Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.116

1.5       mspo        1: Introduction
1.13      gdt         2: ============
1.1       mspo        3: 
                      4: [![[Xen
1.57      gdt         5: screenshot]](](
1.1       mspo        6: 
1.58      gdt         7: Xen is a hypervisor (or virtual machine monitor) for x86 hardware
1.12      gdt         8: (i686-class or higher), which supports running multiple guest
1.58      gdt         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.
1.12      gdt        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.
                     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.
1.29      gdt        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).
1.116   ! gdt        33: For HVM guests, hardware support is needed, but it is common on recent
        !            34: machines.  For Intel CPUs, one needs the VT-x extension, shown in
        !            35: "cpuctl identify 0" as VMX.  For AMD CPus, one needs the AMD-V
        !            36: extensions, shown in "cpuctl identify 0" as SVM.  There are further
        !            37: features for IOMMU virtualization, Intel's VT-d and AMD's AMD-Vi.
        !            38: TODO: Explain whether Xen on NetBSD makes use of these features.
        !            39: TODO: Review by someone who really understands this.
1.19      gdt        40: 
1.27      jnemeth    41: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
1.12      gdt        42: The dom0 can start one or more domUs.  (Booting is explained in detail
                     43: in the dom0 section.)
                     45: NetBSD supports Xen in that it can serve as dom0, be used as a domU,
                     46: and that Xen kernels and tools are available in pkgsrc.  This HOWTO
                     47: attempts to address both the case of running a NetBSD dom0 on hardware
1.24      gdt        48: and running domUs under it (NetBSD and other), and also running NetBSD
                     49: as a domU in a VPS.
1.12      gdt        50: 
1.20      gdt        51: Some versions of Xen support "PCI passthrough", which means that
                     52: specific PCI devices can be made available to a specific domU instead
                     53: of the dom0.  This can be useful to let a domU run X11, or access some
                     54: network interface or other peripheral.
1.111     wiz        56: NetBSD 6 and earlier supported Xen 2; support was removed from NetBSD
1.104     gdt        57: 7.  Xen 2 has been removed from pkgsrc.
1.54      gdt        58: 
1.12      gdt        59: Prerequisites
1.13      gdt        60: -------------
1.12      gdt        61: 
                     62: Installing NetBSD/Xen is not extremely difficult, but it is more
                     63: complex than a normal installation of NetBSD.
1.15      gdt        64: In general, this HOWTO is occasionally overly restrictive about how
                     65: things must be done, guiding the reader to stay on the established
                     66: path when there are no known good reasons to stray.
1.12      gdt        67: 
                     68: This HOWTO presumes a basic familiarity with the Xen system
1.16      gdt        69: architecture.  This HOWTO presumes familiarity with installing NetBSD
                     70: on i386/amd64 hardware and installing software from pkgsrc.
1.27      jnemeth    71: See also the [Xen website](
1.1       mspo       72: 
1.15      gdt        73: Versions of Xen and NetBSD
                     74: ==========================
1.27      jnemeth    76: Most of the installation concepts and instructions are independent
                     77: of Xen version and NetBSD version.  This section gives advice on
                     78: which version to choose.  Versions not in pkgsrc and older unsupported
                     79: versions of NetBSD are intentionally ignored.
1.15      gdt        80: 
                     81: Xen
                     82: ---
1.111     wiz        84: In NetBSD, Xen is provided in pkgsrc, via matching pairs of packages
1.15      gdt        85: xenkernel and xentools.  We will refer only to the kernel versions,
                     86: but note that both packages must be installed together and must have
                     87: matching versions.
1.104     gdt        89: xenkernel3 provides Xen 3.1.  It is no longer maintained by Xen, and the last applied security patch was in
                     90: 2011. Thus, it should not be used.  It supports PCI passthrough,
                     91: which is why people use it anyway. Xen 3.1 supports i386, both PAE and
                     92: non-PAE.
                     94: xenkernel33 provides Xen 3.3.  It is no longer maintained by Xen, and
                     95: the last applied security patch was in 2012.  Thus, it should not be
                     96: used.  Xen 3.3 supports i386, but only in PAE mode.  There are no good
                     97: reasons to run this version.
                     99: xenkernel41 provides Xen 4.1.  It is no longer maintained by Xen, but
1.112     gdt       100: as of 2016-12 received backported security patches.  Xen 4.1 supports
1.104     gdt       101: i386, but only in PAE mode.  There are no good reasons to run this
                    102: version.
1.102     gdt       103: 
1.104     gdt       104: xenkernel42 provides Xen 4.2.  It is no longer maintained by Xen, but
1.112     gdt       105: as of 2016-12 received backported security patches.  Xen 4.2 supports
1.104     gdt       106: i386, but only in PAE mode.  The only reason to run this is if you
                    107: need to use xm instead of xl, or if you need to run an i386 dom0
                    108: (because your hardware is i386 only).
1.114     gdt       110: xenkernel45 provides Xen 4.5.  As of 2016-12, security patches were
                    111: released by Xen and applied to pkgsrc.  Xen 4.5 requires an amd64
1.104     gdt       112: dom0, but domUs can be amd64 or i386 PAE.  TODO: It is either a
                    113: conservative choice or somewhat old.
1.115     gdt       115: xenkernel46 provides Xen 4.6.  It is new to pkgsrc as of 2016-05.  As
1.114     gdt       116: of 2016-12, security patches were released by Xen and applied to
                    117: pkgsrc.  Xen 4.6 requires an amd64 dom0, but domUs can be amd64 or
1.104     gdt       118: i386 PAE.  TODO: It is either a somewhat aggressive choice or the
                    119: standard choice
1.85      gdt       120: 
1.114     gdt       121: Xen 4.7 (released 2016-06) and 4.8 (released 2016-12) are not yet in
                    122: pkgsrc.
1.113     gdt       123: 
1.96      gdt       124: See also the [Xen Security Advisory page](
1.85      gdt       126: Note that NetBSD support is called XEN3.  It works with Xen 3 and Xen
                    127: 4 because the hypercall interface has been stable.
1.20      gdt       128: 
1.19      gdt       129: Xen command program
                    130: -------------------
1.79      gdt       132: Early Xen used a program called xm to manipulate the system from the
1.19      gdt       133: dom0.  Starting in 4.1, a replacement program with similar behavior
1.79      gdt       134: called xl is provided, but it does not work well in 4.1.  In 4.2, both
                    135: xm and xl work fine.  4.4 is the last version that has xm.  You must
                    136: choose one or the other, because it affects which daemons you run.
1.106     gdt       137: However, the rc.d scripts provided by xentools packages expect a
                    138: particular version, and you should use the version used by the
                    139: scripts.
1.19      gdt       140: 
1.15      gdt       141: NetBSD
                    142: ------
1.105     gdt       144: The netbsd-6, netbsd-7, and -current branches are all reasonable
                    145: choices, with more or less the same considerations for non-Xen use.
