Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.157
1.144 maxv 1: [[!meta title="Xen HowTo"]]
2:
1.157 ! maxv 3: Xen is a Type 1 hypervisor which supports running multiple guest operating
! 4: systems on a single physical machine. One uses the Xen kernel to control the
! 5: CPU, memory and console, a dom0 operating system which mediates access to
! 6: other hardware (e.g., disks, network, USB), and one or more domU operating
! 7: systems which operate in an unprivileged virtualized environment. IO requests
! 8: from the domU systems are forwarded by the Xen hypervisor to the dom0 to be
! 9: fulfilled.
1.12 gdt 10:
1.149 maxv 11: Xen supports different styles of guest:
12:
13: [[!table data="""
14: Style of guest |Supported by NetBSD
1.150 maxv 15: PV |Yes (dom0, domU)
16: HVM |Yes (domU)
1.149 maxv 17: PVHVM |No
18: PVH |No
19: """]]
20:
21: In Para-Virtualized (PV) mode, the guest OS does not attempt to access
22: hardware directly, but instead makes hypercalls to the hypervisor; PV
23: guests must be specifically coded for Xen. In HVM mode, no guest
24: modification is required; however, hardware support is required, such
25: as VT-x on Intel CPUs and SVM on AMD CPUs.
26:
1.27 jnemeth 27: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
1.12 gdt 28: The dom0 can start one or more domUs. (Booting is explained in detail
29: in the dom0 section.)
30:
31: This HOWTO presumes a basic familiarity with the Xen system
1.123 gdt 32: architecture, with installing NetBSD on i386/amd64 hardware, and with
33: installing software from pkgsrc. See also the [Xen
34: website](http://www.xenproject.org/).
1.1 mspo 35:
1.150 maxv 36: This HOWTO attempts to address both the case of running a NetBSD dom0
37: on hardware and running domUs under it (NetBSD and other), and also
38: running NetBSD as a domU in a VPS.
39:
1.157 ! maxv 40: Versions and Support
! 41: ====================
1.15 gdt 42:
1.111 wiz 43: In NetBSD, Xen is provided in pkgsrc, via matching pairs of packages
1.15 gdt 44: xenkernel and xentools. We will refer only to the kernel versions,
45: but note that both packages must be installed together and must have
46: matching versions.
47:
1.145 maxv 48: Versions available in pkgsrc:
1.85 gdt 49:
1.145 maxv 50: [[!table data="""
51: Xen Version |Package Name |Xen CPU Support |EOL'ed By Upstream
52: 4.2 |xenkernel42 |32bit, 64bit |Yes
53: 4.5 |xenkernel45 |64bit |Yes
54: 4.6 |xenkernel46 |64bit |Partially
55: 4.8 |xenkernel48 |64bit |No
56: 4.11 |xenkernel411 |64bit |No
57: """]]
1.113 gdt 58:
1.96 gdt 59: See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
60:
1.157 ! maxv 61: Multiprocessor (SMP) support in NetBSD differs depending on the domain:
1.145 maxv 62:
1.157 ! maxv 63: [[!table data="""
! 64: Domain |Supports SMP
! 65: dom0 |No
! 66: domU |Yes
! 67: """]]
1.15 gdt 68:
1.147 maxv 69: Note: NetBSD support is called XEN3. However, it does support Xen 4,
70: because the hypercall interface has remained identical.
71:
1.18 gdt 72: Architecture
73: ------------
74:
1.157 ! maxv 75: Xen itself runs on x86_64 hardware.
1.155 maxv 76:
77: The dom0 system, plus each domU, can be either i386PAE or amd64.
78: i386 without PAE is not supported.
79:
1.157 ! maxv 80: The standard approach is to use NetBSD/amd64 for the dom0.
! 81:
! 82: To use an i386PAE dom0, one must build or obtain a 64bit Xen kernel and
! 83: install it on the system.
! 84:
! 85: For domUs, i386PAE is considered as
! 86: [faster](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html)
! 87: than amd64.
1.29 gdt 88:
1.15 gdt 89: NetBSD as a dom0
90: ================
91:
92: NetBSD can be used as a dom0 and works very well. The following
93: sections address installation, updating NetBSD, and updating Xen.
1.157 ! maxv 94:
1.19 gdt 95: Note that it doesn't make sense to talk about installing a dom0 OS
96: without also installing Xen itself. We first address installing
97: NetBSD, which is not yet a dom0, and then adding Xen, pivoting the
98: NetBSD install to a dom0 install by just changing the kernel and boot
99: configuration.
