Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.151

1.144     maxv        1: [[!meta title="Xen HowTo"]]
1.5       mspo        3: Introduction
1.13      gdt         4: ============
1.1       mspo        5: 
                      6: [![[Xen
1.140     khorben     7: screenshot]](](
1.1       mspo        8: 
1.149     maxv        9: Xen is a hypervisor for x86 hardware, which supports running multiple guest
1.58      gdt        10: operating systems on a single physical machine.  Xen is a Type 1 or
                     11: bare-metal hypervisor; one uses the Xen kernel to control the CPU,
                     12: memory and console, a dom0 operating system which mediates access to
                     13: other hardware (e.g., disks, network, USB), and one or more domU
                     14: operating systems which operate in an unprivileged virtualized
                     15: environment.  IO requests from the domU systems are forwarded by the
1.149     maxv       16: Xen hypervisor to the dom0 to be fulfilled.
1.12      gdt        17: 
1.149     maxv       18: Xen supports different styles of guest:
                     20: [[!table data="""
                     21: Style of guest |Supported by NetBSD
1.150     maxv       22: PV             |Yes (dom0, domU)
                     23: HVM            |Yes (domU)
1.149     maxv       24: PVHVM          |No
                     25: PVH            |No
                     26: """]]
                     28: In Para-Virtualized (PV) mode, the guest OS does not attempt to access
                     29: hardware directly, but instead makes hypercalls to the hypervisor; PV
                     30: guests must be specifically coded for Xen. In HVM mode, no guest
                     31: modification is required; however, hardware support is required, such
                     32: as VT-x on Intel CPUs and SVM on AMD CPUs.
                     34: There are further features for IOMMU virtualization, Intel's VT-d and
                     35: AMD's AMD-Vi.  TODO: Explain whether Xen on NetBSD makes use of these
                     36: features.  TODO: Review by someone who really understands this.
1.12      gdt        37: 
1.27      jnemeth    38: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
1.12      gdt        39: The dom0 can start one or more domUs.  (Booting is explained in detail
                     40: in the dom0 section.)
                     42: This HOWTO presumes a basic familiarity with the Xen system
1.123     gdt        43: architecture, with installing NetBSD on i386/amd64 hardware, and with
                     44: installing software from pkgsrc.  See also the [Xen
                     45: website](
1.1       mspo       46: 
1.150     maxv       47: This HOWTO attempts to address both the case of running a NetBSD dom0
                     48: on hardware and running domUs under it (NetBSD and other), and also
                     49: running NetBSD as a domU in a VPS.
1.15      gdt        51: Versions of Xen and NetBSD
                     52: ==========================
1.27      jnemeth    54: Most of the installation concepts and instructions are independent
                     55: of Xen version and NetBSD version.  This section gives advice on
                     56: which version to choose.  Versions not in pkgsrc and older unsupported
                     57: versions of NetBSD are intentionally ignored.
1.15      gdt        58: 
1.133     gdt        59: The term "amd64" is used to refer to both the NetBSD port and to the
1.150     maxv       60: hardware architecture on which it runs.  Such hardware is generally
                     61: made by both Intel and AMD, and common on PC computers.
1.133     gdt        62: 
1.146     maxv       63: Xen versions
                     64: ------------
1.15      gdt        65: 
1.111     wiz        66: In NetBSD, Xen is provided in pkgsrc, via matching pairs of packages
1.15      gdt        67: xenkernel and xentools.  We will refer only to the kernel versions,
                     68: but note that both packages must be installed together and must have
                     69: matching versions.
1.145     maxv       71: Versions available in pkgsrc:
1.85      gdt        72: 
1.145     maxv       73: [[!table data="""
                     74: Xen Version    |Package Name   |Xen CPU Support        |EOL'ed By Upstream
                     75: 4.2            |xenkernel42    |32bit, 64bit           |Yes
                     76: 4.5            |xenkernel45    |64bit                  |Yes
                     77: 4.6            |xenkernel46    |64bit                  |Partially
                     78: 4.8            |xenkernel48    |64bit                  |No
                     79: 4.11           |xenkernel411   |64bit                  |No
                     80: """]]
1.113     gdt        81: 
1.96      gdt        82: See also the [Xen Security Advisory page](
1.145     maxv       84: Note: Xen 4.2 was the last version to support 32bit CPUs.
1.19      gdt        86: Xen command program
                     87: -------------------
1.79      gdt        89: Early Xen used a program called xm to manipulate the system from the
1.19      gdt        90: dom0.  Starting in 4.1, a replacement program with similar behavior
1.79      gdt        91: called xl is provided, but it does not work well in 4.1.  In 4.2, both
1.127     gdt        92: xm and xl work fine.  4.4 is the last version that has xm.
                     94: You must make a global choice to use xm or xl, because it affects not
                     95: only which command you use, but the command used by rc.d scripts
                     96: (specifically xendomains) and which daemons should be run.  The
1.146     maxv       97: xentools packages provide xl for 4.2 and up.
1.127     gdt        98: 
                     99: In 4.2, you can choose to use xm by simply changing the ctl_command
1.135     gdt       100: variable and setting xend=YES in rc.conf.
1.127     gdt       101: 
                    102: With xl, virtual devices are configured in parallel, which can cause
                    103: problems if they are written assuming serial operation (e.g., updating
1.130     gdt       104: firewall rules without explicit locking).  There is now locking for
                    105: the provided scripts, which works for normal casses (e.g, file-backed
                    106: xbd, where a vnd must be allocated).  But, as of 201612, it has not
                    107: been adequately tested for a complex custom setup with a large number
                    108: of interfaces.
1.19      gdt       109: 
1.147     maxv      110: NetBSD versions
                    111: ---------------
1.15      gdt       112: 
1.142     gdt       113: The netbsd-7, netbsd-8, and -current branches are all reasonable
1.105     gdt       114: choices, with more or less the same considerations for non-Xen use.
1.147     maxv      115: NetBSD 8 is recommended as the stable version of the most recent
                    116: release for production use.
1.146     maxv      117: 
                    118: For developing Xen, netbsd-current may be appropriate.
1.15      gdt       119: 
                    120: As of NetBSD 6, a NetBSD domU will support multiple vcpus.  There is
                    121: no SMP support for NetBSD as dom0.  (The dom0 itself doesn't really
1.105     gdt       122: need SMP for dom0 functions; the lack of support is really a problem
                    123: when using a dom0 as a normal computer.)
1.15      gdt       124: 
1.147     maxv      125: Note: NetBSD support is called XEN3. However, it does support Xen 4,
                    126: because the hypercall interface has remained identical.
