Annotation of wikisrc/ports/xen/howto.mdwn, revision 1.185
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:
1.182 gdt 11: This HOWTO presumes a basic familiarity with the Xen system
12: architecture, with installing NetBSD on amd64 hardware, and with
13: installing software from pkgsrc. See also the [Xen
14: website](http://www.xenproject.org/).
15:
16: [[!toc]]
17:
1.183 gdt 18: # Overview
1.182 gdt 19:
20: The basic concept of Xen is that the hypervisor (xenkernel) runs on
21: the hardware, and runs a privileged domain ("dom0") that can access
22: disks/networking/etc. One then runs additonal unprivileged domains
23: (each a "domU"), presumably to do something useful.
24:
25: This HOWTO addresses how to run a NetBSD dom0 (and hence also build
26: xen itself). It also addresses how to run domUs in that environment,
27: and how to deal with having a domU in a Xen environment run by someone
28: else and/or not running NetBSD.
29:
30: ## Guest Styles
31:
32: Xen supports different styles of guests.
1.149 maxv 33:
34: [[!table data="""
35: Style of guest |Supported by NetBSD
1.150 maxv 36: PV |Yes (dom0, domU)
37: HVM |Yes (domU)
1.171 gdt 38: PVHVM |current-only (domU)
1.180 gdt 39: PVH |current-only (domU, dom0 not yet)
1.149 maxv 40: """]]
41:
42: In Para-Virtualized (PV) mode, the guest OS does not attempt to access
43: hardware directly, but instead makes hypercalls to the hypervisor; PV
1.170 gdt 44: guests must be specifically coded for Xen.
1.182 gdt 45: See [PV](https://wiki.xen.org/wiki/Paravirtualization_(PV\)).
1.170 gdt 46:
47: In HVM mode, no guest modification is required; however, hardware
48: support is required, such as VT-x on Intel CPUs and SVM on AMD CPUs.
1.177 gdt 49: The dom0 runs qemu to emulate hardware.
1.170 gdt 50:
1.176 gdt 51: In PVHVM mode, the guest runs as HVM, but additionally can use PV
52: drivers for efficiency.
1.182 gdt 53: See [PV on HVM](https://wiki.xen.org/wiki/PV_on_HVM).
1.170 gdt 54:
1.180 gdt 55: There have been two PVH modes: original PVH and PVHv2. Original PVH
56: was based on PV mode and is no longer relevant at all. PVHv2 is
57: basically lightweight HVM with PV drivers. A critical feature of it
58: is that qemu is not needed; the hypervisor can do the emulation that
59: is required. Thus, a dom0 can be PVHv2.
1.182 gdt 60: The source code uses PVH and config files use pvh; this refers to PVHv2.
61: See [PVH(v2)](https://wiki.xenproject.org/wiki/PVH_(v2\)_Domu).
1.180 gdt 62:
1.182 gdt 63: At system boot, the dom0 kernel is loaded as a module with Xen as the kernel.
1.12 gdt 64: The dom0 can start one or more domUs. (Booting is explained in detail
65: in the dom0 section.)
66:
1.182 gdt 67: ## CPU Architecture
68:
69: Xen runs on x86_64 hardware (the NetBSD amd64 port).
70:
71: There is a concept of Xen running on ARM, but there are no reports of this working with NetBSD.
72:
73: The dom0 system should be amd64. (Instructions for i386PAE dom0 have been removed from the HOWTO.)
1.1 mspo 74:
1.182 gdt 75: The domU can be i386PAE or amd64.
76: i386PAE at one point was considered as [faster](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html) than amd64.
1.150 maxv 77:
1.182 gdt 78: ## Xen Versions
1.15 gdt 79:
1.111 wiz 80: In NetBSD, Xen is provided in pkgsrc, via matching pairs of packages
1.15 gdt 81: xenkernel and xentools. We will refer only to the kernel versions,
82: but note that both packages must be installed together and must have
83: matching versions.