1.15 gdt 100:
1.142 gdt 101: In 2018-05, trouble booting a dom0 was reported with 256M of RAM: with
102: 512M it worked reliably. This does not make sense, but if you see
103: "not ELF" after Xen boots, try increasing dom0 RAM.
104:
1.15 gdt 105: Styles of dom0 operation
106: ------------------------
107:
108: There are two basic ways to use Xen. The traditional method is for
109: the dom0 to do absolutely nothing other than providing support to some
110: number of domUs. Such a system was probably installed for the sole
111: purpose of hosting domUs, and sits in a server room on a UPS.
112:
113: The other way is to put Xen under a normal-usage computer, so that the
114: dom0 is what the computer would have been without Xen, perhaps a
1.157 ! maxv 115: desktop or laptop. Then, one can run domUs at will.
1.15 gdt 116:
1.19 gdt 117: Installation of NetBSD
118: ----------------------
1.13 gdt 119:
1.157 ! maxv 120: [Install NetBSD/amd64](/guide/inst/)
1.19 gdt 121: just as you would if you were not using Xen.
1.1 mspo 122:
1.19 gdt 123: Installation of Xen
124: -------------------
1.1 mspo 125:
1.155 maxv 126: We will consider that you chose to use Xen 4.8, with NetBSD/amd64 as
127: dom0. In the dom0, install xenkernel48 and xentools48 from pkgsrc.
128: Ensure that your packages are recent.
129:
130: Once this is done, install the Xen kernel itself:
131:
132: [[!template id=programlisting text="""
133: # cp /usr/pkg/xen48-kernel/xen.gz /
134: """]]
135:
1.157 ! maxv 136: Then, place a NetBSD XEN3_DOM0 kernel in the `/` directory, copied from
! 137: `releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz` of a NetBSD build.
1.20 gdt 138:
1.155 maxv 139: Add a line to /boot.cfg to boot Xen:
1.20 gdt 140:
1.157 ! maxv 141: [[!template id=filecontent name="/boot.cfg" text="""
1.152 maxv 142: menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
143: """]]
1.20 gdt 144:
1.155 maxv 145: which specifies that the dom0 should have 512MB of ram, leaving the rest
146: to be allocated for domUs. To use a serial console, use
1.77 gdt 147:
1.157 ! maxv 148: [[!template id=filecontent name="/boot.cfg" text="""
1.152 maxv 149: menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
150: """]]
1.77 gdt 151:
152: which will use the first serial port for Xen (which counts starting
1.139 gson 153: from 1, unlike NetBSD which counts starting from 0), forcing
154: speed/parity. Because the NetBSD command line lacks a
155: "console=pc" argument, it will use the default "xencons" console device,
156: which directs the console I/O through Xen to the same console device Xen
157: itself uses (in this case, the serial port).
158:
1.157 ! maxv 159: In an attempt to add performance, one can also add `dom0_max_vcpus=1 dom0_vcpus_pin`,
1.37 gdt 160: to force only one vcpu to be provided (since NetBSD dom0 can't use
1.155 maxv 161: more) and to pin that vcpu to a physical CPU.
1.20 gdt 162:
1.93 gdt 163: Xen has [many boot
164: options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html),
1.111 wiz 165: and other than dom0 memory and max_vcpus, they are generally not
1.93 gdt 166: necessary.
167:
1.76 gdt 168: Now, reboot so that you are running a DOM0 kernel under Xen, rather
169: than GENERIC without Xen.
170:
1.21 gdt 171: Configuring Xen
172: ---------------
173:
1.76 gdt 174: Now, you have a system that will boot Xen and the dom0 kernel, but not
175: do anything else special. Make sure that you have rebooted into Xen.
176: There will be no domUs, and none can be started because you still have
1.102 gdt 177: to configure the dom0 daemons.
1.21 gdt 178:
1.157 ! maxv 179: Since Xen 4.2, the tool which should be used is `xl`.
! 180:
! 181: For 4.1 and up, you should enable `xencommons`:
1.31 gdt 182:
1.157 ! maxv 183: [[!template id=filecontent name="/etc/rc.conf" text="""
1.152 maxv 184: xencommons=YES
185: """]]
1.31 gdt 186:
1.157 ! maxv 187: Not enabling xencommons will result in a hang; it is necessary to hit `^C` on
! 188: the console to let the machine finish booting:
! 189:
1.31 gdt 190: TODO: Recommend for/against xen-watchdog.
1.27 jnemeth 191:
1.53 gdt 192: After you have configured the daemons and either started them (in the
1.157 ! maxv 193: order given) or rebooted, use `xl` to inspect Xen's boot messages,
! 194: available resources, and running domains. For example:
1.34 gdt 195:
1.153 maxv 196: [[!template id=programlisting text="""
197: # xl dmesg
198: ... xen's boot info ...