1.18      gdt       128: Architecture
                    129: ------------
1.133     gdt       131: Xen itself can run on i386 (Xen < 4.2) or amd64 hardware (all Xen
1.151   ! maxv      132: versions).  Practically, almost any computer where one would want to
        !           133: run Xen today supports amd64.
1.99      gdt       134: 
1.133     gdt       135: Xen, the dom0 system, and each domU system can be either i386 or
                    136: amd64.  When building a xenkernel package, one obtains an i386 Xen
1.134     wiz       137: kernel on an i386 host, and an amd64 Xen kernel on an amd64 host.  If
1.133     gdt       138: the Xen kernel is i386, then the dom0 kernel and all domU kernels must
                    139: be i386.  With an amd64 Xen kernel, an amd64 dom0 kernel is known to
                    140: work, and an i386 dom0 kernel should in theory work.  An amd64
                    141: Xen/dom0 is known to support both i386 and amd64 domUs.
1.151   ! maxv      143: i386 dom0 and domU kernels must be PAE. PAE kernels are included in
        !           144: the NetBSD default build.
1.135     gdt       145: 
                    146: Because of the above, the standard approach is to use an amd64 Xen
                    147: kernel and NetBSD/amd64 for the dom0.  For domUs, NetBSD/i386 (with
                    148: the PAE kernel) and NetBSD/amd64 are in widespread use, and there is
                    149: little to no Xen-specific reason to prefer one over the other.
1.133     gdt       150: 
                    151: Note that to use an i386 dom0 with Xen 4.5 or higher, one must build
1.135     gdt       152: (or obtain from pre-built packages) an amd64 Xen kernel and install
                    153: that on the system.  (One must also use a PAE i386 kernel, but this is
                    154: also required with an i386 Xen kernel.).  Almost no one in the
                    155: NetBSD/Xen community does this, and the standard, well-tested,
                    156: approach is to use an amd64 dom0.
                    158: A [posting on
                    159: xen-devel](
                    160: explained that PV system call overhead was higher on amd64, and thus
                    161: there is some notion that i386 guests are faster.  It goes on to
                    162: caution that the total situation is complex and not entirely
                    163: understood. On top of that caution, the post is about Linux, not
                    164: NetBSD.  TODO: Include link to benchmarks, if someone posts them.
1.29      gdt       165: 
1.15      gdt       166: NetBSD as a dom0
                    167: ================
                    169: NetBSD can be used as a dom0 and works very well.  The following
                    170: sections address installation, updating NetBSD, and updating Xen.
1.19      gdt       171: Note that it doesn't make sense to talk about installing a dom0 OS
                    172: without also installing Xen itself.  We first address installing
                    173: NetBSD, which is not yet a dom0, and then adding Xen, pivoting the
                    174: NetBSD install to a dom0 install by just changing the kernel and boot
                    175: configuration.
1.15      gdt       176: 
1.45      gdt       177: For experimenting with Xen, a machine with as little as 1G of RAM and
                    178: 100G of disk can work.  For running many domUs in productions, far
1.135     gdt       179: more will be needed; e.g. 4-8G and 1T of disk is reasonable for a
                    180: half-dozen domUs of 512M and 32G each.  Basically, the RAM and disk
                    181: have to be bigger than the sum of the RAM/disk needs of the dom0 and
                    182: all the domUs.
1.45      gdt       183: 
1.142     gdt       184: In 2018-05, trouble booting a dom0 was reported with 256M of RAM: with
                    185: 512M it worked reliably.  This does not make sense, but if you see
                    186: "not ELF" after Xen boots, try increasing dom0 RAM.
1.15      gdt       188: Styles of dom0 operation
                    189: ------------------------
                    191: There are two basic ways to use Xen.  The traditional method is for
                    192: the dom0 to do absolutely nothing other than providing support to some
                    193: number of domUs.  Such a system was probably installed for the sole
                    194: purpose of hosting domUs, and sits in a server room on a UPS.
                    196: The other way is to put Xen under a normal-usage computer, so that the
                    197: dom0 is what the computer would have been without Xen, perhaps a
                    198: desktop or laptop.  Then, one can run domUs at will.  Purists will
                    199: deride this as less secure than the previous approach, and for a
                    200: computer whose purpose is to run domUs, they are right.  But Xen and a
1.93      gdt       201: dom0 (without domUs) is not meaningfully less secure than the same
1.15      gdt       202: things running without Xen.  One can boot Xen or boot regular NetBSD
                    203: alternately with little problems, simply refraining from starting the
                    204: Xen daemons when not running Xen.
                    206: Note that NetBSD as dom0 does not support multiple CPUs.  This will
1.51      gdt       207: limit the performance of the Xen/dom0 workstation approach.  In theory
                    208: the only issue is that the "backend drivers" are not yet MPSAFE:
1.140     khorben   209:
1.15      gdt       210: 
1.19      gdt       211: Installation of NetBSD
                    212: ----------------------
1.13      gdt       213: 
1.19      gdt       214: First,
1.27      jnemeth   215: [install NetBSD/amd64](/guide/inst/)
1.19      gdt       216: just as you would if you were not using Xen.
                    217: However, the partitioning approach is very important.
                    219: If you want to use RAIDframe for the dom0, there are no special issues
                    220: for Xen.  Typically one provides RAID storage for the dom0, and the
1.22      gdt       221: domU systems are unaware of RAID.  The 2nd-stage loader bootxx_* skips
1.111     wiz       222: over a RAID1 header to find /boot from a file system within a RAID
1.22      gdt       223: partition; this is no different when booting Xen.
1.19      gdt       224: 
                    225: There are 4 styles of providing backing storage for the virtual disks
1.93      gdt       226: used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN.
1.19      gdt       227: 
                    228: With raw partitions, one has a disklabel (or gpt) partition sized for
                    229: each virtual disk to be used by the domU.  (If you are able to predict
                    230: how domU usage will evolve, please add an explanation to the HOWTO.
                    231: Seriously, needs tend to change over time.)
1.27      jnemeth   233: One can use [lvm(8)](/guide/lvm/) to create logical devices to use
                    234: for domU disks.  This is almost as efficient as raw disk partitions
                    235: and more flexible.  Hence raw disk partitions should typically not
                    236: be used.
1.19      gdt       237: 
1.111     wiz       238: One can use files in the dom0 file system, typically created by dd'ing
1.19      gdt       239: /dev/zero to create a specific size.  This is somewhat less efficient,
                    240: but very convenient, as one can cp the files for backup, or move them
                    241: between dom0 hosts.