                    146: Therefore, netbsd-7 is recommended as the stable version of the most
                    147: recent release for production use.  For those wanting to learn Xen or
                    148: without production stability concerns, netbsd-7 is still likely most
1.107     gdt       149: appropriate, but -current is also a reasonable choice.  Xen runs fine
                    150: on netbsd-5, but the xentools packages are likely difficult to build.
1.15      gdt       151: 
                    152: As of NetBSD 6, a NetBSD domU will support multiple vcpus.  There is
                    153: no SMP support for NetBSD as dom0.  (The dom0 itself doesn't really
1.105     gdt       154: need SMP for dom0 functions; the lack of support is really a problem
                    155: when using a dom0 as a normal computer.)
1.15      gdt       156: 
1.18      gdt       157: Architecture
                    158: ------------
1.108     gdt       160: Xen itself can run on i386 (Xen < 3.1) or amd64 machines (all Xen
1.105     gdt       161: versions).  (Practically, almost any computer where one would want to
                    162: run Xen today supports amd64.)
1.99      gdt       163: 
                    164: Xen, the dom0 kernel, and each domU kernel can be either i386 or
                    165: amd64.  When building a xenkernel package, one obtains i386 on an i386
1.111     wiz       166: host, and amd64 on an amd64 host.  If the Xen kernel is i386, then the
                    167: dom0 kernel and all domU kernels must be i386.  With an amd64 Xen
1.105     gdt       168: kernel, an amd64 dom0 kernel is known to work, and an i386PAE dom0
1.111     wiz       169: kernel should in theory work.  An amd64 Xen/dom0 is known to support
1.105     gdt       170: both i386PAE and amd64 domUs.
1.99      gdt       171: 
1.101     gdt       172: i386 dom0 and domU kernels must be PAE (except for Xen 3.1); these are
                    173: built by default.  (Note that emacs (at least) fails if run on i386
                    174: with PAE when built without, and vice versa, presumably due to bugs in
                    175: the undump code.)
1.99      gdt       176: 
                    177: Because of the above, the standard approach is to use amd64 for the
                    178: dom0.
1.29      gdt       179: 
                    180: Xen 4.2 is the last version to support i386 as a host.  TODO: Clarify
1.111     wiz       181: if this is about the CPU, the Xen kernel, or the dom0 kernel having to
1.100     gdt       182: be amd64.
1.29      gdt       184: 
1.89      gdt       185: Stability
                    186: ---------
                    188: Mostly, NetBSD as a dom0 or domU is quite stable.
                    189: However, there are some open PRs indicating problems.
1.91      gdt       191:  - [PR 48125](
                    192:  - [PR 47720](
1.89      gdt       193: 
                    194: Note also that there are issues with sparse vnd(4) instances, but
1.105     gdt       195: these are not about Xen -- they just are noticed with sparse vnd(4)
                    196: instances in support of virtual disks in a dom0.
1.89      gdt       197: 
1.15      gdt       198: Recommendation
                    199: --------------
1.105     gdt       201: Therefore, this HOWTO recommends running xenkernel45 or xenkernel46,
                    202: xl, the NetBSD 7 stable branch, and to use an amd64 kernel as the
                    203: dom0.  Either the i386PAE or amd64 version of NetBSD may be used as
                    204: domUs.
1.15      gdt       205: 
1.36      gdt       206: Build problems
                    207: --------------
                    209: Ideally, all versions of Xen in pkgsrc would build on all versions of
                    210: NetBSD on both i386 and amd64.  However, that isn't the case.  Besides
                    211: aging code and aging compilers, qemu (included in xentools for HVM
1.62      gdt       212: support) is difficult to build.  The following are known to work or FAIL:
1.36      gdt       213: 
1.62      gdt       214:         xenkernel3 netbsd-5 amd64
1.63      gdt       215:         xentools3 netbsd-5 amd64
1.64      gdt       216:         xentools3=hvm netbsd-5 amd64 ????
1.62      gdt       217:         xenkernel33 netbsd-5 amd64
1.63      gdt       218:         xentools33 netbsd-5 amd64
1.36      gdt       219:         xenkernel41 netbsd-5 amd64
                    220:         xentools41 netbsd-5 amd64
1.62      gdt       221:         xenkernel42 netbsd-5 amd64
1.64      gdt       222:         xentools42 netbsd-5 amd64
1.62      gdt       223: 
                    224:         xenkernel3 netbsd-6 i386 FAIL
                    225:         xentools3 netbsd-6 i386
1.63      gdt       226:         xentools3-hvm netbsd-6 i386 FAIL (dependencies fail)
                    227:         xenkernel33 netbsd-6 i386
                    228:         xentools33 netbsd-6 i386
1.36      gdt       229:         xenkernel41 netbsd-6 i386
                    230:         xentools41 netbsd-6 i386
1.63      gdt       231:         xenkernel42 netbsd-6 i386
1.64      gdt       232:         xentools42 netbsd-6 i386 *MIXED
1.69      gdt       234:        (all 3 and 33 seem to FAIL)
                    235:         xenkernel41 netbsd-7 i386
                    236:         xentools41 netbsd-7 i386
                    237:         xenkernel42 netbsd-7 i386
                    238:         xentools42 netbsd-7 i386 ??FAIL
1.64      gdt       240: (*On netbsd-6 i386, there is a xentools42 in the 2014Q3 official builds,
                    241: but it does not build for gdt.)
1.36      gdt       242: 
1.15      gdt       243: NetBSD as a dom0
                    244: ================
                    246: NetBSD can be used as a dom0 and works very well.  The following
                    247: sections address installation, updating NetBSD, and updating Xen.
1.19      gdt       248: Note that it doesn't make sense to talk about installing a dom0 OS
                    249: without also installing Xen itself.  We first address installing
                    250: NetBSD, which is not yet a dom0, and then adding Xen, pivoting the
                    251: NetBSD install to a dom0 install by just changing the kernel and boot
                    252: configuration.
1.15      gdt       253: 
1.45      gdt       254: For experimenting with Xen, a machine with as little as 1G of RAM and
                    255: 100G of disk can work.  For running many domUs in productions, far
                    256: more will be needed.
1.15      gdt       258: Styles of dom0 operation
                    259: ------------------------
                    261: There are two basic ways to use Xen.  The traditional method is for
                    262: the dom0 to do absolutely nothing other than providing support to some
                    263: number of domUs.  Such a system was probably installed for the sole
                    264: purpose of hosting domUs, and sits in a server room on a UPS.