199: # xl info
200: ... available memory, etc ...
201: # xl list
202: Name Id Mem(MB) CPU State Time(s) Console
203: Domain-0 0 64 0 r---- 58.1
204: """]]
205:
206: Xen logs will be in /var/log/xen.
1.33 gdt 207:
1.88 gdt 208: ### Issues with xencommons
209:
1.157 ! maxv 210: `xencommons` starts `xenstored`, which stores data on behalf of dom0 and
1.88 gdt 211: domUs. It does not currently work to stop and start xenstored.
212: Certainly all domUs should be shutdown first, following the sort order
213: of the rc.d scripts. However, the dom0 sets up state with xenstored,
214: and is not notified when xenstored exits, leading to not recreating
215: the state when the new xenstored starts. Until there's a mechanism to
216: make this work, one should not expect to be able to restart xenstored
217: (and thus xencommons). There is currently no reason to expect that
218: this will get fixed any time soon.
219:
1.41 gdt 220: anita (for testing NetBSD)
221: --------------------------
222:
1.157 ! maxv 223: With the setup so far (assuming 4.8/xl), one should be able to run
1.82 gdt 224: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
225: root, because anita must create a domU):
226:
1.153 maxv 227: [[!template id=programlisting text="""
228: anita --vmm=xl test file:///usr/obj/i386/
229: """]]
1.82 gdt 230:
1.40 gdt 231: Xen-specific NetBSD issues
232: --------------------------
233:
234: There are (at least) two additional things different about NetBSD as a
235: dom0 kernel compared to hardware.
236:
1.111 wiz 237: One is that the module ABI is different because some of the #defines
1.109 gdt 238: change, so one must build modules for Xen. As of netbsd-7, the build
1.157 ! maxv 239: system does this automatically.
1.40 gdt 240:
241: The other difference is that XEN3_DOM0 does not have exactly the same
242: options as GENERIC. While it is debatable whether or not this is a
243: bug, users should be aware of this and can simply add missing config
244: items if desired.
245:
1.15 gdt 246: Updating NetBSD in a dom0
247: -------------------------
248:
249: This is just like updating NetBSD on bare hardware, assuming the new
250: version supports the version of Xen you are running. Generally, one
251: replaces the kernel and reboots, and then overlays userland binaries
1.157 ! maxv 252: and adjusts `/etc`.
1.15 gdt 253:
254: Note that one must update both the non-Xen kernel typically used for
255: rescue purposes and the DOM0 kernel used with Xen.
256:
1.55 gdt 257: Converting from grub to /boot
258: -----------------------------
259:
1.157 ! maxv 260: These instructions were used to convert a system from
1.55 gdt 261: grub to /boot. The system was originally installed in February of
262: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
263: over time. Before these commands, it was running NetBSD 6 i386, Xen
264: 4.1 and grub, much like the message linked earlier in the grub
265: section.
266:
1.157 ! maxv 267: [[!template id=programlisting text="""
! 268: # Install MBR bootblocks on both disks.
! 269: fdisk -i /dev/rwd0d
! 270: fdisk -i /dev/rwd1d
! 271: # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
! 272: installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
! 273: installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
! 274: # Install secondary boot loader
! 275: cp -p /usr/mdec/boot /
! 276: # Create boot.cfg following earlier guidance:
! 277: menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
! 278: menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=512M
! 279: menu=GENERIC:boot
! 280: menu=GENERIC single-user:boot -s
! 281: menu=GENERIC.ok:boot netbsd.ok
! 282: menu=GENERIC.ok single-user:boot netbsd.ok -s
! 283: menu=Drop to boot prompt:prompt
! 284: default=1
! 285: timeout=30
! 286: """]]
1.22 gdt 287:
1.102 gdt 288: Upgrading Xen versions
1.15 gdt 289: ---------------------
290:
1.110 gdt 291: Minor version upgrades are trivial. Just rebuild/replace the
1.157 ! maxv 292: xenkernel version and copy the new xen.gz to `/` (where `/boot.cfg`
1.110 gdt 293: references it), and reboot.
294:
1.28 gdt 295: Unprivileged domains (domU)
296: ===========================
297:
298: This section describes general concepts about domUs. It does not
1.33 gdt 299: address specific domU operating systems or how to install them. The
1.157 ! maxv 300: config files for domUs are typically in `/usr/pkg/etc/xen`, and are
1.60 wiki 301: typically named so that the file name, domU name and the domU's host
1.33 gdt 302: name match.
