Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.159

1.144     maxv        1: [[!meta title="Xen HowTo"]]
                      2: 
1.157     maxv        3: Xen is a Type 1 hypervisor which supports running multiple guest operating
                      4: systems on a single physical machine. One uses the Xen kernel to control the
                      5: CPU, memory and console, a dom0 operating system which mediates access to
                      6: other hardware (e.g., disks, network, USB), and one or more domU operating
                      7: systems which operate in an unprivileged virtualized environment. IO requests
                      8: from the domU systems are forwarded by the Xen hypervisor to the dom0 to be
                      9: fulfilled.
1.12      gdt        10: 
1.149     maxv       11: Xen supports different styles of guest:
                     12: 
                     13: [[!table data="""
                     14: Style of guest |Supported by NetBSD
1.150     maxv       15: PV             |Yes (dom0, domU)
                     16: HVM            |Yes (domU)
1.149     maxv       17: PVHVM          |No
                     18: PVH            |No
                     19: """]]
                     20: 
                     21: In Para-Virtualized (PV) mode, the guest OS does not attempt to access
                     22: hardware directly, but instead makes hypercalls to the hypervisor; PV
                     23: guests must be specifically coded for Xen. In HVM mode, no guest
                     24: modification is required; however, hardware support is required, such
                     25: as VT-x on Intel CPUs and SVM on AMD CPUs.
                     26: 
1.27      jnemeth    27: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
1.12      gdt        28: The dom0 can start one or more domUs.  (Booting is explained in detail
                     29: in the dom0 section.)
                     30: 
                     31: This HOWTO presumes a basic familiarity with the Xen system
1.123     gdt        32: architecture, with installing NetBSD on i386/amd64 hardware, and with
                     33: installing software from pkgsrc.  See also the [Xen
                     34: website](http://www.xenproject.org/).
1.1       mspo       35: 
1.150     maxv       36: This HOWTO attempts to address both the case of running a NetBSD dom0
                     37: on hardware and running domUs under it (NetBSD and other), and also
                     38: running NetBSD as a domU in a VPS.
                     39: 
1.157     maxv       40: Versions and Support
                     41: ====================
1.15      gdt        42: 
1.111     wiz        43: In NetBSD, Xen is provided in pkgsrc, via matching pairs of packages
1.15      gdt        44: xenkernel and xentools.  We will refer only to the kernel versions,
                     45: but note that both packages must be installed together and must have
                     46: matching versions.
                     47: 
1.145     maxv       48: Versions available in pkgsrc:
1.85      gdt        49: 
1.145     maxv       50: [[!table data="""
                     51: Xen Version    |Package Name   |Xen CPU Support        |EOL'ed By Upstream
                     52: 4.2            |xenkernel42    |32bit, 64bit           |Yes
                     53: 4.5            |xenkernel45    |64bit                  |Yes
                     54: 4.6            |xenkernel46    |64bit                  |Partially
                     55: 4.8            |xenkernel48    |64bit                  |No
                     56: 4.11           |xenkernel411   |64bit                  |No
                     57: """]]
1.113     gdt        58: 
1.96      gdt        59: See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
                     60: 
1.157     maxv       61: Multiprocessor (SMP) support in NetBSD differs depending on the domain:
1.145     maxv       62: 
1.157     maxv       63: [[!table data="""
                     64: Domain         |Supports SMP
                     65: dom0           |No
                     66: domU           |Yes
                     67: """]]
1.15      gdt        68: 
1.147     maxv       69: Note: NetBSD support is called XEN3. However, it does support Xen 4,
                     70: because the hypercall interface has remained identical.
                     71: 
1.18      gdt        72: Architecture
                     73: ------------
                     74: 
1.157     maxv       75: Xen itself runs on x86_64 hardware.
1.155     maxv       76: 
                     77: The dom0 system, plus each domU, can be either i386PAE or amd64.
                     78: i386 without PAE is not supported.
                     79: 
1.157     maxv       80: The standard approach is to use NetBSD/amd64 for the dom0.
                     81: 
                     82: To use an i386PAE dom0, one must build or obtain a 64bit Xen kernel and
                     83: install it on the system.
                     84: 
                     85: For domUs, i386PAE is considered as
                     86: [faster](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html)
                     87: than amd64.
1.29      gdt        88: 
1.15      gdt        89: NetBSD as a dom0
                     90: ================
                     91: 
1.158     maxv       92: In order to install a NetBSD as a dom0, one must first install a normal
                     93: NetBSD system, and then pivot the install to a dom0 install by changing
                     94: the kernel and boot configuration.