                    243: Finally, in theory one can place the files backing the domU disks in a
                    244: SAN.  (This is an invitation for someone who has done this to add a
                    245: HOWTO page.)
1.1       mspo      246: 
1.19      gdt       247: Installation of Xen
                    248: -------------------
1.1       mspo      249: 
1.20      gdt       250: In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from
1.127     gdt       251: pkgsrc (or another matching pair).  See [the pkgsrc
1.140     khorben   252: documentation]( for help with
1.127     gdt       253: pkgsrc.  Ensure that your packages are recent; the HOWTO does not
                    254: contemplate old builds.
1.20      gdt       256: 
                    257: For Xen 3.1, support for HVM guests is in sysutils/xentool3-hvm.  More
                    258: recent versions have HVM support integrated in the main xentools
                    259: package.  It is entirely reasonable to run only PV guests.
                    261: Next you need to install the selected Xen kernel itself, which is
                    262: installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz".  Copy it to /.
                    263: For debugging, one may copy xen-debug.gz; this is conceptually similar
                    264: to DIAGNOSTIC and DEBUG in NetBSD.  xen-debug.gz is basically only
                    265: useful with a serial console.  Then, place a NetBSD XEN3_DOM0 kernel
                    266: in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
1.75      gdt       267: of a NetBSD build.  If using i386, use
                    268: releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.  (If using Xen
                    269: 3.1 and i386, you may use XEN3_DOM0 with the non-PAE Xen.  But you
                    270: should not use Xen 3.1.)  Both xen and the NetBSD kernel may be (and
                    271: typically are) left compressed.
1.135     gdt       273: In a dom0, kernfs is mandatory for xend to communicate with the
                    274: kernel, so ensure that /kern is in fstab.  (A standard NetBSD install
                    275: should already mount /kern.)
1.20      gdt       276: 
                    277: Because you already installed NetBSD, you have a working boot setup
                    278: with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
1.135     gdt       279: beginning of your root file system, have /boot, and likely also
1.20      gdt       280: /boot.cfg.  (If not, fix before continuing!)
1.76      gdt       282: Add a line to to /boot.cfg to boot Xen.  See boot.cfg(5) for an
                    283: example.  The basic line is
1.20      gdt       284: 
1.142     gdt       285:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
1.20      gdt       286: 
1.142     gdt       287: which specifies that the dom0 should have 512M, leaving the rest to be
1.77      gdt       288: allocated for domUs.  To use a serial console, use
1.142     gdt       290:         menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
1.77      gdt       291: 
                    292: which will use the first serial port for Xen (which counts starting
1.139     gson      293: from 1, unlike NetBSD which counts starting from 0), forcing
                    294: speed/parity.  Because the NetBSD command line lacks a
                    295: "console=pc" argument, it will use the default "xencons" console device,
                    296: which directs the console I/O through Xen to the same console device Xen
                    297: itself uses (in this case, the serial port).
                    299: In an attempt to add performance, one can also add
1.37      gdt       300: 
                    301:         dom0_max_vcpus=1 dom0_vcpus_pin
                    303: to force only one vcpu to be provided (since NetBSD dom0 can't use
1.111     wiz       304: more) and to pin that vcpu to a physical CPU.  TODO: benchmark this.
1.20      gdt       305: 
1.93      gdt       306: Xen has [many boot
                    307: options](,
1.111     wiz       308: and other than dom0 memory and max_vcpus, they are generally not
1.93      gdt       309: necessary.
1.20      gdt       311: As with non-Xen systems, you should have a line to boot /netbsd (a
1.127     gdt       312: kernel that works without Xen).  Consider a line to boot /netbsd.ok (a
                    313: fallback version of the non-Xen kernel, updated manually when you are
                    314: sure /netbsd is ok).  Consider also a line to boot fallback versions
                    315: of Xen and the dom0 kernel, but note that non-Xen NetBSD can be used
                    316: to resolve Xen booting issues.
                    318: Probably you want a default=N line to choose Xen in the absence of
                    319: intervention.
1.1       mspo      320: 
1.76      gdt       321: Now, reboot so that you are running a DOM0 kernel under Xen, rather
                    322: than GENERIC without Xen.
1.54      gdt       324: Using grub (historic)
                    325: ---------------------
                    327: Before NetBSD's native bootloader could support Xen, the use of
                    328: grub was recommended.  If necessary, see the
1.135     gdt       329: [old grub information](/ports/xen/howto-grub).
1.54      gdt       330: 
1.28      gdt       331: The [HowTo on Installing into
1.140     khorben   332: RAID-1](
1.28      gdt       333: explains how to set up booting a dom0 with Xen using grub with
                    334: NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
1.135     gdt       335: boot.  Now, just create a system with RAID-1, and alter /boot.cfg as
                    336: described above.)
1.28      gdt       337: 
1.21      gdt       338: Configuring Xen
                    339: ---------------
1.53      gdt       341: Xen logs will be in /var/log/xen.
1.76      gdt       343: Now, you have a system that will boot Xen and the dom0 kernel, but not
                    344: do anything else special.  Make sure that you have rebooted into Xen.
                    345: There will be no domUs, and none can be started because you still have
1.102     gdt       346: to configure the dom0 daemons.
1.21      gdt       347: 
1.102     gdt       348: The daemons which should be run vary with Xen version and with whether
1.127     gdt       349: one is using xm or xl.  The Xen 3.1, 3.3 and 4.1 packages use xm.  Xen
                    350: 4.2 and up packages use xl.  To use xm with 4.2, edit xendomains to
                    351: use xm instead.
1.132     gdt       353: For 3.1 and 3.3, you should enable xend and xenbackendd:
1.31      gdt       354: 
1.32      gdt       355:         xend=YES
                    356:         xenbackendd=YES
1.31      gdt       357: 
1.132     gdt       358: For 4.1 and up, you should enable xencommons.  Not enabling xencommons
                    359: will result in a hang; it is necessary to hit ^C on the console to let
                    360: the machine finish booting.  If you are using xm (default in 4.1, or
                    361: if you changed xendomains in 4.2), you should also enable xend:
1.31      gdt       362: 
1.132     gdt       363:         xend=YES # only if using xm, and only installed <= 4.2
1.53      gdt       364:         xencommons=YES
1.31      gdt       365: 
                    366: TODO: Recommend for/against xen-watchdog.