303:
1.111 wiz 304: The domU is provided with CPU and memory by Xen, configured by the
1.33 gdt 305: dom0. The domU is provided with disk and network by the dom0,
306: mediated by Xen, and configured in the dom0.
307:
308: Entropy in domUs can be an issue; physical disks and network are on
309: the dom0. NetBSD's /dev/random system works, but is often challenged.
310:
1.48 gdt 311: Config files
312: ------------
313:
314: There is no good order to present config files and the concepts
315: surrounding what is being configured. We first show an example config
316: file, and then in the various sections give details.
317:
1.157 ! maxv 318: See /usr/pkg/share/examples/xen/xmexample*,
1.48 gdt 319: for a large number of well-commented examples, mostly for running
320: GNU/Linux.
321:
1.157 ! maxv 322: The following is an example minimal domain configuration file. The domU
! 323: serves as a network file server.
! 324:
! 325: [[!template id=filecontent name="/usr/pkg/etc/xen/foo" text="""
! 326: name = "domU-id"
! 327: kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
! 328: memory = 1024
! 329: vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
! 330: disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
! 331: 'file:/n0/xen/foo-wd1,0x1,w' ]
! 332: """]]
1.48 gdt 333:
1.157 ! maxv 334: The domain will have name given in the `name` setting. The kernel has the
1.48 gdt 335: host/domU name in it, so that on the dom0 one can update the various
1.157 ! maxv 336: domUs independently. The `vif` line causes an interface to be provided,
1.48 gdt 337: with a specific mac address (do not reuse MAC addresses!), in bridge
338: mode. Two disks are provided, and they are both writable; the bits
339: are stored in files and Xen attaches them to a vnd(4) device in the
1.111 wiz 340: dom0 on domain creation. The system treats xbd0 as the boot device
1.48 gdt 341: without needing explicit configuration.
342:
1.157 ! maxv 343: By default, `xl` looks for domain config files in `/usr/pkg/etc/xen`. Note
! 344: that "xl create" takes the name of a config file, while other commands
! 345: take the name of a domain.
! 346:
! 347: Examples of commands:
1.48 gdt 348:
1.157 ! maxv 349: [[!template id=programlisting text="""
! 350: xl create foo
! 351: xl console foo
! 352: xl create -c foo
! 353: xl shutdown foo
! 354: xl list
! 355: """]]
! 356:
! 357: Typing `^]` will exit the console session. Shutting down a domain is
1.48 gdt 358: equivalent to pushing the power button; a NetBSD domU will receive a
359: power-press event and do a clean shutdown. Shutting down the dom0
360: will trigger controlled shutdowns of all configured domUs.
361:
362: domU kernels
363: ------------
364:
365: On a physical computer, the BIOS reads sector 0, and a chain of boot
366: loaders finds and loads a kernel. Normally this comes from the root
1.111 wiz 367: file system. With Xen domUs, the process is totally different. The
1.48 gdt 368: normal path is for the domU kernel to be a file in the dom0's
1.111 wiz 369: file system. At the request of the dom0, Xen loads that kernel into a
1.157 ! maxv 370: new domU instance and starts execution. domU kernels can be anyplace.
1.48 gdt 371:
1.59 gdt 372: Note that loading the domU kernel from the dom0 implies that boot
373: blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
1.48 gdt 374: See the VPS section near the end for discussion of alternate ways to
375: obtain domU kernels.
376:
1.33 gdt 377: CPU and memory
378: --------------
379:
1.48 gdt 380: A domain is provided with some number of vcpus, less than the number
1.157 ! maxv 381: of CPUs seen by the hypervisor. For a domU, it is controlled
1.48 gdt 382: from the config file by the "vcpus = N" directive.
383:
384: A domain is provided with memory; this is controlled in the config
385: file by "memory = N" (in megabytes). In the straightforward case, the
386: sum of the the memory allocated to the dom0 and all domUs must be less
1.33 gdt 387: than the available memory.
388:
389: Xen also provides a "balloon" driver, which can be used to let domains
1.157 ! maxv 390: use more memory temporarily.
1.28 gdt 391:
392: Virtual disks
393: -------------
394:
1.33 gdt 395: With the file/vnd style, typically one creates a directory,
396: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
397: domUs. Then, for each domU disk, one writes zeros to a file that then
398: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
399: for the first virtual disk for the domU called foo. Writing zeros to
400: the file serves two purposes. One is that preallocating the contents
401: improves performance. The other is that vnd on sparse files has
402: failed to work. TODO: give working/notworking NetBSD versions for
1.127 gdt 403: sparse vnd and gnats reference. Note that the use of file/vnd for Xen
404: is not really different than creating a file-backed virtual disk for
405: some other purpose, except that xentools handles the vnconfig
406: commands. To create an empty 4G virtual disk, simply do
1.39 gdt 407:
408: dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
1.33 gdt 409:
1.89 gdt 410: Do not use qemu-img-xen, because this will create sparse file. There
411: have been recent (2015) reports of sparse vnd(4) devices causing
412: lockups, but there is apparently no PR.