84:
1.145 maxv 85: Versions available in pkgsrc:
1.85 gdt 86:
1.145 maxv 87: [[!table data="""
1.184 gdt 88: Xen Version |Package Name |Xen CPU Support |EOL'ed By Upstream
89: 4.11 |xenkernel411 |x86_64 |No
90: 4.13 |xenkernel413 |x86_64 |No
1.145 maxv 91: """]]
1.113 gdt 92:
1.96 gdt 93: See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
94:
1.166 gdt 95: Older Xen had a python-based management tool called xm, now replaced
1.176 gdt 96: by xl.
1.166 gdt 97:
1.183 gdt 98: ## NetBSD versions
99:
100: Xen has been supported in NetBSD for a long time, at least since 2005.
101: Initially Xen was PV only.
102:
103: NetBSD 8 and up support PV and HVM modes.
104:
105: Support for PVHVM and PVH is available only in NetBSD-current.
106:
1.185 ! gdt 107: NetBSD as a dom0 does not run SMP, because some drivers are not yet
! 108: safe for this. \todo Link to more information about what needs work.
! 109:
! 110: NetBSD, when run as a domU, can and does typically run SMP.
! 111:
! 112: Note: NetBSD support is called XEN3. However, it does support Xen 4,
! 113: because the hypercall interface has remained identical.
! 114:
1.166 gdt 115: # Creating a dom0
1.15 gdt 116:
1.158 maxv 117: In order to install a NetBSD as a dom0, one must first install a normal
118: NetBSD system, and then pivot the install to a dom0 install by changing
119: the kernel and boot configuration.
1.15 gdt 120:
1.142 gdt 121: In 2018-05, trouble booting a dom0 was reported with 256M of RAM: with
122: 512M it worked reliably. This does not make sense, but if you see
123: "not ELF" after Xen boots, try increasing dom0 RAM.
124:
1.181 gdt 125: ## Installation of NetBSD
1.13 gdt 126:
1.157 maxv 127: [Install NetBSD/amd64](/guide/inst/)
1.19 gdt 128: just as you would if you were not using Xen.
1.1 mspo 129:
1.181 gdt 130: ## Installation of Xen
1.1 mspo 131:
1.178 gdt 132: We will consider that you chose to use Xen 4.13, with NetBSD/amd64 as
1.155 maxv 133: dom0. In the dom0, install xenkernel48 and xentools48 from pkgsrc.
134:
135: Once this is done, install the Xen kernel itself:
136:
137: [[!template id=programlisting text="""
138: # cp /usr/pkg/xen48-kernel/xen.gz /
139: """]]
140:
1.159 maxv 141: Then, place a NetBSD XEN3_DOM0 kernel in the `/` directory. Such kernel
142: can either be compiled manually, or downloaded from the NetBSD FTP, for
143: example at:
144:
145: [[!template id=programlisting text="""
146: ftp.netbsd.org/pub/NetBSD/NetBSD-8.0/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
147: """]]
1.20 gdt 148:
1.155 maxv 149: Add a line to /boot.cfg to boot Xen:
1.20 gdt 150:
1.157 maxv 151: [[!template id=filecontent name="/boot.cfg" text="""
1.152 maxv 152: menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
153: """]]
1.20 gdt 154:
1.159 maxv 155: This specifies that the dom0 should have 512MB of ram, leaving the rest
156: to be allocated for domUs. To use a serial console, use:
1.77 gdt 157:
1.157 maxv 158: [[!template id=filecontent name="/boot.cfg" text="""
1.152 maxv 159: menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
160: """]]
1.77 gdt 161:
162: which will use the first serial port for Xen (which counts starting
1.139 gson 163: from 1, unlike NetBSD which counts starting from 0), forcing
164: speed/parity. Because the NetBSD command line lacks a
165: "console=pc" argument, it will use the default "xencons" console device,
166: which directs the console I/O through Xen to the same console device Xen
167: itself uses (in this case, the serial port).
