File:  [NetBSD Developer Wiki] / wikisrc / ports / xen / howto.mdwn
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Mon Nov 4 02:43:35 2013 UTC (8 years, 9 months ago) by mspo
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CVS tags: HEAD
fix some issue sin the howto

<tr class="odd">
<td align="left"><a href="../../about/disclaimer.html#bsd-daemon"></a></td>
<td align="left"><h1>Table Of Contents</h1>
<li>Installing NetBSD as privileged domain (Dom0)</li>
<li>Creating an unprivileged NetBSD domain (DomU)</li>
<li>Creating an unprivileged Linux domain (DomU)</li>
<li>Creating an unprivileged Solaris domain (DomU)</li>
<li>Using PCI devices in guest domains</li>
<li>Links and further information</li>



Xen is a virtual machine monitor for x86 hardware (requires i686-class
CPUs), which supports running multiple guest operating systems on a
single machine. Guest OSes (also called “domains”) require a modified
kernel which supports Xen hypercalls in replacement to access to the
physical hardware. At boot, the Xen kernel (also known as the Xen
hypervisor) is loaded (via the bootloader) along with the guest kernel
for the first domain (called *domain0*). The Xen kernel has to be loaded
using the multiboot protocol. You would use the NetBSD boot loader for
this, or alternatively the `grub` boot loader (`grub` has some
limitations, detailed below). *domain0* has special privileges to access
the physical hardware (PCI and ISA devices), administrate other domains
and provide virtual devices (disks and network) to other domains that
lack those privileges. For more details, see [](

NetBSD can be used for both *domain0 (Dom0)* and further, unprivileged
(DomU) domains. (Actually there can be multiple privileged domains
accessing different parts of the hardware, all providing virtual devices
to unprivileged domains. We will only talk about the case of a single
privileged domain, *domain0*). *domain0* will see physical devices much
like a regular i386 or amd64 kernel, and will own the physical console
(VGA or serial). Unprivileged domains will only see a character-only
virtual console, virtual disks (`xbd`) and virtual network interfaces
(`xennet`) provided by a privileged domain (usually *domain0*). xbd
devices are connected to a block device (i.e., a partition of a disk,
raid, ccd, ... device) in the privileged domain. xennet devices are
connected to virtual devices in the privileged domain, named
xvif\<domain number\>.\<if number for this domain\>, e.g., xvif1.0. Both
xennet and xvif devices are seen as regular Ethernet devices (they can
be seen as a crossover cable between 2 PCs) and can be assigned
addresses (and be routed or NATed, filtered using IPF, etc ...) or be
added as part of a bridge.

Installing NetBSD as privileged domain (Dom0)

First do a NetBSD/i386 or NetBSD/amd64
[installation](../../docs/guide/en/chap-inst.html) of the 5.1 release
(or newer) as you usually do on x86 hardware. The binary releases are
available from []( Binary snapshots
for current and the stable branches are available on daily autobuilds.
If you plan to use the `grub` boot loader, when partitioning the disk
you have to make the root partition smaller than 512Mb, and formatted as
FFSv1 with 8k block/1k fragments. If the partition is larger than this,
uses FFSv2 or has different block/fragment sizes, grub may fail to load
some files. Also keep in mind that you'll probably want to provide
virtual disks to other domains, so reserve some partitions for these
virtual disks. Alternatively, you can create large files in the file
system, map them to vnd(4) devices and export theses vnd devices to
other domains.

Next step is to install the Xen packages via pkgsrc or from binary
packages. See [the pkgsrc
documentation]( if you are unfamiliar
with pkgsrc and/or handling of binary packages. Xen 3.1, 3.3, 4.1 and
4.2 are available. 3.1 supports PCI pass-through while other versions do
not. You'll need either `sysutils/xentools3` and `sysutils/xenkernel3`
for Xen 3.1, `sysutils/xentools33` and `sysutils/xenkernel33` for Xen
3.3, `sysutils/xentools41` and `sysutils/xenkernel41` for Xen 4.1. or
`sysutils/xentools42` and `sysutils/xenkernel42` for Xen 4.2. You'll
also need `sysutils/grub` if you plan do use the grub boot loader. If
using Xen 3.1, you may also want to install `sysutils/xentools3-hvm`
which contains the utilities to run unmodified guests OSes using the
*HVM* support (for later versions this is included in
`sysutils/xentools`). Note that your CPU needs to support this. Intel
CPUs must have the 'VT' instruction, AMD CPUs the 'SVM' instruction. You
can easily find out if your CPU support HVM by using NetBSD's cpuctl