413:
1.33 gdt 414: With the lvm style, one creates logical devices. They are then used
1.48 gdt 415: similarly to vnds. TODO: Add an example with lvm.
416:
417: In domU config files, the disks are defined as a sequence of 3-tuples.
418: The first element is "method:/path/to/disk". Common methods are
419: "file:" for file-backed vnd. and "phy:" for something that is already
420: a (TODO: character or block) device.
421:
422: The second element is an artifact of how virtual disks are passed to
423: Linux, and a source of confusion with NetBSD Xen usage. Linux domUs
424: are given a device name to associate with the disk, and values like
425: "hda1" or "sda1" are common. In a NetBSD domU, the first disk appears
426: as xbd0, the second as xbd1, and so on. However, xm/xl demand a
427: second argument. The name given is converted to a major/minor by
1.49 gdt 428: calling stat(2) on the name in /dev and this is passed to the domU.
429: In the general case, the dom0 and domU can be different operating
1.48 gdt 430: systems, and it is an unwarranted assumption that they have consistent
431: numbering in /dev, or even that the dom0 OS has a /dev. With NetBSD
432: as both dom0 and domU, using values of 0x0 for the first disk and 0x1
1.49 gdt 433: for the second works fine and avoids this issue. For a GNU/Linux
434: guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
435: /dev/hda1.
1.48 gdt 436:
437: The third element is "w" for writable disks, and "r" for read-only
438: disks.
1.28 gdt 439:
1.127 gdt 440: Note that NetBSD by default creates only vnd[0123]. If you need more
441: than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the
442: dom0.
443:
444: Note that NetBSD by default creates only xbd[0123]. If you need more
445: virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU.
446:
1.28 gdt 447: Virtual Networking
448: ------------------
449:
1.111 wiz 450: Xen provides virtual Ethernets, each of which connects the dom0 and a
1.46 gdt 451: domU. For each virtual network, there is an interface "xvifN.M" in
452: the dom0, and in domU index N, a matching interface xennetM (NetBSD
453: name). The interfaces behave as if there is an Ethernet with two
1.111 wiz 454: adapters connected. From this primitive, one can construct various
1.46 gdt 455: configurations. We focus on two common and useful cases for which
456: there are existing scripts: bridging and NAT.
1.28 gdt 457:
1.48 gdt 458: With bridging (in the example above), the domU perceives itself to be
459: on the same network as the dom0. For server virtualization, this is
460: usually best. Bridging is accomplished by creating a bridge(4) device
461: and adding the dom0's physical interface and the various xvifN.0
462: interfaces to the bridge. One specifies "bridge=bridge0" in the domU
463: config file. The bridge must be set up already in the dom0; an
464: example /etc/ifconfig.bridge0 is:
1.46 gdt 465:
1.157 ! maxv 466: [[!template id=filecontent name="/etc/ifconfig.bridge0" text="""
! 467: create
! 468: up
! 469: !brconfig bridge0 add wm0
! 470: """]]
1.28 gdt 471:
472: With NAT, the domU perceives itself to be behind a NAT running on the
473: dom0. This is often appropriate when running Xen on a workstation.
1.48 gdt 474: TODO: NAT appears to be configured by "vif = [ '' ]".
1.28 gdt 475:
1.49 gdt 476: The MAC address specified is the one used for the interface in the new
1.53 gdt 477: domain. The interface in dom0 will use this address XOR'd with
1.49 gdt 478: 00:00:00:01:00:00. Random MAC addresses are assigned if not given.
479:
1.33 gdt 480: Sizing domains
481: --------------
482:
483: Modern x86 hardware has vast amounts of resources. However, many
484: virtual servers can function just fine on far less. A system with
1.142 gdt 485: 512M of RAM and a 4G disk can be a reasonable choice. Note that it is
1.33 gdt 486: far easier to adjust virtual resources than physical ones. For
487: memory, it's just a config file edit and a reboot. For disk, one can
488: create a new file and vnconfig it (or lvm), and then dump/restore,
489: just like updating physical disks, but without having to be there and
490: without those pesky connectors.
491:
1.48 gdt 492: Starting domains automatically
493: ------------------------------
1.28 gdt 494:
1.48 gdt 495: To start domains foo at bar at boot and shut them down cleanly on dom0
496: shutdown, in rc.conf add:
1.28 gdt 497:
1.48 gdt 498: xendomains="foo bar"
1.28 gdt 499:
1.111 wiz 500: Note that earlier versions of the xentools41 xendomains rc.d script
501: used xl, when one should use xm with 4.1.