1.27      jnemeth   367: 
1.53      gdt       368: After you have configured the daemons and either started them (in the
1.79      gdt       369: order given) or rebooted, use xm or xl to inspect Xen's boot messages,
1.102     gdt       370: available resources, and running domains.  An example with xl follows:
1.34      gdt       371: 
1.102     gdt       372:         # xl dmesg
1.43      gdt       373:        [xen's boot info]
1.102     gdt       374:         # xl info
1.43      gdt       375:        [available memory, etc.]
1.102     gdt       376:         # xl list
1.43      gdt       377:         Name              Id  Mem(MB)  CPU  State  Time(s)  Console
                    378:         Domain-0           0       64    0  r----     58.1
1.33      gdt       379: 
1.88      gdt       380: ### Issues with xencommons
                    382: xencommons starts xenstored, which stores data on behalf of dom0 and
                    383: domUs.  It does not currently work to stop and start xenstored.
                    384: Certainly all domUs should be shutdown first, following the sort order
                    385: of the rc.d scripts.  However, the dom0 sets up state with xenstored,
                    386: and is not notified when xenstored exits, leading to not recreating
                    387: the state when the new xenstored starts.  Until there's a mechanism to
                    388: make this work, one should not expect to be able to restart xenstored
                    389: (and thus xencommons).  There is currently no reason to expect that
                    390: this will get fixed any time soon.
1.127     gdt       392: ### No-longer needed advice about devices
                    394: The installation of NetBSD should already have created devices for xen
                    395: (xencons, xenevt, xsd_kva), but if they are not present, create them:
                    397:         cd /dev && sh MAKEDEV xen
1.41      gdt       399: anita (for testing NetBSD)
                    400: --------------------------
1.82      gdt       402: With the setup so far (assuming 4.2/xl), one should be able to run
                    403: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
                    404: root, because anita must create a domU):
                    406:         anita --vmm=xl test file:///usr/obj/i386/
                    408: Alternatively, one can use --vmm=xm to use xm-based domU creation
                    409: instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
1.40      gdt       411: Xen-specific NetBSD issues
                    412: --------------------------
                    414: There are (at least) two additional things different about NetBSD as a
                    415: dom0 kernel compared to hardware.
1.111     wiz       417: One is that the module ABI is different because some of the #defines
1.109     gdt       418: change, so one must build modules for Xen.  As of netbsd-7, the build
                    419: system does this automatically.  TODO: check this.  (Before building
                    420: Xen modules was added, it was awkward to use modules to the point
                    421: where it was considered that it did not work.)
1.40      gdt       422: 
                    423: The other difference is that XEN3_DOM0 does not have exactly the same
                    424: options as GENERIC.  While it is debatable whether or not this is a
                    425: bug, users should be aware of this and can simply add missing config
                    426: items if desired.
1.15      gdt       428: Updating NetBSD in a dom0
                    429: -------------------------
                    431: This is just like updating NetBSD on bare hardware, assuming the new
                    432: version supports the version of Xen you are running.  Generally, one
                    433: replaces the kernel and reboots, and then overlays userland binaries
                    434: and adjusts /etc.
                    436: Note that one must update both the non-Xen kernel typically used for
                    437: rescue purposes and the DOM0 kernel used with Xen.
1.55      gdt       439: Converting from grub to /boot
                    440: -----------------------------
                    442: These instructions were [TODO: will be] used to convert a system from
                    443: grub to /boot.  The system was originally installed in February of
                    444: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
                    445: over time.  Before these commands, it was running NetBSD 6 i386, Xen
                    446: 4.1 and grub, much like the message linked earlier in the grub
                    447: section.
1.111     wiz       449:         # Install MBR bootblocks on both disks. 
1.55      gdt       450:         fdisk -i /dev/rwd0d
                    451:         fdisk -i /dev/rwd1d
                    452:         # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
                    453:         installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
                    454:         installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
                    455:         # Install secondary boot loader
                    456:         cp -p /usr/mdec/boot /
1.111     wiz       457:         # Create boot.cfg following earlier guidance:
1.142     gdt       458:         menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
                    459:         menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=512M
1.55      gdt       460:         menu=GENERIC:boot
                    461:         menu=GENERIC single-user:boot -s
                    462:         menu=GENERIC.ok:boot netbsd.ok
                    463:         menu=GENERIC.ok single-user:boot netbsd.ok -s
                    464:         menu=Drop to boot prompt:prompt
                    465:         default=1
                    466:         timeout=30
                    468: TODO: actually do this and fix it if necessary.
1.22      gdt       469: 
1.102     gdt       470: Upgrading Xen versions
1.15      gdt       471: ---------------------
1.110     gdt       473: Minor version upgrades are trivial.  Just rebuild/replace the
                    474: xenkernel version and copy the new xen.gz to / (where /boot.cfg
                    475: references it), and reboot.
                    477: Major version upgrades are conceptually not difficult, but can run
                    478: into all the issues found when installing Xen.  Assuming migration
                    479: from 4.1 to 4.2, remove the xenkernel41 and xentools41 packages and
                    480: install the xenkernel42 and xentools42 packages.  Copy the 4.2 xen.gz
                    481: to /.
1.21      gdt       482: 
1.102     gdt       483: Ensure that the contents of /etc/rc.d/xen* are correct.  Specifically,
                    484: they must match the package you just installed and not be left over
                    485: from some previous installation.
                    487: Enable the correct set of daemons; see the configuring section above.
                    488: (Upgrading from 3.x to 4.x without doing this will result in a hang.)
                    490: Ensure that the domU config files are valid for the new version.
1.110     gdt       491: Specifically, for 4.x remove autorestart=True, and ensure that disks
                    492: are specified with numbers as the second argument, as the examples
                    493: above show, and not NetBSD device names.
1.15      gdt       494: 
1.97      gdt       495: Hardware known to work
                    496: ----------------------
                    498: Arguably, this section is misplaced, and there should be a page of
                    499: hardware that runs NetBSD/amd64 well, with the mostly-well-founded
                    500: assumption that NetBSD/xen runs fine on any modern hardware that
1.129     gdt       501: NetBSD/amd64 runs well on.  Until then, we give motherboard/CPU (and
                    502: sometimes RAM) pairs/triples to aid those choosing a motherboard.
                    503: Note that Xen systems usually do not run X, so a listing here does not
                    504: imply that X works at all.
1.97      gdt       505: 
                    506:         Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC
                    507:         Supermicro ??, Atom C2758 (8 core), 32 GiB ECC
                    508:         ASUS M5A78L-M/USB3 AM3+ microATX, AMD Piledriver X8 4000MHz, 16 GiB ECC
                    510: Older hardware:
1.98      gdt       512:         Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2
1.129     gdt       513:         INTEL DG33FB, "Intel(R) Core(TM)2 Duo CPU     E6850  @ 3.00GHz"
                    514:         INTEL DG33FB, "Intel(R) Core(TM)2 Duo CPU     E8400  @ 3.00GHz"
1.28      gdt       515: 
1.82      gdt       516: Running Xen under qemu
                    517: ----------------------
                    519: The astute reader will note that this section is somewhat twisted.
