File:  [NetBSD Developer Wiki] / wikisrc / ports / xen / howto.mdwn
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Mon Dec 19 21:48:53 2016 UTC (2 years, 5 months ago) by gdt
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Prune stray sentence

    1: Introduction
    2: ============
    3: 
    4: [![[Xen
    5: screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](http://www.netbsd.org/gallery/in-Action/hubertf-xen.png)
    6: 
    7: Xen is a hypervisor (or virtual machine monitor) for x86 hardware
    8: (i686-class or higher), which supports running multiple guest
    9: operating systems on a single physical machine.  Xen is a Type 1 or
   10: bare-metal hypervisor; one uses the Xen kernel to control the CPU,
   11: memory and console, a dom0 operating system which mediates access to
   12: other hardware (e.g., disks, network, USB), and one or more domU
   13: operating systems which operate in an unprivileged virtualized
   14: environment.  IO requests from the domU systems are forwarded by the
   15: hypervisor (Xen) to the dom0 to be fulfilled.
   16: 
   17: Xen supports two styles of guests.  The original is Para-Virtualized
   18: (PV) which means that the guest OS does not attempt to access hardware
   19: directly, but instead makes hypercalls to the hypervisor.  This is
   20: analogous to a user-space program making system calls.  (The dom0
   21: operating system uses PV calls for some functions, such as updating
   22: memory mapping page tables, but has direct hardware access for disk
   23: and network.)   PV guests must be specifically coded for Xen.
   24: 
   25: The more recent style is HVM, which means that the guest does not have
   26: code for Xen and need not be aware that it is running under Xen.
   27: Attempts to access hardware registers are trapped and emulated.  This
   28: style is less efficient but can run unmodified guests.
   29: 
   30: Generally any amd64 machine will work with Xen and PV guests.  In
   31: theory i386 computers without amd64 support can be used for Xen <=
   32: 4.2, but we have no recent reports of this working (this is a hint).
   33: For HVM guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT
   34: (amd64) is needed; "cpuctl identify 0" will show this.  TODO: Clean up
   35: and check the above features.
   36: 
   37: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
   38: The dom0 can start one or more domUs.  (Booting is explained in detail
   39: in the dom0 section.)
   40: 
   41: NetBSD supports Xen in that it can serve as dom0, be used as a domU,
   42: and that Xen kernels and tools are available in pkgsrc.  This HOWTO
   43: attempts to address both the case of running a NetBSD dom0 on hardware
   44: and running domUs under it (NetBSD and other), and also running NetBSD
   45: as a domU in a VPS.
   46: 
   47: Some versions of Xen support "PCI passthrough", which means that
   48: specific PCI devices can be made available to a specific domU instead
   49: of the dom0.  This can be useful to let a domU run X11, or access some
   50: network interface or other peripheral.
   51: 
   52: NetBSD used to support Xen2; this has been removed.
   53: 
   54: Prerequisites
   55: -------------
   56: 
   57: Installing NetBSD/Xen is not extremely difficult, but it is more
   58: complex than a normal installation of NetBSD.
   59: In general, this HOWTO is occasionally overly restrictive about how
   60: things must be done, guiding the reader to stay on the established
   61: path when there are no known good reasons to stray.
   62: 
   63: This HOWTO presumes a basic familiarity with the Xen system
   64: architecture.  This HOWTO presumes familiarity with installing NetBSD
   65: on i386/amd64 hardware and installing software from pkgsrc.
   66: See also the [Xen website](http://www.xenproject.org/).
   67: 
   68: Versions of Xen and NetBSD
   69: ==========================
   70: 
   71: Most of the installation concepts and instructions are independent
   72: of Xen version and NetBSD version.  This section gives advice on
   73: which version to choose.  Versions not in pkgsrc and older unsupported
   74: versions of NetBSD are intentionally ignored.
   75: 
   76: Xen
   77: ---
   78: 
   79: In NetBSD, xen is provided in pkgsrc, via matching pairs of packages
   80: xenkernel and xentools.  We will refer only to the kernel versions,
   81: but note that both packages must be installed together and must have
   82: matching versions.
   83: 
   84: xenkernel3 provides Xen 3.1.  This no longer receives security patches
   85: and should not be used.  It supports PCI passthrough, which is why
   86: people use it anyway. Xen 3.1 supports non-PAE on i386.
   87: 
   88: xenkernel33 provides Xen 3.3.  This no longer receives security
   89: patches and should not be used.  Xen 3.3 supports non-PAE on i386.
   90: 
   91: xenkernel41 provides Xen 4.1.  This is no longer maintained by Xen,
   92: but as of 2014-12 receives backported security patches.  There are no
   93: good reasons to run this version.
   94: 
   95: xenkernel42 provides Xen 4.2. This is no longer maintained by Xen, but
   96: as of 2014-12 receives backported security patches.  The only reason
   97: to run this is if you need to use xm instead of xl.
   98: 
   99: xenkernel45 provides Xen 4.5.  This is new to pkgsrc as of 2015-01 and
  100: recommended for use as a conservative choice.
  101: 
  102: xenkernel46 provides Xen 4.6.  TODO: Probably this is the recommended
  103: version.
  104: 
  105: See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
  106: 
  107: Ideally newer versions of Xen will be added to pkgsrc.
  108: 
  109: Note that NetBSD support is called XEN3.  It works with Xen 3 and Xen
  110: 4 because the hypercall interface has been stable.
  111: 
  112: Xen command program
  113: -------------------
  114: 
  115: Early Xen used a program called xm to manipulate the system from the
  116: dom0.  Starting in 4.1, a replacement program with similar behavior
  117: called xl is provided, but it does not work well in 4.1.  In 4.2, both
  118: xm and xl work fine.  4.4 is the last version that has xm.  You must
  119: choose one or the other, because it affects which daemons you run.
