Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.110

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).
                     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.
1.19      gdt        36: 
1.27      jnemeth    37: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
1.12      gdt        38: The dom0 can start one or more domUs.  (Booting is explained in detail
                     39: in the dom0 section.)
                     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
1.24      gdt        44: and running domUs under it (NetBSD and other), and also running NetBSD
                     45: as a domU in a VPS.
1.12      gdt        46: 
1.20      gdt        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.
1.104     gdt        52: NetBSD 6 and earlier supported Xen 2; support was removed fro NetBSD
                     53: 7.  Xen 2 has been removed from pkgsrc.
1.54      gdt        54: 
1.12      gdt        55: Prerequisites
1.13      gdt        56: -------------
1.12      gdt        57: 
                     58: Installing NetBSD/Xen is not extremely difficult, but it is more
                     59: complex than a normal installation of NetBSD.
1.15      gdt        60: In general, this HOWTO is occasionally overly restrictive about how
                     61: things must be done, guiding the reader to stay on the established
                     62: path when there are no known good reasons to stray.
1.12      gdt        63: 
                     64: This HOWTO presumes a basic familiarity with the Xen system
1.16      gdt        65: architecture.  This HOWTO presumes familiarity with installing NetBSD
                     66: on i386/amd64 hardware and installing software from pkgsrc.
1.27      jnemeth    67: See also the [Xen website](
1.1       mspo       68: 
1.15      gdt        69: Versions of Xen and NetBSD
                     70: ==========================
1.27      jnemeth    72: Most of the installation concepts and instructions are independent
                     73: of Xen version and NetBSD version.  This section gives advice on
                     74: which version to choose.  Versions not in pkgsrc and older unsupported
                     75: versions of NetBSD are intentionally ignored.
1.15      gdt        76: 
                     77: Xen
                     78: ---
                     80: In NetBSD, xen is provided in pkgsrc, via matching pairs of packages
                     81: xenkernel and xentools.  We will refer only to the kernel versions,
                     82: but note that both packages must be installed together and must have
                     83: matching versions.
1.104     gdt        85: xenkernel3 provides Xen 3.1.  It is no longer maintained by Xen, and the last applied security patch was in
                     86: 2011. Thus, it should not be used.  It supports PCI passthrough,
                     87: which is why people use it anyway. Xen 3.1 supports i386, both PAE and
                     88: non-PAE.
                     90: xenkernel33 provides Xen 3.3.  It is no longer maintained by Xen, and
                     91: the last applied security patch was in 2012.  Thus, it should not be
                     92: used.  Xen 3.3 supports i386, but only in PAE mode.  There are no good
                     93: reasons to run this version.
                     95: xenkernel41 provides Xen 4.1.  It is no longer maintained by Xen, but
                     96: as of 2016-11 received backported security patches.  Xen 4.1 supports
                     97: i386, but only in PAE mode.  There are no good reasons to run this
                     98: version.
1.102     gdt        99: 
1.104     gdt       100: xenkernel42 provides Xen 4.2.  It is no longer maintained by Xen, but
                    101: as of 2016-11 received backported security patches.  Xen 4.2 supports
                    102: i386, but only in PAE mode.  The only reason to run this is if you
                    103: need to use xm instead of xl, or if you need to run an i386 dom0
                    104: (because your hardware is i386 only).
                    106: xenkernel45 provides Xen 4.5.  It is no longer maintained by Xen, but
                    107: as of 2016-11 it received security patches.  Xen 4.5 requires an amd64
                    108: dom0, but domUs can be amd64 or i386 PAE.  TODO: It is either a
                    109: conservative choice or somewhat old.
                    111: xenkernel45 provides Xen 4.6.  It is new to pkgsrc in 2016-05.  It is
                    112: no longer maintained by Xen, but as of 2016-11 it received security
                    113: patches.  Xen 4.6 requires an amd64 dom0, but domUs can be amd64 or
                    114: i386 PAE.  TODO: It is either a somewhat aggressive choice or the
                    115: standard choice
1.85      gdt       116: 
1.96      gdt       117: See also the [Xen Security Advisory page](
1.15      gdt       119: Ideally newer versions of Xen will be added to pkgsrc.
1.85      gdt       121: Note that NetBSD support is called XEN3.  It works with Xen 3 and Xen
                    122: 4 because the hypercall interface has been stable.
1.20      gdt       123: 
1.19      gdt       124: Xen command program
                    125: -------------------
1.79      gdt       127: Early Xen used a program called xm to manipulate the system from the
1.19      gdt       128: dom0.  Starting in 4.1, a replacement program with similar behavior
1.79      gdt       129: called xl is provided, but it does not work well in 4.1.  In 4.2, both
                    130: xm and xl work fine.  4.4 is the last version that has xm.  You must
                    131: choose one or the other, because it affects which daemons you run.
1.106     gdt       132: However, the rc.d scripts provided by xentools packages expect a
                    133: particular version, and you should use the version used by the
                    134: scripts.
1.19      gdt       135: 
1.15      gdt       136: NetBSD
                    137: ------
1.105     gdt       139: The netbsd-6, netbsd-7, and -current branches are all reasonable
                    140: choices, with more or less the same considerations for non-Xen use.
                    141: Therefore, netbsd-7 is recommended as the stable version of the most
                    142: recent release for production use.  For those wanting to learn Xen or
                    143: without production stability concerns, netbsd-7 is still likely most
1.107     gdt       144: appropriate, but -current is also a reasonable choice.  Xen runs fine
                    145: on netbsd-5, but the xentools packages are likely difficult to build.
1.15      gdt       146: 
                    147: As of NetBSD 6, a NetBSD domU will support multiple vcpus.  There is
                    148: no SMP support for NetBSD as dom0.  (The dom0 itself doesn't really
1.105     gdt       149: need SMP for dom0 functions; the lack of support is really a problem
                    150: when using a dom0 as a normal computer.)
1.15      gdt       151: 
1.18      gdt       152: Architecture
                    153: ------------
1.108     gdt       155: Xen itself can run on i386 (Xen < 3.1) or amd64 machines (all Xen
1.105     gdt       156: versions).  (Practically, almost any computer where one would want to
                    157: run Xen today supports amd64.)
1.99      gdt       158: 
                    159: Xen, the dom0 kernel, and each domU kernel can be either i386 or
                    160: amd64.  When building a xenkernel package, one obtains i386 on an i386
                    161: host, and amd64 on an amd64 host.  If the xen kernel is i386, then the
                    162: dom0 kernel and all domU kernels must be i386.  With an amd64 xen
1.105     gdt       163: kernel, an amd64 dom0 kernel is known to work, and an i386PAE dom0
                    164: kernel should in theory work.  An amd64 xen/dom0 is known to support
                    165: both i386PAE and amd64 domUs.