1.15      gdt        95: 
1.142     gdt        96: In 2018-05, trouble booting a dom0 was reported with 256M of RAM: with
                     97: 512M it worked reliably.  This does not make sense, but if you see
                     98: "not ELF" after Xen boots, try increasing dom0 RAM.
                     99: 
1.19      gdt       100: Installation of NetBSD
                    101: ----------------------
1.13      gdt       102: 
1.157     maxv      103: [Install NetBSD/amd64](/guide/inst/)
1.19      gdt       104: just as you would if you were not using Xen.
1.1       mspo      105: 
1.19      gdt       106: Installation of Xen
                    107: -------------------
1.1       mspo      108: 
1.155     maxv      109: We will consider that you chose to use Xen 4.8, with NetBSD/amd64 as
                    110: dom0. In the dom0, install xenkernel48 and xentools48 from pkgsrc.
                    111: 
                    112: Once this is done, install the Xen kernel itself:
                    113: 
                    114: [[!template id=programlisting text="""
                    115: # cp /usr/pkg/xen48-kernel/xen.gz /
                    116: """]]
                    117: 
1.159   ! maxv      118: Then, place a NetBSD XEN3_DOM0 kernel in the `/` directory. Such kernel
        !           119: can either be compiled manually, or downloaded from the NetBSD FTP, for
        !           120: example at:
        !           121: 
        !           122: [[!template id=programlisting text="""
        !           123: ftp.netbsd.org/pub/NetBSD/NetBSD-8.0/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
        !           124: """]]
1.20      gdt       125: 
1.155     maxv      126: Add a line to /boot.cfg to boot Xen:
1.20      gdt       127: 
1.157     maxv      128: [[!template id=filecontent name="/boot.cfg" text="""
1.152     maxv      129: menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
                    130: """]]
1.20      gdt       131: 
1.159   ! maxv      132: This specifies that the dom0 should have 512MB of ram, leaving the rest
        !           133: to be allocated for domUs.  To use a serial console, use:
1.77      gdt       134: 
1.157     maxv      135: [[!template id=filecontent name="/boot.cfg" text="""
1.152     maxv      136: menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
                    137: """]]
1.77      gdt       138: 
                    139: which will use the first serial port for Xen (which counts starting
1.139     gson      140: from 1, unlike NetBSD which counts starting from 0), forcing
                    141: speed/parity.  Because the NetBSD command line lacks a
                    142: "console=pc" argument, it will use the default "xencons" console device,
                    143: which directs the console I/O through Xen to the same console device Xen
                    144: itself uses (in this case, the serial port).
                    145: 
1.157     maxv      146: In an attempt to add performance, one can also add `dom0_max_vcpus=1 dom0_vcpus_pin`,
1.37      gdt       147: to force only one vcpu to be provided (since NetBSD dom0 can't use
1.158     maxv      148: more) and to pin that vcpu to a physical CPU. Xen has
                    149: [many boot options](http://xenbits.xenproject.org/docs/4.8-testing/misc/xen-command-line.html),
1.111     wiz       150: and other than dom0 memory and max_vcpus, they are generally not
1.93      gdt       151: necessary.
                    152: 
1.159   ! maxv      153: Copy the boot scripts into `/etc/rc.d`:
        !           154: 
        !           155: [[!template id=programlisting text="""
        !           156: # cp /usr/pkg/share/examples/rc.d/xen* /etc/rc.d/
        !           157: """]]
        !           158: 
1.158     maxv      159: Enable `xencommons`:
1.31      gdt       160: 
1.157     maxv      161: [[!template id=filecontent name="/etc/rc.conf" text="""
1.152     maxv      162: xencommons=YES
                    163: """]]
1.31      gdt       164: 
1.158     maxv      165: Now, reboot so that you are running a DOM0 kernel under Xen, rather
                    166: than GENERIC without Xen.
1.157     maxv      167: 
1.31      gdt       168: TODO: Recommend for/against xen-watchdog.
1.27      jnemeth   169: 
1.158     maxv      170: Once the reboot is done, use `xl` to inspect Xen's boot messages,
1.157     maxv      171: available resources, and running domains.  For example:
1.34      gdt       172: 
1.153     maxv      173: [[!template id=programlisting text="""
                    174: # xl dmesg
                    175: ... xen's boot info ...
