Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.153

1.144     maxv        1: [[!meta title="Xen HowTo"]]
                      2: 
1.5       mspo        3: Introduction
1.13      gdt         4: ============
1.1       mspo        5: 
                      6: [![[Xen
1.140     khorben     7: screenshot]](https://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](https://www.netbsd.org/gallery/in-Action/hubertf-xen.png)
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:
                     19: 
                     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: """]]
                     27: 
                     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.
                     33: 
                     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.)
                     41: 
                     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](http://www.xenproject.org/).
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.
                     50: 
1.15      gdt        51: Versions of Xen and NetBSD
                     52: ==========================
                     53: 
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.
                     70: 
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](http://xenbits.xen.org/xsa/).
                     83: 
1.145     maxv       84: Note: Xen 4.2 was the last version to support 32bit CPUs.
                     85: 
1.19      gdt        86: Xen command program
                     87: -------------------
                     88: 
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.
                     93: 
                     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.
                    127: 
1.18      gdt       128: Architecture
                    129: ------------
                    130: 
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.
                    142: 
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.
                    157: 
                    158: A [posting on
                    159: xen-devel](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html)
                    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: ================
                    168: 
                    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.
                    187: 
1.15      gdt       188: Styles of dom0 operation
                    189: ------------------------
                    190: 
                    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.
                    195: 
                    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.
                    205: 
                    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:   https://mail-index.netbsd.org/netbsd-users/2014/08/29/msg015195.html
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.
                    218: 
                    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.)
                    232: 
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.
                    242: 
                    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](https://www.NetBSD.org/docs/pkgsrc/) for help with
1.127     gdt       253: pkgsrc.  Ensure that your packages are recent; the HOWTO does not
                    254: contemplate old builds.
                    255: 
1.20      gdt       256: Next you need to install the selected Xen kernel itself, which is
                    257: installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz".  Copy it to /.
                    258: For debugging, one may copy xen-debug.gz; this is conceptually similar
                    259: to DIAGNOSTIC and DEBUG in NetBSD.  xen-debug.gz is basically only
                    260: useful with a serial console.  Then, place a NetBSD XEN3_DOM0 kernel
                    261: in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
1.75      gdt       262: of a NetBSD build.  If using i386, use
1.153   ! maxv      263: releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.  Both xen and
        !           264: the NetBSD kernel may be (and typically are) left compressed.
1.75      gdt       265: 
1.135     gdt       266: In a dom0, kernfs is mandatory for xend to communicate with the
                    267: kernel, so ensure that /kern is in fstab.  (A standard NetBSD install
                    268: should already mount /kern.)
1.20      gdt       269: 
                    270: Because you already installed NetBSD, you have a working boot setup
                    271: with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
1.135     gdt       272: beginning of your root file system, have /boot, and likely also
1.20      gdt       273: /boot.cfg.  (If not, fix before continuing!)
                    274: 
1.152     maxv      275: Add a line to /boot.cfg to boot Xen.  See boot.cfg(5) for an
                    276: example.  The basic line is:
1.20      gdt       277: 
1.152     maxv      278: [[!template id=programlisting text="""
                    279: menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
                    280: """]]
1.20      gdt       281: 
1.142     gdt       282: which specifies that the dom0 should have 512M, leaving the rest to be
1.77      gdt       283: allocated for domUs.  To use a serial console, use
                    284: 
1.152     maxv      285: [[!template id=programlisting text="""
                    286: menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
                    287: """]]
1.77      gdt       288: 
                    289: which will use the first serial port for Xen (which counts starting
1.139     gson      290: from 1, unlike NetBSD which counts starting from 0), forcing
                    291: speed/parity.  Because the NetBSD command line lacks a
                    292: "console=pc" argument, it will use the default "xencons" console device,
                    293: which directs the console I/O through Xen to the same console device Xen
                    294: itself uses (in this case, the serial port).
                    295: 
1.152     maxv      296: In an attempt to add performance, one can also add:
1.37      gdt       297: 
1.152     maxv      298: [[!template id=programlisting text="""
                    299: dom0_max_vcpus=1 dom0_vcpus_pin
                    300: """]]
1.37      gdt       301: 
                    302: to force only one vcpu to be provided (since NetBSD dom0 can't use
1.111     wiz       303: more) and to pin that vcpu to a physical CPU.  TODO: benchmark this.
1.20      gdt       304: 
1.93      gdt       305: Xen has [many boot
                    306: options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html),
1.111     wiz       307: and other than dom0 memory and max_vcpus, they are generally not
1.93      gdt       308: necessary.
                    309: 
1.20      gdt       310: As with non-Xen systems, you should have a line to boot /netbsd (a
1.127     gdt       311: kernel that works without Xen).  Consider a line to boot /netbsd.ok (a
                    312: fallback version of the non-Xen kernel, updated manually when you are
                    313: sure /netbsd is ok).  Consider also a line to boot fallback versions
                    314: of Xen and the dom0 kernel, but note that non-Xen NetBSD can be used
                    315: to resolve Xen booting issues.