1.99      gdt       166: 
1.101     gdt       167: i386 dom0 and domU kernels must be PAE (except for Xen 3.1); these are
                    168: built by default.  (Note that emacs (at least) fails if run on i386
                    169: with PAE when built without, and vice versa, presumably due to bugs in
                    170: the undump code.)
1.99      gdt       171: 
                    172: Because of the above, the standard approach is to use amd64 for the
                    173: dom0.
1.29      gdt       174: 
                    175: Xen 4.2 is the last version to support i386 as a host.  TODO: Clarify
1.100     gdt       176: if this is about the CPU, the xen kernel, or the dom0 kernel having to
                    177: be amd64.
1.29      gdt       179: 
1.89      gdt       180: Stability
                    181: ---------
                    183: Mostly, NetBSD as a dom0 or domU is quite stable.
                    184: However, there are some open PRs indicating problems.
1.91      gdt       186:  - [PR 48125](
                    187:  - [PR 47720](
1.89      gdt       188: 
                    189: Note also that there are issues with sparse vnd(4) instances, but
1.105     gdt       190: these are not about Xen -- they just are noticed with sparse vnd(4)
                    191: instances in support of virtual disks in a dom0.
1.89      gdt       192: 
1.15      gdt       193: Recommendation
                    194: --------------
1.105     gdt       196: Therefore, this HOWTO recommends running xenkernel45 or xenkernel46,
                    197: xl, the NetBSD 7 stable branch, and to use an amd64 kernel as the
                    198: dom0.  Either the i386PAE or amd64 version of NetBSD may be used as
                    199: domUs.
1.15      gdt       200: 
1.36      gdt       201: Build problems
                    202: --------------
                    204: Ideally, all versions of Xen in pkgsrc would build on all versions of
                    205: NetBSD on both i386 and amd64.  However, that isn't the case.  Besides
                    206: aging code and aging compilers, qemu (included in xentools for HVM
1.62      gdt       207: support) is difficult to build.  The following are known to work or FAIL:
1.36      gdt       208: 
1.62      gdt       209:         xenkernel3 netbsd-5 amd64
1.63      gdt       210:         xentools3 netbsd-5 amd64
1.64      gdt       211:         xentools3=hvm netbsd-5 amd64 ????
1.62      gdt       212:         xenkernel33 netbsd-5 amd64
1.63      gdt       213:         xentools33 netbsd-5 amd64
1.36      gdt       214:         xenkernel41 netbsd-5 amd64
                    215:         xentools41 netbsd-5 amd64
1.62      gdt       216:         xenkernel42 netbsd-5 amd64
1.64      gdt       217:         xentools42 netbsd-5 amd64
1.62      gdt       218: 
                    219:         xenkernel3 netbsd-6 i386 FAIL
                    220:         xentools3 netbsd-6 i386
1.63      gdt       221:         xentools3-hvm netbsd-6 i386 FAIL (dependencies fail)
                    222:         xenkernel33 netbsd-6 i386
                    223:         xentools33 netbsd-6 i386
1.36      gdt       224:         xenkernel41 netbsd-6 i386
                    225:         xentools41 netbsd-6 i386
1.63      gdt       226:         xenkernel42 netbsd-6 i386
1.64      gdt       227:         xentools42 netbsd-6 i386 *MIXED
1.69      gdt       229:        (all 3 and 33 seem to FAIL)
                    230:         xenkernel41 netbsd-7 i386
                    231:         xentools41 netbsd-7 i386
                    232:         xenkernel42 netbsd-7 i386
                    233:         xentools42 netbsd-7 i386 ??FAIL
1.64      gdt       235: (*On netbsd-6 i386, there is a xentools42 in the 2014Q3 official builds,
                    236: but it does not build for gdt.)
1.36      gdt       237: 
1.15      gdt       238: NetBSD as a dom0
                    239: ================
                    241: NetBSD can be used as a dom0 and works very well.  The following
                    242: sections address installation, updating NetBSD, and updating Xen.
1.19      gdt       243: Note that it doesn't make sense to talk about installing a dom0 OS
                    244: without also installing Xen itself.  We first address installing
                    245: NetBSD, which is not yet a dom0, and then adding Xen, pivoting the
                    246: NetBSD install to a dom0 install by just changing the kernel and boot
                    247: configuration.
1.15      gdt       248: 
1.45      gdt       249: For experimenting with Xen, a machine with as little as 1G of RAM and
                    250: 100G of disk can work.  For running many domUs in productions, far
                    251: more will be needed.
1.15      gdt       253: Styles of dom0 operation
                    254: ------------------------
                    256: There are two basic ways to use Xen.  The traditional method is for
                    257: the dom0 to do absolutely nothing other than providing support to some
                    258: number of domUs.  Such a system was probably installed for the sole
                    259: purpose of hosting domUs, and sits in a server room on a UPS.
                    261: The other way is to put Xen under a normal-usage computer, so that the
                    262: dom0 is what the computer would have been without Xen, perhaps a
                    263: desktop or laptop.  Then, one can run domUs at will.  Purists will
                    264: deride this as less secure than the previous approach, and for a
                    265: computer whose purpose is to run domUs, they are right.  But Xen and a
1.93      gdt       266: dom0 (without domUs) is not meaningfully less secure than the same
1.15      gdt       267: things running without Xen.  One can boot Xen or boot regular NetBSD
                    268: alternately with little problems, simply refraining from starting the
                    269: Xen daemons when not running Xen.
                    271: Note that NetBSD as dom0 does not support multiple CPUs.  This will
1.51      gdt       272: limit the performance of the Xen/dom0 workstation approach.  In theory
                    273: the only issue is that the "backend drivers" are not yet MPSAFE:
1.15      gdt       275: 
1.19      gdt       276: Installation of NetBSD
                    277: ----------------------
1.13      gdt       278: 
1.19      gdt       279: First,
1.27      jnemeth   280: [install NetBSD/amd64](/guide/inst/)
1.19      gdt       281: just as you would if you were not using Xen.
                    282: However, the partitioning approach is very important.
                    284: If you want to use RAIDframe for the dom0, there are no special issues
                    285: for Xen.  Typically one provides RAID storage for the dom0, and the
1.22      gdt       286: domU systems are unaware of RAID.  The 2nd-stage loader bootxx_* skips
                    287: over a RAID1 header to find /boot from a filesystem within a RAID
                    288: partition; this is no different when booting Xen.