  120: 
  121: NetBSD
  122: ------
  123: 
  124: The netbsd-5, netbsd-6, netbsd-7, and -current branches are all
  125: reasonable choices, with more or less the same considerations for
  126: non-Xen use.  Therefore, netbsd-6 is recommended as the stable version
  127: of the most recent release for production use.  For those wanting to
  128: learn Xen or without production stability concerns, netbsd-7 is likely
  129: most appropriate.
  130: 
  131: As of NetBSD 6, a NetBSD domU will support multiple vcpus.  There is
  132: no SMP support for NetBSD as dom0.  (The dom0 itself doesn't really
  133: need SMP; the lack of support is really a problem when using a dom0 as
  134: a normal computer.)
  135: 
  136: Architecture
  137: ------------
  138: 
  139: Xen itself can run on i386 or amd64 machines.  (Practically, almost
  140: any computer where one would want to run Xen today supports amd64.)
  141: 
  142: Xen, the dom0 kernel, and each domU kernel can be either i386 or
  143: amd64.  When building a xenkernel package, one obtains i386 on an i386
  144: host, and amd64 on an amd64 host.  If the xen kernel is i386, then the
  145: dom0 kernel and all domU kernels must be i386.  With an amd64 xen
  146: kernel, an amd64 dom0 kernel is known to work, and an i386 dom0 kernel
  147: should in theory work.  An amd64 xen/dom0 is known to support both
  148: i386 and amd64 domUs.
  149: 
  150: i386 dom0 and domU kernels must be PAE (except for Xen 3.1); these are
  151: built by default.  (Note that emacs (at least) fails if run on i386
  152: with PAE when built without, and vice versa, presumably due to bugs in
  153: the undump code.)
  154: 
  155: Because of the above, the standard approach is to use amd64 for the
  156: dom0.
  157: 
  158: Xen 4.2 is the last version to support i386 as a host.  TODO: Clarify
  159: if this is about the CPU, the xen kernel, or the dom0 kernel having to
  160: be amd64.
  161: 
  162: 
  163: Stability
  164: ---------
  165: 
  166: Mostly, NetBSD as a dom0 or domU is quite stable.
  167: However, there are some open PRs indicating problems.
  168: 
  169:  - [PR 48125](http://gnats.netbsd.org/48125)
  170:  - [PR 47720](http://gnats.netbsd.org/47720)
  171: 
  172: Note also that there are issues with sparse vnd(4) instances, but
  173: these are not about Xen.
  174: 
  175: Recommendation
  176: --------------
  177: 
  178: Therefore, this HOWTO recommends running xenkernel42 (and xentools42),
  179: xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the
  180: dom0.  Either the i386 or amd64 of NetBSD may be used as domUs.
  181: 
  182: Build problems
  183: --------------
  184: 
  185: Ideally, all versions of Xen in pkgsrc would build on all versions of
  186: NetBSD on both i386 and amd64.  However, that isn't the case.  Besides
  187: aging code and aging compilers, qemu (included in xentools for HVM
  188: support) is difficult to build.  The following are known to work or FAIL:
  189: 
  190:         xenkernel3 netbsd-5 amd64
  191:         xentools3 netbsd-5 amd64
  192:         xentools3=hvm netbsd-5 amd64 ????
  193:         xenkernel33 netbsd-5 amd64
  194:         xentools33 netbsd-5 amd64
  195:         xenkernel41 netbsd-5 amd64
  196:         xentools41 netbsd-5 amd64
  197:         xenkernel42 netbsd-5 amd64
  198:         xentools42 netbsd-5 amd64
  199: 
  200:         xenkernel3 netbsd-6 i386 FAIL
  201:         xentools3 netbsd-6 i386
  202:         xentools3-hvm netbsd-6 i386 FAIL (dependencies fail)
  203:         xenkernel33 netbsd-6 i386
  204:         xentools33 netbsd-6 i386
  205:         xenkernel41 netbsd-6 i386
  206:         xentools41 netbsd-6 i386
  207:         xenkernel42 netbsd-6 i386
  208:         xentools42 netbsd-6 i386 *MIXED
  209: 
  210: 	(all 3 and 33 seem to FAIL)
  211:         xenkernel41 netbsd-7 i386
  212:         xentools41 netbsd-7 i386
  213:         xenkernel42 netbsd-7 i386
  214:         xentools42 netbsd-7 i386 ??FAIL
  215: 
  216: (*On netbsd-6 i386, there is a xentools42 in the 2014Q3 official builds,
  217: but it does not build for gdt.)
  218: 
  219: NetBSD as a dom0
  220: ================
  221: 
  222: NetBSD can be used as a dom0 and works very well.  The following
  223: sections address installation, updating NetBSD, and updating Xen.
  224: Note that it doesn't make sense to talk about installing a dom0 OS
  225: without also installing Xen itself.  We first address installing
  226: NetBSD, which is not yet a dom0, and then adding Xen, pivoting the
  227: NetBSD install to a dom0 install by just changing the kernel and boot
  228: configuration.
  229: 
  230: For experimenting with Xen, a machine with as little as 1G of RAM and
  231: 100G of disk can work.  For running many domUs in productions, far
  232: more will be needed.
  233: 
  234: Styles of dom0 operation
  235: ------------------------
  236: 
  237: There are two basic ways to use Xen.  The traditional method is for
  238: the dom0 to do absolutely nothing other than providing support to some
  239: number of domUs.  Such a system was probably installed for the sole
  240: purpose of hosting domUs, and sits in a server room on a UPS.
  241: 
  242: The other way is to put Xen under a normal-usage computer, so that the
  243: dom0 is what the computer would have been without Xen, perhaps a
  244: desktop or laptop.  Then, one can run domUs at will.  Purists will
  245: deride this as less secure than the previous approach, and for a
  246: computer whose purpose is to run domUs, they are right.  But Xen and a
  247: dom0 (without domUs) is not meaningfully less secure than the same
  248: things running without Xen.  One can boot Xen or boot regular NetBSD
  249: alternately with little problems, simply refraining from starting the
  250: Xen daemons when not running Xen.