                    520: However, it can be useful to run Xen under qemu either because the
                    521: version of NetBSD as a dom0 does not run on the hardware in use, or to
                    522: generate automated test cases involving Xen.
1.84      gdt       524: In 2015-01, the following combination was reported to mostly work:
1.82      gdt       525: 
                    526:         host OS: NetBSD/amd64 6.1.4
                    527:         qemu: 2.2.0 from pkgsrc
                    528:         Xen kernel: xenkernel42-4.2.5nb1 from pkgsrc
                    529:         dom0 kernel: NetBSD/amd64 6.1.5
                    530:         Xen tools: xentools42-4.2.5 from pkgsrc
1.140     khorben   532: See [PR 47720]( for a problem with dom0
1.91      gdt       533: shutdown.
1.84      gdt       534: 
1.28      gdt       535: Unprivileged domains (domU)
                    536: ===========================
                    538: This section describes general concepts about domUs.  It does not
1.33      gdt       539: address specific domU operating systems or how to install them.  The
                    540: config files for domUs are typically in /usr/pkg/etc/xen, and are
1.60      wiki      541: typically named so that the file name, domU name and the domU's host
1.33      gdt       542: name match.
1.111     wiz       544: The domU is provided with CPU and memory by Xen, configured by the
1.33      gdt       545: dom0.  The domU is provided with disk and network by the dom0,
                    546: mediated by Xen, and configured in the dom0.
                    548: Entropy in domUs can be an issue; physical disks and network are on
                    549: the dom0.  NetBSD's /dev/random system works, but is often challenged.
1.48      gdt       551: Config files
                    552: ------------
                    554: There is no good order to present config files and the concepts
                    555: surrounding what is being configured.  We first show an example config
                    556: file, and then in the various sections give details.
                    558: See (at least in xentools41) /usr/pkg/share/examples/xen/xmexample*,
                    559: for a large number of well-commented examples, mostly for running
                    560: GNU/Linux.
                    562: The following is an example minimal domain configuration file
                    563: "/usr/pkg/etc/xen/foo".  It is (with only a name change) an actual
                    564: known working config file on Xen 4.1 (NetBSD 5 amd64 dom0 and NetBSD 5
                    565: i386 domU).  The domU serves as a network file server.
                    567:         # -*- mode: python; -*-
                    569:         kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
                    570:         memory = 1024
                    571:         vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
                    572:         disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
                    573:                  'file:/n0/xen/foo-wd1,0x1,w' ]
                    575: The domain will have the same name as the file.  The kernel has the
                    576: host/domU name in it, so that on the dom0 one can update the various
                    577: domUs independently.  The vif line causes an interface to be provided,
                    578: with a specific mac address (do not reuse MAC addresses!), in bridge
                    579: mode.  Two disks are provided, and they are both writable; the bits
                    580: are stored in files and Xen attaches them to a vnd(4) device in the
1.111     wiz       581: dom0 on domain creation.  The system treats xbd0 as the boot device
1.48      gdt       582: without needing explicit configuration.
                    584: By default xm looks for domain config files in /usr/pkg/etc/xen.  Note
                    585: that "xm create" takes the name of a config file, while other commands
                    586: take the name of a domain.  To create the domain, connect to the
                    587: console, create the domain while attaching the console, shutdown the
                    588: domain, and see if it has finished stopping, do (or xl with Xen >=
                    589: 4.2):
                    591:         xm create foo
                    592:         xm console foo
                    593:         xm create -c foo
                    594:         xm shutdown foo
1.90      gdt       595:         xm list
1.48      gdt       596: 
                    597: Typing ^] will exit the console session.  Shutting down a domain is
                    598: equivalent to pushing the power button; a NetBSD domU will receive a
                    599: power-press event and do a clean shutdown.  Shutting down the dom0
                    600: will trigger controlled shutdowns of all configured domUs.
                    602: domU kernels
                    603: ------------
                    605: On a physical computer, the BIOS reads sector 0, and a chain of boot
                    606: loaders finds and loads a kernel.  Normally this comes from the root
1.111     wiz       607: file system.  With Xen domUs, the process is totally different.  The
1.48      gdt       608: normal path is for the domU kernel to be a file in the dom0's
1.111     wiz       609: file system.  At the request of the dom0, Xen loads that kernel into a
1.48      gdt       610: new domU instance and starts execution.  While domU kernels can be
                    611: anyplace, reasonable places to store domU kernels on the dom0 are in /
                    612: (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
                    613: config files), or in /u0/xen (where the vdisks are).
1.59      gdt       615: Note that loading the domU kernel from the dom0 implies that boot
                    616: blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
1.48      gdt       617: See the VPS section near the end for discussion of alternate ways to
                    618: obtain domU kernels.
1.33      gdt       620: CPU and memory
                    621: --------------
1.48      gdt       623: A domain is provided with some number of vcpus, less than the number
1.111     wiz       624: of CPUs seen by the hypervisor.  (For a dom0, this is controlled by
1.48      gdt       625: the boot argument "dom0_max_vcpus=1".)  For a domU, it is controlled
                    626: from the config file by the "vcpus = N" directive.
                    628: A domain is provided with memory; this is controlled in the config
                    629: file by "memory = N" (in megabytes).  In the straightforward case, the
                    630: sum of the the memory allocated to the dom0 and all domUs must be less
1.33      gdt       631: than the available memory.
                    633: Xen also provides a "balloon" driver, which can be used to let domains
                    634: use more memory temporarily.  TODO: Explain better, and explain how
                    635: well it works with NetBSD.
1.28      gdt       636: 
                    637: Virtual disks
                    638: -------------
1.33      gdt       640: With the file/vnd style, typically one creates a directory,
                    641: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
                    642: domUs.  Then, for each domU disk, one writes zeros to a file that then
                    643: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
                    644: for the first virtual disk for the domU called foo.  Writing zeros to
                    645: the file serves two purposes.  One is that preallocating the contents
                    646: improves performance.  The other is that vnd on sparse files has
                    647: failed to work.  TODO: give working/notworking NetBSD versions for
1.127     gdt       648: sparse vnd and gnats reference.  Note that the use of file/vnd for Xen
                    649: is not really different than creating a file-backed virtual disk for
                    650: some other purpose, except that xentools handles the vnconfig
                    651: commands.  To create an empty 4G virtual disk, simply do
1.39      gdt       652: 
                    653:         dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
1.33      gdt       654: 
1.89      gdt       655: Do not use qemu-img-xen, because this will create sparse file.  There
                    656: have been recent (2015) reports of sparse vnd(4) devices causing
                    657: lockups, but there is apparently no PR.