    # cpuctl identify 0
    cpu0: Intel Core 2 (Merom) (686-class), id 0x6f6
    cpu0: features 0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
    cpu0: features 0xbfebfbff<PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX>
    cpu0: features 0xbfebfbff<FXSR,SSE,SSE2,SS,HTT,TM,SBF>
    cpu0: features2 0x4e33d<SSE3,DTES64,MONITOR,DS-CPL,,TM2,SSSE3,CX16,xTPR,PDCM,DCA>
    cpu0: features3 0x20100800<SYSCALL/SYSRET,XD,EM64T>
    cpu0: "Intel(R) Xeon(R) CPU            5130  @ 2.00GHz"
    cpu0: I-cache 32KB 64B/line 8-way, D-cache 32KB 64B/line 8-way
    cpu0: L2 cache 4MB 64B/line 16-way
    cpu0: ITLB 128 4KB entries 4-way
    cpu0: DTLB 256 4KB entries 4-way, 32 4MB entries 4-way
    cpu0: Initial APIC ID 0
    cpu0: Cluster/Package ID 0
    cpu0: Core ID 0
    cpu0: family 06 model 0f extfamily 00 extmodel 00

Depending on your CPU, the feature you are looking for is called HVM,

Next you need to copy the selected Xen kernel itself. pkgsrc installed
them under `/usr/pkg/xen*-kernel/`. The file you're looking for is
`xen.gz`. Copy it to your root file system. `xen-debug.gz` is a kernel
with more consistency checks and more details printed on the serial
console. It is useful for debugging crashing guests if you use a serial
console. It is not useful with a VGA console.

You'll then need a NetBSD/Xen kernel for *domain0* on your root file
system. The XEN3PAE\_DOM0 kernel or XEN3\_DOM0 provided as part of the
i386 or amd64 binaries is suitable for this, but you may want to
customize it. Keep your native kernel around, as it can be useful for
recovery. *Note:* the *domain0* kernel must support KERNFS and `/kern`
must be mounted because *xend* needs access to `/kern/xen/privcmd`.

Next you need to get a bootloader to load the `xen.gz` kernel, and the
NetBSD *domain0* kernel as a module. This can be `grub` or NetBSD's boot
loader. Below is a detailled example for grub, see the boot.cfg(5)
manual page for an example using the latter.

This is also where you'll specify the memory allocated to *domain0*, the
console to use, etc ...

Here is a commented `/grub/menu.lst` file:

    #Grub config file for NetBSD/xen. Copy as /grub/menu.lst and run
    # grub-install /dev/rwd0d (assuming your boot device is wd0).
    # The default entry to load will be the first one

    # boot the default entry after 10s if the user didn't hit keyboard

    # Configure serial port to use as console. Ignore if you'll use VGA only
    serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1

    # Let the user select which console to use (serial or VGA), default
    # to serial after 10s
    terminal --timeout=10 serial console

    # An entry for NetBSD/xen, using /netbsd as the domain0 kernel, and serial
    # console. Domain0 will have 64MB RAM allocated.
    # Assume NetBSD is installed in the first MBR partition.
    title Xen 3 / NetBSD (hda0, serial)
      kernel (hd0,a)/xen.gz dom0_mem=65536 com1=115200,8n1
      module (hd0,a)/netbsd bootdev=wd0a ro console=ttyS0

    # Same as above, but using VGA console
    # We can use console=tty0 (Linux syntax) or console=pc (NetBSD syntax)
    title Xen 3 / NetBSD (hda0, vga)
      kernel (hd0,a)/xen.gz dom0_mem=65536
      module (hd0,a)/netbsd bootdev=wd0a ro console=tty0