  251: 
  252: Note that NetBSD as dom0 does not support multiple CPUs.  This will
  253: limit the performance of the Xen/dom0 workstation approach.  In theory
  254: the only issue is that the "backend drivers" are not yet MPSAFE:
  255:   http://mail-index.netbsd.org/netbsd-users/2014/08/29/msg015195.html
  256: 
  257: Installation of NetBSD
  258: ----------------------
  259: 
  260: First,
  261: [install NetBSD/amd64](/guide/inst/)
  262: just as you would if you were not using Xen.
  263: However, the partitioning approach is very important.
  264: 
  265: If you want to use RAIDframe for the dom0, there are no special issues
  266: for Xen.  Typically one provides RAID storage for the dom0, and the
  267: domU systems are unaware of RAID.  The 2nd-stage loader bootxx_* skips
  268: over a RAID1 header to find /boot from a filesystem within a RAID
  269: partition; this is no different when booting Xen.
  270: 
  271: There are 4 styles of providing backing storage for the virtual disks
  272: used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN.
  273: 
  274: With raw partitions, one has a disklabel (or gpt) partition sized for
  275: each virtual disk to be used by the domU.  (If you are able to predict
  276: how domU usage will evolve, please add an explanation to the HOWTO.
  277: Seriously, needs tend to change over time.)
  278: 
  279: One can use [lvm(8)](/guide/lvm/) to create logical devices to use
  280: for domU disks.  This is almost as efficient as raw disk partitions
  281: and more flexible.  Hence raw disk partitions should typically not
  282: be used.
  283: 
  284: One can use files in the dom0 filesystem, typically created by dd'ing
  285: /dev/zero to create a specific size.  This is somewhat less efficient,
  286: but very convenient, as one can cp the files for backup, or move them
  287: between dom0 hosts.
  288: 
  289: Finally, in theory one can place the files backing the domU disks in a
  290: SAN.  (This is an invitation for someone who has done this to add a
  291: HOWTO page.)
  292: 
  293: Installation of Xen
  294: -------------------
  295: 
  296: In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from
  297: pkgsrc (or another matching pair).
  298: See [the pkgsrc
  299: documentation](http://www.NetBSD.org/docs/pkgsrc/) for help with pkgsrc.
  300: 
  301: For Xen 3.1, support for HVM guests is in sysutils/xentool3-hvm.  More
  302: recent versions have HVM support integrated in the main xentools
  303: package.  It is entirely reasonable to run only PV guests.
  304: 
  305: Next you need to install the selected Xen kernel itself, which is
  306: installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz".  Copy it to /.
  307: For debugging, one may copy xen-debug.gz; this is conceptually similar
  308: to DIAGNOSTIC and DEBUG in NetBSD.  xen-debug.gz is basically only
  309: useful with a serial console.  Then, place a NetBSD XEN3_DOM0 kernel
  310: in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
  311: of a NetBSD build.  If using i386, use
  312: releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.  (If using Xen
  313: 3.1 and i386, you may use XEN3_DOM0 with the non-PAE Xen.  But you
  314: should not use Xen 3.1.)  Both xen and the NetBSD kernel may be (and
  315: typically are) left compressed.
  316: 
  317: In a dom0 kernel, kernfs is mandatory for xend to comunicate with the
  318: kernel, so ensure that /kern is in fstab.  TODO: Say this is default,
  319: or file a PR and give a reference.
  320: 
  321: Because you already installed NetBSD, you have a working boot setup
  322: with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
  323: beginning of your root filesystem, /boot present, and likely
  324: /boot.cfg.  (If not, fix before continuing!)
  325: 
  326: Add a line to to /boot.cfg to boot Xen.  See boot.cfg(5) for an
  327: example.  The basic line is
  328: 
  329:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
  330: 
  331: which specifies that the dom0 should have 256M, leaving the rest to be
  332: allocated for domUs.  To use a serial console, use
  333: 
  334:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=com0;multiboot /xen.gz dom0_mem=256M console=com1 com1=9600,8n1
  335: 
  336: which will use the first serial port for Xen (which counts starting
  337: from 1), forcing speed/parity, and also for NetBSD (which counts
  338: starting at 0).  In an attempt to add performance, one can also add
  339: 
  340:         dom0_max_vcpus=1 dom0_vcpus_pin
  341: 
  342: to force only one vcpu to be provided (since NetBSD dom0 can't use
  343: more) and to pin that vcpu to a physical cpu.  TODO: benchmark this.
  344: 
  345: Xen has [many boot
  346: options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html),
  347: and other tham dom0 memory and max_vcpus, they are generally not
  348: necessary.
  349: 
  350: As with non-Xen systems, you should have a line to boot /netbsd (a
  351: kernel that works without Xen) and fallback versions of the non-Xen
  352: kernel, Xen, and the dom0 kernel.
  353: 
  354: Now, reboot so that you are running a DOM0 kernel under Xen, rather
  355: than GENERIC without Xen.
  356: 
  357: Using grub (historic)
  358: ---------------------
  359: 
  360: Before NetBSD's native bootloader could support Xen, the use of
  361: grub was recommended.  If necessary, see the
  362: [old grub information](/ports/xen/howto-grub/).
  363: 
  364: The [HowTo on Installing into
  365: RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
  366: explains how to set up booting a dom0 with Xen using grub with
  367: NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
  368: boot.)
  369: 
  370: Configuring Xen
  371: ---------------
  372: 
  373: Xen logs will be in /var/log/xen.
  374: 
  375: Now, you have a system that will boot Xen and the dom0 kernel, but not
  376: do anything else special.  Make sure that you have rebooted into Xen.
  377: There will be no domUs, and none can be started because you still have
  378: to configure the dom0 daemons.
  379: 
  380: The daemons which should be run vary with Xen version and with whether
  381: one is using xm or xl.  The Xen 3.1 and 3.3 packages use xm.  Xen 4.1
  382: and higher packages use xl.  While is is possible to use xm with some
  383: 4.x versions (TODO: 4.1 and 4.2?), the pkgsrc-provided rc.d scripts do
  384: not support this as of 2014-12-26, and thus the HOWTO does not support
  385: it either.  (Make sure your packages are reasonably recent.)