                    176: # xl info
                    177: ... available memory, etc ...
                    178: # xl list
                    179: Name              Id  Mem(MB)  CPU  State  Time(s)  Console
                    180: Domain-0           0       64    0  r----     58.1
                    181: """]]
                    182: 
                    183: Xen logs will be in /var/log/xen.
1.33      gdt       184: 
1.88      gdt       185: ### Issues with xencommons
                    186: 
1.157     maxv      187: `xencommons` starts `xenstored`, which stores data on behalf of dom0 and
1.88      gdt       188: domUs.  It does not currently work to stop and start xenstored.
                    189: Certainly all domUs should be shutdown first, following the sort order
                    190: of the rc.d scripts.  However, the dom0 sets up state with xenstored,
                    191: and is not notified when xenstored exits, leading to not recreating
                    192: the state when the new xenstored starts.  Until there's a mechanism to
                    193: make this work, one should not expect to be able to restart xenstored
                    194: (and thus xencommons).  There is currently no reason to expect that
                    195: this will get fixed any time soon.
                    196: 
1.41      gdt       197: anita (for testing NetBSD)
                    198: --------------------------
                    199: 
1.157     maxv      200: With the setup so far (assuming 4.8/xl), one should be able to run
1.82      gdt       201: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
                    202: root, because anita must create a domU):
                    203: 
1.153     maxv      204: [[!template id=programlisting text="""
                    205: anita --vmm=xl test file:///usr/obj/i386/
                    206: """]]
1.82      gdt       207: 
1.40      gdt       208: Xen-specific NetBSD issues
                    209: --------------------------
                    210: 
                    211: There are (at least) two additional things different about NetBSD as a
                    212: dom0 kernel compared to hardware.
                    213: 
1.111     wiz       214: One is that the module ABI is different because some of the #defines
1.109     gdt       215: change, so one must build modules for Xen.  As of netbsd-7, the build
1.157     maxv      216: system does this automatically.
1.40      gdt       217: 
                    218: The other difference is that XEN3_DOM0 does not have exactly the same
                    219: options as GENERIC.  While it is debatable whether or not this is a
                    220: bug, users should be aware of this and can simply add missing config
                    221: items if desired.
                    222: 
1.15      gdt       223: Updating NetBSD in a dom0
                    224: -------------------------
                    225: 
                    226: This is just like updating NetBSD on bare hardware, assuming the new
                    227: version supports the version of Xen you are running.  Generally, one
                    228: replaces the kernel and reboots, and then overlays userland binaries
1.157     maxv      229: and adjusts `/etc`.
1.15      gdt       230: 
                    231: Note that one must update both the non-Xen kernel typically used for
                    232: rescue purposes and the DOM0 kernel used with Xen.
                    233: 
1.55      gdt       234: Converting from grub to /boot
                    235: -----------------------------
                    236: 
1.157     maxv      237: These instructions were used to convert a system from
1.55      gdt       238: grub to /boot.  The system was originally installed in February of
                    239: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
                    240: over time.  Before these commands, it was running NetBSD 6 i386, Xen
                    241: 4.1 and grub, much like the message linked earlier in the grub
                    242: section.
                    243: 
1.157     maxv      244: [[!template id=programlisting text="""
                    245: # Install MBR bootblocks on both disks.
                    246: fdisk -i /dev/rwd0d
                    247: fdisk -i /dev/rwd1d
                    248: # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
                    249: installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
                    250: installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
                    251: # Install secondary boot loader
                    252: cp -p /usr/mdec/boot /
                    253: # Create boot.cfg following earlier guidance:
                    254: menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
                    255: menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=512M
                    256: menu=GENERIC:boot
                    257: menu=GENERIC single-user:boot -s
                    258: menu=GENERIC.ok:boot netbsd.ok
                    259: menu=GENERIC.ok single-user:boot netbsd.ok -s
                    260: menu=Drop to boot prompt:prompt
                    261: default=1
                    262: timeout=30
                    263: """]]
1.22      gdt       264: 
1.102     gdt       265: Upgrading Xen versions
1.15      gdt       266: ---------------------
                    267: 
1.110     gdt       268: Minor version upgrades are trivial.  Just rebuild/replace the
1.157     maxv      269: xenkernel version and copy the new xen.gz to `/` (where `/boot.cfg`
1.110     gdt       270: references it), and reboot.
