1: Introduction
2: ============
3:
4: [![[Xen
5: screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](../../gallery/in-Action/hubertf-xen.png)
6:
7: Xen is a virtual machine monitor or hypervisor for x86 hardware
8: (i686-class or higher), which supports running multiple guest
9: operating systems on a single physical machine. With Xen, one uses
10: the Xen kernel to control the CPU, memory and console, a dom0
11: operating system which mediates access to other hardware (e.g., disks,
12: network, USB), and one or more domU operating systems which operate in
13: an unprivileged virtualized environment. IO requests from the domU
14: systems are forwarded by the hypervisor (Xen) to the dom0 to be
15: fulfilled.
16:
17: Xen supports two styles of guests. The original is Para-Virtualized
18: (PV) which means that the guest OS does not attempt to access hardware
19: directly, but instead makes hypercalls to the hypervisor. This is
20: analogous to a user-space program making system calls. (The dom0
21: operating system uses PV calls for some functions, such as updating
22: memory mapping page tables, but has direct hardware access for disk
23: and network.) PV guests must be specifically coded for Xen.
24:
25: The more recent style is HVM, which means that the guest does not have
26: code for Xen and need not be aware that it is running under Xen.
27: Attempts to access hardware registers are trapped and emulated. This
28: style is less efficient but can run unmodified guests.
29:
30: Generally any amd64 machine will work with Xen and PV guests. In
31: theory i386 computers without amd64 support can be used for Xen <=
32: 4.2, but we have no recent reports of this working (this is a hint).
33: For HVM guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT
34: (amd64) is needed; "cpuctl identify 0" will show this. TODO: Clean up
35: and check the above features.
36:
37: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
38: The dom0 can start one or more domUs. (Booting is explained in detail
39: in the dom0 section.)
40:
41: NetBSD supports Xen in that it can serve as dom0, be used as a domU,
42: and that Xen kernels and tools are available in pkgsrc. This HOWTO
43: attempts to address both the case of running a NetBSD dom0 on hardware
44: and running domUs under it (NetBSD and other), and also running NetBSD
45: as a domU in a VPS.
46:
47: Some versions of Xen support "PCI passthrough", which means that
48: specific PCI devices can be made available to a specific domU instead
49: of the dom0. This can be useful to let a domU run X11, or access some
50: network interface or other peripheral.
51:
52: Prerequisites
53: -------------
54:
55: Installing NetBSD/Xen is not extremely difficult, but it is more
56: complex than a normal installation of NetBSD.
57: In general, this HOWTO is occasionally overly restrictive about how
58: things must be done, guiding the reader to stay on the established
59: path when there are no known good reasons to stray.
60:
61: This HOWTO presumes a basic familiarity with the Xen system
62: architecture. This HOWTO presumes familiarity with installing NetBSD
63: on i386/amd64 hardware and installing software from pkgsrc.
64: See also the [Xen website](http://www.xenproject.org/).
65:
66: History
67: -------
68:
69: NetBSD used to support Xen2; this has been removed.
70:
71: Before NetBSD's native bootloader could support Xen, the use of
72: grub was recommended. If necessary, see the
73: [old grub information](/ports/xen/howto-grub/).
74:
75: Versions of Xen and NetBSD
76: ==========================
77:
78: Most of the installation concepts and instructions are independent
79: of Xen version and NetBSD version. This section gives advice on
80: which version to choose. Versions not in pkgsrc and older unsupported
81: versions of NetBSD are intentionally ignored.
82:
83: Xen
84: ---
85:
86: In NetBSD, xen is provided in pkgsrc, via matching pairs of packages
87: xenkernel and xentools. We will refer only to the kernel versions,
88: but note that both packages must be installed together and must have
89: matching versions.
90:
91: xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3. These no longer
92: receive security patches and should not be used. Xen 3.1 supports PCI
93: passthrough. Xen 3.1 supports non-PAE on i386.
94:
95: xenkernel41 provides Xen 4.1. This is no longer maintained by Xen,
96: but as of 2014-12 receives backported security patches. It is a
97: reasonable although trailing-edge choice.
98:
99: xenkernel42 provides Xen 4.2. This is maintained by Xen, but old as
100: of 2014-12.
101:
102: Ideally newer versions of Xen will be added to pkgsrc.
103:
104: Note that NetBSD support is called XEN3. It works with 3.1 through
105: 4.2 because the hypercall interface has been stable.
106:
107: Xen command program
108: -------------------
109:
110: Early Xen used a program called "xm" to manipulate the system from the
111: dom0. Starting in 4.1, a replacement program with similar behavior
112: called "xl" is provided. In 4.2 and later, "xl" is preferred. 4.4 is
113: the last version that has "xm".
114:
115: NetBSD
116: ------
117:
118: The netbsd-5, netbsd-6, netbsd-7, and -current branches are all
119: reasonable choices, with more or less the same considerations for
120: non-Xen use. Therefore, netbsd-6 is recommended as the stable version
121: of the most recent release for production use. For those wanting to
122: learn Xen or without production stability concerns, netbsd-7 is likely
123: most appropriate.
124:
125: As of NetBSD 6, a NetBSD domU will support multiple vcpus. There is
126: no SMP support for NetBSD as dom0. (The dom0 itself doesn't really
127: need SMP; the lack of support is really a problem when using a dom0 as
128: a normal computer.)