1.33      gdt       659: With the lvm style, one creates logical devices.  They are then used
1.48      gdt       660: similarly to vnds.  TODO: Add an example with lvm.
                    662: In domU config files, the disks are defined as a sequence of 3-tuples.
                    663: The first element is "method:/path/to/disk".  Common methods are
                    664: "file:" for file-backed vnd. and "phy:" for something that is already
                    665: a (TODO: character or block) device.
                    667: The second element is an artifact of how virtual disks are passed to
                    668: Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
                    669: are given a device name to associate with the disk, and values like
                    670: "hda1" or "sda1" are common.  In a NetBSD domU, the first disk appears
                    671: as xbd0, the second as xbd1, and so on.  However, xm/xl demand a
                    672: second argument.  The name given is converted to a major/minor by
1.49      gdt       673: calling stat(2) on the name in /dev and this is passed to the domU.
                    674: In the general case, the dom0 and domU can be different operating
1.48      gdt       675: systems, and it is an unwarranted assumption that they have consistent
                    676: numbering in /dev, or even that the dom0 OS has a /dev.  With NetBSD
                    677: as both dom0 and domU, using values of 0x0 for the first disk and 0x1
1.49      gdt       678: for the second works fine and avoids this issue.  For a GNU/Linux
                    679: guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
                    680: /dev/hda1.
1.48      gdt       681: 
                    682: The third element is "w" for writable disks, and "r" for read-only
                    683: disks.
1.28      gdt       684: 
1.127     gdt       685: Note that NetBSD by default creates only vnd[0123].  If you need more
                    686: than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the
                    687: dom0.
                    689: Note that NetBSD by default creates only xbd[0123].  If you need more
                    690: virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU.
1.28      gdt       692: Virtual Networking
                    693: ------------------
1.111     wiz       695: Xen provides virtual Ethernets, each of which connects the dom0 and a
1.46      gdt       696: domU.  For each virtual network, there is an interface "xvifN.M" in
                    697: the dom0, and in domU index N, a matching interface xennetM (NetBSD
                    698: name).  The interfaces behave as if there is an Ethernet with two
1.111     wiz       699: adapters connected.  From this primitive, one can construct various
1.46      gdt       700: configurations.  We focus on two common and useful cases for which
                    701: there are existing scripts: bridging and NAT.
1.28      gdt       702: 
1.48      gdt       703: With bridging (in the example above), the domU perceives itself to be
                    704: on the same network as the dom0.  For server virtualization, this is
                    705: usually best.  Bridging is accomplished by creating a bridge(4) device
                    706: and adding the dom0's physical interface and the various xvifN.0
                    707: interfaces to the bridge.  One specifies "bridge=bridge0" in the domU
                    708: config file.  The bridge must be set up already in the dom0; an
                    709: example /etc/ifconfig.bridge0 is:
1.46      gdt       710: 
                    711:         create
                    712:         up
                    713:         !brconfig bridge0 add wm0
1.28      gdt       714: 
                    715: With NAT, the domU perceives itself to be behind a NAT running on the
                    716: dom0.  This is often appropriate when running Xen on a workstation.
1.48      gdt       717: TODO: NAT appears to be configured by "vif = [ '' ]".
1.28      gdt       718: 
1.49      gdt       719: The MAC address specified is the one used for the interface in the new
1.53      gdt       720: domain.  The interface in dom0 will use this address XOR'd with
1.49      gdt       721: 00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
1.33      gdt       723: Sizing domains
                    724: --------------
                    726: Modern x86 hardware has vast amounts of resources.  However, many
                    727: virtual servers can function just fine on far less.  A system with
1.142     gdt       728: 512M of RAM and a 4G disk can be a reasonable choice.  Note that it is
1.33      gdt       729: far easier to adjust virtual resources than physical ones.  For
                    730: memory, it's just a config file edit and a reboot.  For disk, one can
                    731: create a new file and vnconfig it (or lvm), and then dump/restore,
                    732: just like updating physical disks, but without having to be there and
                    733: without those pesky connectors.
1.48      gdt       735: Starting domains automatically
                    736: ------------------------------
1.28      gdt       737: 
1.48      gdt       738: To start domains foo at bar at boot and shut them down cleanly on dom0
                    739: shutdown, in rc.conf add:
1.28      gdt       740: 
1.48      gdt       741:         xendomains="foo bar"
1.28      gdt       742: 
1.111     wiz       743: Note that earlier versions of the xentools41 xendomains rc.d script
                    744: used xl, when one should use xm with 4.1.
1.28      gdt       745: 
                    746: Creating specific unprivileged domains (domU)
                    747: =============================================
1.14      gdt       748: 
                    749: Creating domUs is almost entirely independent of operating system.  We
1.49      gdt       750: have already presented the basics of config files.  Note that you must
                    751: have already completed the dom0 setup so that "xl list" (or "xm list")
                    752: works.
1.14      gdt       753: 
                    754: Creating an unprivileged NetBSD domain (domU)
                    755: ---------------------------------------------
1.1       mspo      756: 
1.49      gdt       757: See the earlier config file, and adjust memory.  Decide on how much
                    758: storage you will provide, and prepare it (file or lvm).
1.111     wiz       760: While the kernel will be obtained from the dom0 file system, the same
1.49      gdt       761: file should be present in the domU as /netbsd so that tools like
                    762: savecore(8) can work.   (This is helpful but not necessary.)
                    764: The kernel must be specifically for Xen and for use as a domU.  The
                    765: i386 and amd64 provide the following kernels:
                    767:         i386 XEN3_DOMU
                    768:         i386 XEN3PAE_DOMU
1.95      gdt       769:         amd64 XEN3_DOMU
1.5       mspo      770: 
1.49      gdt       771: Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must
                    772: use the PAE version of the i386 kernel.
                    774: This will boot NetBSD, but this is not that useful if the disk is
                    775: empty.  One approach is to unpack sets onto the disk outside of xen
                    776: (by mounting it, just as you would prepare a physical disk for a
                    777: system you can't run the installer on).