                    316: 
1.76      gdt       317: Now, reboot so that you are running a DOM0 kernel under Xen, rather
                    318: than GENERIC without Xen.
                    319: 
1.54      gdt       320: Using grub (historic)
                    321: ---------------------
                    322: 
                    323: Before NetBSD's native bootloader could support Xen, the use of
                    324: grub was recommended.  If necessary, see the
1.135     gdt       325: [old grub information](/ports/xen/howto-grub).
1.54      gdt       326: 
1.28      gdt       327: The [HowTo on Installing into
1.140     khorben   328: RAID-1](https://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
1.28      gdt       329: explains how to set up booting a dom0 with Xen using grub with
                    330: NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
1.135     gdt       331: boot.  Now, just create a system with RAID-1, and alter /boot.cfg as
                    332: described above.)
1.28      gdt       333: 
1.21      gdt       334: Configuring Xen
                    335: ---------------
                    336: 
1.76      gdt       337: Now, you have a system that will boot Xen and the dom0 kernel, but not
                    338: do anything else special.  Make sure that you have rebooted into Xen.
                    339: There will be no domUs, and none can be started because you still have
1.102     gdt       340: to configure the dom0 daemons.
1.21      gdt       341: 
1.102     gdt       342: The daemons which should be run vary with Xen version and with whether
1.152     maxv      343: one is using xm or xl. Xen 4.2 and up packages use xl. To use xm with 4.2,
                    344: edit xendomains to use xm instead.
1.31      gdt       345: 
1.132     gdt       346: For 4.1 and up, you should enable xencommons.  Not enabling xencommons
                    347: will result in a hang; it is necessary to hit ^C on the console to let
                    348: the machine finish booting.  If you are using xm (default in 4.1, or
                    349: if you changed xendomains in 4.2), you should also enable xend:
1.31      gdt       350: 
1.152     maxv      351: [[!template id=programlisting text="""
                    352: xend=YES # only if using xm, and only installed <= 4.2
                    353: xencommons=YES
                    354: """]]
1.31      gdt       355: 
                    356: TODO: Recommend for/against xen-watchdog.
1.27      jnemeth   357: 
1.53      gdt       358: After you have configured the daemons and either started them (in the
1.79      gdt       359: order given) or rebooted, use xm or xl to inspect Xen's boot messages,
1.102     gdt       360: available resources, and running domains.  An example with xl follows:
1.34      gdt       361: 
1.153   ! maxv      362: [[!template id=programlisting text="""
        !           363: # xl dmesg
        !           364: ... xen's boot info ...
        !           365: # xl info
        !           366: ... available memory, etc ...
        !           367: # xl list
        !           368: Name              Id  Mem(MB)  CPU  State  Time(s)  Console
        !           369: Domain-0           0       64    0  r----     58.1
        !           370: """]]
        !           371: 
        !           372: Xen logs will be in /var/log/xen.
1.33      gdt       373: 
1.88      gdt       374: ### Issues with xencommons
                    375: 
                    376: xencommons starts xenstored, which stores data on behalf of dom0 and
                    377: domUs.  It does not currently work to stop and start xenstored.
                    378: Certainly all domUs should be shutdown first, following the sort order
                    379: of the rc.d scripts.  However, the dom0 sets up state with xenstored,
                    380: and is not notified when xenstored exits, leading to not recreating
                    381: the state when the new xenstored starts.  Until there's a mechanism to
                    382: make this work, one should not expect to be able to restart xenstored
                    383: (and thus xencommons).  There is currently no reason to expect that
                    384: this will get fixed any time soon.
                    385: 
1.127     gdt       386: ### No-longer needed advice about devices
                    387: 
                    388: The installation of NetBSD should already have created devices for xen
                    389: (xencons, xenevt, xsd_kva), but if they are not present, create them:
                    390: 
1.153   ! maxv      391: [[!template id=programlisting text="""
        !           392: cd /dev && sh MAKEDEV xen
        !           393: """]]
1.127     gdt       394: 
1.41      gdt       395: anita (for testing NetBSD)
                    396: --------------------------
                    397: 
1.82      gdt       398: With the setup so far (assuming 4.2/xl), one should be able to run
                    399: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
                    400: root, because anita must create a domU):
                    401: 
1.153   ! maxv      402: [[!template id=programlisting text="""
        !           403: anita --vmm=xl test file:///usr/obj/i386/
        !           404: """]]
1.82      gdt       405: 
                    406: Alternatively, one can use --vmm=xm to use xm-based domU creation
                    407: instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
                    408:     
1.40      gdt       409: Xen-specific NetBSD issues
                    410: --------------------------
                    411: 
                    412: There are (at least) two additional things different about NetBSD as a
                    413: dom0 kernel compared to hardware.