                    271: 
1.28      gdt       272: Unprivileged domains (domU)
                    273: ===========================
                    274: 
                    275: This section describes general concepts about domUs.  It does not
1.33      gdt       276: address specific domU operating systems or how to install them.  The
1.157     maxv      277: config files for domUs are typically in `/usr/pkg/etc/xen`, and are
1.60      wiki      278: typically named so that the file name, domU name and the domU's host
1.33      gdt       279: name match.
                    280: 
1.111     wiz       281: The domU is provided with CPU and memory by Xen, configured by the
1.33      gdt       282: dom0.  The domU is provided with disk and network by the dom0,
                    283: mediated by Xen, and configured in the dom0.
                    284: 
                    285: Entropy in domUs can be an issue; physical disks and network are on
                    286: the dom0.  NetBSD's /dev/random system works, but is often challenged.
                    287: 
1.48      gdt       288: Config files
                    289: ------------
                    290: 
1.158     maxv      291: See /usr/pkg/share/examples/xen/xlexample*,
1.48      gdt       292: for a large number of well-commented examples, mostly for running
                    293: GNU/Linux.
                    294: 
1.157     maxv      295: The following is an example minimal domain configuration file. The domU
                    296: serves as a network file server.
                    297: 
                    298: [[!template id=filecontent name="/usr/pkg/etc/xen/foo" text="""
                    299: name = "domU-id"
                    300: kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
                    301: memory = 1024
                    302: vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
                    303: disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
                    304:          'file:/n0/xen/foo-wd1,0x1,w' ]
                    305: """]]
1.48      gdt       306: 
1.157     maxv      307: The domain will have name given in the `name` setting.  The kernel has the
1.48      gdt       308: host/domU name in it, so that on the dom0 one can update the various
1.157     maxv      309: domUs independently.  The `vif` line causes an interface to be provided,
1.48      gdt       310: with a specific mac address (do not reuse MAC addresses!), in bridge
                    311: mode.  Two disks are provided, and they are both writable; the bits
                    312: are stored in files and Xen attaches them to a vnd(4) device in the
1.111     wiz       313: dom0 on domain creation.  The system treats xbd0 as the boot device
1.48      gdt       314: without needing explicit configuration.
                    315: 
1.157     maxv      316: By default, `xl` looks for domain config files in `/usr/pkg/etc/xen`.  Note
                    317: that "xl create" takes the name of a config file, while other commands
                    318: take the name of a domain.
                    319: 
                    320: Examples of commands:
1.48      gdt       321: 
1.157     maxv      322: [[!template id=programlisting text="""
                    323: xl create foo
                    324: xl console foo
                    325: xl create -c foo
                    326: xl shutdown foo
                    327: xl list
                    328: """]]
                    329: 
                    330: Typing `^]` will exit the console session.  Shutting down a domain is
1.48      gdt       331: equivalent to pushing the power button; a NetBSD domU will receive a
                    332: power-press event and do a clean shutdown.  Shutting down the dom0
                    333: will trigger controlled shutdowns of all configured domUs.
                    334: 
1.33      gdt       335: CPU and memory
                    336: --------------
                    337: 
1.48      gdt       338: A domain is provided with some number of vcpus, less than the number
1.157     maxv      339: of CPUs seen by the hypervisor. For a domU, it is controlled
1.48      gdt       340: from the config file by the "vcpus = N" directive.
                    341: 
                    342: A domain is provided with memory; this is controlled in the config
                    343: file by "memory = N" (in megabytes).  In the straightforward case, the
                    344: sum of the the memory allocated to the dom0 and all domUs must be less
1.33      gdt       345: than the available memory.
                    346: 
                    347: Xen also provides a "balloon" driver, which can be used to let domains
1.157     maxv      348: use more memory temporarily.
1.28      gdt       349: 
                    350: Virtual disks
                    351: -------------
                    352: 
1.158     maxv      353: In domU config files, the disks are defined as a sequence of 3-tuples:
                    354: 
                    355:  * The first element is "method:/path/to/disk". Common methods are
                    356:    "file:" for file-backed vnd, and "phy:" for something that is already
                    357:    a device.
                    358: 
                    359:  * The second element is an artifact of how virtual disks are passed to
                    360:    Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
                    361:    are given a device name to associate with the disk, and values like
                    362:    "hda1" or "sda1" are common.  In a NetBSD domU, the first disk appears
                    363:    as xbd0, the second as xbd1, and so on.  However, xl demands a
                    364:    second argument.  The name given is converted to a major/minor by
                    365:    calling stat(2) on the name in /dev and this is passed to the domU.