1.19      gdt       289: 
                    290: There are 4 styles of providing backing storage for the virtual disks
1.93      gdt       291: used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN.
1.19      gdt       292: 
                    293: With raw partitions, one has a disklabel (or gpt) partition sized for
                    294: each virtual disk to be used by the domU.  (If you are able to predict
                    295: how domU usage will evolve, please add an explanation to the HOWTO.
                    296: Seriously, needs tend to change over time.)
1.27      jnemeth   298: One can use [lvm(8)](/guide/lvm/) to create logical devices to use
                    299: for domU disks.  This is almost as efficient as raw disk partitions
                    300: and more flexible.  Hence raw disk partitions should typically not
                    301: be used.
1.19      gdt       302: 
                    303: One can use files in the dom0 filesystem, typically created by dd'ing
                    304: /dev/zero to create a specific size.  This is somewhat less efficient,
                    305: but very convenient, as one can cp the files for backup, or move them
                    306: between dom0 hosts.
                    308: Finally, in theory one can place the files backing the domU disks in a
                    309: SAN.  (This is an invitation for someone who has done this to add a
                    310: HOWTO page.)
1.1       mspo      311: 
1.19      gdt       312: Installation of Xen
                    313: -------------------
1.1       mspo      314: 
1.20      gdt       315: In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from
                    316: pkgsrc (or another matching pair).
                    317: See [the pkgsrc
                    318: documentation]( for help with pkgsrc.
                    320: For Xen 3.1, support for HVM guests is in sysutils/xentool3-hvm.  More
                    321: recent versions have HVM support integrated in the main xentools
                    322: package.  It is entirely reasonable to run only PV guests.
                    324: Next you need to install the selected Xen kernel itself, which is
                    325: installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz".  Copy it to /.
                    326: For debugging, one may copy xen-debug.gz; this is conceptually similar
                    327: to DIAGNOSTIC and DEBUG in NetBSD.  xen-debug.gz is basically only
                    328: useful with a serial console.  Then, place a NetBSD XEN3_DOM0 kernel
                    329: in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
1.75      gdt       330: of a NetBSD build.  If using i386, use
                    331: releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.  (If using Xen
                    332: 3.1 and i386, you may use XEN3_DOM0 with the non-PAE Xen.  But you
                    333: should not use Xen 3.1.)  Both xen and the NetBSD kernel may be (and
                    334: typically are) left compressed.
                    336: In a dom0 kernel, kernfs is mandatory for xend to comunicate with the
                    337: kernel, so ensure that /kern is in fstab.  TODO: Say this is default,
                    338: or file a PR and give a reference.
1.20      gdt       339: 
                    340: Because you already installed NetBSD, you have a working boot setup
                    341: with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
                    342: beginning of your root filesystem, /boot present, and likely
                    343: /boot.cfg.  (If not, fix before continuing!)
1.76      gdt       345: Add a line to to /boot.cfg to boot Xen.  See boot.cfg(5) for an
                    346: example.  The basic line is
1.20      gdt       347: 
1.37      gdt       348:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
1.20      gdt       349: 
                    350: which specifies that the dom0 should have 256M, leaving the rest to be
1.77      gdt       351: allocated for domUs.  To use a serial console, use
                    353:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=com0;multiboot /xen.gz dom0_mem=256M console=com1 com1=9600,8n1
                    355: which will use the first serial port for Xen (which counts starting
                    356: from 1), forcing speed/parity, and also for NetBSD (which counts
                    357: starting at 0).  In an attempt to add performance, one can also add
1.37      gdt       358: 
                    359:         dom0_max_vcpus=1 dom0_vcpus_pin
                    361: to force only one vcpu to be provided (since NetBSD dom0 can't use
                    362: more) and to pin that vcpu to a physical cpu.  TODO: benchmark this.
1.20      gdt       363: 
1.93      gdt       364: Xen has [many boot
                    365: options](,
                    366: and other tham dom0 memory and max_vcpus, they are generally not
                    367: necessary.
1.20      gdt       369: As with non-Xen systems, you should have a line to boot /netbsd (a
                    370: kernel that works without Xen) and fallback versions of the non-Xen
                    371: kernel, Xen, and the dom0 kernel.
1.1       mspo      372: 
1.76      gdt       373: Now, reboot so that you are running a DOM0 kernel under Xen, rather
                    374: than GENERIC without Xen.
1.54      gdt       376: Using grub (historic)
                    377: ---------------------
                    379: Before NetBSD's native bootloader could support Xen, the use of
                    380: grub was recommended.  If necessary, see the
                    381: [old grub information](/ports/xen/howto-grub/).
1.28      gdt       383: The [HowTo on Installing into
                    384: RAID-1](
                    385: explains how to set up booting a dom0 with Xen using grub with
                    386: NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
                    387: boot.)
1.21      gdt       389: Configuring Xen
                    390: ---------------
1.53      gdt       392: Xen logs will be in /var/log/xen.
1.76      gdt       394: Now, you have a system that will boot Xen and the dom0 kernel, but not
                    395: do anything else special.  Make sure that you have rebooted into Xen.
                    396: There will be no domUs, and none can be started because you still have
1.102     gdt       397: to configure the dom0 daemons.
1.21      gdt       398: 
1.102     gdt       399: The daemons which should be run vary with Xen version and with whether
                    400: one is using xm or xl.  The Xen 3.1 and 3.3 packages use xm.  Xen 4.1
                    401: and higher packages use xl.  While is is possible to use xm with some
                    402: 4.x versions (TODO: 4.1 and 4.2?), the pkgsrc-provided rc.d scripts do
                    403: not support this as of 2014-12-26, and thus the HOWTO does not support
                    404: it either.  (Make sure your packages are reasonably recent.)
1.43      gdt       405: 
1.102     gdt       406: For "xm" (3.1 and 3.3), you should enable xend and xenbackendd (but
                    407: note that you should be using 4.x):
1.31      gdt       408: 
1.32      gdt       409:         xend=YES
                    410:         xenbackendd=YES
1.31      gdt       411: 
1.102     gdt       412: For "xl" (4.x), you should enabled xend and xencommons (xenstored).
                    413: Trying to boot 4.x without xencommons=YES will result in a hang; it is
                    414: necessary to hig ^C on the console to let the machine finish booting.
                    415: TODO: explain why xend is installed by the package.