                    414: 
1.111     wiz       415: One is that the module ABI is different because some of the #defines
1.109     gdt       416: change, so one must build modules for Xen.  As of netbsd-7, the build
                    417: system does this automatically.  TODO: check this.  (Before building
                    418: Xen modules was added, it was awkward to use modules to the point
                    419: where it was considered that it did not work.)
1.40      gdt       420: 
                    421: The other difference is that XEN3_DOM0 does not have exactly the same
                    422: options as GENERIC.  While it is debatable whether or not this is a
                    423: bug, users should be aware of this and can simply add missing config
                    424: items if desired.
                    425: 
1.15      gdt       426: Updating NetBSD in a dom0
                    427: -------------------------
                    428: 
                    429: This is just like updating NetBSD on bare hardware, assuming the new
                    430: version supports the version of Xen you are running.  Generally, one
                    431: replaces the kernel and reboots, and then overlays userland binaries
                    432: and adjusts /etc.
                    433: 
                    434: Note that one must update both the non-Xen kernel typically used for
                    435: rescue purposes and the DOM0 kernel used with Xen.
                    436: 
1.55      gdt       437: Converting from grub to /boot
                    438: -----------------------------
                    439: 
                    440: These instructions were [TODO: will be] used to convert a system from
                    441: grub to /boot.  The system was originally installed in February of
                    442: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
                    443: over time.  Before these commands, it was running NetBSD 6 i386, Xen
                    444: 4.1 and grub, much like the message linked earlier in the grub
                    445: section.
                    446: 
1.111     wiz       447:         # Install MBR bootblocks on both disks. 
1.55      gdt       448:         fdisk -i /dev/rwd0d
                    449:         fdisk -i /dev/rwd1d
                    450:         # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
                    451:         installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
                    452:         installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
                    453:         # Install secondary boot loader
                    454:         cp -p /usr/mdec/boot /
1.111     wiz       455:         # Create boot.cfg following earlier guidance:
1.142     gdt       456:         menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
                    457:         menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=512M
1.55      gdt       458:         menu=GENERIC:boot
                    459:         menu=GENERIC single-user:boot -s
                    460:         menu=GENERIC.ok:boot netbsd.ok
                    461:         menu=GENERIC.ok single-user:boot netbsd.ok -s
                    462:         menu=Drop to boot prompt:prompt
                    463:         default=1
                    464:         timeout=30
                    465: 
                    466: TODO: actually do this and fix it if necessary.
1.22      gdt       467: 
1.102     gdt       468: Upgrading Xen versions
1.15      gdt       469: ---------------------
                    470: 
1.110     gdt       471: Minor version upgrades are trivial.  Just rebuild/replace the
                    472: xenkernel version and copy the new xen.gz to / (where /boot.cfg
                    473: references it), and reboot.
                    474: 
                    475: Major version upgrades are conceptually not difficult, but can run
                    476: into all the issues found when installing Xen.  Assuming migration
                    477: from 4.1 to 4.2, remove the xenkernel41 and xentools41 packages and
                    478: install the xenkernel42 and xentools42 packages.  Copy the 4.2 xen.gz
                    479: to /.
1.21      gdt       480: 
1.102     gdt       481: Ensure that the contents of /etc/rc.d/xen* are correct.  Specifically,
                    482: they must match the package you just installed and not be left over
                    483: from some previous installation.
                    484: 
                    485: Enable the correct set of daemons; see the configuring section above.
                    486: (Upgrading from 3.x to 4.x without doing this will result in a hang.)
                    487: 
                    488: Ensure that the domU config files are valid for the new version.
1.110     gdt       489: Specifically, for 4.x remove autorestart=True, and ensure that disks
                    490: are specified with numbers as the second argument, as the examples
                    491: above show, and not NetBSD device names.
1.15      gdt       492: 
1.28      gdt       493: Unprivileged domains (domU)
                    494: ===========================
                    495: 
                    496: This section describes general concepts about domUs.  It does not
1.33      gdt       497: address specific domU operating systems or how to install them.  The
                    498: config files for domUs are typically in /usr/pkg/etc/xen, and are
1.60      wiki      499: typically named so that the file name, domU name and the domU's host
1.33      gdt       500: name match.
                    501: 
1.111     wiz       502: The domU is provided with CPU and memory by Xen, configured by the
1.33      gdt       503: dom0.  The domU is provided with disk and network by the dom0,
                    504: mediated by Xen, and configured in the dom0.
                    505: 
                    506: Entropy in domUs can be an issue; physical disks and network are on
                    507: the dom0.  NetBSD's /dev/random system works, but is often challenged.
                    508: 
1.48      gdt       509: Config files
                    510: ------------
                    511: 
                    512: There is no good order to present config files and the concepts
                    513: surrounding what is being configured.  We first show an example config
                    514: file, and then in the various sections give details.
                    515: 
                    516: See (at least in xentools41) /usr/pkg/share/examples/xen/xmexample*,
                    517: for a large number of well-commented examples, mostly for running
                    518: GNU/Linux.
