Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.135

1.5       mspo        1: Introduction
1.13      gdt         2: ============
1.1       mspo        3: 
                      4: [![[Xen
1.57      gdt         5: screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](http://www.netbsd.org/gallery/in-Action/hubertf-xen.png)
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.
                     24: 
                     25: The more recent style is HVM, which means that the guest does not have
                     26: code for Xen and need not be aware that it is running under Xen.
                     27: Attempts to access hardware registers are trapped and emulated.  This
                     28: style is less efficient but can run unmodified guests.
                     29: 
1.123     gdt        30: Generally any machine that runs NetBSD/amd64 will work with Xen and PV
                     31: guests.  In theory i386 computers (without x86_64/amd64 support) can
                     32: be used for Xen <= 4.2, but we have no recent reports of this working
                     33: (this is a hint).  For HVM guests, hardware support is needed, but it
                     34: is common on recent machines.  For Intel CPUs, one needs the VT-x
                     35: extension, shown in "cpuctl identify 0" as VMX.  For AMD CPUs, one
                     36: needs the AMD-V extensions, shown in "cpuctl identify 0" as SVM.
                     37: There are further features for IOMMU virtualization, Intel's VT-d and
                     38: AMD's AMD-Vi.  TODO: Explain whether Xen on NetBSD makes use of these
                     39: features.  TODO: Review by someone who really understands this.
1.19      gdt        40: 
1.123     gdt        41: Note that a FreeBSD dom0 requires VT-x and VT-d (or equivalent); this
                     42: is because the FreeBSD dom0 does not run in PV mode.
1.118     gdt        43: 
1.27      jnemeth    44: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
1.12      gdt        45: The dom0 can start one or more domUs.  (Booting is explained in detail
                     46: in the dom0 section.)
                     47: 
                     48: NetBSD supports Xen in that it can serve as dom0, be used as a domU,
                     49: and that Xen kernels and tools are available in pkgsrc.  This HOWTO
                     50: attempts to address both the case of running a NetBSD dom0 on hardware
1.24      gdt        51: and running domUs under it (NetBSD and other), and also running NetBSD
                     52: as a domU in a VPS.
1.12      gdt        53: 
1.123     gdt        54: Xen 3.1 in pkgsrc supports "PCI passthrough", which means that
1.20      gdt        55: specific PCI devices can be made available to a specific domU instead
                     56: of the dom0.  This can be useful to let a domU run X11, or access some
                     57: network interface or other peripheral.
                     58: 
1.111     wiz        59: NetBSD 6 and earlier supported Xen 2; support was removed from NetBSD
1.104     gdt        60: 7.  Xen 2 has been removed from pkgsrc.
1.54      gdt        61: 
1.12      gdt        62: Prerequisites
1.13      gdt        63: -------------
1.12      gdt        64: 
                     65: Installing NetBSD/Xen is not extremely difficult, but it is more
                     66: complex than a normal installation of NetBSD.
1.15      gdt        67: In general, this HOWTO is occasionally overly restrictive about how
                     68: things must be done, guiding the reader to stay on the established
                     69: path when there are no known good reasons to stray.
1.12      gdt        70: 
                     71: This HOWTO presumes a basic familiarity with the Xen system
1.123     gdt        72: architecture, with installing NetBSD on i386/amd64 hardware, and with
                     73: installing software from pkgsrc.  See also the [Xen
                     74: website](http://www.xenproject.org/).
1.1       mspo       75: 
1.15      gdt        76: Versions of Xen and NetBSD
                     77: ==========================
                     78: 
1.27      jnemeth    79: Most of the installation concepts and instructions are independent
                     80: of Xen version and NetBSD version.  This section gives advice on
                     81: which version to choose.  Versions not in pkgsrc and older unsupported
                     82: versions of NetBSD are intentionally ignored.
1.15      gdt        83: 
1.133     gdt        84: The term "amd64" is used to refer to both the NetBSD port and to the
                     85: hardware architecture on which it runs.  (Such hardware is made by
                     86: both Intel and AMD, and in 2016 a normal PC has this CPU
                     87: architecture.)
                     88: 
1.15      gdt        89: Xen
                     90: ---
                     91: 
1.111     wiz        92: In NetBSD, Xen is provided in pkgsrc, via matching pairs of packages
1.15      gdt        93: xenkernel and xentools.  We will refer only to the kernel versions,
                     94: but note that both packages must be installed together and must have
                     95: matching versions.
                     96: 
1.133     gdt        97: xenkernel3 provides Xen 3.1.  It is no longer maintained by Xen, and
                     98: the last applied security patch was in 2011. Thus, it should not be
                     99: used.  It supports PCI passthrough, which is why people use it anyway.
                    100: Xen 3.1 runs on i386 (both non-PAE and PAE) and amd64 hardware.
1.104     gdt       101: 
                    102: xenkernel33 provides Xen 3.3.  It is no longer maintained by Xen, and
                    103: the last applied security patch was in 2012.  Thus, it should not be
1.133     gdt       104: used.  Xen 3.3 runs on i386 PAE and amd64 hardware.  There are no good
1.104     gdt       105: reasons to run this version.
                    106: 
                    107: xenkernel41 provides Xen 4.1.  It is no longer maintained by Xen, but
1.133     gdt       108: as of 2016-12 received backported security patches.  Xen 4.1 runs on
                    109: i386 PAE and amd64 hardware.  There are no good reasons to run this
1.104     gdt       110: version.
1.102     gdt       111: 
1.104     gdt       112: xenkernel42 provides Xen 4.2.  It is no longer maintained by Xen, but
1.133     gdt       113: as of 2016-12 received backported security patches.  Xen 4.2 runs on
                    114: i386 PAE and amd64 hardware.  The only reason to run this is if you
                    115: need to use xm instead of xl, or if you need to run on hardware that
                    116: supports i386 but not amd64.  (This might also be useful if you need
                    117: an i386 dom0, if it turns out that an amd64 Xen kernel and an i386
                    118: dom0 is problematic.)
1.104     gdt       119: 
1.114     gdt       120: xenkernel45 provides Xen 4.5.  As of 2016-12, security patches were
1.133     gdt       121: released by Xen and applied to pkgsrc.  Xen 4.5 runs on amd64 hardware
                    122: only.  While slightly old, 4.5 has been tested and run by others, so
                    123: it is the conservative choice.
1.104     gdt       124: 
1.115     gdt       125: xenkernel46 provides Xen 4.6.  It is new to pkgsrc as of 2016-05.  As
1.114     gdt       126: of 2016-12, security patches were released by Xen and applied to
1.133     gdt       127: pkgsrc.  Xen 4.6 runs on amd64 hardware only For new installations,
                    128: 4.6 is probably the appropriate choice and it will likely soon be the
                    129: standard approach.
1.85      gdt       130: 
1.114     gdt       131: Xen 4.7 (released 2016-06) and 4.8 (released 2016-12) are not yet in
                    132: pkgsrc.
1.113     gdt       133: 
1.96      gdt       134: See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
                    135: 
1.85      gdt       136: Note that NetBSD support is called XEN3.  It works with Xen 3 and Xen
                    137: 4 because the hypercall interface has been stable.
1.20      gdt       138: 
1.19      gdt       139: Xen command program
                    140: -------------------
                    141: 
1.79      gdt       142: Early Xen used a program called xm to manipulate the system from the
1.19      gdt       143: dom0.  Starting in 4.1, a replacement program with similar behavior
1.79      gdt       144: called xl is provided, but it does not work well in 4.1.  In 4.2, both
1.127     gdt       145: xm and xl work fine.  4.4 is the last version that has xm.
                    146: 
                    147: You must make a global choice to use xm or xl, because it affects not
                    148: only which command you use, but the command used by rc.d scripts
                    149: (specifically xendomains) and which daemons should be run.  The
                    150: xentools packages provide xm for 3.1, 3.3 and 4.1 and xl for 4.2 and up.