                    266: The other way is to put Xen under a normal-usage computer, so that the
                    267: dom0 is what the computer would have been without Xen, perhaps a
                    268: desktop or laptop.  Then, one can run domUs at will.  Purists will
                    269: deride this as less secure than the previous approach, and for a
                    270: computer whose purpose is to run domUs, they are right.  But Xen and a
1.93      gdt       271: dom0 (without domUs) is not meaningfully less secure than the same
1.15      gdt       272: things running without Xen.  One can boot Xen or boot regular NetBSD
                    273: alternately with little problems, simply refraining from starting the
                    274: Xen daemons when not running Xen.
                    276: Note that NetBSD as dom0 does not support multiple CPUs.  This will
1.51      gdt       277: limit the performance of the Xen/dom0 workstation approach.  In theory
                    278: the only issue is that the "backend drivers" are not yet MPSAFE:
1.15      gdt       280: 
1.19      gdt       281: Installation of NetBSD
                    282: ----------------------
1.13      gdt       283: 
1.19      gdt       284: First,
1.27      jnemeth   285: [install NetBSD/amd64](/guide/inst/)
1.19      gdt       286: just as you would if you were not using Xen.
                    287: However, the partitioning approach is very important.
                    289: If you want to use RAIDframe for the dom0, there are no special issues
                    290: for Xen.  Typically one provides RAID storage for the dom0, and the
1.22      gdt       291: domU systems are unaware of RAID.  The 2nd-stage loader bootxx_* skips
1.111     wiz       292: over a RAID1 header to find /boot from a file system within a RAID
1.22      gdt       293: partition; this is no different when booting Xen.
1.19      gdt       294: 
                    295: There are 4 styles of providing backing storage for the virtual disks
1.93      gdt       296: used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN.
1.19      gdt       297: 
                    298: With raw partitions, one has a disklabel (or gpt) partition sized for
                    299: each virtual disk to be used by the domU.  (If you are able to predict
                    300: how domU usage will evolve, please add an explanation to the HOWTO.
                    301: Seriously, needs tend to change over time.)
1.27      jnemeth   303: One can use [lvm(8)](/guide/lvm/) to create logical devices to use
                    304: for domU disks.  This is almost as efficient as raw disk partitions
                    305: and more flexible.  Hence raw disk partitions should typically not
                    306: be used.
1.19      gdt       307: 
1.111     wiz       308: One can use files in the dom0 file system, typically created by dd'ing
1.19      gdt       309: /dev/zero to create a specific size.  This is somewhat less efficient,
                    310: but very convenient, as one can cp the files for backup, or move them
                    311: between dom0 hosts.
                    313: Finally, in theory one can place the files backing the domU disks in a
                    314: SAN.  (This is an invitation for someone who has done this to add a
                    315: HOWTO page.)
1.1       mspo      316: 
1.19      gdt       317: Installation of Xen
                    318: -------------------
1.1       mspo      319: 
1.20      gdt       320: In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from
                    321: pkgsrc (or another matching pair).
                    322: See [the pkgsrc
                    323: documentation]( for help with pkgsrc.
                    325: For Xen 3.1, support for HVM guests is in sysutils/xentool3-hvm.  More
                    326: recent versions have HVM support integrated in the main xentools
                    327: package.  It is entirely reasonable to run only PV guests.
                    329: Next you need to install the selected Xen kernel itself, which is
                    330: installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz".  Copy it to /.
                    331: For debugging, one may copy xen-debug.gz; this is conceptually similar
                    332: to DIAGNOSTIC and DEBUG in NetBSD.  xen-debug.gz is basically only
                    333: useful with a serial console.  Then, place a NetBSD XEN3_DOM0 kernel
                    334: in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
1.75      gdt       335: of a NetBSD build.  If using i386, use
                    336: releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.  (If using Xen
                    337: 3.1 and i386, you may use XEN3_DOM0 with the non-PAE Xen.  But you
                    338: should not use Xen 3.1.)  Both xen and the NetBSD kernel may be (and
                    339: typically are) left compressed.
1.111     wiz       341: In a dom0 kernel, kernfs is mandatory for xend to communicate with the
1.75      gdt       342: kernel, so ensure that /kern is in fstab.  TODO: Say this is default,
                    343: or file a PR and give a reference.
1.20      gdt       344: 
                    345: Because you already installed NetBSD, you have a working boot setup
                    346: with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
1.111     wiz       347: beginning of your root file system, /boot present, and likely
1.20      gdt       348: /boot.cfg.  (If not, fix before continuing!)
1.76      gdt       350: Add a line to to /boot.cfg to boot Xen.  See boot.cfg(5) for an
                    351: example.  The basic line is
1.20      gdt       352: 
1.37      gdt       353:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
1.20      gdt       354: 
                    355: which specifies that the dom0 should have 256M, leaving the rest to be
1.77      gdt       356: allocated for domUs.  To use a serial console, use
                    358:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=com0;multiboot /xen.gz dom0_mem=256M console=com1 com1=9600,8n1
                    360: which will use the first serial port for Xen (which counts starting
                    361: from 1), forcing speed/parity, and also for NetBSD (which counts
                    362: starting at 0).  In an attempt to add performance, one can also add
1.37      gdt       363: 
                    364:         dom0_max_vcpus=1 dom0_vcpus_pin
                    366: to force only one vcpu to be provided (since NetBSD dom0 can't use
1.111     wiz       367: more) and to pin that vcpu to a physical CPU.  TODO: benchmark this.
1.20      gdt       368: 
1.93      gdt       369: Xen has [many boot
                    370: options](,
1.111     wiz       371: and other than dom0 memory and max_vcpus, they are generally not
1.93      gdt       372: necessary.
1.20      gdt       374: As with non-Xen systems, you should have a line to boot /netbsd (a
                    375: kernel that works without Xen) and fallback versions of the non-Xen
                    376: kernel, Xen, and the dom0 kernel.
1.1       mspo      377: 
1.76      gdt       378: Now, reboot so that you are running a DOM0 kernel under Xen, rather
                    379: than GENERIC without Xen.
1.54      gdt       381: Using grub (historic)
                    382: ---------------------
                    384: Before NetBSD's native bootloader could support Xen, the use of
                    385: grub was recommended.  If necessary, see the
                    386: [old grub information](/ports/xen/howto-grub/).
1.28      gdt       388: The [HowTo on Installing into
                    389: RAID-1](
                    390: explains how to set up booting a dom0 with Xen using grub with
                    391: NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
                    392: boot.)
1.21      gdt       394: Configuring Xen
                    395: ---------------
1.53      gdt       397: Xen logs will be in /var/log/xen.
1.76      gdt       399: Now, you have a system that will boot Xen and the dom0 kernel, but not
                    400: do anything else special.  Make sure that you have rebooted into Xen.
                    401: There will be no domUs, and none can be started because you still have
1.102     gdt       402: to configure the dom0 daemons.