                    519: 
                    520: The following is an example minimal domain configuration file
                    521: "/usr/pkg/etc/xen/foo".  It is (with only a name change) an actual
                    522: known working config file on Xen 4.1 (NetBSD 5 amd64 dom0 and NetBSD 5
                    523: i386 domU).  The domU serves as a network file server.
                    524: 
                    525:         # -*- mode: python; -*-
                    526: 
                    527:         kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
                    528:         memory = 1024
                    529:         vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
                    530:         disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
                    531:                  'file:/n0/xen/foo-wd1,0x1,w' ]
                    532: 
                    533: The domain will have the same name as the file.  The kernel has the
                    534: host/domU name in it, so that on the dom0 one can update the various
                    535: domUs independently.  The vif line causes an interface to be provided,
                    536: with a specific mac address (do not reuse MAC addresses!), in bridge
                    537: mode.  Two disks are provided, and they are both writable; the bits
                    538: are stored in files and Xen attaches them to a vnd(4) device in the
1.111     wiz       539: dom0 on domain creation.  The system treats xbd0 as the boot device
1.48      gdt       540: without needing explicit configuration.
                    541: 
                    542: By default xm looks for domain config files in /usr/pkg/etc/xen.  Note
                    543: that "xm create" takes the name of a config file, while other commands
                    544: take the name of a domain.  To create the domain, connect to the
                    545: console, create the domain while attaching the console, shutdown the
                    546: domain, and see if it has finished stopping, do (or xl with Xen >=
                    547: 4.2):
                    548: 
                    549:         xm create foo
                    550:         xm console foo
                    551:         xm create -c foo
                    552:         xm shutdown foo
1.90      gdt       553:         xm list
1.48      gdt       554: 
                    555: Typing ^] will exit the console session.  Shutting down a domain is
                    556: equivalent to pushing the power button; a NetBSD domU will receive a
                    557: power-press event and do a clean shutdown.  Shutting down the dom0
                    558: will trigger controlled shutdowns of all configured domUs.
                    559: 
                    560: domU kernels
                    561: ------------
                    562: 
                    563: On a physical computer, the BIOS reads sector 0, and a chain of boot
                    564: loaders finds and loads a kernel.  Normally this comes from the root
1.111     wiz       565: file system.  With Xen domUs, the process is totally different.  The
1.48      gdt       566: normal path is for the domU kernel to be a file in the dom0's
1.111     wiz       567: file system.  At the request of the dom0, Xen loads that kernel into a
1.48      gdt       568: new domU instance and starts execution.  While domU kernels can be
                    569: anyplace, reasonable places to store domU kernels on the dom0 are in /
                    570: (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
                    571: config files), or in /u0/xen (where the vdisks are).
                    572: 
1.59      gdt       573: Note that loading the domU kernel from the dom0 implies that boot
                    574: blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
1.48      gdt       575: See the VPS section near the end for discussion of alternate ways to
                    576: obtain domU kernels.
                    577: 
1.33      gdt       578: CPU and memory
                    579: --------------
                    580: 
1.48      gdt       581: A domain is provided with some number of vcpus, less than the number
1.111     wiz       582: of CPUs seen by the hypervisor.  (For a dom0, this is controlled by
1.48      gdt       583: the boot argument "dom0_max_vcpus=1".)  For a domU, it is controlled
                    584: from the config file by the "vcpus = N" directive.
                    585: 
                    586: A domain is provided with memory; this is controlled in the config
                    587: file by "memory = N" (in megabytes).  In the straightforward case, the
                    588: sum of the the memory allocated to the dom0 and all domUs must be less
1.33      gdt       589: than the available memory.
                    590: 
                    591: Xen also provides a "balloon" driver, which can be used to let domains
                    592: use more memory temporarily.  TODO: Explain better, and explain how
                    593: well it works with NetBSD.
1.28      gdt       594: 
                    595: Virtual disks
                    596: -------------
                    597: 
1.33      gdt       598: With the file/vnd style, typically one creates a directory,
                    599: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
                    600: domUs.  Then, for each domU disk, one writes zeros to a file that then
                    601: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
                    602: for the first virtual disk for the domU called foo.  Writing zeros to
                    603: the file serves two purposes.  One is that preallocating the contents
                    604: improves performance.  The other is that vnd on sparse files has
                    605: failed to work.  TODO: give working/notworking NetBSD versions for
1.127     gdt       606: sparse vnd and gnats reference.  Note that the use of file/vnd for Xen
                    607: is not really different than creating a file-backed virtual disk for
                    608: some other purpose, except that xentools handles the vnconfig
                    609: commands.  To create an empty 4G virtual disk, simply do
1.39      gdt       610: 
                    611:         dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
1.33      gdt       612: 
1.89      gdt       613: Do not use qemu-img-xen, because this will create sparse file.  There
                    614: have been recent (2015) reports of sparse vnd(4) devices causing
                    615: lockups, but there is apparently no PR.
                    616: 
1.33      gdt       617: With the lvm style, one creates logical devices.  They are then used
1.48      gdt       618: similarly to vnds.  TODO: Add an example with lvm.