                    151: 
                    152: In 4.2, you can choose to use xm by simply changing the ctl_command
1.135   ! gdt       153: variable and setting xend=YES in rc.conf.
1.127     gdt       154: 
                    155: With xl, virtual devices are configured in parallel, which can cause
                    156: problems if they are written assuming serial operation (e.g., updating
1.130     gdt       157: firewall rules without explicit locking).  There is now locking for
                    158: the provided scripts, which works for normal casses (e.g, file-backed
                    159: xbd, where a vnd must be allocated).  But, as of 201612, it has not
                    160: been adequately tested for a complex custom setup with a large number
                    161: of interfaces.
1.19      gdt       162: 
1.15      gdt       163: NetBSD
                    164: ------
                    165: 
1.105     gdt       166: The netbsd-6, netbsd-7, and -current branches are all reasonable
                    167: choices, with more or less the same considerations for non-Xen use.
                    168: Therefore, netbsd-7 is recommended as the stable version of the most
1.117     gdt       169: recent release for production use.  In addition, netbsd-7 and -current
                    170: have a important scheduler fix (in November of 2015) affecting
                    171: contention between dom0 and domUs; see
                    172: https://releng.netbsd.org/cgi-bin/req-7.cgi?show=1040 for a
                    173: description.  For those wanting to learn Xen or without production
                    174: stability concerns, netbsd-7 is still likely most appropriate, but
                    175: -current is also a reasonable choice.  (Xen runs ok on netbsd-5, but
                    176: the xentools packages are likely difficult to build, and netbsd-5 is
                    177: not supported.)
1.15      gdt       178: 
                    179: As of NetBSD 6, a NetBSD domU will support multiple vcpus.  There is
                    180: no SMP support for NetBSD as dom0.  (The dom0 itself doesn't really
1.105     gdt       181: need SMP for dom0 functions; the lack of support is really a problem
                    182: when using a dom0 as a normal computer.)
1.15      gdt       183: 
1.18      gdt       184: Architecture
                    185: ------------
                    186: 
1.133     gdt       187: Xen itself can run on i386 (Xen < 4.2) or amd64 hardware (all Xen
1.105     gdt       188: versions).  (Practically, almost any computer where one would want to
                    189: run Xen today supports amd64.)
1.99      gdt       190: 
1.133     gdt       191: Xen, the dom0 system, and each domU system can be either i386 or
                    192: amd64.  When building a xenkernel package, one obtains an i386 Xen
1.134     wiz       193: kernel on an i386 host, and an amd64 Xen kernel on an amd64 host.  If
1.133     gdt       194: the Xen kernel is i386, then the dom0 kernel and all domU kernels must
                    195: be i386.  With an amd64 Xen kernel, an amd64 dom0 kernel is known to
                    196: work, and an i386 dom0 kernel should in theory work.  An amd64
                    197: Xen/dom0 is known to support both i386 and amd64 domUs.
                    198: 
                    199: i386 dom0 and domU kernels must be PAE (except for an i386 Xen 3.1
1.135   ! gdt       200: kernel, where one can use non-PAE for dom0 and all domUs); PAE kernels
        !           201: are included in the NetBSD default build.  (Note that emacs (at least)
        !           202: fails if run on i386 with PAE when built without, and vice versa,
        !           203: presumably due to bugs in the undump code.)
        !           204: 
        !           205: Because of the above, the standard approach is to use an amd64 Xen
        !           206: kernel and NetBSD/amd64 for the dom0.  For domUs, NetBSD/i386 (with
        !           207: the PAE kernel) and NetBSD/amd64 are in widespread use, and there is
        !           208: little to no Xen-specific reason to prefer one over the other.
1.133     gdt       209: 
                    210: Note that to use an i386 dom0 with Xen 4.5 or higher, one must build
1.135   ! gdt       211: (or obtain from pre-built packages) an amd64 Xen kernel and install
        !           212: that on the system.  (One must also use a PAE i386 kernel, but this is
        !           213: also required with an i386 Xen kernel.).  Almost no one in the
        !           214: NetBSD/Xen community does this, and the standard, well-tested,
        !           215: approach is to use an amd64 dom0.
        !           216: 
        !           217: A [posting on
        !           218: xen-devel](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html)
        !           219: explained that PV system call overhead was higher on amd64, and thus
        !           220: there is some notion that i386 guests are faster.  It goes on to
        !           221: caution that the total situation is complex and not entirely
        !           222: understood. On top of that caution, the post is about Linux, not
        !           223: NetBSD.  TODO: Include link to benchmarks, if someone posts them.
1.29      gdt       224: 
1.89      gdt       225: Stability
                    226: ---------
                    227: 
                    228: Mostly, NetBSD as a dom0 or domU is quite stable.
                    229: However, there are some open PRs indicating problems.
                    230: 
1.91      gdt       231:  - [PR 48125](http://gnats.netbsd.org/48125)
                    232:  - [PR 47720](http://gnats.netbsd.org/47720)
1.89      gdt       233: 
                    234: Note also that there are issues with sparse vnd(4) instances, but
1.105     gdt       235: these are not about Xen -- they just are noticed with sparse vnd(4)
                    236: instances in support of virtual disks in a dom0.
1.89      gdt       237: 
1.15      gdt       238: Recommendation
                    239: --------------
                    240: 
1.105     gdt       241: Therefore, this HOWTO recommends running xenkernel45 or xenkernel46,
                    242: xl, the NetBSD 7 stable branch, and to use an amd64 kernel as the
                    243: dom0.  Either the i386PAE or amd64 version of NetBSD may be used as
                    244: domUs.
1.15      gdt       245: 
1.125     gdt       246: Status
                    247: ------
1.36      gdt       248: 
1.120     gdt       249: Ideally, all versions of Xen in pkgsrc would build on all supported
1.121     gdt       250: versions of NetBSD/amd64, to the point where this section would be
                    251: silly.  However, that has not always been the case.  Besides aging
                    252: code and aging compilers, qemu (included in xentools for HVM support)
1.124     gdt       253: is difficult to build.  Note that there is intentionally no data for
1.125     gdt       254: 4.5+ up for i386, and often omits xentools info if the corresponding
                    255: kernel fails.
                    256: 
                    257: The following table gives status, with the date last checked
                    258: (generally on the most recent quarterly branch).  The first code is
                    259: "builds" if it builds ok, and "FAIL" for a failure to build.  The
                    260: second code/date only appears for xenkernel* and is "works" if it runs
1.135   ! gdt       261: ok as a dom0 and can support a domU, and "FAIL" if it won't boot or
        !           262: run a domU.