1.21      gdt       403: 
1.102     gdt       404: The daemons which should be run vary with Xen version and with whether
                    405: one is using xm or xl.  The Xen 3.1 and 3.3 packages use xm.  Xen 4.1
                    406: and higher packages use xl.  While is is possible to use xm with some
                    407: 4.x versions (TODO: 4.1 and 4.2?), the pkgsrc-provided rc.d scripts do
                    408: not support this as of 2014-12-26, and thus the HOWTO does not support
                    409: it either.  (Make sure your packages are reasonably recent.)
1.43      gdt       410: 
1.102     gdt       411: For "xm" (3.1 and 3.3), you should enable xend and xenbackendd (but
                    412: note that you should be using 4.x):
1.31      gdt       413: 
1.32      gdt       414:         xend=YES
                    415:         xenbackendd=YES
1.31      gdt       416: 
1.102     gdt       417: For "xl" (4.x), you should enabled xend and xencommons (xenstored).
                    418: Trying to boot 4.x without xencommons=YES will result in a hang; it is
1.111     wiz       419: necessary to hit ^C on the console to let the machine finish booting.
1.102     gdt       420: TODO: explain why xend is installed by the package.
1.31      gdt       421: 
1.53      gdt       422:         xencommons=YES
1.31      gdt       423: 
1.102     gdt       424: The installation of NetBSD should already have created devices for xen
                    425: (xencons, xenevt), but if they are not present, create them:
1.31      gdt       426: 
1.102     gdt       427:         cd /dev && sh MAKEDEV xen
1.86      gdt       428: 
1.31      gdt       429: TODO: Recommend for/against xen-watchdog.
1.27      jnemeth   430: 
1.53      gdt       431: After you have configured the daemons and either started them (in the
1.79      gdt       432: order given) or rebooted, use xm or xl to inspect Xen's boot messages,
1.102     gdt       433: available resources, and running domains.  An example with xl follows:
1.34      gdt       434: 
1.102     gdt       435:         # xl dmesg
1.43      gdt       436:        [xen's boot info]
1.102     gdt       437:         # xl info
1.43      gdt       438:        [available memory, etc.]
1.102     gdt       439:         # xl list
1.43      gdt       440:         Name              Id  Mem(MB)  CPU  State  Time(s)  Console
                    441:         Domain-0           0       64    0  r----     58.1
1.33      gdt       442: 
1.88      gdt       443: ### Issues with xencommons
                    445: xencommons starts xenstored, which stores data on behalf of dom0 and
                    446: domUs.  It does not currently work to stop and start xenstored.
                    447: Certainly all domUs should be shutdown first, following the sort order
                    448: of the rc.d scripts.  However, the dom0 sets up state with xenstored,
                    449: and is not notified when xenstored exits, leading to not recreating
                    450: the state when the new xenstored starts.  Until there's a mechanism to
                    451: make this work, one should not expect to be able to restart xenstored
                    452: (and thus xencommons).  There is currently no reason to expect that
                    453: this will get fixed any time soon.
1.41      gdt       455: anita (for testing NetBSD)
                    456: --------------------------
1.82      gdt       458: With the setup so far (assuming 4.2/xl), one should be able to run
                    459: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
                    460: root, because anita must create a domU):
                    462:         anita --vmm=xl test file:///usr/obj/i386/
                    464: Alternatively, one can use --vmm=xm to use xm-based domU creation
                    465: instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
1.40      gdt       467: Xen-specific NetBSD issues
                    468: --------------------------
                    470: There are (at least) two additional things different about NetBSD as a
                    471: dom0 kernel compared to hardware.
1.111     wiz       473: One is that the module ABI is different because some of the #defines
1.109     gdt       474: change, so one must build modules for Xen.  As of netbsd-7, the build
                    475: system does this automatically.  TODO: check this.  (Before building
                    476: Xen modules was added, it was awkward to use modules to the point
                    477: where it was considered that it did not work.)
1.40      gdt       478: 
                    479: The other difference is that XEN3_DOM0 does not have exactly the same
                    480: options as GENERIC.  While it is debatable whether or not this is a
                    481: bug, users should be aware of this and can simply add missing config
                    482: items if desired.
1.15      gdt       484: Updating NetBSD in a dom0
                    485: -------------------------
                    487: This is just like updating NetBSD on bare hardware, assuming the new
                    488: version supports the version of Xen you are running.  Generally, one
                    489: replaces the kernel and reboots, and then overlays userland binaries
                    490: and adjusts /etc.
                    492: Note that one must update both the non-Xen kernel typically used for
                    493: rescue purposes and the DOM0 kernel used with Xen.
1.55      gdt       495: Converting from grub to /boot
                    496: -----------------------------
                    498: These instructions were [TODO: will be] used to convert a system from
                    499: grub to /boot.  The system was originally installed in February of
                    500: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
                    501: over time.  Before these commands, it was running NetBSD 6 i386, Xen
                    502: 4.1 and grub, much like the message linked earlier in the grub
                    503: section.
1.111     wiz       505:         # Install MBR bootblocks on both disks. 
1.55      gdt       506:         fdisk -i /dev/rwd0d
                    507:         fdisk -i /dev/rwd1d
                    508:         # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
                    509:         installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
                    510:         installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
                    511:         # Install secondary boot loader
                    512:         cp -p /usr/mdec/boot /
1.111     wiz       513:         # Create boot.cfg following earlier guidance:
1.55      gdt       514:         menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
                    515:         menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=256M
                    516:         menu=GENERIC:boot
                    517:         menu=GENERIC single-user:boot -s
                    518:         menu=GENERIC.ok:boot netbsd.ok
                    519:         menu=GENERIC.ok single-user:boot netbsd.ok -s
                    520:         menu=Drop to boot prompt:prompt
                    521:         default=1
                    522:         timeout=30
                    524: TODO: actually do this and fix it if necessary.
1.22      gdt       525: 
1.102     gdt       526: Upgrading Xen versions
1.15      gdt       527: ---------------------
1.110     gdt       529: Minor version upgrades are trivial.  Just rebuild/replace the
                    530: xenkernel version and copy the new xen.gz to / (where /boot.cfg
                    531: references it), and reboot.
                    533: Major version upgrades are conceptually not difficult, but can run
                    534: into all the issues found when installing Xen.  Assuming migration
                    535: from 4.1 to 4.2, remove the xenkernel41 and xentools41 packages and
                    536: install the xenkernel42 and xentools42 packages.  Copy the 4.2 xen.gz
                    537: to /.
1.21      gdt       538: 
1.102     gdt       539: Ensure that the contents of /etc/rc.d/xen* are correct.  Specifically,
                    540: they must match the package you just installed and not be left over
                    541: from some previous installation.
                    543: Enable the correct set of daemons; see the configuring section above.
                    544: (Upgrading from 3.x to 4.x without doing this will result in a hang.)
                    546: Ensure that the domU config files are valid for the new version.