168:
1.157 maxv 169: In an attempt to add performance, one can also add `dom0_max_vcpus=1 dom0_vcpus_pin`,
1.37 gdt 170: to force only one vcpu to be provided (since NetBSD dom0 can't use
1.158 maxv 171: more) and to pin that vcpu to a physical CPU. Xen has
1.178 gdt 172: [many boot options](http://xenbits.xenproject.org/docs/4.13-testing/misc/xen-command-line.html),
1.111 wiz 173: and other than dom0 memory and max_vcpus, they are generally not
1.93 gdt 174: necessary.
175:
1.159 maxv 176: Copy the boot scripts into `/etc/rc.d`:
177:
178: [[!template id=programlisting text="""
179: # cp /usr/pkg/share/examples/rc.d/xen* /etc/rc.d/
180: """]]
181:
1.158 maxv 182: Enable `xencommons`:
1.31 gdt 183:
1.157 maxv 184: [[!template id=filecontent name="/etc/rc.conf" text="""
1.152 maxv 185: xencommons=YES
186: """]]
1.31 gdt 187:
1.158 maxv 188: Now, reboot so that you are running a DOM0 kernel under Xen, rather
189: than GENERIC without Xen.
1.157 maxv 190:
1.31 gdt 191: TODO: Recommend for/against xen-watchdog.
1.27 jnemeth 192:
1.158 maxv 193: Once the reboot is done, use `xl` to inspect Xen's boot messages,
1.157 maxv 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:
1.181 gdt 220: ## anita (for testing NetBSD)
1.41 gdt 221:
1.178 gdt 222: With the setup so far, one should be able to run
1.82 gdt 223: anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
224: root, because anita must create a domU):
225:
1.153 maxv 226: [[!template id=programlisting text="""
227: anita --vmm=xl test file:///usr/obj/i386/
228: """]]
1.82 gdt 229:
1.181 gdt 230: ## Xen-specific NetBSD issues
1.40 gdt 231:
232: There are (at least) two additional things different about NetBSD as a
233: dom0 kernel compared to hardware.
234:
1.111 wiz 235: One is that the module ABI is different because some of the #defines
1.109 gdt 236: change, so one must build modules for Xen. As of netbsd-7, the build
1.157 maxv 237: system does this automatically.
1.40 gdt 238:
239: The other difference is that XEN3_DOM0 does not have exactly the same
240: options as GENERIC. While it is debatable whether or not this is a
241: bug, users should be aware of this and can simply add missing config
242: items if desired.
243:
1.181 gdt 244: ## Updating NetBSD in a dom0
1.15 gdt 245:
246: This is just like updating NetBSD on bare hardware, assuming the new
247: version supports the version of Xen you are running. Generally, one
248: replaces the kernel and reboots, and then overlays userland binaries
1.157 maxv 249: and adjusts `/etc`.
1.15 gdt 250:
251: Note that one must update both the non-Xen kernel typically used for
252: rescue purposes and the DOM0 kernel used with Xen.
253:
1.181 gdt 254: ## Converting from grub to /boot
1.55 gdt 255:
1.157 maxv 256: These instructions were used to convert a system from
1.55 gdt 257: grub to /boot. The system was originally installed in February of
258: 2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
259: over time. Before these commands, it was running NetBSD 6 i386, Xen
260: 4.1 and grub, much like the message linked earlier in the grub
261: section.
262:
1.157 maxv 263: [[!template id=programlisting text="""
264: # Install MBR bootblocks on both disks.
265: fdisk -i /dev/rwd0d
266: fdisk -i /dev/rwd1d
267: # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
268: installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
269: installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
270: # Install secondary boot loader
271: cp -p /usr/mdec/boot /
272: # Create boot.cfg following earlier guidance:
273: menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
274: menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=512M
275: menu=GENERIC:boot
276: menu=GENERIC single-user:boot -s
277: menu=GENERIC.ok:boot netbsd.ok
278: menu=GENERIC.ok single-user:boot netbsd.ok -s
279: menu=Drop to boot prompt:prompt
280: default=1
281: timeout=30
282: """]]
1.22 gdt 283:
1.181 gdt 284: ## Upgrading Xen versions
1.15 gdt 285:
1.110 gdt 286: Minor version upgrades are trivial. Just rebuild/replace the
1.157 maxv 287: xenkernel version and copy the new xen.gz to `/` (where `/boot.cfg`
1.110 gdt 288: references it), and reboot.