1.31      gdt       416: 
1.53      gdt       417:         xencommons=YES
1.31      gdt       418: 
1.102     gdt       419: The installation of NetBSD should already have created devices for xen
                    420: (xencons, xenevt), but if they are not present, create them:
1.31      gdt       421: 
1.102     gdt       422:         cd /dev && sh MAKEDEV xen
1.86      gdt       423: 
1.31      gdt       424: TODO: Recommend for/against xen-watchdog.
1.27      jnemeth   425: 
1.53      gdt       426: After you have configured the daemons and either started them (in the
1.79      gdt       427: order given) or rebooted, use xm or xl to inspect Xen's boot messages,
1.102     gdt       428: available resources, and running domains.  An example with xl follows:
1.34      gdt       429: 
1.102     gdt       430:         # xl dmesg
1.43      gdt       431:        [xen's boot info]
1.102     gdt       432:         # xl info
1.43      gdt       433:        [available memory, etc.]
1.102     gdt       434:         # xl list
1.43      gdt       435:         Name              Id  Mem(MB)  CPU  State  Time(s)  Console
                    436:         Domain-0           0       64    0  r----     58.1
1.33      gdt       437: 
1.88      gdt       438: ### Issues with xencommons
                    440: xencommons starts xenstored, which stores data on behalf of dom0 and
                    441: domUs.  It does not currently work to stop and start xenstored.
                    442: Certainly all domUs should be shutdown first, following the sort order
                    443: of the rc.d scripts.  However, the dom0 sets up state with xenstored,
                    444: and is not notified when xenstored exits, leading to not recreating
                    445: the state when the new xenstored starts.  Until there's a mechanism to
                    446: make this work, one should not expect to be able to restart xenstored
                    447: (and thus xencommons).  There is currently no reason to expect that
                    448: this will get fixed any time soon.
1.41      gdt       450: anita (for testing NetBSD)
                    451: --------------------------
1.82      gdt       453: With the setup so far (assuming 4.2/xl), one should be able to run
                    454: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
                    455: root, because anita must create a domU):
                    457:         anita --vmm=xl test file:///usr/obj/i386/
                    459: Alternatively, one can use --vmm=xm to use xm-based domU creation
                    460: instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
1.40      gdt       462: Xen-specific NetBSD issues
                    463: --------------------------
                    465: There are (at least) two additional things different about NetBSD as a
                    466: dom0 kernel compared to hardware.
1.109     gdt       468: One is that the module ABI is different because some of the #ddefines
                    469: change, so one must build modules for Xen.  As of netbsd-7, the build
                    470: system does this automatically.  TODO: check this.  (Before building
                    471: Xen modules was added, it was awkward to use modules to the point
                    472: where it was considered that it did not work.)
1.40      gdt       473: 
                    474: The other difference is that XEN3_DOM0 does not have exactly the same
                    475: options as GENERIC.  While it is debatable whether or not this is a
                    476: bug, users should be aware of this and can simply add missing config
                    477: items if desired.
1.15      gdt       479: Updating NetBSD in a dom0
                    480: -------------------------
                    482: This is just like updating NetBSD on bare hardware, assuming the new
                    483: version supports the version of Xen you are running.  Generally, one
                    484: replaces the kernel and reboots, and then overlays userland binaries
                    485: and adjusts /etc.
                    487: Note that one must update both the non-Xen kernel typically used for
                    488: rescue purposes and the DOM0 kernel used with Xen.
1.55      gdt       490: Converting from grub to /boot
                    491: -----------------------------
                    493: These instructions were [TODO: will be] used to convert a system from
                    494: grub to /boot.  The system was originally installed in February of
                    495: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
                    496: over time.  Before these commands, it was running NetBSD 6 i386, Xen
                    497: 4.1 and grub, much like the message linked earlier in the grub
                    498: section.
                    500:         # Install mbr bootblocks on both disks. 
                    501:         fdisk -i /dev/rwd0d
                    502:         fdisk -i /dev/rwd1d
                    503:         # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
                    504:         installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
                    505:         installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
                    506:         # Install secondary boot loader
                    507:         cp -p /usr/mdec/boot /
                    508:         # Create boog.cfg following earlier guidance:
                    509:         menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
                    510:         menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=256M
                    511:         menu=GENERIC:boot
                    512:         menu=GENERIC single-user:boot -s
                    513:         menu=GENERIC.ok:boot netbsd.ok
                    514:         menu=GENERIC.ok single-user:boot netbsd.ok -s
                    515:         menu=Drop to boot prompt:prompt
                    516:         default=1
                    517:         timeout=30
                    519: TODO: actually do this and fix it if necessary.
1.22      gdt       520: 
1.102     gdt       521: Upgrading Xen versions
1.15      gdt       522: ---------------------
1.110   ! gdt       524: Minor version upgrades are trivial.  Just rebuild/replace the
        !           525: xenkernel version and copy the new xen.gz to / (where /boot.cfg
        !           526: references it), and reboot.
        !           527: 
        !           528: Major version upgrades are conceptually not difficult, but can run
        !           529: into all the issues found when installing Xen.  Assuming migration
        !           530: from 4.1 to 4.2, remove the xenkernel41 and xentools41 packages and
        !           531: install the xenkernel42 and xentools42 packages.  Copy the 4.2 xen.gz
        !           532: to /.
1.21      gdt       533: 
1.102     gdt       534: Ensure that the contents of /etc/rc.d/xen* are correct.  Specifically,
                    535: they must match the package you just installed and not be left over
                    536: from some previous installation.
                    538: Enable the correct set of daemons; see the configuring section above.
                    539: (Upgrading from 3.x to 4.x without doing this will result in a hang.)
                    541: Ensure that the domU config files are valid for the new version.
1.110   ! gdt       542: Specifically, for 4.x remove autorestart=True, and ensure that disks
        !           543: are specified with numbers as the second argument, as the examples
        !           544: above show, and not NetBSD device names.
1.15      gdt       545: 
1.97      gdt       546: Hardware known to work
                    547: ----------------------
                    549: Arguably, this section is misplaced, and there should be a page of
                    550: hardware that runs NetBSD/amd64 well, with the mostly-well-founded
                    551: assumption that NetBSD/xen runs fine on any modern hardware that
                    552: NetBSD/amd64 runs well on.  Until then, we give motherboard/CPU/RAM
                    553: triples to aid those choosing a motherboard.  Note that Xen systems
                    554: usually do not run X, so a listing here does not imply that X works at
                    555: all.