    # NetBSD/xen using a backup domain0 kernel (in case you installed a
    # nonworking kernel as /netbsd
    title Xen 3 / NetBSD (hda0, backup, serial)
      kernel (hd0,a)/xen.gz dom0_mem=65536 com1=115200,8n1
      module (hd0,a)/netbsd.backup bootdev=wd0a ro console=ttyS0
    title Xen 3 / NetBSD (hda0, backup, VGA)
      kernel (hd0,a)/xen.gz dom0_mem=65536
      module (hd0,a)/netbsd.backup bootdev=wd0a ro console=tty0

    #Load a regular NetBSD/i386 kernel. Can be useful if you end up with a
    #nonworking /xen.gz
    title NetBSD 5.1
      root (hd0,a)
      kernel --type=netbsd /netbsd-GENERIC

    #Load the NetBSD bootloader, letting it load the NetBSD/i386 kernel.
    #May be better than the above, as grub can't pass all required infos
    #to the NetBSD/i386 kernel (e.g. console, root device, ...)
    title NetBSD chain
      root        (hd0,0)
      chainloader +1

    ## end of grub config file.

Install grub with the following command:

    # grub --no-floppy

    grub> root (hd0,a)
     Filesystem type is ffs, partition type 0xa9

    grub> setup (hd0)
     Checking if "/boot/grub/stage1" exists... no
     Checking if "/grub/stage1" exists... yes
     Checking if "/grub/stage2" exists... yes
     Checking if "/grub/ffs_stage1_5" exists... yes
     Running "embed /grub/ffs_stage1_5 (hd0)"...  14 sectors are embedded.
     Running "install /grub/stage1 (hd0) (hd0)1+14 p (hd0,0,a)/grub/stage2 /grub/menu.lst"...

Creating an unprivileged NetBSD domain (DomU)

Once you have *domain0* running, you need to start the xen tool daemon
(`/usr/pkg/share/examples/rc.d/xend start`) and the xen backend daemon
(`/usr/pkg/share/examples/rc.d/xenbackendd start` for Xen3\*,
`/usr/pkg/share/examples/rc.d/xencommons start` for Xen4.\*). Make sure
that `/dev/xencons` and `/dev/xenevt` exist before starting `xend`. You
can create them with this command:

    # cd /dev && sh MAKEDEV xen

xend will write logs to `/var/log/xend.log` and
`/var/log/xend-debug.log`. You can then control xen with the xm tool.
'xm list' will show something like:

    # xm list
    Name              Id  Mem(MB)  CPU  State  Time(s)  Console
    Domain-0           0       64    0  r----     58.1

'xm create' allows you to create a new domain. It uses a config file in
PKG\_SYSCONFDIR for its parameters. By default, this file will be in
`/usr/pkg/etc/xen/`. On creation, a kernel has to be specified, which
will be executed in the new domain (this kernel is in the *domain0* file
system, not on the new domain virtual disk; but please note, you should
install the same kernel into *domainU* as `/netbsd` in order to make
your system tools, like MAN.SAVECORE.8, work). A suitable kernel is
provided as part of the i386 and amd64 binary sets: XEN3\_DOMU.

Here is an /usr/pkg/etc/xen/nbsd example config file:

    #  -*- mode: python; -*-
    # Python defaults setup for 'xm create'.
    # Edit this file to reflect the configuration of your system.

    # Kernel image file. This kernel will be loaded in the new domain.
    kernel = "/home/bouyer/netbsd-XEN3_DOMU"
    #kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"

    # Memory allocation (in megabytes) for the new domain.
    memory = 128

    # A handy name for your new domain. This will appear in 'xm list',
    # and you can use this as parameters for xm in place of the domain
    # number. All domains must have different names.
    name = "nbsd"