  386: 
  387: For "xm" (3.1 and 3.3), you should enable xend and xenbackendd (but
  388: note that you should be using 4.x):
  389: 
  390:         xend=YES
  391:         xenbackendd=YES
  392: 
  393: For "xl" (4.x), you should enabled xend and xencommons (xenstored).
  394: Trying to boot 4.x without xencommons=YES will result in a hang; it is
  395: necessary to hig ^C on the console to let the machine finish booting.
  396: TODO: explain why xend is installed by the package.
  397: 
  398:         xencommons=YES
  399: 
  400: The installation of NetBSD should already have created devices for xen
  401: (xencons, xenevt), but if they are not present, create them:
  402: 
  403:         cd /dev && sh MAKEDEV xen
  404: 
  405: TODO: Recommend for/against xen-watchdog.
  406: 
  407: After you have configured the daemons and either started them (in the
  408: order given) or rebooted, use xm or xl to inspect Xen's boot messages,
  409: available resources, and running domains.  An example with xl follows:
  410: 
  411:         # xl dmesg
  412: 	[xen's boot info]
  413:         # xl info
  414: 	[available memory, etc.]
  415:         # xl list
  416:         Name              Id  Mem(MB)  CPU  State  Time(s)  Console
  417:         Domain-0           0       64    0  r----     58.1
  418: 
  419: ### Issues with xencommons
  420: 
  421: xencommons starts xenstored, which stores data on behalf of dom0 and
  422: domUs.  It does not currently work to stop and start xenstored.
  423: Certainly all domUs should be shutdown first, following the sort order
  424: of the rc.d scripts.  However, the dom0 sets up state with xenstored,
  425: and is not notified when xenstored exits, leading to not recreating
  426: the state when the new xenstored starts.  Until there's a mechanism to
  427: make this work, one should not expect to be able to restart xenstored
  428: (and thus xencommons).  There is currently no reason to expect that
  429: this will get fixed any time soon.
  430: 
  431: anita (for testing NetBSD)
  432: --------------------------
  433: 
  434: With the setup so far (assuming 4.2/xl), one should be able to run
  435: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
  436: root, because anita must create a domU):
  437: 
  438:         anita --vmm=xl test file:///usr/obj/i386/
  439: 
  440: Alternatively, one can use --vmm=xm to use xm-based domU creation
  441: instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
  442:     
  443: Xen-specific NetBSD issues
  444: --------------------------
  445: 
  446: There are (at least) two additional things different about NetBSD as a
  447: dom0 kernel compared to hardware.
  448: 
  449: One is that modules are not usable in DOM0 kernels, so one must
  450: compile in what's needed.  It's not really that modules cannot work,
  451: but that modules must be built for XEN3_DOM0 because some of the
  452: defines change and the normal module builds don't do this.  Basically,
  453: enabling Xen changes the kernel ABI, and the module build system
  454: doesn't cope with this.
  455: 
  456: The other difference is that XEN3_DOM0 does not have exactly the same
  457: options as GENERIC.  While it is debatable whether or not this is a
  458: bug, users should be aware of this and can simply add missing config
  459: items if desired.
  460: 
  461: Updating NetBSD in a dom0
  462: -------------------------
  463: 
  464: This is just like updating NetBSD on bare hardware, assuming the new
  465: version supports the version of Xen you are running.  Generally, one
  466: replaces the kernel and reboots, and then overlays userland binaries
  467: and adjusts /etc.
  468: 
  469: Note that one must update both the non-Xen kernel typically used for
  470: rescue purposes and the DOM0 kernel used with Xen.
  471: 
  472: Converting from grub to /boot
  473: -----------------------------
  474: 
  475: These instructions were [TODO: will be] used to convert a system from
  476: grub to /boot.  The system was originally installed in February of
  477: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
  478: over time.  Before these commands, it was running NetBSD 6 i386, Xen
  479: 4.1 and grub, much like the message linked earlier in the grub
  480: section.
  481: 
  482:         # Install mbr bootblocks on both disks. 
  483:         fdisk -i /dev/rwd0d
  484:         fdisk -i /dev/rwd1d
  485:         # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
  486:         installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
  487:         installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
  488:         # Install secondary boot loader
  489:         cp -p /usr/mdec/boot /
  490:         # Create boog.cfg following earlier guidance:
  491:         menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
  492:         menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=256M
  493:         menu=GENERIC:boot
  494:         menu=GENERIC single-user:boot -s
  495:         menu=GENERIC.ok:boot netbsd.ok
  496:         menu=GENERIC.ok single-user:boot netbsd.ok -s
  497:         menu=Drop to boot prompt:prompt
  498:         default=1
  499:         timeout=30
  500: 
  501: TODO: actually do this and fix it if necessary.
  502: 
  503: Upgrading Xen versions
  504: ---------------------
  505: 
  506: Updating Xen is conceptually not difficult, but can run into all the
  507: issues found when installing Xen.  Assuming migration from 4.1 to 4.2,
  508: remove the xenkernel41 and xentools41 packages and install the
  509: xenkernel42 and xentools42 packages.  Copy the 4.2 xen.gz to /.
  510: 
  511: Ensure that the contents of /etc/rc.d/xen* are correct.  Specifically,
  512: they must match the package you just installed and not be left over
  513: from some previous installation.
  514: 
  515: Enable the correct set of daemons; see the configuring section above.
  516: (Upgrading from 3.x to 4.x without doing this will result in a hang.)
  517: 
  518: Ensure that the domU config files are valid for the new version.
  519: Specifically: remove autorestart=True, and ensure that disks are
  520: specified with numbers as the second argument, as the examples above
  521: show, and not NetBSD device names.