                    557:         Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC
                    558:         Supermicro ??, Atom C2758 (8 core), 32 GiB ECC
                    559:         ASUS M5A78L-M/USB3 AM3+ microATX, AMD Piledriver X8 4000MHz, 16 GiB ECC
                    561: Older hardware:
1.98      gdt       563:         Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2
1.28      gdt       564: 
1.82      gdt       565: Running Xen under qemu
                    566: ----------------------
                    568: The astute reader will note that this section is somewhat twisted.
                    569: However, it can be useful to run Xen under qemu either because the
                    570: version of NetBSD as a dom0 does not run on the hardware in use, or to
                    571: generate automated test cases involving Xen.
1.84      gdt       573: In 2015-01, the following combination was reported to mostly work:
1.82      gdt       574: 
                    575:         host OS: NetBSD/amd64 6.1.4
                    576:         qemu: 2.2.0 from pkgsrc
                    577:         Xen kernel: xenkernel42-4.2.5nb1 from pkgsrc
                    578:         dom0 kernel: NetBSD/amd64 6.1.5
                    579:         Xen tools: xentools42-4.2.5 from pkgsrc
1.91      gdt       581: See [PR 47720]( for a problem with dom0
                    582: shutdown.
1.84      gdt       583: 
1.28      gdt       584: Unprivileged domains (domU)
                    585: ===========================
                    587: This section describes general concepts about domUs.  It does not
1.33      gdt       588: address specific domU operating systems or how to install them.  The
                    589: config files for domUs are typically in /usr/pkg/etc/xen, and are
1.60      wiki      590: typically named so that the file name, domU name and the domU's host
1.33      gdt       591: name match.
                    593: The domU is provided with cpu and memory by Xen, configured by the
                    594: dom0.  The domU is provided with disk and network by the dom0,
                    595: mediated by Xen, and configured in the dom0.
                    597: Entropy in domUs can be an issue; physical disks and network are on
                    598: the dom0.  NetBSD's /dev/random system works, but is often challenged.
1.48      gdt       600: Config files
                    601: ------------
                    603: There is no good order to present config files and the concepts
                    604: surrounding what is being configured.  We first show an example config
                    605: file, and then in the various sections give details.
                    607: See (at least in xentools41) /usr/pkg/share/examples/xen/xmexample*,
                    608: for a large number of well-commented examples, mostly for running
                    609: GNU/Linux.
                    611: The following is an example minimal domain configuration file
                    612: "/usr/pkg/etc/xen/foo".  It is (with only a name change) an actual
                    613: known working config file on Xen 4.1 (NetBSD 5 amd64 dom0 and NetBSD 5
                    614: i386 domU).  The domU serves as a network file server.
                    616:         # -*- mode: python; -*-
                    618:         kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
                    619:         memory = 1024
                    620:         vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
                    621:         disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
                    622:                  'file:/n0/xen/foo-wd1,0x1,w' ]
                    624: The domain will have the same name as the file.  The kernel has the
                    625: host/domU name in it, so that on the dom0 one can update the various
                    626: domUs independently.  The vif line causes an interface to be provided,
                    627: with a specific mac address (do not reuse MAC addresses!), in bridge
                    628: mode.  Two disks are provided, and they are both writable; the bits
                    629: are stored in files and Xen attaches them to a vnd(4) device in the
                    630: dom0 on domain creation.  The system treates xbd0 as the boot device
                    631: without needing explicit configuration.
                    633: By default xm looks for domain config files in /usr/pkg/etc/xen.  Note
                    634: that "xm create" takes the name of a config file, while other commands
                    635: take the name of a domain.  To create the domain, connect to the
                    636: console, create the domain while attaching the console, shutdown the
                    637: domain, and see if it has finished stopping, do (or xl with Xen >=
                    638: 4.2):
                    640:         xm create foo
                    641:         xm console foo
                    642:         xm create -c foo
                    643:         xm shutdown foo
1.90      gdt       644:         xm list
1.48      gdt       645: 
                    646: Typing ^] will exit the console session.  Shutting down a domain is
                    647: equivalent to pushing the power button; a NetBSD domU will receive a
                    648: power-press event and do a clean shutdown.  Shutting down the dom0
                    649: will trigger controlled shutdowns of all configured domUs.
                    651: domU kernels
                    652: ------------
                    654: On a physical computer, the BIOS reads sector 0, and a chain of boot
                    655: loaders finds and loads a kernel.  Normally this comes from the root
                    656: filesystem.  With Xen domUs, the process is totally different.  The
                    657: normal path is for the domU kernel to be a file in the dom0's
                    658: filesystem.  At the request of the dom0, Xen loads that kernel into a
                    659: new domU instance and starts execution.  While domU kernels can be
                    660: anyplace, reasonable places to store domU kernels on the dom0 are in /
                    661: (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
                    662: config files), or in /u0/xen (where the vdisks are).
1.59      gdt       664: Note that loading the domU kernel from the dom0 implies that boot
                    665: blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
1.48      gdt       666: See the VPS section near the end for discussion of alternate ways to
                    667: obtain domU kernels.
1.33      gdt       669: CPU and memory
                    670: --------------
1.48      gdt       672: A domain is provided with some number of vcpus, less than the number
                    673: of cpus seen by the hypervisor.  (For a dom0, this is controlled by
                    674: the boot argument "dom0_max_vcpus=1".)  For a domU, it is controlled
                    675: from the config file by the "vcpus = N" directive.
                    677: A domain is provided with memory; this is controlled in the config
                    678: file by "memory = N" (in megabytes).  In the straightforward case, the
                    679: sum of the the memory allocated to the dom0 and all domUs must be less
1.33      gdt       680: than the available memory.
                    682: Xen also provides a "balloon" driver, which can be used to let domains
                    683: use more memory temporarily.  TODO: Explain better, and explain how
                    684: well it works with NetBSD.
1.28      gdt       685: 
                    686: Virtual disks
                    687: -------------
1.33      gdt       689: With the file/vnd style, typically one creates a directory,
                    690: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
                    691: domUs.  Then, for each domU disk, one writes zeros to a file that then
                    692: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
                    693: for the first virtual disk for the domU called foo.  Writing zeros to
                    694: the file serves two purposes.  One is that preallocating the contents
                    695: improves performance.  The other is that vnd on sparse files has
                    696: failed to work.  TODO: give working/notworking NetBSD versions for
                    697: sparse vnd.  Note that the use of file/vnd for Xen is not really
                    698: different than creating a file-backed virtual disk for some other
1.39      gdt       699: purpose, except that xentools handles the vnconfig commands.  To
                    700: create an empty 4G virtual disk, simply do
                    702:         dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
1.33      gdt       703: 
1.89      gdt       704: Do not use qemu-img-xen, because this will create sparse file.  There
                    705: have been recent (2015) reports of sparse vnd(4) devices causing
                    706: lockups, but there is apparently no PR.