1.28 gdt 502:
503: Creating specific unprivileged domains (domU)
504: =============================================
1.14 gdt 505:
506: Creating domUs is almost entirely independent of operating system. We
1.49 gdt 507: have already presented the basics of config files. Note that you must
508: have already completed the dom0 setup so that "xl list" (or "xm list")
509: works.
1.14 gdt 510:
511: Creating an unprivileged NetBSD domain (domU)
512: ---------------------------------------------
1.1 mspo 513:
1.49 gdt 514: See the earlier config file, and adjust memory. Decide on how much
515: storage you will provide, and prepare it (file or lvm).
516:
1.111 wiz 517: While the kernel will be obtained from the dom0 file system, the same
1.49 gdt 518: file should be present in the domU as /netbsd so that tools like
519: savecore(8) can work. (This is helpful but not necessary.)
520:
521: The kernel must be specifically for Xen and for use as a domU. The
522: i386 and amd64 provide the following kernels:
523:
524: i386 XEN3PAE_DOMU
1.95 gdt 525: amd64 XEN3_DOMU
1.5 mspo 526:
1.49 gdt 527: This will boot NetBSD, but this is not that useful if the disk is
528: empty. One approach is to unpack sets onto the disk outside of xen
529: (by mounting it, just as you would prepare a physical disk for a
530: system you can't run the installer on).
531:
532: A second approach is to run an INSTALL kernel, which has a miniroot
533: and can load sets from the network. To do this, copy the INSTALL
534: kernel to / and change the kernel line in the config file to:
1.5 mspo 535:
1.49 gdt 536: kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
1.5 mspo 537:
1.49 gdt 538: Then, start the domain as "xl create -c configname".
1.1 mspo 539:
1.49 gdt 540: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
541: line should be used in the config file.
1.1 mspo 542:
1.3 mspo 543: disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
1.1 mspo 544:
545: After booting the domain, the option to install via CDROM may be
1.49 gdt 546: selected. The CDROM device should be changed to `xbd1d`.
1.1 mspo 547:
1.49 gdt 548: Once done installing, "halt -p" the new domain (don't reboot or halt,
549: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
550: config file), switch the config file back to the XEN3_DOMU kernel,
551: and start the new domain again. Now it should be able to use "root on
552: xbd0a" and you should have a, functional NetBSD domU.
1.1 mspo 553:
1.49 gdt 554: TODO: check if this is still accurate.
1.1 mspo 555: When the new domain is booting you'll see some warnings about *wscons*
556: and the pseudo-terminals. These can be fixed by editing the files
1.5 mspo 557: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
558: `/etc/ttys`, except *console*, like this:
1.1 mspo 559:
1.3 mspo 560: console "/usr/libexec/getty Pc" vt100 on secure
561: ttyE0 "/usr/libexec/getty Pc" vt220 off secure
562: ttyE1 "/usr/libexec/getty Pc" vt220 off secure
563: ttyE2 "/usr/libexec/getty Pc" vt220 off secure
564: ttyE3 "/usr/libexec/getty Pc" vt220 off secure
1.1 mspo 565:
1.5 mspo 566: Finally, all screens must be commented out from `/etc/wscons.conf`.
1.1 mspo 567:
568: It is also desirable to add
569:
1.49 gdt 570: powerd=YES
1.1 mspo 571:
1.5 mspo 572: in rc.conf. This way, the domain will be properly shut down if
1.53 gdt 573: `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
1.1 mspo 574:
1.92 gdt 575: It is not strictly necessary to have a kernel (as /netbsd) in the domU
1.111 wiz 576: file system. However, various programs (e.g. netstat) will use that
1.92 gdt 577: kernel to look up symbols to read from kernel virtual memory. If
578: /netbsd is not the running kernel, those lookups will fail. (This is
579: not really a Xen-specific issue, but because the domU kernel is
580: obtained from the dom0, it is far more likely to be out of sync or
581: missing with Xen.)
582:
1.14 gdt 583: Creating an unprivileged Linux domain (domU)
1.5 mspo 584: --------------------------------------------
1.1 mspo 585:
586: Creating unprivileged Linux domains isn't much different from
587: unprivileged NetBSD domains, but there are some details to know.
588:
589: First, the second parameter passed to the disk declaration (the '0x1' in
590: the example below)
591:
1.3 mspo 592: disk = [ 'phy:/dev/wd0e,0x1,w' ]
1.1 mspo 593:
594: does matter to Linux. It wants a Linux device number here (e.g. 0x300
1.49 gdt 595: for hda). Linux builds device numbers as: (major \<\< 8 + minor).