1.110     gdt       547: Specifically, for 4.x remove autorestart=True, and ensure that disks
                    548: are specified with numbers as the second argument, as the examples
                    549: above show, and not NetBSD device names.
1.15      gdt       550: 
1.97      gdt       551: Hardware known to work
                    552: ----------------------
                    554: Arguably, this section is misplaced, and there should be a page of
                    555: hardware that runs NetBSD/amd64 well, with the mostly-well-founded
                    556: assumption that NetBSD/xen runs fine on any modern hardware that
                    557: NetBSD/amd64 runs well on.  Until then, we give motherboard/CPU/RAM
                    558: triples to aid those choosing a motherboard.  Note that Xen systems
                    559: usually do not run X, so a listing here does not imply that X works at
                    560: all.
                    562:         Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC
                    563:         Supermicro ??, Atom C2758 (8 core), 32 GiB ECC
                    564:         ASUS M5A78L-M/USB3 AM3+ microATX, AMD Piledriver X8 4000MHz, 16 GiB ECC
                    566: Older hardware:
1.98      gdt       568:         Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2
1.28      gdt       569: 
1.82      gdt       570: Running Xen under qemu
                    571: ----------------------
                    573: The astute reader will note that this section is somewhat twisted.
                    574: However, it can be useful to run Xen under qemu either because the
                    575: version of NetBSD as a dom0 does not run on the hardware in use, or to
                    576: generate automated test cases involving Xen.
1.84      gdt       578: In 2015-01, the following combination was reported to mostly work:
1.82      gdt       579: 
                    580:         host OS: NetBSD/amd64 6.1.4
                    581:         qemu: 2.2.0 from pkgsrc
                    582:         Xen kernel: xenkernel42-4.2.5nb1 from pkgsrc
                    583:         dom0 kernel: NetBSD/amd64 6.1.5
                    584:         Xen tools: xentools42-4.2.5 from pkgsrc
1.91      gdt       586: See [PR 47720]( for a problem with dom0
                    587: shutdown.
1.84      gdt       588: 
1.28      gdt       589: Unprivileged domains (domU)
                    590: ===========================
                    592: This section describes general concepts about domUs.  It does not
1.33      gdt       593: address specific domU operating systems or how to install them.  The
                    594: config files for domUs are typically in /usr/pkg/etc/xen, and are
1.60      wiki      595: typically named so that the file name, domU name and the domU's host
1.33      gdt       596: name match.
1.111     wiz       598: The domU is provided with CPU and memory by Xen, configured by the
1.33      gdt       599: dom0.  The domU is provided with disk and network by the dom0,
                    600: mediated by Xen, and configured in the dom0.
                    602: Entropy in domUs can be an issue; physical disks and network are on
                    603: the dom0.  NetBSD's /dev/random system works, but is often challenged.
1.48      gdt       605: Config files
                    606: ------------
                    608: There is no good order to present config files and the concepts
                    609: surrounding what is being configured.  We first show an example config
                    610: file, and then in the various sections give details.
                    612: See (at least in xentools41) /usr/pkg/share/examples/xen/xmexample*,
                    613: for a large number of well-commented examples, mostly for running
                    614: GNU/Linux.
                    616: The following is an example minimal domain configuration file
                    617: "/usr/pkg/etc/xen/foo".  It is (with only a name change) an actual
                    618: known working config file on Xen 4.1 (NetBSD 5 amd64 dom0 and NetBSD 5
                    619: i386 domU).  The domU serves as a network file server.
                    621:         # -*- mode: python; -*-
                    623:         kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
                    624:         memory = 1024
                    625:         vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
                    626:         disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
                    627:                  'file:/n0/xen/foo-wd1,0x1,w' ]
                    629: The domain will have the same name as the file.  The kernel has the
                    630: host/domU name in it, so that on the dom0 one can update the various
                    631: domUs independently.  The vif line causes an interface to be provided,
                    632: with a specific mac address (do not reuse MAC addresses!), in bridge
                    633: mode.  Two disks are provided, and they are both writable; the bits
                    634: are stored in files and Xen attaches them to a vnd(4) device in the
1.111     wiz       635: dom0 on domain creation.  The system treats xbd0 as the boot device
1.48      gdt       636: without needing explicit configuration.
                    638: By default xm looks for domain config files in /usr/pkg/etc/xen.  Note
                    639: that "xm create" takes the name of a config file, while other commands
                    640: take the name of a domain.  To create the domain, connect to the
                    641: console, create the domain while attaching the console, shutdown the
                    642: domain, and see if it has finished stopping, do (or xl with Xen >=
                    643: 4.2):
                    645:         xm create foo
                    646:         xm console foo
                    647:         xm create -c foo
                    648:         xm shutdown foo
1.90      gdt       649:         xm list
1.48      gdt       650: 
                    651: Typing ^] will exit the console session.  Shutting down a domain is
                    652: equivalent to pushing the power button; a NetBSD domU will receive a
                    653: power-press event and do a clean shutdown.  Shutting down the dom0
                    654: will trigger controlled shutdowns of all configured domUs.
                    656: domU kernels
                    657: ------------
                    659: On a physical computer, the BIOS reads sector 0, and a chain of boot
                    660: loaders finds and loads a kernel.  Normally this comes from the root
1.111     wiz       661: file system.  With Xen domUs, the process is totally different.  The
1.48      gdt       662: normal path is for the domU kernel to be a file in the dom0's
1.111     wiz       663: file system.  At the request of the dom0, Xen loads that kernel into a
1.48      gdt       664: new domU instance and starts execution.  While domU kernels can be
                    665: anyplace, reasonable places to store domU kernels on the dom0 are in /
                    666: (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
                    667: config files), or in /u0/xen (where the vdisks are).
1.59      gdt       669: Note that loading the domU kernel from the dom0 implies that boot
                    670: blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
1.48      gdt       671: See the VPS section near the end for discussion of alternate ways to
                    672: obtain domU kernels.
1.33      gdt       674: CPU and memory
                    675: --------------
1.48      gdt       677: A domain is provided with some number of vcpus, less than the number
1.111     wiz       678: of CPUs seen by the hypervisor.  (For a dom0, this is controlled by
1.48      gdt       679: the boot argument "dom0_max_vcpus=1".)  For a domU, it is controlled
                    680: from the config file by the "vcpus = N" directive.
                    682: A domain is provided with memory; this is controlled in the config
                    683: file by "memory = N" (in megabytes).  In the straightforward case, the
                    684: sum of the the memory allocated to the dom0 and all domUs must be less
1.33      gdt       685: than the available memory.
                    687: Xen also provides a "balloon" driver, which can be used to let domains
                    688: use more memory temporarily.  TODO: Explain better, and explain how
                    689: well it works with NetBSD.