                    619: 
                    620: In domU config files, the disks are defined as a sequence of 3-tuples.
                    621: The first element is "method:/path/to/disk".  Common methods are
                    622: "file:" for file-backed vnd. and "phy:" for something that is already
                    623: a (TODO: character or block) device.
                    624: 
                    625: The second element is an artifact of how virtual disks are passed to
                    626: Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
                    627: are given a device name to associate with the disk, and values like
                    628: "hda1" or "sda1" are common.  In a NetBSD domU, the first disk appears
                    629: as xbd0, the second as xbd1, and so on.  However, xm/xl demand a
                    630: second argument.  The name given is converted to a major/minor by
1.49      gdt       631: calling stat(2) on the name in /dev and this is passed to the domU.
                    632: In the general case, the dom0 and domU can be different operating
1.48      gdt       633: systems, and it is an unwarranted assumption that they have consistent
                    634: numbering in /dev, or even that the dom0 OS has a /dev.  With NetBSD
                    635: as both dom0 and domU, using values of 0x0 for the first disk and 0x1
1.49      gdt       636: for the second works fine and avoids this issue.  For a GNU/Linux
                    637: guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
                    638: /dev/hda1.
1.48      gdt       639: 
                    640: The third element is "w" for writable disks, and "r" for read-only
                    641: disks.
1.28      gdt       642: 
1.127     gdt       643: Note that NetBSD by default creates only vnd[0123].  If you need more
                    644: than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the
                    645: dom0.
                    646: 
                    647: Note that NetBSD by default creates only xbd[0123].  If you need more
                    648: virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU.
                    649: 
1.28      gdt       650: Virtual Networking
                    651: ------------------
                    652: 
1.111     wiz       653: Xen provides virtual Ethernets, each of which connects the dom0 and a
1.46      gdt       654: domU.  For each virtual network, there is an interface "xvifN.M" in
                    655: the dom0, and in domU index N, a matching interface xennetM (NetBSD
                    656: name).  The interfaces behave as if there is an Ethernet with two
1.111     wiz       657: adapters connected.  From this primitive, one can construct various
1.46      gdt       658: configurations.  We focus on two common and useful cases for which
                    659: there are existing scripts: bridging and NAT.
1.28      gdt       660: 
1.48      gdt       661: With bridging (in the example above), the domU perceives itself to be
                    662: on the same network as the dom0.  For server virtualization, this is
                    663: usually best.  Bridging is accomplished by creating a bridge(4) device
                    664: and adding the dom0's physical interface and the various xvifN.0
                    665: interfaces to the bridge.  One specifies "bridge=bridge0" in the domU
                    666: config file.  The bridge must be set up already in the dom0; an
                    667: example /etc/ifconfig.bridge0 is:
1.46      gdt       668: 
                    669:         create
                    670:         up
                    671:         !brconfig bridge0 add wm0
1.28      gdt       672: 
                    673: With NAT, the domU perceives itself to be behind a NAT running on the
                    674: dom0.  This is often appropriate when running Xen on a workstation.
1.48      gdt       675: TODO: NAT appears to be configured by "vif = [ '' ]".
1.28      gdt       676: 
1.49      gdt       677: The MAC address specified is the one used for the interface in the new
1.53      gdt       678: domain.  The interface in dom0 will use this address XOR'd with
1.49      gdt       679: 00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
                    680: 
1.33      gdt       681: Sizing domains
                    682: --------------
                    683: 
                    684: Modern x86 hardware has vast amounts of resources.  However, many
                    685: virtual servers can function just fine on far less.  A system with
1.142     gdt       686: 512M of RAM and a 4G disk can be a reasonable choice.  Note that it is
1.33      gdt       687: far easier to adjust virtual resources than physical ones.  For
                    688: memory, it's just a config file edit and a reboot.  For disk, one can
                    689: create a new file and vnconfig it (or lvm), and then dump/restore,
                    690: just like updating physical disks, but without having to be there and
                    691: without those pesky connectors.
                    692: 
1.48      gdt       693: Starting domains automatically
                    694: ------------------------------
1.28      gdt       695: 
1.48      gdt       696: To start domains foo at bar at boot and shut them down cleanly on dom0
                    697: shutdown, in rc.conf add:
1.28      gdt       698: 
1.48      gdt       699:         xendomains="foo bar"
1.28      gdt       700: 
1.111     wiz       701: Note that earlier versions of the xentools41 xendomains rc.d script
                    702: used xl, when one should use xm with 4.1.
1.28      gdt       703: 
                    704: Creating specific unprivileged domains (domU)
                    705: =============================================
1.14      gdt       706: 
                    707: Creating domUs is almost entirely independent of operating system.  We
1.49      gdt       708: have already presented the basics of config files.  Note that you must
                    709: have already completed the dom0 setup so that "xl list" (or "xm list")
                    710: works.