129:
130: Architecture
131: ------------
132:
133: Xen itself can run on i386 or amd64 machines. (Practically, almost
134: any computer where one would want to run Xen supports amd64.) If
135: using an i386 NetBSD kernel for the dom0, PAE is required (PAE
136: versions are built by default). While i386 dom0 works fine, amd64 is
137: recommended as more normal.
138:
139: Xen 4.2 is the last version to support i386 as a host. TODO: Clarify
140: if this is about the CPU having to be amd64, or about the dom0 kernel
141: having to be amd64.
142:
143: One can then run i386 domUs and amd64 domUs, in any combination. If
144: running an i386 NetBSD kernel as a domU, the PAE version is required.
145: (Note that emacs (at least) fails if run on i386 with PAE when built
146: without, and vice versa, presumably due to bugs in the undump code.)
147:
148: Recommendation
149: --------------
150:
151: Therefore, this HOWTO recommends running xenkernel42 (and xentools42),
152: xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the
153: dom0. Either the i386 or amd64 of NetBSD may be used as domUs.
154:
155: Build problems
156: --------------
157:
158: Ideally, all versions of Xen in pkgsrc would build on all versions of
159: NetBSD on both i386 and amd64. However, that isn't the case. Besides
160: aging code and aging compilers, qemu (included in xentools for HVM
161: support) is difficult to build. The following are known to fail:
162:
163: xenkernel3 netbsd-6 i386
164: xentools42 netbsd-6 i386
165:
166: The following are known to work:
167:
168: xenkernel41 netbsd-5 amd64
169: xentools41 netbsd-5 amd64
170: xenkernel41 netbsd-6 i386
171: xentools41 netbsd-6 i386
172:
173: NetBSD as a dom0
174: ================
175:
176: NetBSD can be used as a dom0 and works very well. The following
177: sections address installation, updating NetBSD, and updating Xen.
178: Note that it doesn't make sense to talk about installing a dom0 OS
179: without also installing Xen itself. We first address installing
180: NetBSD, which is not yet a dom0, and then adding Xen, pivoting the
181: NetBSD install to a dom0 install by just changing the kernel and boot
182: configuration.
183:
184: Styles of dom0 operation
185: ------------------------
186:
187: There are two basic ways to use Xen. The traditional method is for
188: the dom0 to do absolutely nothing other than providing support to some
189: number of domUs. Such a system was probably installed for the sole
190: purpose of hosting domUs, and sits in a server room on a UPS.
191:
192: The other way is to put Xen under a normal-usage computer, so that the
193: dom0 is what the computer would have been without Xen, perhaps a
194: desktop or laptop. Then, one can run domUs at will. Purists will
195: deride this as less secure than the previous approach, and for a
196: computer whose purpose is to run domUs, they are right. But Xen and a
197: dom0 (without domUs) is not meaingfully less secure than the same
198: things running without Xen. One can boot Xen or boot regular NetBSD
199: alternately with little problems, simply refraining from starting the
200: Xen daemons when not running Xen.
201:
202: Note that NetBSD as dom0 does not support multiple CPUs. This will
203: limit the performance of the Xen/dom0 workstation approach.
204:
205: Installation of NetBSD
206: ----------------------
207:
208: First,
209: [install NetBSD/amd64](/guide/inst/)
210: just as you would if you were not using Xen.
211: However, the partitioning approach is very important.
212:
213: If you want to use RAIDframe for the dom0, there are no special issues
214: for Xen. Typically one provides RAID storage for the dom0, and the
215: domU systems are unaware of RAID. The 2nd-stage loader bootxx_* skips
216: over a RAID1 header to find /boot from a filesystem within a RAID
217: partition; this is no different when booting Xen.
218:
219: There are 4 styles of providing backing storage for the virtual disks
220: used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN,
221:
222: With raw partitions, one has a disklabel (or gpt) partition sized for
223: each virtual disk to be used by the domU. (If you are able to predict
224: how domU usage will evolve, please add an explanation to the HOWTO.
225: Seriously, needs tend to change over time.)
226:
227: One can use [lvm(8)](/guide/lvm/) to create logical devices to use
228: for domU disks. This is almost as efficient as raw disk partitions
229: and more flexible. Hence raw disk partitions should typically not
230: be used.
231:
232: One can use files in the dom0 filesystem, typically created by dd'ing
233: /dev/zero to create a specific size. This is somewhat less efficient,
234: but very convenient, as one can cp the files for backup, or move them
235: between dom0 hosts.
236:
237: Finally, in theory one can place the files backing the domU disks in a
238: SAN. (This is an invitation for someone who has done this to add a
239: HOWTO page.)
240:
241: Installation of Xen
242: -------------------
243:
244: In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from
245: pkgsrc (or another matching pair).
246: See [the pkgsrc
247: documentation](http://www.NetBSD.org/docs/pkgsrc/) for help with pkgsrc.
248:
249: For Xen 3.1, support for HVM guests is in sysutils/xentool3-hvm. More
250: recent versions have HVM support integrated in the main xentools
251: package. It is entirely reasonable to run only PV guests.
252:
253: Next you need to install the selected Xen kernel itself, which is
254: installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz". Copy it to /.