                    366:    In the general case, the dom0 and domU can be different operating
                    367:    systems, and it is an unwarranted assumption that they have consistent
                    368:    numbering in /dev, or even that the dom0 OS has a /dev.  With NetBSD
                    369:    as both dom0 and domU, using values of 0x0 for the first disk and 0x1
                    370:    for the second works fine and avoids this issue.  For a GNU/Linux
                    371:    guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
                    372:    /dev/hda1.
1.48      gdt       373: 
1.158     maxv      374:  * The third element is "w" for writable disks, and "r" for read-only
                    375:    disks.
                    376: 
                    377: Example:
                    378: [[!template id=filecontent name="/usr/pkg/etc/xen/foo" text="""
                    379: disk = [ 'file:/n0/xen/foo-wd0,0x0,w' ]
                    380: """]]
1.28      gdt       381: 
1.127     gdt       382: Note that NetBSD by default creates only vnd[0123].  If you need more
                    383: than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the
                    384: dom0.
                    385: 
                    386: Note that NetBSD by default creates only xbd[0123].  If you need more
                    387: virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU.
                    388: 
1.28      gdt       389: Virtual Networking
                    390: ------------------
                    391: 
1.111     wiz       392: Xen provides virtual Ethernets, each of which connects the dom0 and a
1.46      gdt       393: domU.  For each virtual network, there is an interface "xvifN.M" in
1.158     maxv      394: the dom0, and a matching interface xennetM (NetBSD name) in domU index N.
                    395: The interfaces behave as if there is an Ethernet with two
1.111     wiz       396: adapters connected.  From this primitive, one can construct various
1.46      gdt       397: configurations.  We focus on two common and useful cases for which
                    398: there are existing scripts: bridging and NAT.
1.28      gdt       399: 
1.48      gdt       400: With bridging (in the example above), the domU perceives itself to be
                    401: on the same network as the dom0.  For server virtualization, this is
                    402: usually best.  Bridging is accomplished by creating a bridge(4) device
                    403: and adding the dom0's physical interface and the various xvifN.0
                    404: interfaces to the bridge.  One specifies "bridge=bridge0" in the domU
                    405: config file.  The bridge must be set up already in the dom0; an
                    406: example /etc/ifconfig.bridge0 is:
1.46      gdt       407: 
1.157     maxv      408: [[!template id=filecontent name="/etc/ifconfig.bridge0" text="""
                    409: create
                    410: up
                    411: !brconfig bridge0 add wm0
                    412: """]]
1.28      gdt       413: 
                    414: With NAT, the domU perceives itself to be behind a NAT running on the
                    415: dom0.  This is often appropriate when running Xen on a workstation.
1.48      gdt       416: TODO: NAT appears to be configured by "vif = [ '' ]".
1.28      gdt       417: 
1.49      gdt       418: The MAC address specified is the one used for the interface in the new
1.53      gdt       419: domain.  The interface in dom0 will use this address XOR'd with
1.49      gdt       420: 00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
                    421: 
1.48      gdt       422: Starting domains automatically
                    423: ------------------------------
1.28      gdt       424: 
1.158     maxv      425: To start domains `domU-netbsd` and `domU-linux` at boot and shut them
                    426: down cleanly on dom0 shutdown, add the following in rc.conf:
1.28      gdt       427: 
1.158     maxv      428: [[!template id=filecontent name="/etc/rc.conf" text="""
                    429: xendomains="domU-netbsd domU-linux"
                    430: """]]
1.28      gdt       431: 
1.158     maxv      432: Creating a domU
                    433: ===============
1.14      gdt       434: 
                    435: Creating domUs is almost entirely independent of operating system.  We
1.49      gdt       436: have already presented the basics of config files.  Note that you must
1.158     maxv      437: have already completed the dom0 setup so that "xl list" works.
1.14      gdt       438: 
1.158     maxv      439: Creating a NetBSD domU
                    440: ----------------------
1.1       mspo      441: 
1.49      gdt       442: See the earlier config file, and adjust memory.  Decide on how much
                    443: storage you will provide, and prepare it (file or lvm).
                    444: 
1.111     wiz       445: While the kernel will be obtained from the dom0 file system, the same
1.49      gdt       446: file should be present in the domU as /netbsd so that tools like
                    447: savecore(8) can work.   (This is helpful but not necessary.)