1.124     gdt       263: 
                    264:        xenkernel3 netbsd-6 i386 FAIL 201612
                    265:        xenkernel33 netbsd-6 i386 FAIL 201612
1.125     gdt       266:        xenkernel41 netbsd-6 i386 builds 201612
                    267:        xenkernel42 netbsd-6 i386 builds 201612
1.126     gdt       268:        xentools3 netbsd-6 i386 FAIL 201612
1.128     gdt       269:        xentools33 netbsd-6 i386 FAIL 201612
1.125     gdt       270:        xentools41 netbsd-6 i386 builds 201612
1.126     gdt       271:        xentools42 netbsd-6 i386 FAIL 201612
1.64      gdt       272: 
1.124     gdt       273:        xenkernel3 netbsd-7 i386 FAIL 201412
                    274:        xenkernel33 netbsd-7 i386 FAIL 201412
1.125     gdt       275:        xenkernel41 netbsd-7 i386 builds 201412
                    276:        xenkernel42 netbsd-7 i386 builds 201412
                    277:        xentools41 netbsd-7 i386 builds 201412
1.122     gdt       278:        xentools42 netbsd-7 i386 ??FAIL 201412
1.121     gdt       279: 
1.124     gdt       280:        xenkernel3 netbsd-6 amd64 FAIL 201612
                    281:        xenkernel33 netbsd-6 amd64 FAIL 201612
1.125     gdt       282:        xenkernel41 netbsd-6 amd64 builds 201612 works 201612
1.126     gdt       283:        xenkernel42 netbsd-6 amd64 builds 201612 works 201612
1.125     gdt       284:        xenkernel45 netbsd-6 amd64 builds 201612
                    285:        xenkernel46 netbsd-6 amd64 builds 201612
                    286:        xentools41 netbsd-6 amd64 builds 201612
                    287:        xentools42 netbsd-6 amd64 builds 201612
                    288:        xentools45 netbsd-6 amd64 builds 201612
1.124     gdt       289:        xentools46 netbsd-6 amd64 FAIL 201612
1.121     gdt       290: 
1.125     gdt       291:        xenkernel3 netbsd-7 amd64 builds 201612
                    292:        xenkernel33 netbsd-7 amd64 builds 201612
                    293:        xenkernel41 netbsd-7 amd64 builds 201612
                    294:        xenkernel42 netbsd-7 amd64 builds 201612
                    295:        xenkernel45 netbsd-7 amd64 builds 201612
                    296:        xenkernel46 netbsd-7 amd64 builds 201612
                    297:        xentools3 netbsd-7 amd64 builds 201612
                    298:        xentools3-hvm netbsd-7 amd64 builds 201612
1.121     gdt       299:        xentools33 netbsd-7 amd64 FAIL 201612
1.125     gdt       300:        xentools41 netbsd-7 amd64 builds 201612
                    301:        xentools42 netbsd-7 amd64 builds 201612
                    302:        xentools45 netbsd-7 amd64 builds 201612
                    303:        xentools46 netbsd-7 amd64 builds 201612
1.69      gdt       304: 
1.15      gdt       305: NetBSD as a dom0
                    306: ================
                    307: 
                    308: NetBSD can be used as a dom0 and works very well.  The following
                    309: sections address installation, updating NetBSD, and updating Xen.
1.19      gdt       310: Note that it doesn't make sense to talk about installing a dom0 OS
                    311: without also installing Xen itself.  We first address installing
                    312: NetBSD, which is not yet a dom0, and then adding Xen, pivoting the
                    313: NetBSD install to a dom0 install by just changing the kernel and boot
                    314: configuration.
1.15      gdt       315: 
1.45      gdt       316: For experimenting with Xen, a machine with as little as 1G of RAM and
                    317: 100G of disk can work.  For running many domUs in productions, far
1.135   ! gdt       318: more will be needed; e.g. 4-8G and 1T of disk is reasonable for a
        !           319: half-dozen domUs of 512M and 32G each.  Basically, the RAM and disk
        !           320: have to be bigger than the sum of the RAM/disk needs of the dom0 and
        !           321: all the domUs.
1.45      gdt       322: 
1.15      gdt       323: Styles of dom0 operation
                    324: ------------------------
                    325: 
                    326: There are two basic ways to use Xen.  The traditional method is for
                    327: the dom0 to do absolutely nothing other than providing support to some
                    328: number of domUs.  Such a system was probably installed for the sole
                    329: purpose of hosting domUs, and sits in a server room on a UPS.
                    330: 
                    331: The other way is to put Xen under a normal-usage computer, so that the
                    332: dom0 is what the computer would have been without Xen, perhaps a
                    333: desktop or laptop.  Then, one can run domUs at will.  Purists will
                    334: deride this as less secure than the previous approach, and for a
                    335: computer whose purpose is to run domUs, they are right.  But Xen and a
1.93      gdt       336: dom0 (without domUs) is not meaningfully less secure than the same
1.15      gdt       337: things running without Xen.  One can boot Xen or boot regular NetBSD
                    338: alternately with little problems, simply refraining from starting the
                    339: Xen daemons when not running Xen.
                    340: 
                    341: Note that NetBSD as dom0 does not support multiple CPUs.  This will
1.51      gdt       342: limit the performance of the Xen/dom0 workstation approach.  In theory
                    343: the only issue is that the "backend drivers" are not yet MPSAFE:
                    344:   http://mail-index.netbsd.org/netbsd-users/2014/08/29/msg015195.html
1.15      gdt       345: 
1.19      gdt       346: Installation of NetBSD
                    347: ----------------------
1.13      gdt       348: 
1.19      gdt       349: First,
1.27      jnemeth   350: [install NetBSD/amd64](/guide/inst/)
1.19      gdt       351: just as you would if you were not using Xen.
                    352: However, the partitioning approach is very important.
                    353: 
                    354: If you want to use RAIDframe for the dom0, there are no special issues
                    355: for Xen.  Typically one provides RAID storage for the dom0, and the
1.22      gdt       356: domU systems are unaware of RAID.  The 2nd-stage loader bootxx_* skips
1.111     wiz       357: over a RAID1 header to find /boot from a file system within a RAID
1.22      gdt       358: partition; this is no different when booting Xen.
1.19      gdt       359: 
                    360: There are 4 styles of providing backing storage for the virtual disks
1.93      gdt       361: used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN.
1.19      gdt       362: 
                    363: With raw partitions, one has a disklabel (or gpt) partition sized for
                    364: each virtual disk to be used by the domU.  (If you are able to predict
                    365: how domU usage will evolve, please add an explanation to the HOWTO.
                    366: Seriously, needs tend to change over time.)
                    367: 
1.27      jnemeth   368: One can use [lvm(8)](/guide/lvm/) to create logical devices to use
                    369: for domU disks.  This is almost as efficient as raw disk partitions
                    370: and more flexible.  Hence raw disk partitions should typically not
                    371: be used.
1.19      gdt       372: 
1.111     wiz       373: One can use files in the dom0 file system, typically created by dd'ing
1.19      gdt       374: /dev/zero to create a specific size.  This is somewhat less efficient,
                    375: but very convenient, as one can cp the files for backup, or move them
                    376: between dom0 hosts.
                    377: 
                    378: Finally, in theory one can place the files backing the domU disks in a
                    379: SAN.  (This is an invitation for someone who has done this to add a
                    380: HOWTO page.)
1.1       mspo      381: 
1.19      gdt       382: Installation of Xen
                    383: -------------------
1.1       mspo      384: 
1.20      gdt       385: In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from
1.127     gdt       386: pkgsrc (or another matching pair).  See [the pkgsrc
                    387: documentation](http://www.NetBSD.org/docs/pkgsrc/) for help with
                    388: pkgsrc.  Ensure that your packages are recent; the HOWTO does not
                    389: contemplate old builds.
                    390: 
1.20      gdt       391: 
                    392: For Xen 3.1, support for HVM guests is in sysutils/xentool3-hvm.  More
                    393: recent versions have HVM support integrated in the main xentools
                    394: package.  It is entirely reasonable to run only PV guests.
                    395: 
                    396: Next you need to install the selected Xen kernel itself, which is
                    397: installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz".  Copy it to /.
                    398: For debugging, one may copy xen-debug.gz; this is conceptually similar
                    399: to DIAGNOSTIC and DEBUG in NetBSD.  xen-debug.gz is basically only
                    400: useful with a serial console.  Then, place a NetBSD XEN3_DOM0 kernel
                    401: in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
1.75      gdt       402: of a NetBSD build.  If using i386, use
                    403: releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.  (If using Xen
                    404: 3.1 and i386, you may use XEN3_DOM0 with the non-PAE Xen.  But you
                    405: should not use Xen 3.1.)  Both xen and the NetBSD kernel may be (and
                    406: typically are) left compressed.
                    407: 
1.135   ! gdt       408: In a dom0, kernfs is mandatory for xend to communicate with the
        !           409: kernel, so ensure that /kern is in fstab.  (A standard NetBSD install
        !           410: should already mount /kern.)
1.20      gdt       411: 
                    412: Because you already installed NetBSD, you have a working boot setup
                    413: with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
1.135   ! gdt       414: beginning of your root file system, have /boot, and likely also
1.20      gdt       415: /boot.cfg.  (If not, fix before continuing!)