596: So, hda1 which has major 3 and minor 1 on a Linux system will have
597: device number 0x301. Alternatively, devices names can be used (hda,
598: hdb, ...) as xentools has a table to map these names to devices
599: numbers. To export a partition to a Linux guest we can use:
1.1 mspo 600:
1.49 gdt 601: disk = [ 'phy:/dev/wd0e,0x300,w' ]
602: root = "/dev/hda1 ro"
1.1 mspo 603:
604: and it will appear as /dev/hda on the Linux system, and be used as root
605: partition.
606:
1.49 gdt 607: To install the Linux system on the partition to be exported to the
608: guest domain, the following method can be used: install
609: sysutils/e2fsprogs from pkgsrc. Use mke2fs to format the partition
610: that will be the root partition of your Linux domain, and mount it.
611: Then copy the files from a working Linux system, make adjustments in
612: `/etc` (fstab, network config). It should also be possible to extract
613: binary packages such as .rpm or .deb directly to the mounted partition
614: using the appropriate tool, possibly running under NetBSD's Linux
1.111 wiz 615: emulation. Once the file system has been populated, umount it. If
616: desirable, the file system can be converted to ext3 using tune2fs -j.
1.49 gdt 617: It should now be possible to boot the Linux guest domain, using one of
618: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
1.1 mspo 619:
1.111 wiz 620: To get the Linux console right, you need to add:
1.1 mspo 621:
1.3 mspo 622: extra = "xencons=tty1"
1.1 mspo 623:
1.111 wiz 624: to your configuration since not all Linux distributions auto-attach a
1.1 mspo 625: tty to the xen console.
626:
1.14 gdt 627: Creating an unprivileged Solaris domain (domU)
1.5 mspo 628: ----------------------------------------------
1.1 mspo 629:
1.50 gdt 630: See possibly outdated
631: [Solaris domU instructions](/ports/xen/howto-solaris/).
1.5 mspo 632:
1.1 mspo 633:
1.52 gdt 634: PCI passthrough: Using PCI devices in guest domains
635: ---------------------------------------------------
1.1 mspo 636:
1.53 gdt 637: The dom0 can give other domains access to selected PCI
1.52 gdt 638: devices. This can allow, for example, a non-privileged domain to have
639: access to a physical network interface or disk controller. However,
640: keep in mind that giving a domain access to a PCI device most likely
641: will give the domain read/write access to the whole physical memory,
642: as PCs don't have an IOMMU to restrict memory access to DMA-capable
1.53 gdt 643: device. Also, it's not possible to export ISA devices to non-dom0
1.52 gdt 644: domains, which means that the primary VGA adapter can't be exported.
645: A guest domain trying to access the VGA registers will panic.
646:
1.53 gdt 647: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
1.52 gdt 648: not been ported to later versions at this time.
649:
650: For a PCI device to be exported to a domU, is has to be attached to
651: the "pciback" driver in dom0. Devices passed to the dom0 via the
652: pciback.hide boot parameter will attach to "pciback" instead of the
653: usual driver. The list of devices is specified as "(bus:dev.func)",
1.5 mspo 654: where bus and dev are 2-digit hexadecimal numbers, and func a
655: single-digit number:
1.1 mspo 656:
1.52 gdt 657: pciback.hide=(00:0a.0)(00:06.0)
1.1 mspo 658:
1.52 gdt 659: pciback devices should show up in the dom0's boot messages, and the
1.5 mspo 660: devices should be listed in the `/kern/xen/pci` directory.
1.1 mspo 661:
1.52 gdt 662: PCI devices to be exported to a domU are listed in the "pci" array of
663: the domU's config file, with the format "0000:bus:dev.func".
1.1 mspo 664:
1.52 gdt 665: pci = [ '0000:00:06.0', '0000:00:0a.0' ]
1.1 mspo 666:
1.52 gdt 667: In the domU an "xpci" device will show up, to which one or more pci
1.111 wiz 668: buses will attach. Then the PCI drivers will attach to PCI buses as
1.52 gdt 669: usual. Note that the default NetBSD DOMU kernels do not have "xpci"
670: or any PCI drivers built in by default; you have to build your own
671: kernel to use PCI devices in a domU. Here's a kernel config example;
672: note that only the "xpci" lines are unusual.
673:
674: include "arch/i386/conf/XEN3_DOMU"
675:
1.111 wiz 676: # Add support for PCI buses to the XEN3_DOMU kernel
1.52 gdt 677: xpci* at xenbus ?