                    448: 
                    449: The kernel must be specifically for Xen and for use as a domU.  The
                    450: i386 and amd64 provide the following kernels:
                    451: 
                    452:         i386 XEN3PAE_DOMU
1.95      gdt       453:         amd64 XEN3_DOMU
1.5       mspo      454: 
1.49      gdt       455: This will boot NetBSD, but this is not that useful if the disk is
                    456: empty.  One approach is to unpack sets onto the disk outside of xen
                    457: (by mounting it, just as you would prepare a physical disk for a
                    458: system you can't run the installer on).
                    459: 
                    460: A second approach is to run an INSTALL kernel, which has a miniroot
                    461: and can load sets from the network.  To do this, copy the INSTALL
                    462: kernel to / and change the kernel line in the config file to:
1.5       mspo      463: 
1.49      gdt       464:         kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
1.5       mspo      465: 
1.49      gdt       466: Then, start the domain as "xl create -c configname".
1.1       mspo      467: 
1.49      gdt       468: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
                    469: line should be used in the config file.
1.1       mspo      470: 
1.3       mspo      471:     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
1.1       mspo      472: 
                    473: After booting the domain, the option to install via CDROM may be
1.49      gdt       474: selected.  The CDROM device should be changed to `xbd1d`.
1.1       mspo      475: 
1.49      gdt       476: Once done installing, "halt -p" the new domain (don't reboot or halt,
                    477: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
                    478: config file), switch the config file back to the XEN3_DOMU kernel,
                    479: and start the new domain again. Now it should be able to use "root on
                    480: xbd0a" and you should have a, functional NetBSD domU.
1.1       mspo      481: 
1.49      gdt       482: TODO: check if this is still accurate.
1.1       mspo      483: When the new domain is booting you'll see some warnings about *wscons*
                    484: and the pseudo-terminals. These can be fixed by editing the files
1.5       mspo      485: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
                    486: `/etc/ttys`, except *console*, like this:
1.1       mspo      487: 
1.3       mspo      488:     console "/usr/libexec/getty Pc"         vt100   on secure
                    489:     ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
                    490:     ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
                    491:     ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
                    492:     ttyE3   "/usr/libexec/getty Pc"         vt220   off secure
1.1       mspo      493: 
1.5       mspo      494: Finally, all screens must be commented out from `/etc/wscons.conf`.
1.1       mspo      495: 
                    496: It is also desirable to add
                    497: 
1.49      gdt       498:         powerd=YES
1.1       mspo      499: 
1.5       mspo      500: in rc.conf. This way, the domain will be properly shut down if
1.53      gdt       501: `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
1.1       mspo      502: 
1.92      gdt       503: It is not strictly necessary to have a kernel (as /netbsd) in the domU
1.111     wiz       504: file system.  However, various programs (e.g. netstat) will use that
1.92      gdt       505: kernel to look up symbols to read from kernel virtual memory.  If
                    506: /netbsd is not the running kernel, those lookups will fail.  (This is
                    507: not really a Xen-specific issue, but because the domU kernel is
                    508: obtained from the dom0, it is far more likely to be out of sync or
                    509: missing with Xen.)
                    510: 
1.158     maxv      511: Creating a Linux domU
                    512: ---------------------
1.1       mspo      513: 
                    514: Creating unprivileged Linux domains isn't much different from
                    515: unprivileged NetBSD domains, but there are some details to know.
                    516: 
                    517: First, the second parameter passed to the disk declaration (the '0x1' in
                    518: the example below)
                    519: 
1.3       mspo      520:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
1.1       mspo      521: 
                    522: does matter to Linux. It wants a Linux device number here (e.g. 0x300
1.49      gdt       523: for hda).  Linux builds device numbers as: (major \<\< 8 + minor).
                    524: So, hda1 which has major 3 and minor 1 on a Linux system will have
                    525: device number 0x301.  Alternatively, devices names can be used (hda,
                    526: hdb, ...)  as xentools has a table to map these names to devices
                    527: numbers.  To export a partition to a Linux guest we can use:
1.1       mspo      528: 
1.49      gdt       529:         disk = [ 'phy:/dev/wd0e,0x300,w' ]
                    530:         root = "/dev/hda1 ro"
1.1       mspo      531: 
                    532: and it will appear as /dev/hda on the Linux system, and be used as root
                    533: partition.