  522: 
  523: Hardware known to work
  524: ----------------------
  525: 
  526: Arguably, this section is misplaced, and there should be a page of
  527: hardware that runs NetBSD/amd64 well, with the mostly-well-founded
  528: assumption that NetBSD/xen runs fine on any modern hardware that
  529: NetBSD/amd64 runs well on.  Until then, we give motherboard/CPU/RAM
  530: triples to aid those choosing a motherboard.  Note that Xen systems
  531: usually do not run X, so a listing here does not imply that X works at
  532: all.
  533: 
  534:         Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC
  535:         Supermicro ??, Atom C2758 (8 core), 32 GiB ECC
  536:         ASUS M5A78L-M/USB3 AM3+ microATX, AMD Piledriver X8 4000MHz, 16 GiB ECC
  537: 
  538: Older hardware:
  539: 
  540:         Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2
  541: 
  542: Running Xen under qemu
  543: ----------------------
  544: 
  545: The astute reader will note that this section is somewhat twisted.
  546: However, it can be useful to run Xen under qemu either because the
  547: version of NetBSD as a dom0 does not run on the hardware in use, or to
  548: generate automated test cases involving Xen.
  549: 
  550: In 2015-01, the following combination was reported to mostly work:
  551: 
  552:         host OS: NetBSD/amd64 6.1.4
  553:         qemu: 2.2.0 from pkgsrc
  554:         Xen kernel: xenkernel42-4.2.5nb1 from pkgsrc
  555:         dom0 kernel: NetBSD/amd64 6.1.5
  556:         Xen tools: xentools42-4.2.5 from pkgsrc
  557: 
  558: See [PR 47720](http://gnats.netbsd.org/47720) for a problem with dom0
  559: shutdown.
  560: 
  561: Unprivileged domains (domU)
  562: ===========================
  563: 
  564: This section describes general concepts about domUs.  It does not
  565: address specific domU operating systems or how to install them.  The
  566: config files for domUs are typically in /usr/pkg/etc/xen, and are
  567: typically named so that the file name, domU name and the domU's host
  568: name match.
  569: 
  570: The domU is provided with cpu and memory by Xen, configured by the
  571: dom0.  The domU is provided with disk and network by the dom0,
  572: mediated by Xen, and configured in the dom0.
  573: 
  574: Entropy in domUs can be an issue; physical disks and network are on
  575: the dom0.  NetBSD's /dev/random system works, but is often challenged.
  576: 
  577: Config files
  578: ------------
  579: 
  580: There is no good order to present config files and the concepts
  581: surrounding what is being configured.  We first show an example config
  582: file, and then in the various sections give details.
  583: 
  584: See (at least in xentools41) /usr/pkg/share/examples/xen/xmexample*,
  585: for a large number of well-commented examples, mostly for running
  586: GNU/Linux.
  587: 
  588: The following is an example minimal domain configuration file
  589: "/usr/pkg/etc/xen/foo".  It is (with only a name change) an actual
  590: known working config file on Xen 4.1 (NetBSD 5 amd64 dom0 and NetBSD 5
  591: i386 domU).  The domU serves as a network file server.
  592: 
  593:         # -*- mode: python; -*-
  594: 
  595:         kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
  596:         memory = 1024
  597:         vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
  598:         disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
  599:                  'file:/n0/xen/foo-wd1,0x1,w' ]
  600: 
  601: The domain will have the same name as the file.  The kernel has the
  602: host/domU name in it, so that on the dom0 one can update the various
  603: domUs independently.  The vif line causes an interface to be provided,
  604: with a specific mac address (do not reuse MAC addresses!), in bridge
  605: mode.  Two disks are provided, and they are both writable; the bits
  606: are stored in files and Xen attaches them to a vnd(4) device in the
  607: dom0 on domain creation.  The system treates xbd0 as the boot device
  608: without needing explicit configuration.
  609: 
  610: By default xm looks for domain config files in /usr/pkg/etc/xen.  Note
  611: that "xm create" takes the name of a config file, while other commands
  612: take the name of a domain.  To create the domain, connect to the
  613: console, create the domain while attaching the console, shutdown the
  614: domain, and see if it has finished stopping, do (or xl with Xen >=
  615: 4.2):
  616: 
  617:         xm create foo
  618:         xm console foo
  619:         xm create -c foo
  620:         xm shutdown foo
  621:         xm list
  622: 
  623: Typing ^] will exit the console session.  Shutting down a domain is
  624: equivalent to pushing the power button; a NetBSD domU will receive a
  625: power-press event and do a clean shutdown.  Shutting down the dom0
  626: will trigger controlled shutdowns of all configured domUs.
  627: 
  628: domU kernels
  629: ------------
  630: 
  631: On a physical computer, the BIOS reads sector 0, and a chain of boot
  632: loaders finds and loads a kernel.  Normally this comes from the root
  633: filesystem.  With Xen domUs, the process is totally different.  The
  634: normal path is for the domU kernel to be a file in the dom0's
  635: filesystem.  At the request of the dom0, Xen loads that kernel into a
  636: new domU instance and starts execution.  While domU kernels can be
  637: anyplace, reasonable places to store domU kernels on the dom0 are in /
  638: (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
  639: config files), or in /u0/xen (where the vdisks are).
  640: 
  641: Note that loading the domU kernel from the dom0 implies that boot
  642: blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
  643: See the VPS section near the end for discussion of alternate ways to
  644: obtain domU kernels.
  645: 
  646: CPU and memory
  647: --------------
  648: 
  649: A domain is provided with some number of vcpus, less than the number
  650: of cpus seen by the hypervisor.  (For a dom0, this is controlled by
  651: the boot argument "dom0_max_vcpus=1".)  For a domU, it is controlled
  652: from the config file by the "vcpus = N" directive.
  653: 
  654: A domain is provided with memory; this is controlled in the config
  655: file by "memory = N" (in megabytes).  In the straightforward case, the
  656: sum of the the memory allocated to the dom0 and all domUs must be less
  657: than the available memory.