    # The number of virtual CPUs this domain has.
    vcpus = 1

    # Define network interfaces for the new domain.

    # Number of network interfaces (must be at least 1). Default is 1.
    nics = 1

    # Define MAC and/or bridge for the network interfaces.
    # The MAC address specified in ``mac'' is the one used for the interface
    # in the new domain. The interface in domain0 will use this address XOR'd
    # with 00:00:00:01:00:00 (i.e. aa:00:00:51:02:f0 in our example). Random
    # MACs are assigned if not given.
    # ``bridge'' is a required parameter, which will be passed to the
    # vif-script called by xend(8) when a new domain is created to configure
    # the new xvif interface in domain0.
    # In this example, the xvif is added to bridge0, which should have been
    # set up prior to the new domain being created -- either in the
    # ``network'' script or using a /etc/ifconfig.bridge0 file.
    vif = [ 'mac=aa:00:00:50:02:f0, bridge=bridge0' ]

    # Define the disk devices you want the domain to have access to, and
    # what you want them accessible as.
    # Each disk entry is of the form:
    #   phy:DEV,VDEV,MODE
    # where DEV is the device, VDEV is the device name the domain will see,
    # and MODE is r for read-only, w for read-write.  You can also create
    # file-backed domains using disk entries of the form:
    #   file:PATH,VDEV,MODE
    # where PATH is the path to the file used as the virtual disk, and VDEV
    # and MODE have the same meaning as for ``phy'' devices.
    # VDEV doesn't really matter for a NetBSD guest OS (it's just used as an index),
    # but it does for Linux.
    # Worse, the device has to exist in /dev/ of domain0, because xm will
    # try to stat() it. This means that in order to load a Linux guest OS
    # from a NetBSD domain0, you'll have to create /dev/hda1, /dev/hda2, ...
    # on domain0, with the major/minor from Linux :(
    # Alternatively it's possible to specify the device number in hex,
    # e.g. 0x301 for /dev/hda1, 0x302 for /dev/hda2, etc ...

    disk = [ 'phy:/dev/wd0e,0x1,w' ]
    #disk = [ 'file:/var/xen/nbsd-disk,0x01,w' ]
    #disk = [ 'file:/var/xen/nbsd-disk,0x301,w' ]

    # Set the kernel command line for the new domain.

    # Set root device. This one does matter for NetBSD
    root = "xbd0"
    # extra parameters passed to the kernel
    # this is where you can set boot flags like -s, -a, etc ...
    #extra = ""

    # Set according to whether you want the domain restarted when it exits.
    # The default is False.
    #autorestart = True

    # end of nbsd config file ====================================================

When a new domain is created, xen calls the
`/usr/pkg/etc/xen/vif-bridge` script for each virtual network interface
created in *domain0*. This can be used to automatically configure the
xvif?.? interfaces in *domain0*. In our example, these will be bridged
with the bridge0 device in *domain0*, but the bridge has to exist first.
To do this, create the file `/etc/ifconfig.bridge0` and make it look
like this:

    !brconfig $int add ex0 up

(replace `ex0` with the name of your physical interface). Then bridge0
will be created on boot. See the MAN.BRIDGE.4 man page for details.

So, here is a suitable `/usr/pkg/etc/xen/vif-bridge` for xvif?.? (a
working vif-bridge is also provided with xentools20) configuring:

    # $NetBSD: howto.mdwn,v 1.7 2013/11/04 02:43:35 mspo Exp $
    # /usr/pkg/etc/xen/vif-bridge
    # Script for configuring a vif in bridged mode with a dom0 interface.
    # The xend(8) daemon calls a vif script when bringing a vif up or down.
    # The script name to use is defined in /usr/pkg/etc/xen/xend-config.sxp
    # in the ``vif-script'' field.
    # Usage: vif-bridge up|down [var=value ...]
    # Actions:
    #    up     Adds the vif interface to the bridge.
    #    down   Removes the vif interface from the bridge.
    # Variables:
    #    domain name of the domain the interface is on (required).
    #    vifq   vif interface name (required).
    #    mac    vif MAC address (required).
    #    bridge bridge to add the vif to (required).
    # Example invocation:
    # vif-bridge up domain=VM1 vif=xvif1.0 mac="ee:14:01:d0:ec:af" bridge=bridge0

    # Exit if anything goes wrong
    set -e

    echo "vif-bridge $*"