1.14      gdt       711: 
                    712: Creating an unprivileged NetBSD domain (domU)
                    713: ---------------------------------------------
1.1       mspo      714: 
1.49      gdt       715: See the earlier config file, and adjust memory.  Decide on how much
                    716: storage you will provide, and prepare it (file or lvm).
                    717: 
1.111     wiz       718: While the kernel will be obtained from the dom0 file system, the same
1.49      gdt       719: file should be present in the domU as /netbsd so that tools like
                    720: savecore(8) can work.   (This is helpful but not necessary.)
                    721: 
                    722: The kernel must be specifically for Xen and for use as a domU.  The
                    723: i386 and amd64 provide the following kernels:
                    724: 
                    725:         i386 XEN3_DOMU
                    726:         i386 XEN3PAE_DOMU
1.95      gdt       727:         amd64 XEN3_DOMU
1.5       mspo      728: 
1.49      gdt       729: Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must
                    730: use the PAE version of the i386 kernel.
                    731: 
                    732: This will boot NetBSD, but this is not that useful if the disk is
                    733: empty.  One approach is to unpack sets onto the disk outside of xen
                    734: (by mounting it, just as you would prepare a physical disk for a
                    735: system you can't run the installer on).
                    736: 
                    737: A second approach is to run an INSTALL kernel, which has a miniroot
                    738: and can load sets from the network.  To do this, copy the INSTALL
                    739: kernel to / and change the kernel line in the config file to:
1.5       mspo      740: 
1.49      gdt       741:         kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
1.5       mspo      742: 
1.49      gdt       743: Then, start the domain as "xl create -c configname".
1.1       mspo      744: 
1.49      gdt       745: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
                    746: line should be used in the config file.
1.1       mspo      747: 
1.3       mspo      748:     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
1.1       mspo      749: 
                    750: After booting the domain, the option to install via CDROM may be
1.49      gdt       751: selected.  The CDROM device should be changed to `xbd1d`.
1.1       mspo      752: 
1.49      gdt       753: Once done installing, "halt -p" the new domain (don't reboot or halt,
                    754: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
                    755: config file), switch the config file back to the XEN3_DOMU kernel,
                    756: and start the new domain again. Now it should be able to use "root on
                    757: xbd0a" and you should have a, functional NetBSD domU.
1.1       mspo      758: 
1.49      gdt       759: TODO: check if this is still accurate.
1.1       mspo      760: When the new domain is booting you'll see some warnings about *wscons*
                    761: and the pseudo-terminals. These can be fixed by editing the files
1.5       mspo      762: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
                    763: `/etc/ttys`, except *console*, like this:
1.1       mspo      764: 
1.3       mspo      765:     console "/usr/libexec/getty Pc"         vt100   on secure
                    766:     ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
                    767:     ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
                    768:     ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
                    769:     ttyE3   "/usr/libexec/getty Pc"         vt220   off secure
1.1       mspo      770: 
1.5       mspo      771: Finally, all screens must be commented out from `/etc/wscons.conf`.
1.1       mspo      772: 
                    773: It is also desirable to add
                    774: 
1.49      gdt       775:         powerd=YES
1.1       mspo      776: 
1.5       mspo      777: in rc.conf. This way, the domain will be properly shut down if
1.53      gdt       778: `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
1.1       mspo      779: 
1.92      gdt       780: It is not strictly necessary to have a kernel (as /netbsd) in the domU
1.111     wiz       781: file system.  However, various programs (e.g. netstat) will use that
1.92      gdt       782: kernel to look up symbols to read from kernel virtual memory.  If
                    783: /netbsd is not the running kernel, those lookups will fail.  (This is
                    784: not really a Xen-specific issue, but because the domU kernel is
                    785: obtained from the dom0, it is far more likely to be out of sync or
                    786: missing with Xen.)
                    787: 
1.14      gdt       788: Creating an unprivileged Linux domain (domU)
1.5       mspo      789: --------------------------------------------
1.1       mspo      790: 
                    791: Creating unprivileged Linux domains isn't much different from
                    792: unprivileged NetBSD domains, but there are some details to know.
                    793: 
                    794: First, the second parameter passed to the disk declaration (the '0x1' in
                    795: the example below)
                    796: 
1.3       mspo      797:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
1.1       mspo      798: 
                    799: does matter to Linux. It wants a Linux device number here (e.g. 0x300
1.49      gdt       800: for hda).  Linux builds device numbers as: (major \<\< 8 + minor).
                    801: So, hda1 which has major 3 and minor 1 on a Linux system will have
                    802: device number 0x301.  Alternatively, devices names can be used (hda,
                    803: hdb, ...)  as xentools has a table to map these names to devices
                    804: numbers.  To export a partition to a Linux guest we can use:
1.1       mspo      805: 
1.49      gdt       806:         disk = [ 'phy:/dev/wd0e,0x300,w' ]
                    807:         root = "/dev/hda1 ro"
1.1       mspo      808: 
                    809: and it will appear as /dev/hda on the Linux system, and be used as root
                    810: partition.