                    779: A second approach is to run an INSTALL kernel, which has a miniroot
                    780: and can load sets from the network.  To do this, copy the INSTALL
                    781: kernel to / and change the kernel line in the config file to:
1.5       mspo      782: 
1.49      gdt       783:         kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
1.5       mspo      784: 
1.49      gdt       785: Then, start the domain as "xl create -c configname".
1.1       mspo      786: 
1.49      gdt       787: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
                    788: line should be used in the config file.
1.1       mspo      789: 
1.3       mspo      790:     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
1.1       mspo      791: 
                    792: After booting the domain, the option to install via CDROM may be
1.49      gdt       793: selected.  The CDROM device should be changed to `xbd1d`.
1.1       mspo      794: 
1.49      gdt       795: Once done installing, "halt -p" the new domain (don't reboot or halt,
                    796: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
                    797: config file), switch the config file back to the XEN3_DOMU kernel,
                    798: and start the new domain again. Now it should be able to use "root on
                    799: xbd0a" and you should have a, functional NetBSD domU.
1.1       mspo      800: 
1.49      gdt       801: TODO: check if this is still accurate.
1.1       mspo      802: When the new domain is booting you'll see some warnings about *wscons*
                    803: and the pseudo-terminals. These can be fixed by editing the files
1.5       mspo      804: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
                    805: `/etc/ttys`, except *console*, like this:
1.1       mspo      806: 
1.3       mspo      807:     console "/usr/libexec/getty Pc"         vt100   on secure
                    808:     ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
                    809:     ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
                    810:     ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
                    811:     ttyE3   "/usr/libexec/getty Pc"         vt220   off secure
1.1       mspo      812: 
1.5       mspo      813: Finally, all screens must be commented out from `/etc/wscons.conf`.
1.1       mspo      814: 
                    815: It is also desirable to add
1.49      gdt       817:         powerd=YES
1.1       mspo      818: 
1.5       mspo      819: in rc.conf. This way, the domain will be properly shut down if
1.53      gdt       820: `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
1.1       mspo      821: 
1.92      gdt       822: It is not strictly necessary to have a kernel (as /netbsd) in the domU
1.111     wiz       823: file system.  However, various programs (e.g. netstat) will use that
1.92      gdt       824: kernel to look up symbols to read from kernel virtual memory.  If
                    825: /netbsd is not the running kernel, those lookups will fail.  (This is
                    826: not really a Xen-specific issue, but because the domU kernel is
                    827: obtained from the dom0, it is far more likely to be out of sync or
                    828: missing with Xen.)
1.14      gdt       830: Creating an unprivileged Linux domain (domU)
1.5       mspo      831: --------------------------------------------
1.1       mspo      832: 
                    833: Creating unprivileged Linux domains isn't much different from
                    834: unprivileged NetBSD domains, but there are some details to know.
                    836: First, the second parameter passed to the disk declaration (the '0x1' in
                    837: the example below)
1.3       mspo      839:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
1.1       mspo      840: 
                    841: does matter to Linux. It wants a Linux device number here (e.g. 0x300
1.49      gdt       842: for hda).  Linux builds device numbers as: (major \<\< 8 + minor).
                    843: So, hda1 which has major 3 and minor 1 on a Linux system will have
                    844: device number 0x301.  Alternatively, devices names can be used (hda,
                    845: hdb, ...)  as xentools has a table to map these names to devices
                    846: numbers.  To export a partition to a Linux guest we can use:
1.1       mspo      847: 
1.49      gdt       848:         disk = [ 'phy:/dev/wd0e,0x300,w' ]
                    849:         root = "/dev/hda1 ro"
1.1       mspo      850: 
                    851: and it will appear as /dev/hda on the Linux system, and be used as root
                    852: partition.
1.49      gdt       854: To install the Linux system on the partition to be exported to the
                    855: guest domain, the following method can be used: install
                    856: sysutils/e2fsprogs from pkgsrc.  Use mke2fs to format the partition
                    857: that will be the root partition of your Linux domain, and mount it.
                    858: Then copy the files from a working Linux system, make adjustments in
                    859: `/etc` (fstab, network config).  It should also be possible to extract
                    860: binary packages such as .rpm or .deb directly to the mounted partition
                    861: using the appropriate tool, possibly running under NetBSD's Linux
1.111     wiz       862: emulation.  Once the file system has been populated, umount it.  If
                    863: desirable, the file system can be converted to ext3 using tune2fs -j.
1.49      gdt       864: It should now be possible to boot the Linux guest domain, using one of
                    865: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
1.1       mspo      866: 
1.111     wiz       867: To get the Linux console right, you need to add:
1.1       mspo      868: 
1.3       mspo      869:     extra = "xencons=tty1"
1.1       mspo      870: 
1.111     wiz       871: to your configuration since not all Linux distributions auto-attach a
1.1       mspo      872: tty to the xen console.
1.14      gdt       874: Creating an unprivileged Solaris domain (domU)
1.5       mspo      875: ----------------------------------------------
1.1       mspo      876: 
1.50      gdt       877: See possibly outdated
                    878: [Solaris domU instructions](/ports/xen/howto-solaris/).
1.5       mspo      879: 
1.1       mspo      880: 
1.52      gdt       881: PCI passthrough: Using PCI devices in guest domains
                    882: ---------------------------------------------------
1.1       mspo      883: 
1.53      gdt       884: The dom0 can give other domains access to selected PCI
1.52      gdt       885: devices. This can allow, for example, a non-privileged domain to have
                    886: access to a physical network interface or disk controller.  However,
                    887: keep in mind that giving a domain access to a PCI device most likely
                    888: will give the domain read/write access to the whole physical memory,
                    889: as PCs don't have an IOMMU to restrict memory access to DMA-capable
1.53      gdt       890: device.  Also, it's not possible to export ISA devices to non-dom0
1.52      gdt       891: domains, which means that the primary VGA adapter can't be exported.
                    892: A guest domain trying to access the VGA registers will panic.
1.53      gdt       894: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
1.52      gdt       895: not been ported to later versions at this time.
                    897: For a PCI device to be exported to a domU, is has to be attached to
                    898: the "pciback" driver in dom0.  Devices passed to the dom0 via the
                    899: pciback.hide boot parameter will attach to "pciback" instead of the
                    900: usual driver.  The list of devices is specified as "(bus:dev.func)",
1.5       mspo      901: where bus and dev are 2-digit hexadecimal numbers, and func a
                    902: single-digit number:
1.1       mspo      903: 
1.52      gdt       904:         pciback.hide=(00:0a.0)(00:06.0)
1.1       mspo      905: 
1.52      gdt       906: pciback devices should show up in the dom0's boot messages, and the
1.5       mspo      907: devices should be listed in the `/kern/xen/pci` directory.