255: For debugging, one may copy xen-debug.gz; this is conceptually similar
256: to DIAGNOSTIC and DEBUG in NetBSD. xen-debug.gz is basically only
257: useful with a serial console. Then, place a NetBSD XEN3_DOM0 kernel
258: in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
259: of a NetBSD build. Both xen and NetBSD may be left compressed. (If
260: using i386, use releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.)
261:
262: In a dom0 kernel, kernfs is mandatory for xend to comunicate with the
263: kernel, so ensure that /kern is in fstab.
264:
265: Because you already installed NetBSD, you have a working boot setup
266: with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
267: beginning of your root filesystem, /boot present, and likely
268: /boot.cfg. (If not, fix before continuing!)
269:
270: See boot.cfg(5) for an example. The basic line is
271:
272: menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
273:
274: which specifies that the dom0 should have 256M, leaving the rest to be
275: allocated for domUs. In an attempt to add performance, one can also
276: add
277:
278: dom0_max_vcpus=1 dom0_vcpus_pin
279:
280: to force only one vcpu to be provided (since NetBSD dom0 can't use
281: more) and to pin that vcpu to a physical cpu. TODO: benchmark this.
282:
283: As with non-Xen systems, you should have a line to boot /netbsd (a
284: kernel that works without Xen) and fallback versions of the non-Xen
285: kernel, Xen, and the dom0 kernel.
286:
287: The [HowTo on Installing into
288: RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
289: explains how to set up booting a dom0 with Xen using grub with
290: NetBSD's RAIDframe. (This is obsolete with the use of NetBSD's native
291: boot.)
292:
293: Configuring Xen
294: ---------------
295:
296: Now, you have a system that will boot Xen and the dom0 kernel, and
297: just run the dom0 kernel. There will be no domUs, and none can be
298: started because you still have to configure the dom0 tools. The
299: daemons which should be run vary with Xen version and with whether one
300: is using xm or xl. Note that xend is for supporting "xm", and should
301: only be used if you plan on using "xm". Do NOT enable xend if you
302: plan on using "xl" as it will cause problems.
303:
304: TODO: Give 3.1 advice (or remove it from pkgsrc).
305:
306: For 3.3 (and thus xm), add to rc.conf (but note that you should have
307: installed 4.1 or 4.2):
308:
309: xend=YES
310: xenbackendd=YES
311:
312: For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:
313:
314: xend=YES
315: xencommons=YES
316:
317: TODO: Explain why if xm is preferred on 4.1, rc.d/xendomains has xl.
318: Or fix the package.
319:
320: For 4.2 with xm, add to rc.conf
321:
322: xend=YES
323: xencommons=YES
324:
325: For 4.2 with xl (preferred), add to rc.conf:
326:
327: TODO: explain if there is a xend replacement
328: xencommons=YES
329:
330: TODO: Recommend for/against xen-watchdog.
331:
332: After you have configured the daemons and rebooted, run the following
333: (or use xl) to inspect Xen's boot messages, available resources, and
334: running domains:
335:
336: xm dmesg
337: xm info
338: xm list
339:
340: Xen-specific NetBSD issues
341: --------------------------
342:
343: There are (at least) two additional things different about NetBSD as a
344: dom0 kernel compared to hardware.
345:
346: One is that modules are not usable in DOM0 kernels, so one must
347: compile in what's needed. It's not really that modules cannot work,
348: but that modules must be built for XEN3_DOM0 because some of the
349: defines change and the normal module builds don't do this. Basically,
350: enabling Xen changes the kernel ABI, and the module build system
351: doesn't cope with this.
352:
353: The other difference is that XEN3_DOM0 does not have exactly the same
354: options as GENERIC. While it is debatable whether or not this is a
355: bug, users should be aware of this and can simply add missing config
356: items if desired.
357:
358: Updating NetBSD in a dom0
359: -------------------------
360:
361: This is just like updating NetBSD on bare hardware, assuming the new
362: version supports the version of Xen you are running. Generally, one
363: replaces the kernel and reboots, and then overlays userland binaries
364: and adjusts /etc.
365:
366: Note that one must update both the non-Xen kernel typically used for
367: rescue purposes and the DOM0 kernel used with Xen.
368:
369: To convert from grub to /boot, install an mbr bootblock with fdisk,
370: bootxx_ with installboot, /boot and /boot.cfg. This really should be
371: no different than completely reinstalling boot blocks on a non-Xen
372: system.
373:
374: Updating Xen versions
375: ---------------------
376:
377: Updating Xen is conceptually not difficult, but can run into all the
378: issues found when installing Xen. Assuming migration from 4.1 to 4.2,
379: remove the xenkernel41 and xentools41 packages and install the
380: xenkernel42 and xentools42 packages. Copy the 4.2 xen.gz to /.
381:
382: Ensure that the contents of /etc/rc.d/xen* are correct. Enable the
383: correct set of daemons. Ensure that the domU config files are valid
384: for the new version.
385:
386:
387: Unprivileged domains (domU)
388: ===========================
389:
390: This section describes general concepts about domUs. It does not
391: address specific domU operating systems or how to install them. The
392: config files for domUs are typically in /usr/pkg/etc/xen, and are
393: typically named so that the file anme, domU name and the domU's host
394: name match.