                    534: 
1.49      gdt       535: To install the Linux system on the partition to be exported to the
                    536: guest domain, the following method can be used: install
                    537: sysutils/e2fsprogs from pkgsrc.  Use mke2fs to format the partition
                    538: that will be the root partition of your Linux domain, and mount it.
                    539: Then copy the files from a working Linux system, make adjustments in
                    540: `/etc` (fstab, network config).  It should also be possible to extract
                    541: binary packages such as .rpm or .deb directly to the mounted partition
                    542: using the appropriate tool, possibly running under NetBSD's Linux
1.111     wiz       543: emulation.  Once the file system has been populated, umount it.  If
                    544: desirable, the file system can be converted to ext3 using tune2fs -j.
1.49      gdt       545: It should now be possible to boot the Linux guest domain, using one of
                    546: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
1.1       mspo      547: 
1.111     wiz       548: To get the Linux console right, you need to add:
1.1       mspo      549: 
1.3       mspo      550:     extra = "xencons=tty1"
1.1       mspo      551: 
1.111     wiz       552: to your configuration since not all Linux distributions auto-attach a
1.1       mspo      553: tty to the xen console.
                    554: 
1.158     maxv      555: Creating a Solaris domU
                    556: -----------------------
1.1       mspo      557: 
1.50      gdt       558: See possibly outdated
                    559: [Solaris domU instructions](/ports/xen/howto-solaris/).
1.5       mspo      560: 
1.1       mspo      561: 
1.52      gdt       562: PCI passthrough: Using PCI devices in guest domains
                    563: ---------------------------------------------------
1.1       mspo      564: 
1.53      gdt       565: The dom0 can give other domains access to selected PCI
1.52      gdt       566: devices. This can allow, for example, a non-privileged domain to have
                    567: access to a physical network interface or disk controller.  However,
                    568: keep in mind that giving a domain access to a PCI device most likely
                    569: will give the domain read/write access to the whole physical memory,
                    570: as PCs don't have an IOMMU to restrict memory access to DMA-capable
1.53      gdt       571: device.  Also, it's not possible to export ISA devices to non-dom0
1.52      gdt       572: domains, which means that the primary VGA adapter can't be exported.
                    573: A guest domain trying to access the VGA registers will panic.
                    574: 
1.53      gdt       575: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
1.52      gdt       576: not been ported to later versions at this time.
                    577: 
                    578: For a PCI device to be exported to a domU, is has to be attached to
                    579: the "pciback" driver in dom0.  Devices passed to the dom0 via the
                    580: pciback.hide boot parameter will attach to "pciback" instead of the
                    581: usual driver.  The list of devices is specified as "(bus:dev.func)",
1.5       mspo      582: where bus and dev are 2-digit hexadecimal numbers, and func a
                    583: single-digit number:
1.1       mspo      584: 
1.52      gdt       585:         pciback.hide=(00:0a.0)(00:06.0)
1.1       mspo      586: 
1.52      gdt       587: pciback devices should show up in the dom0's boot messages, and the
1.5       mspo      588: devices should be listed in the `/kern/xen/pci` directory.
1.1       mspo      589: 
1.52      gdt       590: PCI devices to be exported to a domU are listed in the "pci" array of
                    591: the domU's config file, with the format "0000:bus:dev.func".
1.1       mspo      592: 
1.52      gdt       593:         pci = [ '0000:00:06.0', '0000:00:0a.0' ]
1.1       mspo      594: 
1.52      gdt       595: In the domU an "xpci" device will show up, to which one or more pci
1.111     wiz       596: buses will attach.  Then the PCI drivers will attach to PCI buses as
1.52      gdt       597: usual.  Note that the default NetBSD DOMU kernels do not have "xpci"
                    598: or any PCI drivers built in by default; you have to build your own
                    599: kernel to use PCI devices in a domU.  Here's a kernel config example;
                    600: note that only the "xpci" lines are unusual.
                    601: 
                    602:         include         "arch/i386/conf/XEN3_DOMU"
                    603: 
1.111     wiz       604:         # Add support for PCI buses to the XEN3_DOMU kernel
1.52      gdt       605:         xpci* at xenbus ?
                    606:         pci* at xpci ?
                    607: 
                    608:         # PCI USB controllers
                    609:         uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
                    610: 
                    611:         # USB bus support
                    612:         usb*    at uhci?
                    613: 
                    614:         # USB Hubs
                    615:         uhub*   at usb?
