnf0 interface to appear.
  682: 
  683:     opensolaris console login: jack
  684:     Password: jack
  685:     Sun Microsystems Inc.   SunOS 5.11      snv_124 November 2008
  686:     jack@opensolaris:~$ pfexec sh
  687:     sh-3.2# ifconfig -a
  688:     sh-3.2# exit
  689:           
  690: 
  691: Set a password for VNC and start the VNC server which provides the X11
  692: display where the installation program runs.
  693: 
  694:     jack@opensolaris:~$ vncpasswd
  695:     Password: solaris
  696:     Verify: solaris
  697:     jack@opensolaris:~$ cp .Xclients .vnc/xstartup
  698:     jack@opensolaris:~$ vncserver :1
  699:           
  700: 
  701: From a remote machine connect to the VNC server. Use `ifconfig xnf0` on
  702: the guest to find the correct IP address to use.
  703: 
  704:     remote$ vncviewer 172.18.2.99:1
  705:           
  706: 
  707: It is also possible to launch the installation on a remote X11 display.
  708: 
  709:     jack@opensolaris:~$ export DISPLAY=172.18.1.1:0
  710:     jack@opensolaris:~$ pfexec gui-install
  711:            
  712: 
  713: After the GUI installation is complete you will be asked to reboot.
  714: Before that you need to determine the ZFS ID for the new boot filesystem
  715: and update the configuration file accordingly. Return to the guest
  716: console.
  717: 
  718:     jack@opensolaris:~$ pfexec zdb -vvv rpool | grep bootfs
  719:                     bootfs = 43
  720:     ^C
  721:     jack@opensolaris:~$
  722:            
  723: 
  724: The final configuration file should look like this. Note in particular
  725: the last line.
  726: 
  727:     memory = 640
  728:     name = 'solaris'
  729:     disk = [ 'phy:/dev/wd0k,0,w' ]
  730:     vif = [ 'bridge=bridge0' ]
  731:     kernel = '/root/solaris/unix'
  732:     ramdisk = '/root/solaris/x86.microroot'
  733:     extra = '/platform/i86xpv/kernel/amd64/unix -B zfs-bootfs=rpool/43,bootpath="/xpvd/xdf@0:a"'
  734:            
  735: 
  736: Restart the guest to verify it works correctly.
  737: 
  738:     dom0# xm destroy solaris
  739:     dom0# xm create -c solaris.cfg
  740:     Using config file "./solaris.cfg".
  741:     v3.3.2 chgset 'unavailable'
  742:     Started domain solaris
  743:     SunOS Release 5.11 Version snv_124 64-bit
  744:     Copyright 1983-2009 Sun Microsystems, Inc.  All rights reserved.
  745:     Use is subject to license terms.
  746:     WARNING: emlxs: ddi_modopen drv/fct failed: err 2
  747:     Hostname: osol
  748:     Configuring devices.
  749:     Loading smf(5) service descriptions: 160/160
  750:     svccfg import warnings. See /var/svc/log/system-manifest-import:default.log .
  751:     Reading ZFS config: done.
  752:     Mounting ZFS filesystems: (6/6)
  753:     Creating new rsa public/private host key pair
  754:     Creating new dsa public/private host key pair
  755: 
  756:     osol console login:
  757:            
  758: 
  759: Using PCI devices in guest domains
  760: ----------------------------------
  761: 
  762: The domain0 can give other domains access to selected PCI devices. This
  763: can allow, for example, a non-privileged domain to have access to a
  764: physical network interface or disk controller. However, keep in mind
  765: that giving a domain access to a PCI device most likely will give the
  766: domain read/write access to the whole physical memory, as PCs don't have
  767: an IOMMU to restrict memory access to DMA-capable device. Also, it's not
  768: possible to export ISA devices to non-domain0 domains (which means that
  769: the primary VGA adapter can't be exported. A guest domain trying to
  770: access the VGA registers will panic).
  771: 
  772: This functionality is only available in NetBSD-5.1 (and later) domain0
  773: and domU. If the domain0 is NetBSD, it has to be running Xen 3.1, as
  774: support has not been ported to later versions at this time.
  775: 
  776: For a PCI device to be exported to a domU, is has to be attached to the
  777: `pciback` driver in domain0. Devices passed to the domain0 via the
  778: pciback.hide boot parameter will attach to `pciback` instead of the
  779: usual driver. The list of devices is specified as `(bus:dev.func)`,
  780: where bus and dev are 2-digit hexadecimal numbers, and func a
  781: single-digit number:
  782: 
  783:     pciback.hide=(00:0a.0)(00:06.0)
  784: 
  785: pciback devices should show up in the domain0's boot messages, and the
  786: devices should be listed in the `/kern/xen/pci` directory.
  787: 
  788: PCI devices to be exported to a domU are listed in the `pci` array of
  789: the domU's config file, with the format `'0000:bus:dev.func'`
  790: 
  791:     pci = [ '0000:00:06.0', '0000:00:0a.0' ]
  792: 
  793: In the domU an `xpci` device will show up, to which one or more pci
  794: busses will attach. Then the PCI drivers will attach to PCI busses as
  795: usual. Note that the default NetBSD DOMU kernels do not have `xpci` or
  796: any PCI drivers built in by default; you have to build your own kernel
  797: to use PCI devices in a domU. Here's a kernel config example:
  798: 
  799:     include         "arch/i386/conf/XEN3_DOMU"
  800:     #include         "arch/i386/conf/XENU"           # in NetBSD 3.0
  801: 
  802:     # Add support for PCI busses to the XEN3_DOMU kernel
  803:     xpci* at xenbus ?
  804:     pci* at xpci ?
  805: 
  806:     # Now add PCI and related devices to be used by this domain
  807:     # USB Controller and Devices
  808: 
  809:     # PCI USB controllers
  810:     uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
  811: 
  812:     # USB bus support
  813:     usb*    at uhci?
  814: 
  815:     # USB Hubs
  816:     uhub*   at usb?
  817:     uhub*   at uhub? port ? configuration ? interface ?
  818: 
  819:     # USB Mass Storage
  820:     umass*  at uhub? port ? configuration ? interface ?
  821:     wd*     at umass?
  822:     # SCSI controllers
  823:     ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
  824: 
  825:     # SCSI bus support (for both ahc and umass)
  826:     scsibus* at scsi?
  827: 
  828:     # SCSI devices
  829:     sd*     at scsibus? target ? lun ?      # SCSI disk drives
  830:     cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
  831: 
  832: Links and further information
  833: =============================
  834: 
  835: -   The [HowTo on Installing into RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
  836:     explains how to set up booting a dom0 with Xen using grub 
  837:     with NetBSD's RAIDframe.  (This is obsolete with the use of
  838:     NetBSD's native boot.)
  839: -   An example of how to use NetBSD's native bootloader to load
  840:     NetBSD/Xen instead of Grub can be found in the i386/amd64 boot(8)
  841:     and boot.cfg(5) manpages.

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