395:
396: The domU is provided with cpu and memory by Xen, configured by the
397: dom0. The domU is provided with disk and network by the dom0,
398: mediated by Xen, and configured in the dom0.
399:
400: Entropy in domUs can be an issue; physical disks and network are on
401: the dom0. NetBSD's /dev/random system works, but is often challenged.
402:
403: CPU and memory
404: --------------
405:
406: A domain is provided with some number of vcpus, less than the
407: number of cpus seen by the hypervisor. For a dom0, this is controlled
408: by the boot argument "dom0_max_vcpus=1". For a domU, it is controlled
409: from the config file.
410:
411: A domain is provided with memory, In the straightforward case, the sum
412: of the the memory allocated to the dom0 and all domUs must be less
413: than the available memory.
414:
415: Xen also provides a "balloon" driver, which can be used to let domains
416: use more memory temporarily. TODO: Explain better, and explain how
417: well it works with NetBSD.
418:
419: Virtual disks
420: -------------
421:
422: With the file/vnd style, typically one creates a directory,
423: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
424: domUs. Then, for each domU disk, one writes zeros to a file that then
425: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
426: for the first virtual disk for the domU called foo. Writing zeros to
427: the file serves two purposes. One is that preallocating the contents
428: improves performance. The other is that vnd on sparse files has
429: failed to work. TODO: give working/notworking NetBSD versions for
430: sparse vnd. Note that the use of file/vnd for Xen is not really
431: different than creating a file-backed virtual disk for some other
432: purpose, except that xentools handles the vnconfig commands. To
433: create an empty 4G virtual disk, simply do
434:
435: dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
436:
437: With the lvm style, one creates logical devices. They are then used
438: similarly to vnds.
439:
440: Virtual Networking
441: ------------------
442:
443: TODO: explain xvif concept, and that it's general.
444:
445: There are two normal styles: bridging and NAT.
446:
447: With bridging, the domU perceives itself to be on the same network as
448: the dom0. For server virtualization, this is usually best.
449:
450: With NAT, the domU perceives itself to be behind a NAT running on the
451: dom0. This is often appropriate when running Xen on a workstation.
452:
453: One can construct arbitrary other configurations, but there is no
454: script support.
455:
456: Sizing domains
457: --------------
458:
459: Modern x86 hardware has vast amounts of resources. However, many
460: virtual servers can function just fine on far less. A system with
461: 256M of RAM and a 4G disk can be a reasonable choice. Note that it is
462: far easier to adjust virtual resources than physical ones. For
463: memory, it's just a config file edit and a reboot. For disk, one can
464: create a new file and vnconfig it (or lvm), and then dump/restore,
465: just like updating physical disks, but without having to be there and
466: without those pesky connectors.
467:
468: domU kernels
469: ------------
470:
471: On a physical computer, the BIOS reads sector 0, and a chain of boot
472: loaders finds and loads a kernel. Normally this comes from the root
473: filesystem. With Xen domUs, the process is totally different. The
474: normal path is for the domU kernel to be a file in the dom0's
475: filesystem. At the request of the dom0, Xen loads that kernel into a
476: new domU instance and starts execution. While domU kernels can be
477: anyplace, reasonable places to store domU kernels on the dom0 are in /
478: (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
479: config files), or in /u0/xen (where the vdisks are).
480:
481: See the VPS section near the end for discussion of alternate ways to
482: obtain domU kernels.
483:
484: Config files
485: ------------
486:
487: TODO: give example config files. Use both lvm and vnd.
488:
489: TODO: explain the mess with 3 arguments for disks and how to cope (0x1).
490:
491: Starting domains
492: ----------------
493:
494: TODO: Explain "xm start" and "xl start". Explain rc.d/xendomains.
495:
496: TODO: Explain why 4.1 rc.d/xendomains has xl, when one should use xm
497: on 4.1.
498:
499: Creating specific unprivileged domains (domU)
500: =============================================
501:
502: Creating domUs is almost entirely independent of operating system. We
503: first explain NetBSD, and then differences for Linux and Solaris.
504:
505: Creating an unprivileged NetBSD domain (domU)
506: ---------------------------------------------
507:
508: Once you have *domain0* running, you need to start the xen tool daemon
509: (`/usr/pkg/share/examples/rc.d/xend start`) and the xen backend daemon
510: (`/usr/pkg/share/examples/rc.d/xenbackendd start` for Xen3\*,
511: `/usr/pkg/share/examples/rc.d/xencommons start` for Xen4.\*). Make sure
512: that `/dev/xencons` and `/dev/xenevt` exist before starting `xend`. You
513: can create them with this command:
514:
515: # cd /dev && sh MAKEDEV xen
516:
517: xend will write logs to `/var/log/xend.log` and
518: `/var/log/xend-debug.log`. You can then control xen with the xm tool.
519: 'xm list' will show something like:
520:
521: # xm list
522: Name Id Mem(MB) CPU State Time(s) Console
523: Domain-0 0 64 0 r---- 58.1
524:
525: 'xm create' allows you to create a new domain. It uses a config file in
526: PKG\_SYSCONFDIR for its parameters. By default, this file will be in
527: `/usr/pkg/etc/xen/`. On creation, a kernel has to be specified, which
528: will be executed in the new domain (this kernel is in the *domain0* file
529: system, not on the new domain virtual disk; but please note, you should
530: install the same kernel into *domainU* as `/netbsd` in order to make
531: your system tools, like savecore(8), work). A suitable kernel is
532: provided as part of the i386 and amd64 binary sets: XEN3\_DOMU.