                    811: 
1.49      gdt       812: To install the Linux system on the partition to be exported to the
                    813: guest domain, the following method can be used: install
                    814: sysutils/e2fsprogs from pkgsrc.  Use mke2fs to format the partition
                    815: that will be the root partition of your Linux domain, and mount it.
                    816: Then copy the files from a working Linux system, make adjustments in
                    817: `/etc` (fstab, network config).  It should also be possible to extract
                    818: binary packages such as .rpm or .deb directly to the mounted partition
                    819: using the appropriate tool, possibly running under NetBSD's Linux
1.111     wiz       820: emulation.  Once the file system has been populated, umount it.  If
                    821: desirable, the file system can be converted to ext3 using tune2fs -j.
1.49      gdt       822: It should now be possible to boot the Linux guest domain, using one of
                    823: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
1.1       mspo      824: 
1.111     wiz       825: To get the Linux console right, you need to add:
1.1       mspo      826: 
1.3       mspo      827:     extra = "xencons=tty1"
1.1       mspo      828: 
1.111     wiz       829: to your configuration since not all Linux distributions auto-attach a
1.1       mspo      830: tty to the xen console.
                    831: 
1.14      gdt       832: Creating an unprivileged Solaris domain (domU)
1.5       mspo      833: ----------------------------------------------
1.1       mspo      834: 
1.50      gdt       835: See possibly outdated
                    836: [Solaris domU instructions](/ports/xen/howto-solaris/).
1.5       mspo      837: 
1.1       mspo      838: 
1.52      gdt       839: PCI passthrough: Using PCI devices in guest domains
                    840: ---------------------------------------------------
1.1       mspo      841: 
1.53      gdt       842: The dom0 can give other domains access to selected PCI
1.52      gdt       843: devices. This can allow, for example, a non-privileged domain to have
                    844: access to a physical network interface or disk controller.  However,
                    845: keep in mind that giving a domain access to a PCI device most likely
                    846: will give the domain read/write access to the whole physical memory,
                    847: as PCs don't have an IOMMU to restrict memory access to DMA-capable
1.53      gdt       848: device.  Also, it's not possible to export ISA devices to non-dom0
1.52      gdt       849: domains, which means that the primary VGA adapter can't be exported.
                    850: A guest domain trying to access the VGA registers will panic.
                    851: 
1.53      gdt       852: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
1.52      gdt       853: not been ported to later versions at this time.
                    854: 
                    855: For a PCI device to be exported to a domU, is has to be attached to
                    856: the "pciback" driver in dom0.  Devices passed to the dom0 via the
                    857: pciback.hide boot parameter will attach to "pciback" instead of the
                    858: usual driver.  The list of devices is specified as "(bus:dev.func)",
1.5       mspo      859: where bus and dev are 2-digit hexadecimal numbers, and func a
                    860: single-digit number:
1.1       mspo      861: 
1.52      gdt       862:         pciback.hide=(00:0a.0)(00:06.0)
1.1       mspo      863: 
1.52      gdt       864: pciback devices should show up in the dom0's boot messages, and the
1.5       mspo      865: devices should be listed in the `/kern/xen/pci` directory.
1.1       mspo      866: 
1.52      gdt       867: PCI devices to be exported to a domU are listed in the "pci" array of
                    868: the domU's config file, with the format "0000:bus:dev.func".
1.1       mspo      869: 
1.52      gdt       870:         pci = [ '0000:00:06.0', '0000:00:0a.0' ]
1.1       mspo      871: 
1.52      gdt       872: In the domU an "xpci" device will show up, to which one or more pci
1.111     wiz       873: buses will attach.  Then the PCI drivers will attach to PCI buses as
1.52      gdt       874: usual.  Note that the default NetBSD DOMU kernels do not have "xpci"
                    875: or any PCI drivers built in by default; you have to build your own
                    876: kernel to use PCI devices in a domU.  Here's a kernel config example;
                    877: note that only the "xpci" lines are unusual.
                    878: 
                    879:         include         "arch/i386/conf/XEN3_DOMU"
                    880: 
1.111     wiz       881:         # Add support for PCI buses to the XEN3_DOMU kernel
1.52      gdt       882:         xpci* at xenbus ?
                    883:         pci* at xpci ?
                    884: 
                    885:         # PCI USB controllers
                    886:         uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
                    887: 
                    888:         # USB bus support
                    889:         usb*    at uhci?
                    890: 
                    891:         # USB Hubs
                    892:         uhub*   at usb?
                    893:         uhub*   at uhub? port ? configuration ? interface ?
                    894: 
                    895:         # USB Mass Storage
                    896:         umass*  at uhub? port ? configuration ? interface ?
                    897:         wd*     at umass?
                    898:         # SCSI controllers
                    899:         ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
                    900: 
                    901:         # SCSI bus support (for both ahc and umass)
                    902:         scsibus* at scsi?