1.33      gdt       708: With the lvm style, one creates logical devices.  They are then used
1.48      gdt       709: similarly to vnds.  TODO: Add an example with lvm.
                    711: In domU config files, the disks are defined as a sequence of 3-tuples.
                    712: The first element is "method:/path/to/disk".  Common methods are
                    713: "file:" for file-backed vnd. and "phy:" for something that is already
                    714: a (TODO: character or block) device.
                    716: The second element is an artifact of how virtual disks are passed to
                    717: Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
                    718: are given a device name to associate with the disk, and values like
                    719: "hda1" or "sda1" are common.  In a NetBSD domU, the first disk appears
                    720: as xbd0, the second as xbd1, and so on.  However, xm/xl demand a
                    721: second argument.  The name given is converted to a major/minor by
1.49      gdt       722: calling stat(2) on the name in /dev and this is passed to the domU.
                    723: In the general case, the dom0 and domU can be different operating
1.48      gdt       724: systems, and it is an unwarranted assumption that they have consistent
                    725: numbering in /dev, or even that the dom0 OS has a /dev.  With NetBSD
                    726: as both dom0 and domU, using values of 0x0 for the first disk and 0x1
1.49      gdt       727: for the second works fine and avoids this issue.  For a GNU/Linux
                    728: guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
                    729: /dev/hda1.
1.48      gdt       730: 
                    731: The third element is "w" for writable disks, and "r" for read-only
                    732: disks.
1.28      gdt       733: 
                    734: Virtual Networking
                    735: ------------------
1.46      gdt       737: Xen provides virtual ethernets, each of which connects the dom0 and a
                    738: domU.  For each virtual network, there is an interface "xvifN.M" in
                    739: the dom0, and in domU index N, a matching interface xennetM (NetBSD
                    740: name).  The interfaces behave as if there is an Ethernet with two
                    741: adaptors connected.  From this primitive, one can construct various
                    742: configurations.  We focus on two common and useful cases for which
                    743: there are existing scripts: bridging and NAT.
1.28      gdt       744: 
1.48      gdt       745: With bridging (in the example above), the domU perceives itself to be
                    746: on the same network as the dom0.  For server virtualization, this is
                    747: usually best.  Bridging is accomplished by creating a bridge(4) device
                    748: and adding the dom0's physical interface and the various xvifN.0
                    749: interfaces to the bridge.  One specifies "bridge=bridge0" in the domU
                    750: config file.  The bridge must be set up already in the dom0; an
                    751: example /etc/ifconfig.bridge0 is:
1.46      gdt       752: 
                    753:         create
                    754:         up
                    755:         !brconfig bridge0 add wm0
1.28      gdt       756: 
                    757: With NAT, the domU perceives itself to be behind a NAT running on the
                    758: dom0.  This is often appropriate when running Xen on a workstation.
1.48      gdt       759: TODO: NAT appears to be configured by "vif = [ '' ]".
1.28      gdt       760: 
1.49      gdt       761: The MAC address specified is the one used for the interface in the new
1.53      gdt       762: domain.  The interface in dom0 will use this address XOR'd with
1.49      gdt       763: 00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
1.33      gdt       765: Sizing domains
                    766: --------------
                    768: Modern x86 hardware has vast amounts of resources.  However, many
                    769: virtual servers can function just fine on far less.  A system with
                    770: 256M of RAM and a 4G disk can be a reasonable choice.  Note that it is
                    771: far easier to adjust virtual resources than physical ones.  For
                    772: memory, it's just a config file edit and a reboot.  For disk, one can
                    773: create a new file and vnconfig it (or lvm), and then dump/restore,
                    774: just like updating physical disks, but without having to be there and
                    775: without those pesky connectors.
1.48      gdt       777: Starting domains automatically
                    778: ------------------------------
1.28      gdt       779: 
1.48      gdt       780: To start domains foo at bar at boot and shut them down cleanly on dom0
                    781: shutdown, in rc.conf add:
1.28      gdt       782: 
1.48      gdt       783:         xendomains="foo bar"
1.28      gdt       784: 
1.86      gdt       785: Note that earlier versions of the xentools41 xendomains rc.d scripth
                    786: usd xl, when one should use xm with 4.1.
1.28      gdt       787: 
                    788: Creating specific unprivileged domains (domU)
                    789: =============================================
1.14      gdt       790: 
                    791: Creating domUs is almost entirely independent of operating system.  We
1.49      gdt       792: have already presented the basics of config files.  Note that you must
                    793: have already completed the dom0 setup so that "xl list" (or "xm list")
                    794: works.
1.14      gdt       795: 
                    796: Creating an unprivileged NetBSD domain (domU)
                    797: ---------------------------------------------
1.1       mspo      798: 
1.49      gdt       799: See the earlier config file, and adjust memory.  Decide on how much
                    800: storage you will provide, and prepare it (file or lvm).
                    802: While the kernel will be obtained from the dom0 filesystem, the same
                    803: file should be present in the domU as /netbsd so that tools like
                    804: savecore(8) can work.   (This is helpful but not necessary.)
                    806: The kernel must be specifically for Xen and for use as a domU.  The
                    807: i386 and amd64 provide the following kernels:
                    809:         i386 XEN3_DOMU
                    810:         i386 XEN3PAE_DOMU
1.95      gdt       811:         amd64 XEN3_DOMU
1.5       mspo      812: 
1.49      gdt       813: Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must
                    814: use the PAE version of the i386 kernel.
                    816: This will boot NetBSD, but this is not that useful if the disk is
                    817: empty.  One approach is to unpack sets onto the disk outside of xen
                    818: (by mounting it, just as you would prepare a physical disk for a
                    819: system you can't run the installer on).
                    821: A second approach is to run an INSTALL kernel, which has a miniroot
                    822: and can load sets from the network.  To do this, copy the INSTALL
                    823: kernel to / and change the kernel line in the config file to:
1.5       mspo      824: 
1.49      gdt       825:         kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
1.5       mspo      826: 
1.49      gdt       827: Then, start the domain as "xl create -c configname".
1.1       mspo      828: 
1.49      gdt       829: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
                    830: line should be used in the config file.