289:
1.160 maxv 290: #Unprivileged domains (domU)
1.28 gdt 291:
292: This section describes general concepts about domUs. It does not
1.33 gdt 293: address specific domU operating systems or how to install them. The
1.157 maxv 294: config files for domUs are typically in `/usr/pkg/etc/xen`, and are
1.60 wiki 295: typically named so that the file name, domU name and the domU's host
1.33 gdt 296: name match.
297:
1.111 wiz 298: The domU is provided with CPU and memory by Xen, configured by the
1.33 gdt 299: dom0. The domU is provided with disk and network by the dom0,
300: mediated by Xen, and configured in the dom0.
301:
302: Entropy in domUs can be an issue; physical disks and network are on
303: the dom0. NetBSD's /dev/random system works, but is often challenged.
304:
1.181 gdt 305: ## Config files
1.48 gdt 306:
1.165 gson 307: See /usr/pkg/share/examples/xen/xlexample*
1.164 gson 308: for a small number of well-commented examples, mostly for running
1.48 gdt 309: GNU/Linux.
310:
1.157 maxv 311: The following is an example minimal domain configuration file. The domU
312: serves as a network file server.
313:
314: [[!template id=filecontent name="/usr/pkg/etc/xen/foo" text="""
315: name = "domU-id"
316: kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
317: memory = 1024
318: vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
319: disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
320: 'file:/n0/xen/foo-wd1,0x1,w' ]
321: """]]
1.48 gdt 322:
1.157 maxv 323: The domain will have name given in the `name` setting. The kernel has the
1.48 gdt 324: host/domU name in it, so that on the dom0 one can update the various
1.157 maxv 325: domUs independently. The `vif` line causes an interface to be provided,
1.48 gdt 326: with a specific mac address (do not reuse MAC addresses!), in bridge
327: mode. Two disks are provided, and they are both writable; the bits
328: are stored in files and Xen attaches them to a vnd(4) device in the
1.111 wiz 329: dom0 on domain creation. The system treats xbd0 as the boot device
1.48 gdt 330: without needing explicit configuration.
331:
1.163 gson 332: By convention, domain config files are kept in `/usr/pkg/etc/xen`. Note
1.157 maxv 333: that "xl create" takes the name of a config file, while other commands
334: take the name of a domain.
335:
336: Examples of commands:
1.48 gdt 337:
1.157 maxv 338: [[!template id=programlisting text="""
1.163 gson 339: xl create /usr/pkg/etc/xen/foo
340: xl console domU-id
341: xl create -c /usr/pkg/etc/xen/foo
342: xl shutdown domU-id
1.157 maxv 343: xl list
344: """]]
345:
346: Typing `^]` will exit the console session. Shutting down a domain is
1.48 gdt 347: equivalent to pushing the power button; a NetBSD domU will receive a
348: power-press event and do a clean shutdown. Shutting down the dom0
349: will trigger controlled shutdowns of all configured domUs.
350:
1.181 gdt 351: ## CPU and memory
1.33 gdt 352:
1.169 plunky 353: A domain is provided with some number of vcpus, up to the number
1.157 maxv 354: of CPUs seen by the hypervisor. For a domU, it is controlled
1.48 gdt 355: from the config file by the "vcpus = N" directive.
356:
357: A domain is provided with memory; this is controlled in the config
358: file by "memory = N" (in megabytes). In the straightforward case, the
359: sum of the the memory allocated to the dom0 and all domUs must be less
1.33 gdt 360: than the available memory.