1.28      gdt       690: 
                    691: Virtual disks
                    692: -------------
1.33      gdt       694: With the file/vnd style, typically one creates a directory,
                    695: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
                    696: domUs.  Then, for each domU disk, one writes zeros to a file that then
                    697: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
                    698: for the first virtual disk for the domU called foo.  Writing zeros to
                    699: the file serves two purposes.  One is that preallocating the contents
                    700: improves performance.  The other is that vnd on sparse files has
                    701: failed to work.  TODO: give working/notworking NetBSD versions for
                    702: sparse vnd.  Note that the use of file/vnd for Xen is not really
                    703: different than creating a file-backed virtual disk for some other
1.39      gdt       704: purpose, except that xentools handles the vnconfig commands.  To
                    705: create an empty 4G virtual disk, simply do
                    707:         dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
1.33      gdt       708: 
1.89      gdt       709: Do not use qemu-img-xen, because this will create sparse file.  There
                    710: have been recent (2015) reports of sparse vnd(4) devices causing
                    711: lockups, but there is apparently no PR.
1.33      gdt       713: With the lvm style, one creates logical devices.  They are then used
1.48      gdt       714: similarly to vnds.  TODO: Add an example with lvm.
                    716: In domU config files, the disks are defined as a sequence of 3-tuples.
                    717: The first element is "method:/path/to/disk".  Common methods are
                    718: "file:" for file-backed vnd. and "phy:" for something that is already
                    719: a (TODO: character or block) device.
                    721: The second element is an artifact of how virtual disks are passed to
                    722: Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
                    723: are given a device name to associate with the disk, and values like
                    724: "hda1" or "sda1" are common.  In a NetBSD domU, the first disk appears
                    725: as xbd0, the second as xbd1, and so on.  However, xm/xl demand a
                    726: second argument.  The name given is converted to a major/minor by
1.49      gdt       727: calling stat(2) on the name in /dev and this is passed to the domU.
                    728: In the general case, the dom0 and domU can be different operating
1.48      gdt       729: systems, and it is an unwarranted assumption that they have consistent
                    730: numbering in /dev, or even that the dom0 OS has a /dev.  With NetBSD
                    731: as both dom0 and domU, using values of 0x0 for the first disk and 0x1
1.49      gdt       732: for the second works fine and avoids this issue.  For a GNU/Linux
                    733: guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
                    734: /dev/hda1.
1.48      gdt       735: 
                    736: The third element is "w" for writable disks, and "r" for read-only
                    737: disks.
1.28      gdt       738: 
                    739: Virtual Networking
                    740: ------------------
1.111     wiz       742: Xen provides virtual Ethernets, each of which connects the dom0 and a
1.46      gdt       743: domU.  For each virtual network, there is an interface "xvifN.M" in
                    744: the dom0, and in domU index N, a matching interface xennetM (NetBSD
                    745: name).  The interfaces behave as if there is an Ethernet with two
1.111     wiz       746: adapters connected.  From this primitive, one can construct various
1.46      gdt       747: configurations.  We focus on two common and useful cases for which
                    748: there are existing scripts: bridging and NAT.
1.28      gdt       749: 
1.48      gdt       750: With bridging (in the example above), the domU perceives itself to be
                    751: on the same network as the dom0.  For server virtualization, this is
                    752: usually best.  Bridging is accomplished by creating a bridge(4) device
                    753: and adding the dom0's physical interface and the various xvifN.0
                    754: interfaces to the bridge.  One specifies "bridge=bridge0" in the domU
                    755: config file.  The bridge must be set up already in the dom0; an
                    756: example /etc/ifconfig.bridge0 is:
1.46      gdt       757: 
                    758:         create
                    759:         up
                    760:         !brconfig bridge0 add wm0
1.28      gdt       761: 
                    762: With NAT, the domU perceives itself to be behind a NAT running on the
                    763: dom0.  This is often appropriate when running Xen on a workstation.
1.48      gdt       764: TODO: NAT appears to be configured by "vif = [ '' ]".
1.28      gdt       765: 
1.49      gdt       766: The MAC address specified is the one used for the interface in the new
1.53      gdt       767: domain.  The interface in dom0 will use this address XOR'd with
1.49      gdt       768: 00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
1.33      gdt       770: Sizing domains
                    771: --------------
                    773: Modern x86 hardware has vast amounts of resources.  However, many
                    774: virtual servers can function just fine on far less.  A system with
                    775: 256M of RAM and a 4G disk can be a reasonable choice.  Note that it is
                    776: far easier to adjust virtual resources than physical ones.  For
                    777: memory, it's just a config file edit and a reboot.  For disk, one can
                    778: create a new file and vnconfig it (or lvm), and then dump/restore,
                    779: just like updating physical disks, but without having to be there and
                    780: without those pesky connectors.
1.48      gdt       782: Starting domains automatically
                    783: ------------------------------
1.28      gdt       784: 
1.48      gdt       785: To start domains foo at bar at boot and shut them down cleanly on dom0
                    786: shutdown, in rc.conf add:
1.28      gdt       787: 
1.48      gdt       788:         xendomains="foo bar"
1.28      gdt       789: 
1.111     wiz       790: Note that earlier versions of the xentools41 xendomains rc.d script
                    791: used xl, when one should use xm with 4.1.
1.28      gdt       792: 
                    793: Creating specific unprivileged domains (domU)
                    794: =============================================
1.14      gdt       795: 
                    796: Creating domUs is almost entirely independent of operating system.  We
1.49      gdt       797: have already presented the basics of config files.  Note that you must
                    798: have already completed the dom0 setup so that "xl list" (or "xm list")
                    799: works.
1.14      gdt       800: 
                    801: Creating an unprivileged NetBSD domain (domU)
                    802: ---------------------------------------------
1.1       mspo      803: 
1.49      gdt       804: See the earlier config file, and adjust memory.  Decide on how much
                    805: storage you will provide, and prepare it (file or lvm).
1.111     wiz       807: While the kernel will be obtained from the dom0 file system, the same
1.49      gdt       808: file should be present in the domU as /netbsd so that tools like
                    809: savecore(8) can work.   (This is helpful but not necessary.)
                    811: The kernel must be specifically for Xen and for use as a domU.  The
                    812: i386 and amd64 provide the following kernels:
                    814:         i386 XEN3_DOMU
                    815:         i386 XEN3PAE_DOMU
1.95      gdt       816:         amd64 XEN3_DOMU
1.5       mspo      817: 
1.49      gdt       818: Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must
                    819: use the PAE version of the i386 kernel.
                    821: This will boot NetBSD, but this is not that useful if the disk is
                    822: empty.  One approach is to unpack sets onto the disk outside of xen
                    823: (by mounting it, just as you would prepare a physical disk for a
                    824: system you can't run the installer on).