                    616:         uhub*   at uhub? port ? configuration ? interface ?
                    617: 
                    618:         # USB Mass Storage
                    619:         umass*  at uhub? port ? configuration ? interface ?
                    620:         wd*     at umass?
                    621:         # SCSI controllers
                    622:         ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
                    623: 
                    624:         # SCSI bus support (for both ahc and umass)
                    625:         scsibus* at scsi?
                    626: 
                    627:         # SCSI devices
                    628:         sd*     at scsibus? target ? lun ?      # SCSI disk drives
                    629:         cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
1.1       mspo      630: 
                    631: 
1.28      gdt       632: NetBSD as a domU in a VPS
                    633: =========================
                    634: 
                    635: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
                    636: hardware.  This section explains how to deal with Xen in a domU as a
                    637: virtual private server where you do not control or have access to the
1.70      gdt       638: dom0.  This is not intended to be an exhaustive list of VPS providers;
                    639: only a few are mentioned that specifically support NetBSD.
1.28      gdt       640: 
1.52      gdt       641: VPS operators provide varying degrees of access and mechanisms for
                    642: configuration.  The big issue is usually how one controls which kernel
1.111     wiz       643: is booted, because the kernel is nominally in the dom0 file system (to
                    644: which VPS users do not normally have access).  A second issue is how
1.70      gdt       645: to install NetBSD.
1.52      gdt       646: A VPS user may want to compile a kernel for security updates, to run
                    647: npf, run IPsec, or any other reason why someone would want to change
                    648: their kernel.
                    649: 
1.111     wiz       650: One approach is to have an administrative interface to upload a kernel,
1.68      gdt       651: or to select from a prepopulated list.  Other approaches are pygrub
1.59      gdt       652: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
1.111     wiz       653: kernel from the domU file system.  This is closer to a regular physical
1.59      gdt       654: computer, where someone who controls a machine can replace the kernel.
1.52      gdt       655: 
1.74      gdt       656: A second issue is multiple CPUs.  With NetBSD 6, domUs support
                    657: multiple vcpus, and it is typical for VPS providers to enable multiple
                    658: CPUs for NetBSD domUs.
                    659: 
1.68      gdt       660: pygrub
1.59      gdt       661: -------
1.52      gdt       662: 
1.111     wiz       663: pygrub runs in the dom0 and looks into the domU file system.  This
                    664: implies that the domU must have a kernel in a file system in a format
1.68      gdt       665: known to pygrub.  As of 2014, pygrub seems to be of mostly historical
                    666: interest.
1.52      gdt       667: 
1.59      gdt       668: pvgrub
                    669: ------
                    670: 
                    671: pvgrub is a version of grub that uses PV operations instead of BIOS
                    672: calls.  It is booted from the dom0 as the domU kernel, and then reads
1.111     wiz       673: /grub/menu.lst and loads a kernel from the domU file system.
1.59      gdt       674: 
1.70      gdt       675: [Panix](http://www.panix.com/) lets users use pvgrub.  Panix reports
1.71      gdt       676: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
                    677: (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
1.70      gdt       678: page](http://www.panix.com/v-colo/grub.html), which describes only
1.74      gdt       679: Linux but should be updated to cover NetBSD :-).
1.70      gdt       680: 
                    681: [prgmr.com](http://prgmr.com/) also lets users with pvgrub to boot
                    682: their own kernel.  See then [prgmr.com NetBSD
1.74      gdt       683: HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU)
                    684: (which is in need of updating).
1.59      gdt       685: 
1.70      gdt       686: It appears that [grub's FFS
                    687: code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
                    688: does not support all aspects of modern FFS, but there are also reports
1.72      gdt       689: that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT
1.70      gdt       690: partition for the kernel with the intent that grub can understand it,
                    691: which leads to /netbsd not being the actual kernel.  One must remember
1.111     wiz       692: to update the special boot partition.
1.59      gdt       693: 
                    694: Amazon
                    695: ------
                    696: 
1.143     wiki      697: See the [Amazon EC2 page](/amazon_ec2/).
1.44      gdt       698: 
1.93      gdt       699: Random pointers
                    700: ===============
                    701: 
1.117     gdt       702: This section contains links from elsewhere not yet integrated into the
                    703: HOWTO, and other guides.
1.93      gdt       704: 
                    705: * http://www.lumbercartel.ca/library/xen/
                    706: * http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html
1.117     gdt       707: * https://gmplib.org/~tege/xen.html

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