361:
362: Xen also provides a "balloon" driver, which can be used to let domains
1.157 maxv 363: use more memory temporarily.
1.28 gdt 364:
1.181 gdt 365: ## Virtual disks
1.28 gdt 366:
1.158 maxv 367: In domU config files, the disks are defined as a sequence of 3-tuples:
368:
369: * The first element is "method:/path/to/disk". Common methods are
1.162 gutterid 370: "file:" for a file-backed vnd, and "phy:" for something that is already
371: a device, such as an LVM logical volume.
1.158 maxv 372:
373: * The second element is an artifact of how virtual disks are passed to
374: Linux, and a source of confusion with NetBSD Xen usage. Linux domUs
375: are given a device name to associate with the disk, and values like
376: "hda1" or "sda1" are common. In a NetBSD domU, the first disk appears
377: as xbd0, the second as xbd1, and so on. However, xl demands a
378: second argument. The name given is converted to a major/minor by
379: calling stat(2) on the name in /dev and this is passed to the domU.
380: In the general case, the dom0 and domU can be different operating
381: systems, and it is an unwarranted assumption that they have consistent
382: numbering in /dev, or even that the dom0 OS has a /dev. With NetBSD
383: as both dom0 and domU, using values of 0x0 for the first disk and 0x1
384: for the second works fine and avoids this issue. For a GNU/Linux
385: guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
386: /dev/hda1.
1.48 gdt 387:
1.158 maxv 388: * The third element is "w" for writable disks, and "r" for read-only
389: disks.
390:
391: Example:
392: [[!template id=filecontent name="/usr/pkg/etc/xen/foo" text="""
393: disk = [ 'file:/n0/xen/foo-wd0,0x0,w' ]
394: """]]
1.28 gdt 395:
1.127 gdt 396: Note that NetBSD by default creates only vnd[0123]. If you need more
397: than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the
398: dom0.
399:
400: Note that NetBSD by default creates only xbd[0123]. If you need more
401: virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU.
402:
1.28 gdt 403: Virtual Networking
404: ------------------
405:
1.111 wiz 406: Xen provides virtual Ethernets, each of which connects the dom0 and a
1.46 gdt 407: domU. For each virtual network, there is an interface "xvifN.M" in
1.158 maxv 408: the dom0, and a matching interface xennetM (NetBSD name) in domU index N.
409: The interfaces behave as if there is an Ethernet with two
1.111 wiz 410: adapters connected. From this primitive, one can construct various
1.46 gdt 411: configurations. We focus on two common and useful cases for which
412: there are existing scripts: bridging and NAT.
1.28 gdt 413:
1.48 gdt 414: With bridging (in the example above), the domU perceives itself to be
415: on the same network as the dom0. For server virtualization, this is
416: usually best. Bridging is accomplished by creating a bridge(4) device
417: and adding the dom0's physical interface and the various xvifN.0
418: interfaces to the bridge. One specifies "bridge=bridge0" in the domU
419: config file. The bridge must be set up already in the dom0; an
420: example /etc/ifconfig.bridge0 is:
1.46 gdt 421:
1.157 maxv 422: [[!template id=filecontent name="/etc/ifconfig.bridge0" text="""
423: create
424: up
425: !brconfig bridge0 add wm0
426: """]]
1.28 gdt 427:
428: With NAT, the domU perceives itself to be behind a NAT running on the
429: dom0. This is often appropriate when running Xen on a workstation.
1.48 gdt 430: TODO: NAT appears to be configured by "vif = [ '' ]".
1.28 gdt 431:
1.49 gdt 432: The MAC address specified is the one used for the interface in the new
1.53 gdt 433: domain. The interface in dom0 will use this address XOR'd with
1.49 gdt 434: 00:00:00:01:00:00. Random MAC addresses are assigned if not given.