                    416: 
1.76      gdt       417: Add a line to to /boot.cfg to boot Xen.  See boot.cfg(5) for an
                    418: example.  The basic line is
1.20      gdt       419: 
1.37      gdt       420:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
1.20      gdt       421: 
                    422: which specifies that the dom0 should have 256M, leaving the rest to be
1.77      gdt       423: allocated for domUs.  To use a serial console, use
                    424: 
                    425:         menu=Xen:load /netbsd-XEN3_DOM0.gz console=com0;multiboot /xen.gz dom0_mem=256M console=com1 com1=9600,8n1
                    426: 
                    427: which will use the first serial port for Xen (which counts starting
                    428: from 1), forcing speed/parity, and also for NetBSD (which counts
                    429: starting at 0).  In an attempt to add performance, one can also add
1.37      gdt       430: 
                    431:         dom0_max_vcpus=1 dom0_vcpus_pin
                    432: 
                    433: to force only one vcpu to be provided (since NetBSD dom0 can't use
1.111     wiz       434: more) and to pin that vcpu to a physical CPU.  TODO: benchmark this.
1.20      gdt       435: 
1.93      gdt       436: Xen has [many boot
                    437: options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html),
1.111     wiz       438: and other than dom0 memory and max_vcpus, they are generally not
1.93      gdt       439: necessary.
                    440: 
1.20      gdt       441: As with non-Xen systems, you should have a line to boot /netbsd (a
1.127     gdt       442: kernel that works without Xen).  Consider a line to boot /netbsd.ok (a
                    443: fallback version of the non-Xen kernel, updated manually when you are
                    444: sure /netbsd is ok).  Consider also a line to boot fallback versions
                    445: of Xen and the dom0 kernel, but note that non-Xen NetBSD can be used
                    446: to resolve Xen booting issues.
                    447: 
                    448: Probably you want a default=N line to choose Xen in the absence of
                    449: intervention.
1.1       mspo      450: 
1.76      gdt       451: Now, reboot so that you are running a DOM0 kernel under Xen, rather
                    452: than GENERIC without Xen.
                    453: 
1.54      gdt       454: Using grub (historic)
                    455: ---------------------
                    456: 
                    457: Before NetBSD's native bootloader could support Xen, the use of
                    458: grub was recommended.  If necessary, see the
1.135   ! gdt       459: [old grub information](/ports/xen/howto-grub).
1.54      gdt       460: 
1.28      gdt       461: The [HowTo on Installing into
                    462: RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
                    463: explains how to set up booting a dom0 with Xen using grub with
                    464: NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
1.135   ! gdt       465: boot.  Now, just create a system with RAID-1, and alter /boot.cfg as
        !           466: described above.)
1.28      gdt       467: 
1.21      gdt       468: Configuring Xen
                    469: ---------------
                    470: 
1.53      gdt       471: Xen logs will be in /var/log/xen.
                    472: 
1.76      gdt       473: Now, you have a system that will boot Xen and the dom0 kernel, but not
                    474: do anything else special.  Make sure that you have rebooted into Xen.
                    475: There will be no domUs, and none can be started because you still have
1.102     gdt       476: to configure the dom0 daemons.
1.21      gdt       477: 
1.102     gdt       478: The daemons which should be run vary with Xen version and with whether
1.127     gdt       479: one is using xm or xl.  The Xen 3.1, 3.3 and 4.1 packages use xm.  Xen
                    480: 4.2 and up packages use xl.  To use xm with 4.2, edit xendomains to
                    481: use xm instead.
                    482: 
1.132     gdt       483: For 3.1 and 3.3, you should enable xend and xenbackendd:
1.31      gdt       484: 
1.32      gdt       485:         xend=YES
                    486:         xenbackendd=YES
1.31      gdt       487: 
1.132     gdt       488: For 4.1 and up, you should enable xencommons.  Not enabling xencommons
                    489: will result in a hang; it is necessary to hit ^C on the console to let
                    490: the machine finish booting.  If you are using xm (default in 4.1, or
                    491: if you changed xendomains in 4.2), you should also enable xend:
1.31      gdt       492: 
1.132     gdt       493:         xend=YES # only if using xm, and only installed <= 4.2
1.53      gdt       494:         xencommons=YES
1.31      gdt       495: 
                    496: TODO: Recommend for/against xen-watchdog.
1.27      jnemeth   497: 
1.53      gdt       498: After you have configured the daemons and either started them (in the
1.79      gdt       499: order given) or rebooted, use xm or xl to inspect Xen's boot messages,
1.102     gdt       500: available resources, and running domains.  An example with xl follows:
1.34      gdt       501: 
1.102     gdt       502:         # xl dmesg
1.43      gdt       503:        [xen's boot info]
1.102     gdt       504:         # xl info
1.43      gdt       505:        [available memory, etc.]
1.102     gdt       506:         # xl list
1.43      gdt       507:         Name              Id  Mem(MB)  CPU  State  Time(s)  Console
                    508:         Domain-0           0       64    0  r----     58.1
1.33      gdt       509: 
1.88      gdt       510: ### Issues with xencommons
                    511: 
                    512: xencommons starts xenstored, which stores data on behalf of dom0 and
                    513: domUs.  It does not currently work to stop and start xenstored.
                    514: Certainly all domUs should be shutdown first, following the sort order
                    515: of the rc.d scripts.  However, the dom0 sets up state with xenstored,
                    516: and is not notified when xenstored exits, leading to not recreating
                    517: the state when the new xenstored starts.  Until there's a mechanism to
                    518: make this work, one should not expect to be able to restart xenstored
                    519: (and thus xencommons).  There is currently no reason to expect that
                    520: this will get fixed any time soon.
                    521: 
1.127     gdt       522: ### No-longer needed advice about devices
                    523: 
                    524: The installation of NetBSD should already have created devices for xen
                    525: (xencons, xenevt, xsd_kva), but if they are not present, create them:
                    526: 
                    527:         cd /dev && sh MAKEDEV xen
                    528: 
1.41      gdt       529: anita (for testing NetBSD)
                    530: --------------------------
                    531: 
1.82      gdt       532: With the setup so far (assuming 4.2/xl), one should be able to run
                    533: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
                    534: root, because anita must create a domU):
                    535: 
                    536:         anita --vmm=xl test file:///usr/obj/i386/
                    537: 
                    538: Alternatively, one can use --vmm=xm to use xm-based domU creation
                    539: instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
                    540:     
1.40      gdt       541: Xen-specific NetBSD issues
                    542: --------------------------
                    543: 
                    544: There are (at least) two additional things different about NetBSD as a
                    545: dom0 kernel compared to hardware.
                    546: 
1.111     wiz       547: One is that the module ABI is different because some of the #defines
1.109     gdt       548: change, so one must build modules for Xen.  As of netbsd-7, the build
                    549: system does this automatically.  TODO: check this.  (Before building
                    550: Xen modules was added, it was awkward to use modules to the point
                    551: where it was considered that it did not work.)
1.40      gdt       552: 
                    553: The other difference is that XEN3_DOM0 does not have exactly the same
                    554: options as GENERIC.  While it is debatable whether or not this is a
                    555: bug, users should be aware of this and can simply add missing config
                    556: items if desired.
                    557: 
1.15      gdt       558: Updating NetBSD in a dom0
                    559: -------------------------
                    560: 
                    561: This is just like updating NetBSD on bare hardware, assuming the new
                    562: version supports the version of Xen you are running.  Generally, one
                    563: replaces the kernel and reboots, and then overlays userland binaries
                    564: and adjusts /etc.
                    565: 
                    566: Note that one must update both the non-Xen kernel typically used for
                    567: rescue purposes and the DOM0 kernel used with Xen.
                    568: 
1.55      gdt       569: Converting from grub to /boot
                    570: -----------------------------
                    571: 
                    572: These instructions were [TODO: will be] used to convert a system from
                    573: grub to /boot.  The system was originally installed in February of
                    574: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
                    575: over time.  Before these commands, it was running NetBSD 6 i386, Xen
                    576: 4.1 and grub, much like the message linked earlier in the grub
                    577: section.