533:
534: Here is an /usr/pkg/etc/xen/nbsd example config file:
535:
536: # -*- mode: python; -*-
537: #============================================================================
538: # Python defaults setup for 'xm create'.
539: # Edit this file to reflect the configuration of your system.
540: #============================================================================
541:
542: #----------------------------------------------------------------------------
543: # Kernel image file. This kernel will be loaded in the new domain.
544: kernel = "/home/bouyer/netbsd-XEN3_DOMU"
545: #kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
546:
547: # Memory allocation (in megabytes) for the new domain.
548: memory = 128
549:
550: # A handy name for your new domain. This will appear in 'xm list',
551: # and you can use this as parameters for xm in place of the domain
552: # number. All domains must have different names.
553: #
554: name = "nbsd"
555:
556: # The number of virtual CPUs this domain has.
557: #
558: vcpus = 1
559:
560: #----------------------------------------------------------------------------
561: # Define network interfaces for the new domain.
562:
563: # Number of network interfaces (must be at least 1). Default is 1.
564: nics = 1
565:
566: # Define MAC and/or bridge for the network interfaces.
567: #
568: # The MAC address specified in ``mac'' is the one used for the interface
569: # in the new domain. The interface in domain0 will use this address XOR'd
570: # with 00:00:00:01:00:00 (i.e. aa:00:00:51:02:f0 in our example). Random
571: # MACs are assigned if not given.
572: #
573: # ``bridge'' is a required parameter, which will be passed to the
574: # vif-script called by xend(8) when a new domain is created to configure
575: # the new xvif interface in domain0.
576: #
577: # In this example, the xvif is added to bridge0, which should have been
578: # set up prior to the new domain being created -- either in the
579: # ``network'' script or using a /etc/ifconfig.bridge0 file.
580: #
581: vif = [ 'mac=aa:00:00:50:02:f0, bridge=bridge0' ]
582:
583: #----------------------------------------------------------------------------
584: # Define the disk devices you want the domain to have access to, and
585: # what you want them accessible as.
586: #
587: # Each disk entry is of the form:
588: #
589: # phy:DEV,VDEV,MODE
590: #
591: # where DEV is the device, VDEV is the device name the domain will see,
592: # and MODE is r for read-only, w for read-write. You can also create
593: # file-backed domains using disk entries of the form:
594: #
595: # file:PATH,VDEV,MODE
596: #
597: # where PATH is the path to the file used as the virtual disk, and VDEV
598: # and MODE have the same meaning as for ``phy'' devices.
599: #
600: # VDEV doesn't really matter for a NetBSD guest OS (it's just used as an index),
601: # but it does for Linux.
602: # Worse, the device has to exist in /dev/ of domain0, because xm will
603: # try to stat() it. This means that in order to load a Linux guest OS
604: # from a NetBSD domain0, you'll have to create /dev/hda1, /dev/hda2, ...
605: # on domain0, with the major/minor from Linux :(
606: # Alternatively it's possible to specify the device number in hex,
607: # e.g. 0x301 for /dev/hda1, 0x302 for /dev/hda2, etc ...
608:
609: disk = [ 'phy:/dev/wd0e,0x1,w' ]
610: #disk = [ 'file:/var/xen/nbsd-disk,0x01,w' ]
611: #disk = [ 'file:/var/xen/nbsd-disk,0x301,w' ]
612:
613: #----------------------------------------------------------------------------
614: # Set the kernel command line for the new domain.
615:
616: # Set root device. This one does matter for NetBSD
617: root = "xbd0"
618: # extra parameters passed to the kernel
619: # this is where you can set boot flags like -s, -a, etc ...
620: #extra = ""
621:
622: #----------------------------------------------------------------------------
623: # Set according to whether you want the domain restarted when it exits.
624: # The default is False.
625: #autorestart = True
626:
627: # end of nbsd config file ====================================================
628:
629: When a new domain is created, xen calls the
630: `/usr/pkg/etc/xen/vif-bridge` script for each virtual network interface
631: created in *domain0*. This can be used to automatically configure the
632: xvif?.? interfaces in *domain0*. In our example, these will be bridged
633: with the bridge0 device in *domain0*, but the bridge has to exist first.
634: To do this, create the file `/etc/ifconfig.bridge0` and make it look
635: like this:
636:
637: create
638: !brconfig $int add ex0 up
639:
640: (replace `ex0` with the name of your physical interface). Then bridge0
641: will be created on boot. See the bridge(4) man page for details.
642:
643: So, here is a suitable `/usr/pkg/etc/xen/vif-bridge` for xvif?.? (a
644: working vif-bridge is also provided with xentools20) configuring:
645:
646: #!/bin/sh
647: #============================================================================
648: # $NetBSD: howto.mdwn,v 1.40 2014/12/26 13:00:23 gdt Exp $
649: #
650: # /usr/pkg/etc/xen/vif-bridge
651: #
652: # Script for configuring a vif in bridged mode with a dom0 interface.