                    826: A second approach is to run an INSTALL kernel, which has a miniroot
                    827: and can load sets from the network.  To do this, copy the INSTALL
                    828: kernel to / and change the kernel line in the config file to:
1.5       mspo      829: 
1.49      gdt       830:         kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
1.5       mspo      831: 
1.49      gdt       832: Then, start the domain as "xl create -c configname".
1.1       mspo      833: 
1.49      gdt       834: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
                    835: line should be used in the config file.
1.1       mspo      836: 
1.3       mspo      837:     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
1.1       mspo      838: 
                    839: After booting the domain, the option to install via CDROM may be
1.49      gdt       840: selected.  The CDROM device should be changed to `xbd1d`.
1.1       mspo      841: 
1.49      gdt       842: Once done installing, "halt -p" the new domain (don't reboot or halt,
                    843: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
                    844: config file), switch the config file back to the XEN3_DOMU kernel,
                    845: and start the new domain again. Now it should be able to use "root on
                    846: xbd0a" and you should have a, functional NetBSD domU.
1.1       mspo      847: 
1.49      gdt       848: TODO: check if this is still accurate.
1.1       mspo      849: When the new domain is booting you'll see some warnings about *wscons*
                    850: and the pseudo-terminals. These can be fixed by editing the files
1.5       mspo      851: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
                    852: `/etc/ttys`, except *console*, like this:
1.1       mspo      853: 
1.3       mspo      854:     console "/usr/libexec/getty Pc"         vt100   on secure
                    855:     ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
                    856:     ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
                    857:     ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
                    858:     ttyE3   "/usr/libexec/getty Pc"         vt220   off secure
1.1       mspo      859: 
1.5       mspo      860: Finally, all screens must be commented out from `/etc/wscons.conf`.
1.1       mspo      861: 
                    862: It is also desirable to add
1.49      gdt       864:         powerd=YES
1.1       mspo      865: 
1.5       mspo      866: in rc.conf. This way, the domain will be properly shut down if
1.53      gdt       867: `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
1.1       mspo      868: 
1.92      gdt       869: It is not strictly necessary to have a kernel (as /netbsd) in the domU
1.111     wiz       870: file system.  However, various programs (e.g. netstat) will use that
1.92      gdt       871: kernel to look up symbols to read from kernel virtual memory.  If
                    872: /netbsd is not the running kernel, those lookups will fail.  (This is
                    873: not really a Xen-specific issue, but because the domU kernel is
                    874: obtained from the dom0, it is far more likely to be out of sync or
                    875: missing with Xen.)
1.14      gdt       877: Creating an unprivileged Linux domain (domU)
1.5       mspo      878: --------------------------------------------
1.1       mspo      879: 
                    880: Creating unprivileged Linux domains isn't much different from
                    881: unprivileged NetBSD domains, but there are some details to know.
                    883: First, the second parameter passed to the disk declaration (the '0x1' in
                    884: the example below)
1.3       mspo      886:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
1.1       mspo      887: 
                    888: does matter to Linux. It wants a Linux device number here (e.g. 0x300
1.49      gdt       889: for hda).  Linux builds device numbers as: (major \<\< 8 + minor).
                    890: So, hda1 which has major 3 and minor 1 on a Linux system will have
                    891: device number 0x301.  Alternatively, devices names can be used (hda,
                    892: hdb, ...)  as xentools has a table to map these names to devices
                    893: numbers.  To export a partition to a Linux guest we can use:
1.1       mspo      894: 
1.49      gdt       895:         disk = [ 'phy:/dev/wd0e,0x300,w' ]
                    896:         root = "/dev/hda1 ro"
1.1       mspo      897: 
                    898: and it will appear as /dev/hda on the Linux system, and be used as root
                    899: partition.
1.49      gdt       901: To install the Linux system on the partition to be exported to the
                    902: guest domain, the following method can be used: install
                    903: sysutils/e2fsprogs from pkgsrc.  Use mke2fs to format the partition
                    904: that will be the root partition of your Linux domain, and mount it.
                    905: Then copy the files from a working Linux system, make adjustments in
                    906: `/etc` (fstab, network config).  It should also be possible to extract
                    907: binary packages such as .rpm or .deb directly to the mounted partition
                    908: using the appropriate tool, possibly running under NetBSD's Linux
1.111     wiz       909: emulation.  Once the file system has been populated, umount it.  If
                    910: desirable, the file system can be converted to ext3 using tune2fs -j.
1.49      gdt       911: It should now be possible to boot the Linux guest domain, using one of
                    912: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
1.1       mspo      913: 
1.111     wiz       914: To get the Linux console right, you need to add:
1.1       mspo      915: 
1.3       mspo      916:     extra = "xencons=tty1"
1.1       mspo      917: 
1.111     wiz       918: to your configuration since not all Linux distributions auto-attach a
1.1       mspo      919: tty to the xen console.
1.14      gdt       921: Creating an unprivileged Solaris domain (domU)
1.5       mspo      922: ----------------------------------------------
1.1       mspo      923: 
1.50      gdt       924: See possibly outdated
                    925: [Solaris domU instructions](/ports/xen/howto-solaris/).
1.5       mspo      926: 
1.1       mspo      927: 
1.52      gdt       928: PCI passthrough: Using PCI devices in guest domains
                    929: ---------------------------------------------------
1.1       mspo      930: 
1.53      gdt       931: The dom0 can give other domains access to selected PCI
1.52      gdt       932: devices. This can allow, for example, a non-privileged domain to have
                    933: access to a physical network interface or disk controller.  However,
                    934: keep in mind that giving a domain access to a PCI device most likely
                    935: will give the domain read/write access to the whole physical memory,
                    936: as PCs don't have an IOMMU to restrict memory access to DMA-capable
1.53      gdt       937: device.  Also, it's not possible to export ISA devices to non-dom0
1.52      gdt       938: domains, which means that the primary VGA adapter can't be exported.
                    939: A guest domain trying to access the VGA registers will panic.
1.53      gdt       941: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
1.52      gdt       942: not been ported to later versions at this time.
                    944: For a PCI device to be exported to a domU, is has to be attached to
                    945: the "pciback" driver in dom0.  Devices passed to the dom0 via the
                    946: pciback.hide boot parameter will attach to "pciback" instead of the
                    947: usual driver.  The list of devices is specified as "(bus:dev.func)",
1.5       mspo      948: where bus and dev are 2-digit hexadecimal numbers, and func a
                    949: single-digit number:
1.1       mspo      950: 
1.52      gdt       951:         pciback.hide=(00:0a.0)(00:06.0)
1.1       mspo      952: 
1.52      gdt       953: pciback devices should show up in the dom0's boot messages, and the
1.5       mspo      954: devices should be listed in the `/kern/xen/pci` directory.
1.1       mspo      955: 
1.52      gdt       956: PCI devices to be exported to a domU are listed in the "pci" array of
                    957: the domU's config file, with the format "0000:bus:dev.func".