                    578: 
1.111     wiz       579:         # Install MBR bootblocks on both disks. 
1.55      gdt       580:         fdisk -i /dev/rwd0d
                    581:         fdisk -i /dev/rwd1d
                    582:         # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
                    583:         installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
                    584:         installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
                    585:         # Install secondary boot loader
                    586:         cp -p /usr/mdec/boot /
1.111     wiz       587:         # Create boot.cfg following earlier guidance:
1.55      gdt       588:         menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
                    589:         menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=256M
                    590:         menu=GENERIC:boot
                    591:         menu=GENERIC single-user:boot -s
                    592:         menu=GENERIC.ok:boot netbsd.ok
                    593:         menu=GENERIC.ok single-user:boot netbsd.ok -s
                    594:         menu=Drop to boot prompt:prompt
                    595:         default=1
                    596:         timeout=30
                    597: 
                    598: TODO: actually do this and fix it if necessary.
1.22      gdt       599: 
1.102     gdt       600: Upgrading Xen versions
1.15      gdt       601: ---------------------
                    602: 
1.110     gdt       603: Minor version upgrades are trivial.  Just rebuild/replace the
                    604: xenkernel version and copy the new xen.gz to / (where /boot.cfg
                    605: references it), and reboot.
                    606: 
                    607: Major version upgrades are conceptually not difficult, but can run
                    608: into all the issues found when installing Xen.  Assuming migration
                    609: from 4.1 to 4.2, remove the xenkernel41 and xentools41 packages and
                    610: install the xenkernel42 and xentools42 packages.  Copy the 4.2 xen.gz
                    611: to /.
1.21      gdt       612: 
1.102     gdt       613: Ensure that the contents of /etc/rc.d/xen* are correct.  Specifically,
                    614: they must match the package you just installed and not be left over
                    615: from some previous installation.
                    616: 
                    617: Enable the correct set of daemons; see the configuring section above.
                    618: (Upgrading from 3.x to 4.x without doing this will result in a hang.)
                    619: 
                    620: Ensure that the domU config files are valid for the new version.
1.110     gdt       621: Specifically, for 4.x remove autorestart=True, and ensure that disks
                    622: are specified with numbers as the second argument, as the examples
                    623: above show, and not NetBSD device names.
1.15      gdt       624: 
1.97      gdt       625: Hardware known to work
                    626: ----------------------
                    627: 
                    628: Arguably, this section is misplaced, and there should be a page of
                    629: hardware that runs NetBSD/amd64 well, with the mostly-well-founded
                    630: assumption that NetBSD/xen runs fine on any modern hardware that
1.129     gdt       631: NetBSD/amd64 runs well on.  Until then, we give motherboard/CPU (and
                    632: sometimes RAM) pairs/triples to aid those choosing a motherboard.
                    633: Note that Xen systems usually do not run X, so a listing here does not
                    634: imply that X works at all.
1.97      gdt       635: 
                    636:         Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC
                    637:         Supermicro ??, Atom C2758 (8 core), 32 GiB ECC
                    638:         ASUS M5A78L-M/USB3 AM3+ microATX, AMD Piledriver X8 4000MHz, 16 GiB ECC
                    639: 
                    640: Older hardware:
                    641: 
1.98      gdt       642:         Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2
1.129     gdt       643:         INTEL DG33FB, "Intel(R) Core(TM)2 Duo CPU     E6850  @ 3.00GHz"
                    644:         INTEL DG33FB, "Intel(R) Core(TM)2 Duo CPU     E8400  @ 3.00GHz"
1.28      gdt       645: 
1.82      gdt       646: Running Xen under qemu
                    647: ----------------------
                    648: 
                    649: The astute reader will note that this section is somewhat twisted.
                    650: However, it can be useful to run Xen under qemu either because the
                    651: version of NetBSD as a dom0 does not run on the hardware in use, or to
                    652: generate automated test cases involving Xen.
                    653: 
1.84      gdt       654: In 2015-01, the following combination was reported to mostly work:
1.82      gdt       655: 
                    656:         host OS: NetBSD/amd64 6.1.4
                    657:         qemu: 2.2.0 from pkgsrc
                    658:         Xen kernel: xenkernel42-4.2.5nb1 from pkgsrc
                    659:         dom0 kernel: NetBSD/amd64 6.1.5
                    660:         Xen tools: xentools42-4.2.5 from pkgsrc
                    661: 
1.91      gdt       662: See [PR 47720](http://gnats.netbsd.org/47720) for a problem with dom0
                    663: shutdown.
1.84      gdt       664: 
1.28      gdt       665: Unprivileged domains (domU)
                    666: ===========================
                    667: 
                    668: This section describes general concepts about domUs.  It does not
1.33      gdt       669: address specific domU operating systems or how to install them.  The
                    670: config files for domUs are typically in /usr/pkg/etc/xen, and are
1.60      wiki      671: typically named so that the file name, domU name and the domU's host
1.33      gdt       672: name match.
                    673: 
1.111     wiz       674: The domU is provided with CPU and memory by Xen, configured by the
1.33      gdt       675: dom0.  The domU is provided with disk and network by the dom0,
                    676: mediated by Xen, and configured in the dom0.
                    677: 
                    678: Entropy in domUs can be an issue; physical disks and network are on
                    679: the dom0.  NetBSD's /dev/random system works, but is often challenged.
                    680: 
1.48      gdt       681: Config files
                    682: ------------
                    683: 
                    684: There is no good order to present config files and the concepts
                    685: surrounding what is being configured.  We first show an example config
                    686: file, and then in the various sections give details.
                    687: 
                    688: See (at least in xentools41) /usr/pkg/share/examples/xen/xmexample*,
                    689: for a large number of well-commented examples, mostly for running
                    690: GNU/Linux.
                    691: 
                    692: The following is an example minimal domain configuration file
                    693: "/usr/pkg/etc/xen/foo".  It is (with only a name change) an actual
                    694: known working config file on Xen 4.1 (NetBSD 5 amd64 dom0 and NetBSD 5
                    695: i386 domU).  The domU serves as a network file server.
                    696: 
                    697:         # -*- mode: python; -*-
                    698: 
                    699:         kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
                    700:         memory = 1024
                    701:         vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
                    702:         disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
                    703:                  'file:/n0/xen/foo-wd1,0x1,w' ]
                    704: 
                    705: The domain will have the same name as the file.  The kernel has the
                    706: host/domU name in it, so that on the dom0 one can update the various
                    707: domUs independently.  The vif line causes an interface to be provided,
                    708: with a specific mac address (do not reuse MAC addresses!), in bridge
                    709: mode.  Two disks are provided, and they are both writable; the bits
                    710: are stored in files and Xen attaches them to a vnd(4) device in the
1.111     wiz       711: dom0 on domain creation.  The system treats xbd0 as the boot device
1.48      gdt       712: without needing explicit configuration.
                    713: 
                    714: By default xm looks for domain config files in /usr/pkg/etc/xen.  Note
                    715: that "xm create" takes the name of a config file, while other commands
                    716: take the name of a domain.  To create the domain, connect to the
                    717: console, create the domain while attaching the console, shutdown the
                    718: domain, and see if it has finished stopping, do (or xl with Xen >=
                    719: 4.2):
                    720: 
                    721:         xm create foo
                    722:         xm console foo
                    723:         xm create -c foo
                    724:         xm shutdown foo
1.90      gdt       725:         xm list
1.48      gdt       726: 
                    727: Typing ^] will exit the console session.  Shutting down a domain is
                    728: equivalent to pushing the power button; a NetBSD domU will receive a
                    729: power-press event and do a clean shutdown.  Shutting down the dom0
                    730: will trigger controlled shutdowns of all configured domUs.