  658: 
  659: Xen also provides a "balloon" driver, which can be used to let domains
  660: use more memory temporarily.  TODO: Explain better, and explain how
  661: well it works with NetBSD.
  662: 
  663: Virtual disks
  664: -------------
  665: 
  666: With the file/vnd style, typically one creates a directory,
  667: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
  668: domUs.  Then, for each domU disk, one writes zeros to a file that then
  669: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
  670: for the first virtual disk for the domU called foo.  Writing zeros to
  671: the file serves two purposes.  One is that preallocating the contents
  672: improves performance.  The other is that vnd on sparse files has
  673: failed to work.  TODO: give working/notworking NetBSD versions for
  674: sparse vnd.  Note that the use of file/vnd for Xen is not really
  675: different than creating a file-backed virtual disk for some other
  676: purpose, except that xentools handles the vnconfig commands.  To
  677: create an empty 4G virtual disk, simply do
  678: 
  679:         dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
  680: 
  681: Do not use qemu-img-xen, because this will create sparse file.  There
  682: have been recent (2015) reports of sparse vnd(4) devices causing
  683: lockups, but there is apparently no PR.
  684: 
  685: With the lvm style, one creates logical devices.  They are then used
  686: similarly to vnds.  TODO: Add an example with lvm.
  687: 
  688: In domU config files, the disks are defined as a sequence of 3-tuples.
  689: The first element is "method:/path/to/disk".  Common methods are
  690: "file:" for file-backed vnd. and "phy:" for something that is already
  691: a (TODO: character or block) device.
  692: 
  693: The second element is an artifact of how virtual disks are passed to
  694: Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
  695: are given a device name to associate with the disk, and values like
  696: "hda1" or "sda1" are common.  In a NetBSD domU, the first disk appears
  697: as xbd0, the second as xbd1, and so on.  However, xm/xl demand a
  698: second argument.  The name given is converted to a major/minor by
  699: calling stat(2) on the name in /dev and this is passed to the domU.
  700: In the general case, the dom0 and domU can be different operating
  701: systems, and it is an unwarranted assumption that they have consistent
  702: numbering in /dev, or even that the dom0 OS has a /dev.  With NetBSD
  703: as both dom0 and domU, using values of 0x0 for the first disk and 0x1
  704: for the second works fine and avoids this issue.  For a GNU/Linux
  705: guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
  706: /dev/hda1.
  707: 
  708: The third element is "w" for writable disks, and "r" for read-only
  709: disks.
  710: 
  711: Virtual Networking
  712: ------------------
  713: 
  714: Xen provides virtual ethernets, each of which connects the dom0 and a
  715: domU.  For each virtual network, there is an interface "xvifN.M" in
  716: the dom0, and in domU index N, a matching interface xennetM (NetBSD
  717: name).  The interfaces behave as if there is an Ethernet with two
  718: adaptors connected.  From this primitive, one can construct various
  719: configurations.  We focus on two common and useful cases for which
  720: there are existing scripts: bridging and NAT.
  721: 
  722: With bridging (in the example above), the domU perceives itself to be
  723: on the same network as the dom0.  For server virtualization, this is
  724: usually best.  Bridging is accomplished by creating a bridge(4) device
  725: and adding the dom0's physical interface and the various xvifN.0
  726: interfaces to the bridge.  One specifies "bridge=bridge0" in the domU
  727: config file.  The bridge must be set up already in the dom0; an
  728: example /etc/ifconfig.bridge0 is:
  729: 
  730:         create
  731:         up
  732:         !brconfig bridge0 add wm0
  733: 
  734: With NAT, the domU perceives itself to be behind a NAT running on the
  735: dom0.  This is often appropriate when running Xen on a workstation.
  736: TODO: NAT appears to be configured by "vif = [ '' ]".
  737: 
  738: The MAC address specified is the one used for the interface in the new
  739: domain.  The interface in dom0 will use this address XOR'd with
  740: 00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
  741: 
  742: Sizing domains
  743: --------------
  744: 
  745: Modern x86 hardware has vast amounts of resources.  However, many
  746: virtual servers can function just fine on far less.  A system with
  747: 256M of RAM and a 4G disk can be a reasonable choice.  Note that it is
  748: far easier to adjust virtual resources than physical ones.  For
  749: memory, it's just a config file edit and a reboot.  For disk, one can
  750: create a new file and vnconfig it (or lvm), and then dump/restore,
  751: just like updating physical disks, but without having to be there and
  752: without those pesky connectors.
  753: 
  754: Starting domains automatically
  755: ------------------------------
  756: 
  757: To start domains foo at bar at boot and shut them down cleanly on dom0
  758: shutdown, in rc.conf add:
  759: 
  760:         xendomains="foo bar"
  761: 
  762: Note that earlier versions of the xentools41 xendomains rc.d scripth
  763: usd xl, when one should use xm with 4.1.
  764: 
  765: Creating specific unprivileged domains (domU)
  766: =============================================
  767: 
  768: Creating domUs is almost entirely independent of operating system.  We
  769: have already presented the basics of config files.  Note that you must
  770: have already completed the dom0 setup so that "xl list" (or "xm list")
  771: works.
  772: 
  773: Creating an unprivileged NetBSD domain (domU)
  774: ---------------------------------------------
  775: 
  776: See the earlier config file, and adjust memory.  Decide on how much
  777: storage you will provide, and prepare it (file or lvm).
  778: 
  779: While the kernel will be obtained from the dom0 filesystem, the same
  780: file should be present in the domU as /netbsd so that tools like
  781: savecore(8) can work.   (This is helpful but not necessary.)
  782: 
  783: The kernel must be specifically for Xen and for use as a domU.  The
  784: i386 and amd64 provide the following kernels:
  785: 
  786:         i386 XEN3_DOMU
  787:         i386 XEN3PAE_DOMU
  788:         amd64 XEN3_DOMU
  789: 
  790: Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must
  791: use the PAE version of the i386 kernel.
