Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.120

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  It is no longer maintained by Xen, and the last applied security patch was in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

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