                    731: 
                    732: domU kernels
                    733: ------------
                    734: 
                    735: On a physical computer, the BIOS reads sector 0, and a chain of boot
                    736: loaders finds and loads a kernel.  Normally this comes from the root
1.111     wiz       737: file system.  With Xen domUs, the process is totally different.  The
1.48      gdt       738: normal path is for the domU kernel to be a file in the dom0's
1.111     wiz       739: file system.  At the request of the dom0, Xen loads that kernel into a
1.48      gdt       740: new domU instance and starts execution.  While domU kernels can be
                    741: anyplace, reasonable places to store domU kernels on the dom0 are in /
                    742: (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
                    743: config files), or in /u0/xen (where the vdisks are).
                    744: 
1.59      gdt       745: Note that loading the domU kernel from the dom0 implies that boot
                    746: blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
1.48      gdt       747: See the VPS section near the end for discussion of alternate ways to
                    748: obtain domU kernels.
                    749: 
1.33      gdt       750: CPU and memory
                    751: --------------
                    752: 
1.48      gdt       753: A domain is provided with some number of vcpus, less than the number
1.111     wiz       754: of CPUs seen by the hypervisor.  (For a dom0, this is controlled by
1.48      gdt       755: the boot argument "dom0_max_vcpus=1".)  For a domU, it is controlled
                    756: from the config file by the "vcpus = N" directive.
                    757: 
                    758: A domain is provided with memory; this is controlled in the config
                    759: file by "memory = N" (in megabytes).  In the straightforward case, the
                    760: sum of the the memory allocated to the dom0 and all domUs must be less
1.33      gdt       761: than the available memory.
                    762: 
                    763: Xen also provides a "balloon" driver, which can be used to let domains
                    764: use more memory temporarily.  TODO: Explain better, and explain how
                    765: well it works with NetBSD.
1.28      gdt       766: 
                    767: Virtual disks
                    768: -------------
                    769: 
1.33      gdt       770: With the file/vnd style, typically one creates a directory,
                    771: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
                    772: domUs.  Then, for each domU disk, one writes zeros to a file that then
                    773: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
                    774: for the first virtual disk for the domU called foo.  Writing zeros to
                    775: the file serves two purposes.  One is that preallocating the contents
                    776: improves performance.  The other is that vnd on sparse files has
                    777: failed to work.  TODO: give working/notworking NetBSD versions for
1.127     gdt       778: sparse vnd and gnats reference.  Note that the use of file/vnd for Xen
                    779: is not really different than creating a file-backed virtual disk for
                    780: some other purpose, except that xentools handles the vnconfig
                    781: commands.  To create an empty 4G virtual disk, simply do
1.39      gdt       782: 
                    783:         dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
1.33      gdt       784: 
1.89      gdt       785: Do not use qemu-img-xen, because this will create sparse file.  There
                    786: have been recent (2015) reports of sparse vnd(4) devices causing
                    787: lockups, but there is apparently no PR.
                    788: 
1.33      gdt       789: With the lvm style, one creates logical devices.  They are then used
1.48      gdt       790: similarly to vnds.  TODO: Add an example with lvm.
                    791: 
                    792: In domU config files, the disks are defined as a sequence of 3-tuples.
                    793: The first element is "method:/path/to/disk".  Common methods are
                    794: "file:" for file-backed vnd. and "phy:" for something that is already
                    795: a (TODO: character or block) device.
                    796: 
                    797: The second element is an artifact of how virtual disks are passed to
                    798: Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
                    799: are given a device name to associate with the disk, and values like
                    800: "hda1" or "sda1" are common.  In a NetBSD domU, the first disk appears
                    801: as xbd0, the second as xbd1, and so on.  However, xm/xl demand a
                    802: second argument.  The name given is converted to a major/minor by
1.49      gdt       803: calling stat(2) on the name in /dev and this is passed to the domU.
                    804: In the general case, the dom0 and domU can be different operating
1.48      gdt       805: systems, and it is an unwarranted assumption that they have consistent
                    806: numbering in /dev, or even that the dom0 OS has a /dev.  With NetBSD
                    807: as both dom0 and domU, using values of 0x0 for the first disk and 0x1
1.49      gdt       808: for the second works fine and avoids this issue.  For a GNU/Linux
                    809: guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
                    810: /dev/hda1.
1.48      gdt       811: 
                    812: The third element is "w" for writable disks, and "r" for read-only
                    813: disks.
1.28      gdt       814: 
1.127     gdt       815: Note that NetBSD by default creates only vnd[0123].  If you need more
                    816: than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the
                    817: dom0.
                    818: 
                    819: Note that NetBSD by default creates only xbd[0123].  If you need more
                    820: virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU.
                    821: 
1.28      gdt       822: Virtual Networking
                    823: ------------------
                    824: 
1.111     wiz       825: Xen provides virtual Ethernets, each of which connects the dom0 and a
1.46      gdt       826: domU.  For each virtual network, there is an interface "xvifN.M" in
                    827: the dom0, and in domU index N, a matching interface xennetM (NetBSD
                    828: name).  The interfaces behave as if there is an Ethernet with two
1.111     wiz       829: adapters connected.  From this primitive, one can construct various
1.46      gdt       830: configurations.  We focus on two common and useful cases for which
                    831: there are existing scripts: bridging and NAT.
1.28      gdt       832: 
1.48      gdt       833: With bridging (in the example above), the domU perceives itself to be
                    834: on the same network as the dom0.  For server virtualization, this is
                    835: usually best.  Bridging is accomplished by creating a bridge(4) device
                    836: and adding the dom0's physical interface and the various xvifN.0
                    837: interfaces to the bridge.  One specifies "bridge=bridge0" in the domU
                    838: config file.  The bridge must be set up already in the dom0; an
                    839: example /etc/ifconfig.bridge0 is:
1.46      gdt       840: 
                    841:         create
                    842:         up
                    843:         !brconfig bridge0 add wm0
1.28      gdt       844: 
                    845: With NAT, the domU perceives itself to be behind a NAT running on the
                    846: dom0.  This is often appropriate when running Xen on a workstation.
1.48      gdt       847: TODO: NAT appears to be configured by "vif = [ '' ]".
1.28      gdt       848: 
1.49      gdt       849: The MAC address specified is the one used for the interface in the new
1.53      gdt       850: domain.  The interface in dom0 will use this address XOR'd with
1.49      gdt       851: 00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
                    852: 
1.33      gdt       853: Sizing domains
                    854: --------------
                    855: 
                    856: Modern x86 hardware has vast amounts of resources.  However, many
                    857: virtual servers can function just fine on far less.  A system with
                    858: 256M of RAM and a 4G disk can be a reasonable choice.  Note that it is
                    859: far easier to adjust virtual resources than physical ones.  For
                    860: memory, it's just a config file edit and a reboot.  For disk, one can
                    861: create a new file and vnconfig it (or lvm), and then dump/restore,
                    862: just like updating physical disks, but without having to be there and
                    863: without those pesky connectors.
                    864: 
1.48      gdt       865: Starting domains automatically
                    866: ------------------------------
1.28      gdt       867: 
1.48      gdt       868: To start domains foo at bar at boot and shut them down cleanly on dom0
                    869: shutdown, in rc.conf add:
1.28      gdt       870: 
1.48      gdt       871:         xendomains="foo bar"
1.28      gdt       872: 
1.111     wiz       873: Note that earlier versions of the xentools41 xendomains rc.d script
                    874: used xl, when one should use xm with 4.1.
1.28      gdt       875: 
                    876: Creating specific unprivileged domains (domU)
                    877: =============================================
1.14      gdt       878: 
                    879: Creating domUs is almost entirely independent of operating system.  We
1.49      gdt       880: have already presented the basics of config files.  Note that you must
                    881: have already completed the dom0 setup so that "xl list" (or "xm list")
                    882: works.
1.14      gdt       883: 
                    884: Creating an unprivileged NetBSD domain (domU)
                    885: ---------------------------------------------
1.1       mspo      886: 
1.49      gdt       887: See the earlier config file, and adjust memory.  Decide on how much
                    888: storage you will provide, and prepare it (file or lvm).