  792: 
  793: This will boot NetBSD, but this is not that useful if the disk is
  794: empty.  One approach is to unpack sets onto the disk outside of xen
  795: (by mounting it, just as you would prepare a physical disk for a
  796: system you can't run the installer on).
  797: 
  798: A second approach is to run an INSTALL kernel, which has a miniroot
  799: and can load sets from the network.  To do this, copy the INSTALL
  800: kernel to / and change the kernel line in the config file to:
  801: 
  802:         kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
  803: 
  804: Then, start the domain as "xl create -c configname".
  805: 
  806: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
  807: line should be used in the config file.
  808: 
  809:     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
  810: 
  811: After booting the domain, the option to install via CDROM may be
  812: selected.  The CDROM device should be changed to `xbd1d`.
  813: 
  814: Once done installing, "halt -p" the new domain (don't reboot or halt,
  815: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
  816: config file), switch the config file back to the XEN3_DOMU kernel,
  817: and start the new domain again. Now it should be able to use "root on
  818: xbd0a" and you should have a, functional NetBSD domU.
  819: 
  820: TODO: check if this is still accurate.
  821: When the new domain is booting you'll see some warnings about *wscons*
  822: and the pseudo-terminals. These can be fixed by editing the files
  823: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
  824: `/etc/ttys`, except *console*, like this:
  825: 
  826:     console "/usr/libexec/getty Pc"         vt100   on secure
  827:     ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
  828:     ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
  829:     ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
  830:     ttyE3   "/usr/libexec/getty Pc"         vt220   off secure
  831: 
  832: Finally, all screens must be commented out from `/etc/wscons.conf`.
  833: 
  834: It is also desirable to add
  835: 
  836:         powerd=YES
  837: 
  838: in rc.conf. This way, the domain will be properly shut down if
  839: `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
  840: 
  841: It is not strictly necessary to have a kernel (as /netbsd) in the domU
  842: filesystem.  However, various programs (e.g. netstat) will use that
  843: kernel to look up symbols to read from kernel virtual memory.  If
  844: /netbsd is not the running kernel, those lookups will fail.  (This is
  845: not really a Xen-specific issue, but because the domU kernel is
  846: obtained from the dom0, it is far more likely to be out of sync or
  847: missing with Xen.)
  848: 
  849: Creating an unprivileged Linux domain (domU)
  850: --------------------------------------------
  851: 
  852: Creating unprivileged Linux domains isn't much different from
  853: unprivileged NetBSD domains, but there are some details to know.
  854: 
  855: First, the second parameter passed to the disk declaration (the '0x1' in
  856: the example below)
  857: 
  858:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
  859: 
  860: does matter to Linux. It wants a Linux device number here (e.g. 0x300
  861: for hda).  Linux builds device numbers as: (major \<\< 8 + minor).
  862: So, hda1 which has major 3 and minor 1 on a Linux system will have
  863: device number 0x301.  Alternatively, devices names can be used (hda,
  864: hdb, ...)  as xentools has a table to map these names to devices
  865: numbers.  To export a partition to a Linux guest we can use:
  866: 
  867:         disk = [ 'phy:/dev/wd0e,0x300,w' ]
  868:         root = "/dev/hda1 ro"
  869: 
  870: and it will appear as /dev/hda on the Linux system, and be used as root
  871: partition.
  872: 
  873: To install the Linux system on the partition to be exported to the
  874: guest domain, the following method can be used: install
  875: sysutils/e2fsprogs from pkgsrc.  Use mke2fs to format the partition
  876: that will be the root partition of your Linux domain, and mount it.
  877: Then copy the files from a working Linux system, make adjustments in
  878: `/etc` (fstab, network config).  It should also be possible to extract
  879: binary packages such as .rpm or .deb directly to the mounted partition
  880: using the appropriate tool, possibly running under NetBSD's Linux
  881: emulation.  Once the filesystem has been populated, umount it.  If
  882: desirable, the filesystem can be converted to ext3 using tune2fs -j.
  883: It should now be possible to boot the Linux guest domain, using one of
  884: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
  885: 
  886: To get the linux console right, you need to add:
  887: 
  888:     extra = "xencons=tty1"
  889: 
  890: to your configuration since not all linux distributions auto-attach a
  891: tty to the xen console.
  892: 
  893: Creating an unprivileged Solaris domain (domU)
  894: ----------------------------------------------
  895: 
  896: See possibly outdated
  897: [Solaris domU instructions](/ports/xen/howto-solaris/).
  898: 
  899: 
  900: PCI passthrough: Using PCI devices in guest domains
  901: ---------------------------------------------------
  902: 
  903: The dom0 can give other domains access to selected PCI
  904: devices. This can allow, for example, a non-privileged domain to have
  905: access to a physical network interface or disk controller.  However,
  906: keep in mind that giving a domain access to a PCI device most likely
  907: will give the domain read/write access to the whole physical memory,
  908: as PCs don't have an IOMMU to restrict memory access to DMA-capable
  909: device.  Also, it's not possible to export ISA devices to non-dom0
  910: domains, which means that the primary VGA adapter can't be exported.
  911: A guest domain trying to access the VGA registers will panic.
  912: 
  913: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
  914: not been ported to later versions at this time.
  915: 
  916: For a PCI device to be exported to a domU, is has to be attached to
  917: the "pciback" driver in dom0.  Devices passed to the dom0 via the
  918: pciback.hide boot parameter will attach to "pciback" instead of the
  919: usual driver.  The list of devices is specified as "(bus:dev.func)",
  920: where bus and dev are 2-digit hexadecimal numbers, and func a
  921: single-digit number:
  922: 
  923:         pciback.hide=(00:0a.0)(00:06.0)
  924: 
  925: pciback devices should show up in the dom0's boot messages, and the
  926: devices should be listed in the `/kern/xen/pci` directory.
  927: 
  928: PCI devices to be exported to a domU are listed in the "pci" array of
  929: the domU's config file, with the format "0000:bus:dev.func".