1.1       mspo      958: 
1.52      gdt       959:         pci = [ '0000:00:06.0', '0000:00:0a.0' ]
1.1       mspo      960: 
1.52      gdt       961: In the domU an "xpci" device will show up, to which one or more pci
1.111     wiz       962: buses will attach.  Then the PCI drivers will attach to PCI buses as
1.52      gdt       963: usual.  Note that the default NetBSD DOMU kernels do not have "xpci"
                    964: or any PCI drivers built in by default; you have to build your own
                    965: kernel to use PCI devices in a domU.  Here's a kernel config example;
                    966: note that only the "xpci" lines are unusual.
                    968:         include         "arch/i386/conf/XEN3_DOMU"
1.111     wiz       970:         # Add support for PCI buses to the XEN3_DOMU kernel
1.52      gdt       971:         xpci* at xenbus ?
                    972:         pci* at xpci ?
                    974:         # PCI USB controllers
                    975:         uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
                    977:         # USB bus support
                    978:         usb*    at uhci?
                    980:         # USB Hubs
                    981:         uhub*   at usb?
                    982:         uhub*   at uhub? port ? configuration ? interface ?
                    984:         # USB Mass Storage
                    985:         umass*  at uhub? port ? configuration ? interface ?
                    986:         wd*     at umass?
                    987:         # SCSI controllers
                    988:         ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
                    990:         # SCSI bus support (for both ahc and umass)
                    991:         scsibus* at scsi?
                    993:         # SCSI devices
                    994:         sd*     at scsibus? target ? lun ?      # SCSI disk drives
                    995:         cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
1.1       mspo      996: 
1.28      gdt       998: NetBSD as a domU in a VPS
                    999: =========================
                   1001: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
                   1002: hardware.  This section explains how to deal with Xen in a domU as a
                   1003: virtual private server where you do not control or have access to the
1.70      gdt      1004: dom0.  This is not intended to be an exhaustive list of VPS providers;
                   1005: only a few are mentioned that specifically support NetBSD.
1.28      gdt      1006: 
1.52      gdt      1007: VPS operators provide varying degrees of access and mechanisms for
                   1008: configuration.  The big issue is usually how one controls which kernel
1.111     wiz      1009: is booted, because the kernel is nominally in the dom0 file system (to
                   1010: which VPS users do not normally have access).  A second issue is how
1.70      gdt      1011: to install NetBSD.
1.52      gdt      1012: A VPS user may want to compile a kernel for security updates, to run
                   1013: npf, run IPsec, or any other reason why someone would want to change
                   1014: their kernel.
1.111     wiz      1016: One approach is to have an administrative interface to upload a kernel,
1.68      gdt      1017: or to select from a prepopulated list.  Other approaches are pygrub
1.59      gdt      1018: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
1.111     wiz      1019: kernel from the domU file system.  This is closer to a regular physical
1.59      gdt      1020: computer, where someone who controls a machine can replace the kernel.
1.52      gdt      1021: 
1.74      gdt      1022: A second issue is multiple CPUs.  With NetBSD 6, domUs support
                   1023: multiple vcpus, and it is typical for VPS providers to enable multiple
                   1024: CPUs for NetBSD domUs.
1.68      gdt      1026: pygrub
1.59      gdt      1027: -------
1.52      gdt      1028: 
1.111     wiz      1029: pygrub runs in the dom0 and looks into the domU file system.  This
                   1030: implies that the domU must have a kernel in a file system in a format
1.68      gdt      1031: known to pygrub.  As of 2014, pygrub seems to be of mostly historical
                   1032: interest.
1.52      gdt      1033: 
1.59      gdt      1034: pvgrub
                   1035: ------
                   1037: pvgrub is a version of grub that uses PV operations instead of BIOS
                   1038: calls.  It is booted from the dom0 as the domU kernel, and then reads
1.111     wiz      1039: /grub/menu.lst and loads a kernel from the domU file system.
1.59      gdt      1040: 
1.70      gdt      1041: [Panix]( lets users use pvgrub.  Panix reports
1.71      gdt      1042: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
                   1043: (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
1.70      gdt      1044: page](, which describes only
1.74      gdt      1045: Linux but should be updated to cover NetBSD :-).
1.70      gdt      1046: 
                   1047: []( also lets users with pvgrub to boot
                   1048: their own kernel.  See then [ NetBSD
1.74      gdt      1049: HOWTO](
                   1050: (which is in need of updating).
1.59      gdt      1051: 
1.70      gdt      1052: It appears that [grub's FFS
                   1053: code](
                   1054: does not support all aspects of modern FFS, but there are also reports
1.72      gdt      1055: that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT
1.70      gdt      1056: partition for the kernel with the intent that grub can understand it,
                   1057: which leads to /netbsd not being the actual kernel.  One must remember
1.111     wiz      1058: to update the special boot partition.
1.59      gdt      1059: 
                   1060: Amazon
                   1061: ------
1.95      gdt      1063: See the [Amazon EC2 page](../amazon_ec2/).
1.44      gdt      1064: 
                   1065: Using npf
                   1066: ---------
1.81      gdt      1068: In standard kernels, npf is a module, and thus cannot be loaded in a
1.44      gdt      1069: DOMU kernel.
1.95      gdt      1071: TODO: Explain how to compile npf into a custom kernel, answering (but
                   1072: note that the problem was caused by not booting the right kernel)
                   1073: [this email to
                   1074: netbsd-users](
1.65      gdt      1075: 
                   1076: TODO items for improving NetBSD/xen
                   1077: ===================================
1.93      gdt      1079: * Make the NetBSD dom0 kernel work with SMP.
                   1080: * Test the Xen 4.5 packages adequately to be able to recommend them as
                   1081:   the standard approach.
                   1082: * Get PCI passthrough working on Xen 4.5
1.65      gdt      1083: * Get pvgrub into pkgsrc, either via xentools or separately.
                   1084: * grub
1.70      gdt      1085:   * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
1.66      gdt      1086:     fragsize/blocksize (UFS2 support may be present; the point is to
1.111     wiz      1087:     make it so that with any UFS1/UFS2 file system setup that works
1.66      gdt      1088:     with NetBSD grub will also work).
1.70      gdt      1089:     See [pkg/40258](
1.65      gdt      1090:   * Push patches upstream.
                   1091:   * Get UFS2 patches into pvgrub.
                   1092: * Add support for PV ops to a version of /boot, and make it usable as
                   1093:   a kernel in Xen, similar to pvgrub.
1.93      gdt      1094: * Solve somehow the issue with modules for GENERIC not being loadable
                   1095:   in a Xen dom0 or domU kernel.
                   1097: Random pointers
                   1098: ===============
                   1100: TODO: This section contains links from elsewhere not yet integrated
                   1101: into the HOWTO.
                   1103: *
                   1104: *

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