                    903: 
                    904:         # SCSI devices
                    905:         sd*     at scsibus? target ? lun ?      # SCSI disk drives
                    906:         cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
1.1       mspo      907: 
                    908: 
1.28      gdt       909: NetBSD as a domU in a VPS
                    910: =========================
                    911: 
                    912: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
                    913: hardware.  This section explains how to deal with Xen in a domU as a
                    914: virtual private server where you do not control or have access to the
1.70      gdt       915: dom0.  This is not intended to be an exhaustive list of VPS providers;
                    916: only a few are mentioned that specifically support NetBSD.
1.28      gdt       917: 
1.52      gdt       918: VPS operators provide varying degrees of access and mechanisms for
                    919: configuration.  The big issue is usually how one controls which kernel
1.111     wiz       920: is booted, because the kernel is nominally in the dom0 file system (to
                    921: which VPS users do not normally have access).  A second issue is how
1.70      gdt       922: to install NetBSD.
1.52      gdt       923: A VPS user may want to compile a kernel for security updates, to run
                    924: npf, run IPsec, or any other reason why someone would want to change
                    925: their kernel.
                    926: 
1.111     wiz       927: One approach is to have an administrative interface to upload a kernel,
1.68      gdt       928: or to select from a prepopulated list.  Other approaches are pygrub
1.59      gdt       929: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
1.111     wiz       930: kernel from the domU file system.  This is closer to a regular physical
1.59      gdt       931: computer, where someone who controls a machine can replace the kernel.
1.52      gdt       932: 
1.74      gdt       933: A second issue is multiple CPUs.  With NetBSD 6, domUs support
                    934: multiple vcpus, and it is typical for VPS providers to enable multiple
                    935: CPUs for NetBSD domUs.
                    936: 
1.68      gdt       937: pygrub
1.59      gdt       938: -------
1.52      gdt       939: 
1.111     wiz       940: pygrub runs in the dom0 and looks into the domU file system.  This
                    941: implies that the domU must have a kernel in a file system in a format
1.68      gdt       942: known to pygrub.  As of 2014, pygrub seems to be of mostly historical
                    943: interest.
1.52      gdt       944: 
1.59      gdt       945: pvgrub
                    946: ------
                    947: 
                    948: pvgrub is a version of grub that uses PV operations instead of BIOS
                    949: calls.  It is booted from the dom0 as the domU kernel, and then reads
1.111     wiz       950: /grub/menu.lst and loads a kernel from the domU file system.
1.59      gdt       951: 
1.70      gdt       952: [Panix](http://www.panix.com/) lets users use pvgrub.  Panix reports
1.71      gdt       953: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
                    954: (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
1.70      gdt       955: page](http://www.panix.com/v-colo/grub.html), which describes only
1.74      gdt       956: Linux but should be updated to cover NetBSD :-).
1.70      gdt       957: 
                    958: [prgmr.com](http://prgmr.com/) also lets users with pvgrub to boot
                    959: their own kernel.  See then [prgmr.com NetBSD
1.74      gdt       960: HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU)
                    961: (which is in need of updating).
1.59      gdt       962: 
1.70      gdt       963: It appears that [grub's FFS
                    964: code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
                    965: does not support all aspects of modern FFS, but there are also reports
1.72      gdt       966: that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT
1.70      gdt       967: partition for the kernel with the intent that grub can understand it,
                    968: which leads to /netbsd not being the actual kernel.  One must remember
1.111     wiz       969: to update the special boot partition.
1.59      gdt       970: 
                    971: Amazon
                    972: ------
                    973: 
1.143     wiki      974: See the [Amazon EC2 page](/amazon_ec2/).
1.44      gdt       975: 
1.65      gdt       976: TODO items for improving NetBSD/xen
                    977: ===================================
                    978: 
1.93      gdt       979: * Make the NetBSD dom0 kernel work with SMP.
                    980: * Test the Xen 4.5 packages adequately to be able to recommend them as
                    981:   the standard approach.
                    982: * Get PCI passthrough working on Xen 4.5
1.65      gdt       983: * Get pvgrub into pkgsrc, either via xentools or separately.
                    984: * grub
1.70      gdt       985:   * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
1.66      gdt       986:     fragsize/blocksize (UFS2 support may be present; the point is to
1.111     wiz       987:     make it so that with any UFS1/UFS2 file system setup that works
1.66      gdt       988:     with NetBSD grub will also work).
1.140     khorben   989:     See [pkg/40258](https://gnats.netbsd.org/40258).
1.65      gdt       990:   * Push patches upstream.
                    991:   * Get UFS2 patches into pvgrub.
                    992: * Add support for PV ops to a version of /boot, and make it usable as
                    993:   a kernel in Xen, similar to pvgrub.
1.93      gdt       994: 
                    995: Random pointers
                    996: ===============
                    997: 
1.117     gdt       998: This section contains links from elsewhere not yet integrated into the
                    999: HOWTO, and other guides.
1.93      gdt      1000: 
                   1001: * http://www.lumbercartel.ca/library/xen/
                   1002: * http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html
1.117     gdt      1003: * https://gmplib.org/~tege/xen.html

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