1.1       mspo      831: 
1.3       mspo      832:     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
1.1       mspo      833: 
                    834: After booting the domain, the option to install via CDROM may be
1.49      gdt       835: selected.  The CDROM device should be changed to `xbd1d`.
1.1       mspo      836: 
1.49      gdt       837: Once done installing, "halt -p" the new domain (don't reboot or halt,
                    838: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
                    839: config file), switch the config file back to the XEN3_DOMU kernel,
                    840: and start the new domain again. Now it should be able to use "root on
                    841: xbd0a" and you should have a, functional NetBSD domU.
1.1       mspo      842: 
1.49      gdt       843: TODO: check if this is still accurate.
1.1       mspo      844: When the new domain is booting you'll see some warnings about *wscons*
                    845: and the pseudo-terminals. These can be fixed by editing the files
1.5       mspo      846: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
                    847: `/etc/ttys`, except *console*, like this:
1.1       mspo      848: 
1.3       mspo      849:     console "/usr/libexec/getty Pc"         vt100   on secure
                    850:     ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
                    851:     ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
                    852:     ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
                    853:     ttyE3   "/usr/libexec/getty Pc"         vt220   off secure
1.1       mspo      854: 
1.5       mspo      855: Finally, all screens must be commented out from `/etc/wscons.conf`.
1.1       mspo      856: 
                    857: It is also desirable to add
1.49      gdt       859:         powerd=YES
1.1       mspo      860: 
1.5       mspo      861: in rc.conf. This way, the domain will be properly shut down if
1.53      gdt       862: `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
1.1       mspo      863: 
1.92      gdt       864: It is not strictly necessary to have a kernel (as /netbsd) in the domU
                    865: filesystem.  However, various programs (e.g. netstat) will use that
                    866: kernel to look up symbols to read from kernel virtual memory.  If
                    867: /netbsd is not the running kernel, those lookups will fail.  (This is
                    868: not really a Xen-specific issue, but because the domU kernel is
                    869: obtained from the dom0, it is far more likely to be out of sync or
                    870: missing with Xen.)
1.14      gdt       872: Creating an unprivileged Linux domain (domU)
1.5       mspo      873: --------------------------------------------
1.1       mspo      874: 
                    875: Creating unprivileged Linux domains isn't much different from
                    876: unprivileged NetBSD domains, but there are some details to know.
                    878: First, the second parameter passed to the disk declaration (the '0x1' in
                    879: the example below)
1.3       mspo      881:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
1.1       mspo      882: 
                    883: does matter to Linux. It wants a Linux device number here (e.g. 0x300
1.49      gdt       884: for hda).  Linux builds device numbers as: (major \<\< 8 + minor).
                    885: So, hda1 which has major 3 and minor 1 on a Linux system will have
                    886: device number 0x301.  Alternatively, devices names can be used (hda,
                    887: hdb, ...)  as xentools has a table to map these names to devices
                    888: numbers.  To export a partition to a Linux guest we can use:
1.1       mspo      889: 
1.49      gdt       890:         disk = [ 'phy:/dev/wd0e,0x300,w' ]
                    891:         root = "/dev/hda1 ro"
1.1       mspo      892: 
                    893: and it will appear as /dev/hda on the Linux system, and be used as root
                    894: partition.
1.49      gdt       896: To install the Linux system on the partition to be exported to the
                    897: guest domain, the following method can be used: install
                    898: sysutils/e2fsprogs from pkgsrc.  Use mke2fs to format the partition
                    899: that will be the root partition of your Linux domain, and mount it.
                    900: Then copy the files from a working Linux system, make adjustments in
                    901: `/etc` (fstab, network config).  It should also be possible to extract
                    902: binary packages such as .rpm or .deb directly to the mounted partition
                    903: using the appropriate tool, possibly running under NetBSD's Linux
                    904: emulation.  Once the filesystem has been populated, umount it.  If
                    905: desirable, the filesystem can be converted to ext3 using tune2fs -j.
                    906: It should now be possible to boot the Linux guest domain, using one of
                    907: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
1.1       mspo      908: 
                    909: To get the linux console right, you need to add:
1.3       mspo      911:     extra = "xencons=tty1"
1.1       mspo      912: 
                    913: to your configuration since not all linux distributions auto-attach a
                    914: tty to the xen console.
1.14      gdt       916: Creating an unprivileged Solaris domain (domU)
1.5       mspo      917: ----------------------------------------------
1.1       mspo      918: 
1.50      gdt       919: See possibly outdated
                    920: [Solaris domU instructions](/ports/xen/howto-solaris/).
1.5       mspo      921: 
1.1       mspo      922: 
1.52      gdt       923: PCI passthrough: Using PCI devices in guest domains
                    924: ---------------------------------------------------
1.1       mspo      925: 
1.53      gdt       926: The dom0 can give other domains access to selected PCI
1.52      gdt       927: devices. This can allow, for example, a non-privileged domain to have
                    928: access to a physical network interface or disk controller.  However,
                    929: keep in mind that giving a domain access to a PCI device most likely
                    930: will give the domain read/write access to the whole physical memory,
                    931: as PCs don't have an IOMMU to restrict memory access to DMA-capable
1.53      gdt       932: device.  Also, it's not possible to export ISA devices to non-dom0
1.52      gdt       933: domains, which means that the primary VGA adapter can't be exported.
                    934: A guest domain trying to access the VGA registers will panic.
1.53      gdt       936: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
1.52      gdt       937: not been ported to later versions at this time.
                    939: For a PCI device to be exported to a domU, is has to be attached to
                    940: the "pciback" driver in dom0.  Devices passed to the dom0 via the
                    941: pciback.hide boot parameter will attach to "pciback" instead of the
                    942: usual driver.  The list of devices is specified as "(bus:dev.func)",
1.5       mspo      943: where bus and dev are 2-digit hexadecimal numbers, and func a
                    944: single-digit number:
1.1       mspo      945: 
1.52      gdt       946:         pciback.hide=(00:0a.0)(00:06.0)
1.1       mspo      947: 
1.52      gdt       948: pciback devices should show up in the dom0's boot messages, and the
1.5       mspo      949: devices should be listed in the `/kern/xen/pci` directory.
1.1       mspo      950: 
1.52      gdt       951: PCI devices to be exported to a domU are listed in the "pci" array of
                    952: the domU's config file, with the format "0000:bus:dev.func".