  930: 
  931:         pci = [ '0000:00:06.0', '0000:00:0a.0' ]
  932: 
  933: In the domU an "xpci" device will show up, to which one or more pci
  934: busses will attach.  Then the PCI drivers will attach to PCI busses as
  935: usual.  Note that the default NetBSD DOMU kernels do not have "xpci"
  936: or any PCI drivers built in by default; you have to build your own
  937: kernel to use PCI devices in a domU.  Here's a kernel config example;
  938: note that only the "xpci" lines are unusual.
  939: 
  940:         include         "arch/i386/conf/XEN3_DOMU"
  941: 
  942:         # Add support for PCI busses to the XEN3_DOMU kernel
  943:         xpci* at xenbus ?
  944:         pci* at xpci ?
  945: 
  946:         # PCI USB controllers
  947:         uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
  948: 
  949:         # USB bus support
  950:         usb*    at uhci?
  951: 
  952:         # USB Hubs
  953:         uhub*   at usb?
  954:         uhub*   at uhub? port ? configuration ? interface ?
  955: 
  956:         # USB Mass Storage
  957:         umass*  at uhub? port ? configuration ? interface ?
  958:         wd*     at umass?
  959:         # SCSI controllers
  960:         ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
  961: 
  962:         # SCSI bus support (for both ahc and umass)
  963:         scsibus* at scsi?
  964: 
  965:         # SCSI devices
  966:         sd*     at scsibus? target ? lun ?      # SCSI disk drives
  967:         cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
  968: 
  969: 
  970: NetBSD as a domU in a VPS
  971: =========================
  972: 
  973: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
  974: hardware.  This section explains how to deal with Xen in a domU as a
  975: virtual private server where you do not control or have access to the
  976: dom0.  This is not intended to be an exhaustive list of VPS providers;
  977: only a few are mentioned that specifically support NetBSD.
  978: 
  979: VPS operators provide varying degrees of access and mechanisms for
  980: configuration.  The big issue is usually how one controls which kernel
  981: is booted, because the kernel is nominally in the dom0 filesystem (to
  982: which VPS users do not normally have acesss).  A second issue is how
  983: to install NetBSD.
  984: A VPS user may want to compile a kernel for security updates, to run
  985: npf, run IPsec, or any other reason why someone would want to change
  986: their kernel.
  987: 
  988: One approach is to have an adminstrative interface to upload a kernel,
  989: or to select from a prepopulated list.  Other approaches are pygrub
  990: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
  991: kernel from the domU filesystem.  This is closer to a regular physical
  992: computer, where someone who controls a machine can replace the kernel.
  993: 
  994: A second issue is multiple CPUs.  With NetBSD 6, domUs support
  995: multiple vcpus, and it is typical for VPS providers to enable multiple
  996: CPUs for NetBSD domUs.
  997: 
  998: pygrub
  999: -------
 1000: 
 1001: pygrub runs in the dom0 and looks into the domU filesystem.  This
 1002: implies that the domU must have a kernel in a filesystem in a format
 1003: known to pygrub.  As of 2014, pygrub seems to be of mostly historical
 1004: interest.
 1005: 
 1006: pvgrub
 1007: ------
 1008: 
 1009: pvgrub is a version of grub that uses PV operations instead of BIOS
 1010: calls.  It is booted from the dom0 as the domU kernel, and then reads
 1011: /grub/menu.lst and loads a kernel from the domU filesystem.
 1012: 
 1013: [Panix](http://www.panix.com/) lets users use pvgrub.  Panix reports
 1014: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
 1015: (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
 1016: page](http://www.panix.com/v-colo/grub.html), which describes only
 1017: Linux but should be updated to cover NetBSD :-).
 1018: 
 1019: [prgmr.com](http://prgmr.com/) also lets users with pvgrub to boot
 1020: their own kernel.  See then [prgmr.com NetBSD
 1021: HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU)
 1022: (which is in need of updating).
 1023: 
 1024: It appears that [grub's FFS
 1025: code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
 1026: does not support all aspects of modern FFS, but there are also reports
 1027: that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT
 1028: partition for the kernel with the intent that grub can understand it,
 1029: which leads to /netbsd not being the actual kernel.  One must remember
 1030: to update the special boot partiion.
 1031: 
 1032: Amazon
 1033: ------
 1034: 
 1035: See the [Amazon EC2 page](../amazon_ec2/).
 1036: 
 1037: Using npf
 1038: ---------
 1039: 
 1040: In standard kernels, npf is a module, and thus cannot be loaded in a
 1041: DOMU kernel.
 1042: 
 1043: TODO: Explain how to compile npf into a custom kernel, answering (but
 1044: note that the problem was caused by not booting the right kernel)
 1045: [this email to
 1046: netbsd-users](http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html).
 1047: 
 1048: TODO items for improving NetBSD/xen
 1049: ===================================
 1050: 
 1051: * Make the NetBSD dom0 kernel work with SMP.
 1052: * Test the Xen 4.5 packages adequately to be able to recommend them as
 1053:   the standard approach.
 1054: * Get PCI passthrough working on Xen 4.5
 1055: * Get pvgrub into pkgsrc, either via xentools or separately.
 1056: * grub
 1057:   * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
 1058:     fragsize/blocksize (UFS2 support may be present; the point is to
 1059:     make it so that with any UFS1/UFS2 filesystem setup that works
 1060:     with NetBSD grub will also work).
 1061:     See [pkg/40258](http://gnats.netbsd.org/40258).
 1062:   * Push patches upstream.
 1063:   * Get UFS2 patches into pvgrub.
 1064: * Add support for PV ops to a version of /boot, and make it usable as
 1065:   a kernel in Xen, similar to pvgrub.
 1066: * Solve somehow the issue with modules for GENERIC not being loadable
 1067:   in a Xen dom0 or domU kernel.
 1068: 
 1069: Random pointers
 1070: ===============
 1071: 
 1072: TODO: This section contains links from elsewhere not yet integrated
 1073: into the HOWTO.
 1074: 
 1075: * http://www.lumbercartel.ca/library/xen/
 1076: * http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html

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