    # Operation name.
    OP=$1; shift

    # Pull variables in args into environment
    for arg ; do export "${arg}" ; done

    # Required parameters. Fail if not set.

    # Optional parameters. Set defaults.
    ip=${ip:-''}   # default to null (do nothing)

    # Are we going up or down?
    case $OP in
    up) brcmd='add' ;;
    down)   brcmd='delete' ;;
        echo 'Invalid command: ' $OP
        echo 'Valid commands are: up, down'
        exit 1

    # Don't do anything if the bridge is "null".
    if [ "${bridge}" = "null" ] ; then

    # Don't do anything if the bridge doesn't exist.
    if ! ifconfig -l | grep "${bridge}" >/dev/null; then

    # Add/remove vif to/from bridge.
    ifconfig x${vif} $OP
    brconfig ${bridge} ${brcmd} x${vif}

Now, running

    xm create -c /usr/pkg/etc/xen/nbsd

should create a domain and load a NetBSD kernel in it. (Note: `-c`
causes xm to connect to the domain's console once created.) The kernel
will try to find its root file system on xbd0 (i.e., wd0e) which hasn't
been created yet. wd0e will be seen as a disk device in the new domain,
so it will be 'sub-partitioned'. We could attach a ccd to wd0e in
*domain0* and partition it, newfs and extract the NetBSD/i386 or amd64
tarballs there, but there's an easier way: load the
`netbsd-INSTALL_XEN3_DOMU` kernel provided in the NetBSD binary sets.
Like other install kernels, it contains a ramdisk with sysinst, so you
can install NetBSD using sysinst on your new domain.

If you want to install NetBSD/Xen with a CDROM image, the following line
should be used in the `/usr/pkg/etc/xen/nbsd` file:

    disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]

After booting the domain, the option to install via CDROM may be
selected. The CDROM device should be changed to `xbd1d`.

Once done installing, `halt -p` the new domain (don't reboot or halt, it
would reload the INSTALL\_XEN3\_DOMU kernel even if you changed the
config file), switch the config file back to the XEN3\_DOMU kernel, and
start the new domain again. Now it should be able to use `root on xbd0a`
and you should have a second, functional NetBSD system on your xen

When the new domain is booting you'll see some warnings about *wscons*
and the pseudo-terminals. These can be fixed by editing the files
`/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
`/etc/ttys`, except *console*, like this:

    console "/usr/libexec/getty Pc"         vt100   on secure
    ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
    ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
    ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
    ttyE3   "/usr/libexec/getty Pc"         vt220   off secure

Finally, all screens must be commented out from `/etc/wscons.conf`.

It is also desirable to add


in rc.conf. This way, the domain will be properly shut down if
`xm shutdown -R` or `xm shutdown -H` is used on the domain0.

Your domain should be now ready to work, enjoy.

Creating an unprivileged Linux domain (DomU)

Creating unprivileged Linux domains isn't much different from
unprivileged NetBSD domains, but there are some details to know.

First, the second parameter passed to the disk declaration (the '0x1' in
the example below)

    disk = [ 'phy:/dev/wd0e,0x1,w' ]

does matter to Linux. It wants a Linux device number here (e.g. 0x300
for hda). Linux builds device numbers as: (major \<\< 8 + minor). So,
hda1 which has major 3 and minor 1 on a Linux system will have device
number 0x301. Alternatively, devices names can be used (hda, hdb, ...)
as xentools has a table to map these names to devices numbers. To export
a partition to a Linux guest we can use:

    disk = [ 'phy:/dev/wd0e,0x300,w' ]
    root = "/dev/hda1 ro"

and it will appear as /dev/hda on the Linux system, and be used as root

To install the Linux system on the partition to be exported to the guest
domain, the following method can be used: install sysutils/e2fsprogs
from pkgsrc. Use mke2fs to format the partition that will be the root
partition of your Linux domain, and mount it. Then copy the files from a
working Linux system, make adjustments in `/etc` (fstab, network
config). It should also be possible to extract binary packages such as
.rpm or .deb directly to the mounted partition using the appropriate
tool, possibly running under NetBSD's Linux emulation. Once the
filesystem has been populated, umount it. If desirable, the filesystem
can be converted to ext3 using tune2fs -j. It should now be possible to
boot the Linux guest domain, using one of the vmlinuz-\*-xenU kernels
available in the Xen binary distribution.