1.1       mspo      953: 
1.52      gdt       954:         pci = [ '0000:00:06.0', '0000:00:0a.0' ]
1.1       mspo      955: 
1.52      gdt       956: In the domU an "xpci" device will show up, to which one or more pci
                    957: busses will attach.  Then the PCI drivers will attach to PCI busses as
                    958: usual.  Note that the default NetBSD DOMU kernels do not have "xpci"
                    959: or any PCI drivers built in by default; you have to build your own
                    960: kernel to use PCI devices in a domU.  Here's a kernel config example;
                    961: note that only the "xpci" lines are unusual.
                    963:         include         "arch/i386/conf/XEN3_DOMU"
                    965:         # Add support for PCI busses to the XEN3_DOMU kernel
                    966:         xpci* at xenbus ?
                    967:         pci* at xpci ?
                    969:         # PCI USB controllers
                    970:         uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
                    972:         # USB bus support
                    973:         usb*    at uhci?
                    975:         # USB Hubs
                    976:         uhub*   at usb?
                    977:         uhub*   at uhub? port ? configuration ? interface ?
                    979:         # USB Mass Storage
                    980:         umass*  at uhub? port ? configuration ? interface ?
                    981:         wd*     at umass?
                    982:         # SCSI controllers
                    983:         ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
                    985:         # SCSI bus support (for both ahc and umass)
                    986:         scsibus* at scsi?
                    988:         # SCSI devices
                    989:         sd*     at scsibus? target ? lun ?      # SCSI disk drives
                    990:         cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
1.1       mspo      991: 
1.28      gdt       993: NetBSD as a domU in a VPS
                    994: =========================
                    996: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
                    997: hardware.  This section explains how to deal with Xen in a domU as a
                    998: virtual private server where you do not control or have access to the
1.70      gdt       999: dom0.  This is not intended to be an exhaustive list of VPS providers;
                   1000: only a few are mentioned that specifically support NetBSD.
1.28      gdt      1001: 
1.52      gdt      1002: VPS operators provide varying degrees of access and mechanisms for
                   1003: configuration.  The big issue is usually how one controls which kernel
                   1004: is booted, because the kernel is nominally in the dom0 filesystem (to
1.70      gdt      1005: which VPS users do not normally have acesss).  A second issue is how
                   1006: to install NetBSD.
1.52      gdt      1007: A VPS user may want to compile a kernel for security updates, to run
                   1008: npf, run IPsec, or any other reason why someone would want to change
                   1009: their kernel.
                   1011: One approach is to have an adminstrative interface to upload a kernel,
1.68      gdt      1012: or to select from a prepopulated list.  Other approaches are pygrub
1.59      gdt      1013: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
                   1014: kernel from the domU filesystem.  This is closer to a regular physical
                   1015: computer, where someone who controls a machine can replace the kernel.
1.52      gdt      1016: 
1.74      gdt      1017: A second issue is multiple CPUs.  With NetBSD 6, domUs support
                   1018: multiple vcpus, and it is typical for VPS providers to enable multiple
                   1019: CPUs for NetBSD domUs.
1.68      gdt      1021: pygrub
1.59      gdt      1022: -------
1.52      gdt      1023: 
1.68      gdt      1024: pygrub runs in the dom0 and looks into the domU filesystem.  This
1.59      gdt      1025: implies that the domU must have a kernel in a filesystem in a format
1.68      gdt      1026: known to pygrub.  As of 2014, pygrub seems to be of mostly historical
                   1027: interest.
1.52      gdt      1028: 
1.59      gdt      1029: pvgrub
                   1030: ------
                   1032: pvgrub is a version of grub that uses PV operations instead of BIOS
                   1033: calls.  It is booted from the dom0 as the domU kernel, and then reads
                   1034: /grub/menu.lst and loads a kernel from the domU filesystem.
1.70      gdt      1036: [Panix]( lets users use pvgrub.  Panix reports
1.71      gdt      1037: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
                   1038: (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
1.70      gdt      1039: page](, which describes only
1.74      gdt      1040: Linux but should be updated to cover NetBSD :-).
1.70      gdt      1041: 
                   1042: []( also lets users with pvgrub to boot
                   1043: their own kernel.  See then [ NetBSD
1.74      gdt      1044: HOWTO](
                   1045: (which is in need of updating).
1.59      gdt      1046: 
1.70      gdt      1047: It appears that [grub's FFS
                   1048: code](
                   1049: does not support all aspects of modern FFS, but there are also reports
1.72      gdt      1050: that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT
1.70      gdt      1051: partition for the kernel with the intent that grub can understand it,
                   1052: which leads to /netbsd not being the actual kernel.  One must remember
                   1053: to update the special boot partiion.
1.59      gdt      1054: 
                   1055: Amazon
                   1056: ------
1.95      gdt      1058: See the [Amazon EC2 page](../amazon_ec2/).
1.44      gdt      1059: 
                   1060: Using npf
                   1061: ---------
1.81      gdt      1063: In standard kernels, npf is a module, and thus cannot be loaded in a
1.44      gdt      1064: DOMU kernel.
1.95      gdt      1066: TODO: Explain how to compile npf into a custom kernel, answering (but
                   1067: note that the problem was caused by not booting the right kernel)
                   1068: [this email to
                   1069: netbsd-users](
1.65      gdt      1070: 
                   1071: TODO items for improving NetBSD/xen
                   1072: ===================================
1.93      gdt      1074: * Make the NetBSD dom0 kernel work with SMP.
                   1075: * Test the Xen 4.5 packages adequately to be able to recommend them as
                   1076:   the standard approach.
                   1077: * Get PCI passthrough working on Xen 4.5
1.65      gdt      1078: * Get pvgrub into pkgsrc, either via xentools or separately.
                   1079: * grub
1.70      gdt      1080:   * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
1.66      gdt      1081:     fragsize/blocksize (UFS2 support may be present; the point is to
                   1082:     make it so that with any UFS1/UFS2 filesystem setup that works
                   1083:     with NetBSD grub will also work).
1.70      gdt      1084:     See [pkg/40258](
1.65      gdt      1085:   * Push patches upstream.
                   1086:   * Get UFS2 patches into pvgrub.
                   1087: * Add support for PV ops to a version of /boot, and make it usable as
                   1088:   a kernel in Xen, similar to pvgrub.
1.93      gdt      1089: * Solve somehow the issue with modules for GENERIC not being loadable
                   1090:   in a Xen dom0 or domU kernel.
                   1092: Random pointers
                   1093: ===============
                   1095: TODO: This section contains links from elsewhere not yet integrated
                   1096: into the HOWTO.
                   1098: *
                   1099: *

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