678: pci* at xpci ?
679:
680: # PCI USB controllers
681: uhci* at pci? dev ? function ? # Universal Host Controller (Intel)
682:
683: # USB bus support
684: usb* at uhci?
685:
686: # USB Hubs
687: uhub* at usb?
688: uhub* at uhub? port ? configuration ? interface ?
689:
690: # USB Mass Storage
691: umass* at uhub? port ? configuration ? interface ?
692: wd* at umass?
693: # SCSI controllers
694: ahc* at pci? dev ? function ? # Adaptec [23]94x, aic78x0 SCSI
695:
696: # SCSI bus support (for both ahc and umass)
697: scsibus* at scsi?
698:
699: # SCSI devices
700: sd* at scsibus? target ? lun ? # SCSI disk drives
701: cd* at scsibus? target ? lun ? # SCSI CD-ROM drives
1.1 mspo 702:
703:
1.28 gdt 704: NetBSD as a domU in a VPS
705: =========================
706:
707: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
708: hardware. This section explains how to deal with Xen in a domU as a
709: virtual private server where you do not control or have access to the
1.70 gdt 710: dom0. This is not intended to be an exhaustive list of VPS providers;
711: only a few are mentioned that specifically support NetBSD.
1.28 gdt 712:
1.52 gdt 713: VPS operators provide varying degrees of access and mechanisms for
714: configuration. The big issue is usually how one controls which kernel
1.111 wiz 715: is booted, because the kernel is nominally in the dom0 file system (to
716: which VPS users do not normally have access). A second issue is how
1.70 gdt 717: to install NetBSD.
1.52 gdt 718: A VPS user may want to compile a kernel for security updates, to run
719: npf, run IPsec, or any other reason why someone would want to change
720: their kernel.
721:
1.111 wiz 722: One approach is to have an administrative interface to upload a kernel,
1.68 gdt 723: or to select from a prepopulated list. Other approaches are pygrub
1.59 gdt 724: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
1.111 wiz 725: kernel from the domU file system. This is closer to a regular physical
1.59 gdt 726: computer, where someone who controls a machine can replace the kernel.
1.52 gdt 727:
1.74 gdt 728: A second issue is multiple CPUs. With NetBSD 6, domUs support
729: multiple vcpus, and it is typical for VPS providers to enable multiple
730: CPUs for NetBSD domUs.
731:
1.68 gdt 732: pygrub
1.59 gdt 733: -------
1.52 gdt 734:
1.111 wiz 735: pygrub runs in the dom0 and looks into the domU file system. This
736: implies that the domU must have a kernel in a file system in a format
1.68 gdt 737: known to pygrub. As of 2014, pygrub seems to be of mostly historical
738: interest.
1.52 gdt 739:
1.59 gdt 740: pvgrub
741: ------
742:
743: pvgrub is a version of grub that uses PV operations instead of BIOS
744: calls. It is booted from the dom0 as the domU kernel, and then reads
1.111 wiz 745: /grub/menu.lst and loads a kernel from the domU file system.
1.59 gdt 746:
1.70 gdt 747: [Panix](http://www.panix.com/) lets users use pvgrub. Panix reports
1.71 gdt 748: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
749: (and hence with defaults from "newfs -O 2"). See [Panix's pvgrub
1.70 gdt 750: page](http://www.panix.com/v-colo/grub.html), which describes only
1.74 gdt 751: Linux but should be updated to cover NetBSD :-).
1.70 gdt 752:
753: [prgmr.com](http://prgmr.com/) also lets users with pvgrub to boot
754: their own kernel. See then [prgmr.com NetBSD
1.74 gdt 755: HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU)
756: (which is in need of updating).
1.59 gdt 757:
1.70 gdt 758: It appears that [grub's FFS
759: code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
760: does not support all aspects of modern FFS, but there are also reports
1.72 gdt 761: that FFSv2 works fine. At prgmr, typically one has an ext2 or FAT
1.70 gdt 762: partition for the kernel with the intent that grub can understand it,
763: which leads to /netbsd not being the actual kernel. One must remember
1.111 wiz 764: to update the special boot partition.
1.59 gdt 765:
766: Amazon
767: ------
768:
1.143 wiki 769: See the [Amazon EC2 page](/amazon_ec2/).
1.44 gdt 770:
1.93 gdt 771: Random pointers
772: ===============
773:
1.117 gdt 774: This section contains links from elsewhere not yet integrated into the
775: HOWTO, and other guides.
1.93 gdt 776:
777: * http://www.lumbercartel.ca/library/xen/
778: * http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html
1.117 gdt 779: * https://gmplib.org/~tege/xen.html
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