653: # The xend(8) daemon calls a vif script when bringing a vif up or down.
654: # The script name to use is defined in /usr/pkg/etc/xen/xend-config.sxp
655: # in the ``vif-script'' field.
656: #
657: # Usage: vif-bridge up|down [var=value ...]
658: #
659: # Actions:
660: # up Adds the vif interface to the bridge.
661: # down Removes the vif interface from the bridge.
662: #
663: # Variables:
664: # domain name of the domain the interface is on (required).
665: # vifq vif interface name (required).
666: # mac vif MAC address (required).
667: # bridge bridge to add the vif to (required).
668: #
669: # Example invocation:
670: #
671: # vif-bridge up domain=VM1 vif=xvif1.0 mac="ee:14:01:d0:ec:af" bridge=bridge0
672: #
673: #============================================================================
674:
675: # Exit if anything goes wrong
676: set -e
677:
678: echo "vif-bridge $*"
679:
680: # Operation name.
681: OP=$1; shift
682:
683: # Pull variables in args into environment
684: for arg ; do export "${arg}" ; done
685:
686: # Required parameters. Fail if not set.
687: domain=${domain:?}
688: vif=${vif:?}
689: mac=${mac:?}
690: bridge=${bridge:?}
691:
692: # Optional parameters. Set defaults.
693: ip=${ip:-''} # default to null (do nothing)
694:
695: # Are we going up or down?
696: case $OP in
697: up) brcmd='add' ;;
698: down) brcmd='delete' ;;
699: *)
700: echo 'Invalid command: ' $OP
701: echo 'Valid commands are: up, down'
702: exit 1
703: ;;
704: esac
705:
706: # Don't do anything if the bridge is "null".
707: if [ "${bridge}" = "null" ] ; then
708: exit
709: fi
710:
711: # Don't do anything if the bridge doesn't exist.
712: if ! ifconfig -l | grep "${bridge}" >/dev/null; then
713: exit
714: fi
715:
716: # Add/remove vif to/from bridge.
717: ifconfig x${vif} $OP
718: brconfig ${bridge} ${brcmd} x${vif}
719:
720: Now, running
721:
722: xm create -c /usr/pkg/etc/xen/nbsd
723:
724: should create a domain and load a NetBSD kernel in it. (Note: `-c`
725: causes xm to connect to the domain's console once created.) The kernel
726: will try to find its root file system on xbd0 (i.e., wd0e) which hasn't
727: been created yet. wd0e will be seen as a disk device in the new domain,
728: so it will be 'sub-partitioned'. We could attach a ccd to wd0e in
729: *domain0* and partition it, newfs and extract the NetBSD/i386 or amd64
730: tarballs there, but there's an easier way: load the
731: `netbsd-INSTALL_XEN3_DOMU` kernel provided in the NetBSD binary sets.
732: Like other install kernels, it contains a ramdisk with sysinst, so you
733: can install NetBSD using sysinst on your new domain.
734:
735: If you want to install NetBSD/Xen with a CDROM image, the following line
736: should be used in the `/usr/pkg/etc/xen/nbsd` file:
737:
738: disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
739:
740: After booting the domain, the option to install via CDROM may be
741: selected. The CDROM device should be changed to `xbd1d`.
742:
743: Once done installing, `halt -p` the new domain (don't reboot or halt, it
744: would reload the INSTALL\_XEN3\_DOMU kernel even if you changed the
745: config file), switch the config file back to the XEN3\_DOMU kernel, and
746: start the new domain again. Now it should be able to use `root on xbd0a`
747: and you should have a second, functional NetBSD system on your xen
748: installation.
749:
750: When the new domain is booting you'll see some warnings about *wscons*
751: and the pseudo-terminals. These can be fixed by editing the files
752: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
753: `/etc/ttys`, except *console*, like this:
754:
755: console "/usr/libexec/getty Pc" vt100 on secure
756: ttyE0 "/usr/libexec/getty Pc" vt220 off secure
757: ttyE1 "/usr/libexec/getty Pc" vt220 off secure
758: ttyE2 "/usr/libexec/getty Pc" vt220 off secure
759: ttyE3 "/usr/libexec/getty Pc" vt220 off secure
760:
761: Finally, all screens must be commented out from `/etc/wscons.conf`.
762:
763: It is also desirable to add
764:
765: powerd=YES
766:
767: in rc.conf. This way, the domain will be properly shut down if
768: `xm shutdown -R` or `xm shutdown -H` is used on the domain0.
769:
770: Your domain should be now ready to work, enjoy.
771:
772: Creating an unprivileged Linux domain (domU)
773: --------------------------------------------
774:
775: Creating unprivileged Linux domains isn't much different from
776: unprivileged NetBSD domains, but there are some details to know.
777:
778: First, the second parameter passed to the disk declaration (the '0x1' in
779: the example below)
780:
781: disk = [ 'phy:/dev/wd0e,0x1,w' ]
782:
783: does matter to Linux. It wants a Linux device number here (e.g. 0x300
784: for hda). Linux builds device numbers as: (major \<\< 8 + minor). So,
785: hda1 which has major 3 and minor 1 on a Linux system will have device
786: number 0x301. Alternatively, devices names can be used (hda, hdb, ...)