To get the linux console right, you need to add:

    extra = "xencons=tty1"

to your configuration since not all linux distributions auto-attach a
tty to the xen console.

Creating an unprivileged Solaris domain (DomU)

Download an Opensolaris [release](
or [development snapshot]( DVD image. Attach the DVD
image to a MAN.VND.4 device. Copy the kernel and ramdisk filesystem
image to your dom0 filesystem.

    dom0# mkdir /root/solaris
    dom0# vnconfig vnd0 osol-1002-124-x86.iso
    dom0# mount /dev/vnd0a /mnt

    ## for a 64-bit guest
    dom0# cp /mnt/boot/amd64/x86.microroot /root/solaris
    dom0# cp /mnt/platform/i86xpv/kernel/amd64/unix /root/solaris

    ## for a 32-bit guest
    dom0# cp /mnt/boot/x86.microroot /root/solaris
    dom0# cp /mnt/platform/i86xpv/kernel/unix /root/solaris

    dom0# umount /mnt

Keep the MAN.VND.4 configured. For some reason the boot process stalls
unless the DVD image is attached to the guest as a "phy" device. Create
an initial configuration file with the following contents. Substitute
*/dev/wd0k* with an empty partition at least 8 GB large.

    memory = 640
    name = 'solaris'
    disk = [ 'phy:/dev/wd0k,0,w' ]
    disk += [ 'phy:/dev/vnd0d,6:cdrom,r' ]
    vif = [ 'bridge=bridge0' ]
    kernel = '/root/solaris/unix'
    ramdisk = '/root/solaris/x86.microroot'
    # for a 64-bit guest
    extra = '/platform/i86xpv/kernel/amd64/unix - nowin -B install_media=cdrom'
    # for a 32-bit guest
    #extra = '/platform/i86xpv/kernel/unix - nowin -B install_media=cdrom'

Start the guest.

    dom0# xm create -c solaris.cfg
    Started domain solaris
                          v3.3.2 chgset 'unavailable'
    SunOS Release 5.11 Version snv_124 64-bit
    Copyright 1983-2009 Sun Microsystems, Inc.  All rights reserved.
    Use is subject to license terms.
    Hostname: opensolaris
    Remounting root read/write
    Probing for device nodes ...
    WARNING: emlxs: ddi_modopen drv/fct failed: err 2
    Preparing live image for use
    Done mounting Live image

Make sure the network is configured. Note that it can take a minute for
the xnf0 interface to appear.

    opensolaris console login: jack
    Password: jack
    Sun Microsystems Inc.   SunOS 5.11      snv_124 November 2008
    jack@opensolaris:~$ pfexec sh
    sh-3.2# ifconfig -a
    sh-3.2# exit

Set a password for VNC and start the VNC server which provides the X11
display where the installation program runs.

    jack@opensolaris:~$ vncpasswd
    Password: solaris
    Verify: solaris
    jack@opensolaris:~$ cp .Xclients .vnc/xstartup
    jack@opensolaris:~$ vncserver :1

From a remote machine connect to the VNC server. Use `ifconfig xnf0` on
the guest to find the correct IP address to use.

    remote$ vncviewer

It is also possible to launch the installation on a remote X11 display.

    jack@opensolaris:~$ export DISPLAY=
    jack@opensolaris:~$ pfexec gui-install

After the GUI installation is complete you will be asked to reboot.
Before that you need to determine the ZFS ID for the new boot filesystem
and update the configuration file accordingly. Return to the guest

    jack@opensolaris:~$ pfexec zdb -vvv rpool | grep bootfs
                    bootfs = 43

The final configuration file should look like this. Note in particular
the last line.