                    889: 
1.111     wiz       890: While the kernel will be obtained from the dom0 file system, the same
1.49      gdt       891: file should be present in the domU as /netbsd so that tools like
                    892: savecore(8) can work.   (This is helpful but not necessary.)
                    893: 
                    894: The kernel must be specifically for Xen and for use as a domU.  The
                    895: i386 and amd64 provide the following kernels:
                    896: 
                    897:         i386 XEN3_DOMU
                    898:         i386 XEN3PAE_DOMU
1.95      gdt       899:         amd64 XEN3_DOMU
1.5       mspo      900: 
1.49      gdt       901: Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must
                    902: use the PAE version of the i386 kernel.
                    903: 
                    904: This will boot NetBSD, but this is not that useful if the disk is
                    905: empty.  One approach is to unpack sets onto the disk outside of xen
                    906: (by mounting it, just as you would prepare a physical disk for a
                    907: system you can't run the installer on).
                    908: 
                    909: A second approach is to run an INSTALL kernel, which has a miniroot
                    910: and can load sets from the network.  To do this, copy the INSTALL
                    911: kernel to / and change the kernel line in the config file to:
1.5       mspo      912: 
1.49      gdt       913:         kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
1.5       mspo      914: 
1.49      gdt       915: Then, start the domain as "xl create -c configname".
1.1       mspo      916: 
1.49      gdt       917: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
                    918: line should be used in the config file.
1.1       mspo      919: 
1.3       mspo      920:     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
1.1       mspo      921: 
                    922: After booting the domain, the option to install via CDROM may be
1.49      gdt       923: selected.  The CDROM device should be changed to `xbd1d`.
1.1       mspo      924: 
1.49      gdt       925: Once done installing, "halt -p" the new domain (don't reboot or halt,
                    926: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
                    927: config file), switch the config file back to the XEN3_DOMU kernel,
                    928: and start the new domain again. Now it should be able to use "root on
                    929: xbd0a" and you should have a, functional NetBSD domU.
1.1       mspo      930: 
1.49      gdt       931: TODO: check if this is still accurate.
1.1       mspo      932: When the new domain is booting you'll see some warnings about *wscons*
                    933: and the pseudo-terminals. These can be fixed by editing the files
1.5       mspo      934: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
                    935: `/etc/ttys`, except *console*, like this:
1.1       mspo      936: 
1.3       mspo      937:     console "/usr/libexec/getty Pc"         vt100   on secure
                    938:     ttyE0   "/usr/libexec/getty Pc"         vt220   off secure
                    939:     ttyE1   "/usr/libexec/getty Pc"         vt220   off secure
                    940:     ttyE2   "/usr/libexec/getty Pc"         vt220   off secure
                    941:     ttyE3   "/usr/libexec/getty Pc"         vt220   off secure
1.1       mspo      942: 
1.5       mspo      943: Finally, all screens must be commented out from `/etc/wscons.conf`.
1.1       mspo      944: 
                    945: It is also desirable to add
                    946: 
1.49      gdt       947:         powerd=YES
1.1       mspo      948: 
1.5       mspo      949: in rc.conf. This way, the domain will be properly shut down if
1.53      gdt       950: `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
1.1       mspo      951: 
1.92      gdt       952: It is not strictly necessary to have a kernel (as /netbsd) in the domU
1.111     wiz       953: file system.  However, various programs (e.g. netstat) will use that
1.92      gdt       954: kernel to look up symbols to read from kernel virtual memory.  If
                    955: /netbsd is not the running kernel, those lookups will fail.  (This is
                    956: not really a Xen-specific issue, but because the domU kernel is
                    957: obtained from the dom0, it is far more likely to be out of sync or
                    958: missing with Xen.)
                    959: 
1.14      gdt       960: Creating an unprivileged Linux domain (domU)
1.5       mspo      961: --------------------------------------------
1.1       mspo      962: 
                    963: Creating unprivileged Linux domains isn't much different from
                    964: unprivileged NetBSD domains, but there are some details to know.
                    965: 
                    966: First, the second parameter passed to the disk declaration (the '0x1' in
                    967: the example below)
                    968: 
1.3       mspo      969:     disk = [ 'phy:/dev/wd0e,0x1,w' ]
1.1       mspo      970: 
                    971: does matter to Linux. It wants a Linux device number here (e.g. 0x300
1.49      gdt       972: for hda).  Linux builds device numbers as: (major \<\< 8 + minor).
                    973: So, hda1 which has major 3 and minor 1 on a Linux system will have
                    974: device number 0x301.  Alternatively, devices names can be used (hda,
                    975: hdb, ...)  as xentools has a table to map these names to devices
                    976: numbers.  To export a partition to a Linux guest we can use:
1.1       mspo      977: 
1.49      gdt       978:         disk = [ 'phy:/dev/wd0e,0x300,w' ]
                    979:         root = "/dev/hda1 ro"
1.1       mspo      980: 
                    981: and it will appear as /dev/hda on the Linux system, and be used as root
                    982: partition.
                    983: 
1.49      gdt       984: To install the Linux system on the partition to be exported to the
                    985: guest domain, the following method can be used: install
                    986: sysutils/e2fsprogs from pkgsrc.  Use mke2fs to format the partition
                    987: that will be the root partition of your Linux domain, and mount it.
                    988: Then copy the files from a working Linux system, make adjustments in
                    989: `/etc` (fstab, network config).  It should also be possible to extract
                    990: binary packages such as .rpm or .deb directly to the mounted partition
                    991: using the appropriate tool, possibly running under NetBSD's Linux
1.111     wiz       992: emulation.  Once the file system has been populated, umount it.  If
                    993: desirable, the file system can be converted to ext3 using tune2fs -j.
1.49      gdt       994: It should now be possible to boot the Linux guest domain, using one of
                    995: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
1.1       mspo      996: 
1.111     wiz       997: To get the Linux console right, you need to add:
1.1       mspo      998: 
1.3       mspo      999:     extra = "xencons=tty1"
1.1       mspo     1000: 
1.111     wiz      1001: to your configuration since not all Linux distributions auto-attach a
1.1       mspo     1002: tty to the xen console.
                   1003: 
1.14      gdt      1004: Creating an unprivileged Solaris domain (domU)
1.5       mspo     1005: ----------------------------------------------
1.1       mspo     1006: 
1.50      gdt      1007: See possibly outdated
                   1008: [Solaris domU instructions](/ports/xen/howto-solaris/).
1.5       mspo     1009: 
1.1       mspo     1010: 
1.52      gdt      1011: PCI passthrough: Using PCI devices in guest domains
                   1012: ---------------------------------------------------
1.1       mspo     1013: 
1.53      gdt      1014: The dom0 can give other domains access to selected PCI
1.52      gdt      1015: devices. This can allow, for example, a non-privileged domain to have
                   1016: access to a physical network interface or disk controller.  However,
                   1017: keep in mind that giving a domain access to a PCI device most likely
                   1018: will give the domain read/write access to the whole physical memory,
                   1019: as PCs don't have an IOMMU to restrict memory access to DMA-capable
1.53      gdt      1020: device.  Also, it's not possible to export ISA devices to non-dom0
1.52      gdt      1021: domains, which means that the primary VGA adapter can't be exported.
                   1022: A guest domain trying to access the VGA registers will panic.
                   1023: 
1.53      gdt      1024: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
1.52      gdt      1025: not been ported to later versions at this time.
                   1026: 
                   1027: For a PCI device to be exported to a domU, is has to be attached to
                   1028: the "pciback" driver in dom0.  Devices passed to the dom0 via the
                   1029: pciback.hide boot parameter will attach to "pciback" instead of the
                   1030: usual driver.  The list of devices is specified as "(bus:dev.func)",
1.5       mspo     1031: where bus and dev are 2-digit hexadecimal numbers, and func a
                   1032: single-digit number:
1.1       mspo     1033: 
1.52      gdt      1034:         pciback.hide=(00:0a.0)(00:06.0)
1.1       mspo     1035: 
1.52      gdt      1036: pciback devices should show up in the dom0's boot messages, and the
1.5       mspo     1037: devices should be listed in the `/kern/xen/pci` directory.