1.1       mspo      908: 
1.52      gdt       909: PCI devices to be exported to a domU are listed in the "pci" array of
                    910: the domU's config file, with the format "0000:bus:dev.func".
1.1       mspo      911: 
1.52      gdt       912:         pci = [ '0000:00:06.0', '0000:00:0a.0' ]
1.1       mspo      913: 
1.52      gdt       914: In the domU an "xpci" device will show up, to which one or more pci
1.111     wiz       915: buses will attach.  Then the PCI drivers will attach to PCI buses as
1.52      gdt       916: usual.  Note that the default NetBSD DOMU kernels do not have "xpci"
                    917: or any PCI drivers built in by default; you have to build your own
                    918: kernel to use PCI devices in a domU.  Here's a kernel config example;
                    919: note that only the "xpci" lines are unusual.
                    921:         include         "arch/i386/conf/XEN3_DOMU"
1.111     wiz       923:         # Add support for PCI buses to the XEN3_DOMU kernel
1.52      gdt       924:         xpci* at xenbus ?
                    925:         pci* at xpci ?
                    927:         # PCI USB controllers
                    928:         uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
                    930:         # USB bus support
                    931:         usb*    at uhci?
                    933:         # USB Hubs
                    934:         uhub*   at usb?
                    935:         uhub*   at uhub? port ? configuration ? interface ?
                    937:         # USB Mass Storage
                    938:         umass*  at uhub? port ? configuration ? interface ?
                    939:         wd*     at umass?
                    940:         # SCSI controllers
                    941:         ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
                    943:         # SCSI bus support (for both ahc and umass)
                    944:         scsibus* at scsi?
                    946:         # SCSI devices
                    947:         sd*     at scsibus? target ? lun ?      # SCSI disk drives
                    948:         cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
1.1       mspo      949: 
1.28      gdt       951: NetBSD as a domU in a VPS
                    952: =========================
                    954: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
                    955: hardware.  This section explains how to deal with Xen in a domU as a
                    956: virtual private server where you do not control or have access to the
1.70      gdt       957: dom0.  This is not intended to be an exhaustive list of VPS providers;
                    958: only a few are mentioned that specifically support NetBSD.
1.28      gdt       959: 
1.52      gdt       960: VPS operators provide varying degrees of access and mechanisms for
                    961: configuration.  The big issue is usually how one controls which kernel
1.111     wiz       962: is booted, because the kernel is nominally in the dom0 file system (to
                    963: which VPS users do not normally have access).  A second issue is how
1.70      gdt       964: to install NetBSD.
1.52      gdt       965: A VPS user may want to compile a kernel for security updates, to run
                    966: npf, run IPsec, or any other reason why someone would want to change
                    967: their kernel.
1.111     wiz       969: One approach is to have an administrative interface to upload a kernel,
1.68      gdt       970: or to select from a prepopulated list.  Other approaches are pygrub
1.59      gdt       971: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
1.111     wiz       972: kernel from the domU file system.  This is closer to a regular physical
1.59      gdt       973: computer, where someone who controls a machine can replace the kernel.
1.52      gdt       974: 
1.74      gdt       975: A second issue is multiple CPUs.  With NetBSD 6, domUs support
                    976: multiple vcpus, and it is typical for VPS providers to enable multiple
                    977: CPUs for NetBSD domUs.
1.68      gdt       979: pygrub
1.59      gdt       980: -------
1.52      gdt       981: 
1.111     wiz       982: pygrub runs in the dom0 and looks into the domU file system.  This
                    983: implies that the domU must have a kernel in a file system in a format
1.68      gdt       984: known to pygrub.  As of 2014, pygrub seems to be of mostly historical
                    985: interest.
1.52      gdt       986: 
1.59      gdt       987: pvgrub
                    988: ------
                    990: pvgrub is a version of grub that uses PV operations instead of BIOS
                    991: calls.  It is booted from the dom0 as the domU kernel, and then reads
1.111     wiz       992: /grub/menu.lst and loads a kernel from the domU file system.
1.59      gdt       993: 
1.70      gdt       994: [Panix]( lets users use pvgrub.  Panix reports
1.71      gdt       995: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
                    996: (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
1.70      gdt       997: page](, which describes only
1.74      gdt       998: Linux but should be updated to cover NetBSD :-).
1.70      gdt       999: 
                   1000: []( also lets users with pvgrub to boot
                   1001: their own kernel.  See then [ NetBSD
1.74      gdt      1002: HOWTO](
                   1003: (which is in need of updating).
1.59      gdt      1004: 
1.70      gdt      1005: It appears that [grub's FFS
                   1006: code](
                   1007: does not support all aspects of modern FFS, but there are also reports
1.72      gdt      1008: that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT
1.70      gdt      1009: partition for the kernel with the intent that grub can understand it,
                   1010: which leads to /netbsd not being the actual kernel.  One must remember
1.111     wiz      1011: to update the special boot partition.
1.59      gdt      1012: 
                   1013: Amazon
                   1014: ------
1.143     wiki     1016: See the [Amazon EC2 page](/amazon_ec2/).
1.44      gdt      1017: 
1.65      gdt      1018: TODO items for improving NetBSD/xen
                   1019: ===================================
1.93      gdt      1021: * Make the NetBSD dom0 kernel work with SMP.
                   1022: * Test the Xen 4.5 packages adequately to be able to recommend them as
                   1023:   the standard approach.
                   1024: * Get PCI passthrough working on Xen 4.5
1.65      gdt      1025: * Get pvgrub into pkgsrc, either via xentools or separately.
                   1026: * grub
1.70      gdt      1027:   * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
1.66      gdt      1028:     fragsize/blocksize (UFS2 support may be present; the point is to
1.111     wiz      1029:     make it so that with any UFS1/UFS2 file system setup that works
1.66      gdt      1030:     with NetBSD grub will also work).
1.140     khorben  1031:     See [pkg/40258](
1.65      gdt      1032:   * Push patches upstream.
                   1033:   * Get UFS2 patches into pvgrub.
                   1034: * Add support for PV ops to a version of /boot, and make it usable as
                   1035:   a kernel in Xen, similar to pvgrub.
1.93      gdt      1036: 
                   1037: Random pointers
                   1038: ===============
1.117     gdt      1040: This section contains links from elsewhere not yet integrated into the
                   1041: HOWTO, and other guides.
1.93      gdt      1042: 
                   1043: *
                   1044: *
1.117     gdt      1045: *

CVSweb for NetBSD wikisrc <> software: FreeBSD-CVSweb