787: as xentools has a table to map these names to devices numbers. To export
788: a partition to a Linux guest we can use:
789:
790: disk = [ 'phy:/dev/wd0e,0x300,w' ]
791: root = "/dev/hda1 ro"
792:
793: and it will appear as /dev/hda on the Linux system, and be used as root
794: partition.
795:
796: To install the Linux system on the partition to be exported to the guest
797: domain, the following method can be used: install sysutils/e2fsprogs
798: from pkgsrc. Use mke2fs to format the partition that will be the root
799: partition of your Linux domain, and mount it. Then copy the files from a
800: working Linux system, make adjustments in `/etc` (fstab, network
801: config). It should also be possible to extract binary packages such as
802: .rpm or .deb directly to the mounted partition using the appropriate
803: tool, possibly running under NetBSD's Linux emulation. Once the
804: filesystem has been populated, umount it. If desirable, the filesystem
805: can be converted to ext3 using tune2fs -j. It should now be possible to
806: boot the Linux guest domain, using one of the vmlinuz-\*-xenU kernels
807: available in the Xen binary distribution.
808:
809: To get the linux console right, you need to add:
810:
811: extra = "xencons=tty1"
812:
813: to your configuration since not all linux distributions auto-attach a
814: tty to the xen console.
815:
816: Creating an unprivileged Solaris domain (domU)
817: ----------------------------------------------
818:
819: Download an Opensolaris [release](http://opensolaris.org/os/downloads/)
820: or [development snapshot](http://genunix.org/) DVD image. Attach the DVD
821: image to a MAN.VND.4 device. Copy the kernel and ramdisk filesystem
822: image to your dom0 filesystem.
823:
824: dom0# mkdir /root/solaris
825: dom0# vnconfig vnd0 osol-1002-124-x86.iso
826: dom0# mount /dev/vnd0a /mnt
827:
828: ## for a 64-bit guest
829: dom0# cp /mnt/boot/amd64/x86.microroot /root/solaris
830: dom0# cp /mnt/platform/i86xpv/kernel/amd64/unix /root/solaris
831:
832: ## for a 32-bit guest
833: dom0# cp /mnt/boot/x86.microroot /root/solaris
834: dom0# cp /mnt/platform/i86xpv/kernel/unix /root/solaris
835:
836: dom0# umount /mnt
837:
838:
839: Keep the MAN.VND.4 configured. For some reason the boot process stalls
840: unless the DVD image is attached to the guest as a "phy" device. Create
841: an initial configuration file with the following contents. Substitute
842: */dev/wd0k* with an empty partition at least 8 GB large.
843:
844: memory = 640
845: name = 'solaris'
846: disk = [ 'phy:/dev/wd0k,0,w' ]
847: disk += [ 'phy:/dev/vnd0d,6:cdrom,r' ]
848: vif = [ 'bridge=bridge0' ]
849: kernel = '/root/solaris/unix'
850: ramdisk = '/root/solaris/x86.microroot'
851: # for a 64-bit guest
852: extra = '/platform/i86xpv/kernel/amd64/unix - nowin -B install_media=cdrom'
853: # for a 32-bit guest
854: #extra = '/platform/i86xpv/kernel/unix - nowin -B install_media=cdrom'
855:
856:
857: Start the guest.
858:
859: dom0# xm create -c solaris.cfg
860: Started domain solaris
861: v3.3.2 chgset 'unavailable'
862: SunOS Release 5.11 Version snv_124 64-bit
863: Copyright 1983-2009 Sun Microsystems, Inc. All rights reserved.
864: Use is subject to license terms.
865: Hostname: opensolaris
866: Remounting root read/write
867: Probing for device nodes ...
868: WARNING: emlxs: ddi_modopen drv/fct failed: err 2
869: Preparing live image for use
870: Done mounting Live image
871:
872:
873: Make sure the network is configured. Note that it can take a minute for
874: the xnf0 interface to appear.
875:
876: opensolaris console login: jack
877: Password: jack
878: Sun Microsystems Inc. SunOS 5.11 snv_124 November 2008
879: jack@opensolaris:~$ pfexec sh
880: sh-3.2# ifconfig -a
881: sh-3.2# exit
882:
883:
884: Set a password for VNC and start the VNC server which provides the X11
885: display where the installation program runs.
886:
887: jack@opensolaris:~$ vncpasswd
888: Password: solaris
889: Verify: solaris
890: jack@opensolaris:~$ cp .Xclients .vnc/xstartup
891: jack@opensolaris:~$ vncserver :1
892:
893:
894: From a remote machine connect to the VNC server. Use `ifconfig xnf0` on
895: the guest to find the correct IP address to use.
896:
897: remote$ vncviewer 172.18.2.99:1
898:
899:
900: It is also possible to launch the installation on a remote X11 display.
901:
902: jack@opensolaris:~$ export DISPLAY=172.18.1.1:0
903: jack@opensolaris:~$ pfexec gui-install
904:
905:
906: After the GUI installation is complete you will be asked to reboot.
907: Before that you need to determine the ZFS ID for the new boot filesystem
908: and update the configuration file accordingly. Return to the guest
909: console.