1.1       mspo     1038: 
1.52      gdt      1039: PCI devices to be exported to a domU are listed in the "pci" array of
                   1040: the domU's config file, with the format "0000:bus:dev.func".
1.1       mspo     1041: 
1.52      gdt      1042:         pci = [ '0000:00:06.0', '0000:00:0a.0' ]
1.1       mspo     1043: 
1.52      gdt      1044: In the domU an "xpci" device will show up, to which one or more pci
1.111     wiz      1045: buses will attach.  Then the PCI drivers will attach to PCI buses as
1.52      gdt      1046: usual.  Note that the default NetBSD DOMU kernels do not have "xpci"
                   1047: or any PCI drivers built in by default; you have to build your own
                   1048: kernel to use PCI devices in a domU.  Here's a kernel config example;
                   1049: note that only the "xpci" lines are unusual.
                   1050: 
                   1051:         include         "arch/i386/conf/XEN3_DOMU"
                   1052: 
1.111     wiz      1053:         # Add support for PCI buses to the XEN3_DOMU kernel
1.52      gdt      1054:         xpci* at xenbus ?
                   1055:         pci* at xpci ?
                   1056: 
                   1057:         # PCI USB controllers
                   1058:         uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
                   1059: 
                   1060:         # USB bus support
                   1061:         usb*    at uhci?
                   1062: 
                   1063:         # USB Hubs
                   1064:         uhub*   at usb?
                   1065:         uhub*   at uhub? port ? configuration ? interface ?
                   1066: 
                   1067:         # USB Mass Storage
                   1068:         umass*  at uhub? port ? configuration ? interface ?
                   1069:         wd*     at umass?
                   1070:         # SCSI controllers
                   1071:         ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
                   1072: 
                   1073:         # SCSI bus support (for both ahc and umass)
                   1074:         scsibus* at scsi?
                   1075: 
                   1076:         # SCSI devices
                   1077:         sd*     at scsibus? target ? lun ?      # SCSI disk drives
                   1078:         cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
1.1       mspo     1079: 
                   1080: 
1.28      gdt      1081: NetBSD as a domU in a VPS
                   1082: =========================
                   1083: 
                   1084: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
                   1085: hardware.  This section explains how to deal with Xen in a domU as a
                   1086: virtual private server where you do not control or have access to the
1.70      gdt      1087: dom0.  This is not intended to be an exhaustive list of VPS providers;
                   1088: only a few are mentioned that specifically support NetBSD.
1.28      gdt      1089: 
1.52      gdt      1090: VPS operators provide varying degrees of access and mechanisms for
                   1091: configuration.  The big issue is usually how one controls which kernel
1.111     wiz      1092: is booted, because the kernel is nominally in the dom0 file system (to
                   1093: which VPS users do not normally have access).  A second issue is how
1.70      gdt      1094: to install NetBSD.
1.52      gdt      1095: A VPS user may want to compile a kernel for security updates, to run
                   1096: npf, run IPsec, or any other reason why someone would want to change
                   1097: their kernel.
                   1098: 
1.111     wiz      1099: One approach is to have an administrative interface to upload a kernel,
1.68      gdt      1100: or to select from a prepopulated list.  Other approaches are pygrub
1.59      gdt      1101: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
1.111     wiz      1102: kernel from the domU file system.  This is closer to a regular physical
1.59      gdt      1103: computer, where someone who controls a machine can replace the kernel.
1.52      gdt      1104: 
1.74      gdt      1105: A second issue is multiple CPUs.  With NetBSD 6, domUs support
                   1106: multiple vcpus, and it is typical for VPS providers to enable multiple
                   1107: CPUs for NetBSD domUs.
                   1108: 
1.68      gdt      1109: pygrub
1.59      gdt      1110: -------
1.52      gdt      1111: 
1.111     wiz      1112: pygrub runs in the dom0 and looks into the domU file system.  This
                   1113: implies that the domU must have a kernel in a file system in a format
1.68      gdt      1114: known to pygrub.  As of 2014, pygrub seems to be of mostly historical
                   1115: interest.
1.52      gdt      1116: 
1.59      gdt      1117: pvgrub
                   1118: ------
                   1119: 
                   1120: pvgrub is a version of grub that uses PV operations instead of BIOS
                   1121: calls.  It is booted from the dom0 as the domU kernel, and then reads
1.111     wiz      1122: /grub/menu.lst and loads a kernel from the domU file system.
1.59      gdt      1123: 
1.70      gdt      1124: [Panix](http://www.panix.com/) lets users use pvgrub.  Panix reports
1.71      gdt      1125: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
                   1126: (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
1.70      gdt      1127: page](http://www.panix.com/v-colo/grub.html), which describes only
1.74      gdt      1128: Linux but should be updated to cover NetBSD :-).
1.70      gdt      1129: 
                   1130: [prgmr.com](http://prgmr.com/) also lets users with pvgrub to boot
                   1131: their own kernel.  See then [prgmr.com NetBSD
1.74      gdt      1132: HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU)
                   1133: (which is in need of updating).
1.59      gdt      1134: 
1.70      gdt      1135: It appears that [grub's FFS
                   1136: code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
                   1137: does not support all aspects of modern FFS, but there are also reports
1.72      gdt      1138: that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT
1.70      gdt      1139: partition for the kernel with the intent that grub can understand it,
                   1140: which leads to /netbsd not being the actual kernel.  One must remember
1.111     wiz      1141: to update the special boot partition.
1.59      gdt      1142: 
                   1143: Amazon
                   1144: ------
                   1145: 
1.95      gdt      1146: See the [Amazon EC2 page](../amazon_ec2/).
1.44      gdt      1147: 
                   1148: Using npf
                   1149: ---------
                   1150: 
1.81      gdt      1151: In standard kernels, npf is a module, and thus cannot be loaded in a
1.44      gdt      1152: DOMU kernel.
                   1153: 
1.95      gdt      1154: TODO: Explain how to compile npf into a custom kernel, answering (but
                   1155: note that the problem was caused by not booting the right kernel)
                   1156: [this email to
                   1157: netbsd-users](http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html).
1.65      gdt      1158: 
                   1159: TODO items for improving NetBSD/xen
                   1160: ===================================
                   1161: 
1.93      gdt      1162: * Make the NetBSD dom0 kernel work with SMP.
                   1163: * Test the Xen 4.5 packages adequately to be able to recommend them as
                   1164:   the standard approach.
                   1165: * Get PCI passthrough working on Xen 4.5
1.65      gdt      1166: * Get pvgrub into pkgsrc, either via xentools or separately.
                   1167: * grub
1.70      gdt      1168:   * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
1.66      gdt      1169:     fragsize/blocksize (UFS2 support may be present; the point is to
1.111     wiz      1170:     make it so that with any UFS1/UFS2 file system setup that works
1.66      gdt      1171:     with NetBSD grub will also work).
1.70      gdt      1172:     See [pkg/40258](http://gnats.netbsd.org/40258).
1.65      gdt      1173:   * Push patches upstream.
                   1174:   * Get UFS2 patches into pvgrub.
                   1175: * Add support for PV ops to a version of /boot, and make it usable as
                   1176:   a kernel in Xen, similar to pvgrub.
1.93      gdt      1177: * Solve somehow the issue with modules for GENERIC not being loadable
                   1178:   in a Xen dom0 or domU kernel.
                   1179: 
                   1180: Random pointers
                   1181: ===============
                   1182: 
1.117     gdt      1183: This section contains links from elsewhere not yet integrated into the
                   1184: HOWTO, and other guides.
1.93      gdt      1185: 
                   1186: * http://www.lumbercartel.ca/library/xen/
                   1187: * http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html
1.117     gdt      1188: * https://gmplib.org/~tege/xen.html

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