    memory = 640
    name = 'solaris'
    disk = [ 'phy:/dev/wd0k,0,w' ]
    vif = [ 'bridge=bridge0' ]
    kernel = '/root/solaris/unix'
    ramdisk = '/root/solaris/x86.microroot'
    extra = '/platform/i86xpv/kernel/amd64/unix -B zfs-bootfs=rpool/43,bootpath="/xpvd/xdf@0:a"'

Restart the guest to verify it works correctly.

    dom0# xm destroy solaris
    dom0# xm create -c solaris.cfg
    Using config file "./solaris.cfg".
    v3.3.2 chgset 'unavailable'
    Started domain solaris
    SunOS Release 5.11 Version snv_124 64-bit
    Copyright 1983-2009 Sun Microsystems, Inc.  All rights reserved.
    Use is subject to license terms.
    WARNING: emlxs: ddi_modopen drv/fct failed: err 2
    Hostname: osol
    Configuring devices.
    Loading smf(5) service descriptions: 160/160
    svccfg import warnings. See /var/svc/log/system-manifest-import:default.log .
    Reading ZFS config: done.
    Mounting ZFS filesystems: (6/6)
    Creating new rsa public/private host key pair
    Creating new dsa public/private host key pair

    osol console login:

Using PCI devices in guest domains

The domain0 can give other domains access to selected PCI devices. This
can allow, for example, a non-privileged domain to have access to a
physical network interface or disk controller. However, keep in mind
that giving a domain access to a PCI device most likely will give the
domain read/write access to the whole physical memory, as PCs don't have
an IOMMU to restrict memory access to DMA-capable device. Also, it's not
possible to export ISA devices to non-domain0 domains (which means that
the primary VGA adapter can't be exported. A guest domain trying to
access the VGA registers will panic).

This functionality is only available in NetBSD-5.1 (and later) domain0
and domU. If the domain0 is NetBSD, it has to be running Xen 3.1, as
support has not been ported to later versions at this time.

For a PCI device to be exported to a domU, is has to be attached to the
`pciback` driver in domain0. Devices passed to the domain0 via the
pciback.hide boot parameter will attach to `pciback` instead of the
usual driver. The list of devices is specified as `(bus:dev.func)`,
where bus and dev are 2-digit hexadecimal numbers, and func a
single-digit number:


pciback devices should show up in the domain0's boot messages, and the
devices should be listed in the `/kern/xen/pci` directory.

PCI devices to be exported to a domU are listed in the `pci` array of
the domU's config file, with the format `'0000:bus:dev.func'`

    pci = [ '0000:00:06.0', '0000:00:0a.0' ]

In the domU an `xpci` device will show up, to which one or more pci
busses will attach. Then the PCI drivers will attach to PCI busses as
usual. Note that the default NetBSD DOMU kernels do not have `xpci` or
any PCI drivers built in by default; you have to build your own kernel
to use PCI devices in a domU. Here's a kernel config example:

    include         "arch/i386/conf/XEN3_DOMU"
    #include         "arch/i386/conf/XENU"           # in NetBSD 3.0

    # Add support for PCI busses to the XEN3_DOMU kernel
    xpci* at xenbus ?
    pci* at xpci ?

    # Now add PCI and related devices to be used by this domain
    # USB Controller and Devices

    # PCI USB controllers
    uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)

    # USB bus support
    usb*    at uhci?

    # USB Hubs
    uhub*   at usb?
    uhub*   at uhub? port ? configuration ? interface ?

    # USB Mass Storage
    umass*  at uhub? port ? configuration ? interface ?
    wd*     at umass?
    # SCSI controllers
    ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI

    # SCSI bus support (for both ahc and umass)
    scsibus* at scsi?

    # SCSI devices
    sd*     at scsibus? target ? lun ?      # SCSI disk drives
    cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives

Links and further information

-   The HowTo on
    Installing into RAID-1
    gives some hints on using Xen (grub) with NetBSD's RAIDframe
-   Harold Gutch wrote documentation on
    setting up a Linux DomU with a NetBSD Dom0
-   An example of how to use NetBSD's native bootloader to load
    NetBSD/Xen instead of Grub can be found in the i386/amd64 MAN.BOOT.8
    and MAN.BOOT.CFG.5 manpages.

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