910:
911: jack@opensolaris:~$ pfexec zdb -vvv rpool | grep bootfs
912: bootfs = 43
913: ^C
914: jack@opensolaris:~$
915:
916:
917: The final configuration file should look like this. Note in particular
918: the last line.
919:
920: memory = 640
921: name = 'solaris'
922: disk = [ 'phy:/dev/wd0k,0,w' ]
923: vif = [ 'bridge=bridge0' ]
924: kernel = '/root/solaris/unix'
925: ramdisk = '/root/solaris/x86.microroot'
926: extra = '/platform/i86xpv/kernel/amd64/unix -B zfs-bootfs=rpool/43,bootpath="/xpvd/xdf@0:a"'
927:
928:
929: Restart the guest to verify it works correctly.
930:
931: dom0# xm destroy solaris
932: dom0# xm create -c solaris.cfg
933: Using config file "./solaris.cfg".
934: v3.3.2 chgset 'unavailable'
935: Started domain solaris
936: SunOS Release 5.11 Version snv_124 64-bit
937: Copyright 1983-2009 Sun Microsystems, Inc. All rights reserved.
938: Use is subject to license terms.
939: WARNING: emlxs: ddi_modopen drv/fct failed: err 2
940: Hostname: osol
941: Configuring devices.
942: Loading smf(5) service descriptions: 160/160
943: svccfg import warnings. See /var/svc/log/system-manifest-import:default.log .
944: Reading ZFS config: done.
945: Mounting ZFS filesystems: (6/6)
946: Creating new rsa public/private host key pair
947: Creating new dsa public/private host key pair
948:
949: osol console login:
950:
951:
952: Using PCI devices in guest domains
953: ----------------------------------
954:
955: The domain0 can give other domains access to selected PCI devices. This
956: can allow, for example, a non-privileged domain to have access to a
957: physical network interface or disk controller. However, keep in mind
958: that giving a domain access to a PCI device most likely will give the
959: domain read/write access to the whole physical memory, as PCs don't have
960: an IOMMU to restrict memory access to DMA-capable device. Also, it's not
961: possible to export ISA devices to non-domain0 domains (which means that
962: the primary VGA adapter can't be exported. A guest domain trying to
963: access the VGA registers will panic).
964:
965: This functionality is only available in NetBSD-5.1 (and later) domain0
966: and domU. If the domain0 is NetBSD, it has to be running Xen 3.1, as
967: support has not been ported to later versions at this time.
968:
969: For a PCI device to be exported to a domU, is has to be attached to the
970: `pciback` driver in domain0. Devices passed to the domain0 via the
971: pciback.hide boot parameter will attach to `pciback` instead of the
972: usual driver. The list of devices is specified as `(bus:dev.func)`,
973: where bus and dev are 2-digit hexadecimal numbers, and func a
974: single-digit number:
975:
976: pciback.hide=(00:0a.0)(00:06.0)
977:
978: pciback devices should show up in the domain0's boot messages, and the
979: devices should be listed in the `/kern/xen/pci` directory.
980:
981: PCI devices to be exported to a domU are listed in the `pci` array of
982: the domU's config file, with the format `'0000:bus:dev.func'`
983:
984: pci = [ '0000:00:06.0', '0000:00:0a.0' ]
985:
986: In the domU an `xpci` device will show up, to which one or more pci
987: busses will attach. Then the PCI drivers will attach to PCI busses as
988: usual. Note that the default NetBSD DOMU kernels do not have `xpci` or
989: any PCI drivers built in by default; you have to build your own kernel
990: to use PCI devices in a domU. Here's a kernel config example:
991:
992: include "arch/i386/conf/XEN3_DOMU"
993: #include "arch/i386/conf/XENU" # in NetBSD 3.0
994:
995: # Add support for PCI busses to the XEN3_DOMU kernel
996: xpci* at xenbus ?
997: pci* at xpci ?
998:
999: # Now add PCI and related devices to be used by this domain
1000: # USB Controller and Devices
1001:
1002: # PCI USB controllers
1003: uhci* at pci? dev ? function ? # Universal Host Controller (Intel)
1004:
1005: # USB bus support
1006: usb* at uhci?
1007:
1008: # USB Hubs
1009: uhub* at usb?
1010: uhub* at uhub? port ? configuration ? interface ?
1011:
1012: # USB Mass Storage
1013: umass* at uhub? port ? configuration ? interface ?
1014: wd* at umass?
1015: # SCSI controllers
1016: ahc* at pci? dev ? function ? # Adaptec [23]94x, aic78x0 SCSI
1017:
1018: # SCSI bus support (for both ahc and umass)
1019: scsibus* at scsi?
1020:
1021: # SCSI devices
1022: sd* at scsibus? target ? lun ? # SCSI disk drives
1023: cd* at scsibus? target ? lun ? # SCSI CD-ROM drives
1024:
1025:
1026: NetBSD as a domU in a VPS
1027: =========================
1028:
1029: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
1030: hardware. This section explains how to deal with Xen in a domU as a
1031: virtual private server where you do not control or have access to the
1032: dom0.
1033:
1034: TODO: Perhaps reference panix, prmgr, amazon as interesting examples.
1035:
1036: TODO: Somewhere, discuss pvgrub and py-grub to load the domU kernel
1037: from the domU filesystem.
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