435:
1.48 gdt 436: Starting domains automatically
437: ------------------------------
1.28 gdt 438:
1.158 maxv 439: To start domains `domU-netbsd` and `domU-linux` at boot and shut them
440: down cleanly on dom0 shutdown, add the following in rc.conf:
1.28 gdt 441:
1.158 maxv 442: [[!template id=filecontent name="/etc/rc.conf" text="""
443: xendomains="domU-netbsd domU-linux"
444: """]]
1.28 gdt 445:
1.180 gdt 446: # Creating a domU
1.14 gdt 447:
448: Creating domUs is almost entirely independent of operating system. We
1.49 gdt 449: have already presented the basics of config files. Note that you must
1.158 maxv 450: have already completed the dom0 setup so that "xl list" works.
1.14 gdt 451:
1.180 gdt 452: Creating a NetBSD PV domU
453: --------------------------
1.1 mspo 454:
1.49 gdt 455: See the earlier config file, and adjust memory. Decide on how much
1.162 gutterid 456: storage you will provide, and prepare it (file or LVM).
1.49 gdt 457:
1.111 wiz 458: While the kernel will be obtained from the dom0 file system, the same
1.49 gdt 459: file should be present in the domU as /netbsd so that tools like
460: savecore(8) can work. (This is helpful but not necessary.)
461:
462: The kernel must be specifically for Xen and for use as a domU. The
463: i386 and amd64 provide the following kernels:
464:
465: i386 XEN3PAE_DOMU
1.95 gdt 466: amd64 XEN3_DOMU
1.5 mspo 467:
1.49 gdt 468: This will boot NetBSD, but this is not that useful if the disk is
469: empty. One approach is to unpack sets onto the disk outside of xen
470: (by mounting it, just as you would prepare a physical disk for a
471: system you can't run the installer on).
472:
473: A second approach is to run an INSTALL kernel, which has a miniroot
474: and can load sets from the network. To do this, copy the INSTALL
475: kernel to / and change the kernel line in the config file to:
1.5 mspo 476:
1.49 gdt 477: kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
1.5 mspo 478:
1.163 gson 479: Then, start the domain as "xl create -c configfile".
1.1 mspo 480:
1.49 gdt 481: Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
482: line should be used in the config file.
1.1 mspo 483:
1.3 mspo 484: disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
1.1 mspo 485:
486: After booting the domain, the option to install via CDROM may be
1.49 gdt 487: selected. The CDROM device should be changed to `xbd1d`.
1.1 mspo 488:
1.49 gdt 489: Once done installing, "halt -p" the new domain (don't reboot or halt,
490: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
491: config file), switch the config file back to the XEN3_DOMU kernel,
492: and start the new domain again. Now it should be able to use "root on
493: xbd0a" and you should have a, functional NetBSD domU.
1.1 mspo 494:
1.49 gdt 495: TODO: check if this is still accurate.
1.1 mspo 496: When the new domain is booting you'll see some warnings about *wscons*
497: and the pseudo-terminals. These can be fixed by editing the files
1.5 mspo 498: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
499: `/etc/ttys`, except *console*, like this:
1.1 mspo 500:
1.3 mspo 501: console "/usr/libexec/getty Pc" vt100 on secure
502: ttyE0 "/usr/libexec/getty Pc" vt220 off secure
503: ttyE1 "/usr/libexec/getty Pc" vt220 off secure
504: ttyE2 "/usr/libexec/getty Pc" vt220 off secure
505: ttyE3 "/usr/libexec/getty Pc" vt220 off secure
1.1 mspo 506:
1.5 mspo 507: Finally, all screens must be commented out from `/etc/wscons.conf`.
1.1 mspo 508:
509: It is also desirable to add
510:
1.49 gdt 511: powerd=YES
1.1 mspo 512:
1.5 mspo 513: in rc.conf. This way, the domain will be properly shut down if
1.184 gdt 514: `xl shutdown -R` or `xl shutdown -H` is used on the dom0.
515: \todo Check the translation to xl.
1.1 mspo 516:
1.92 gdt 517: It is not strictly necessary to have a kernel (as /netbsd) in the domU
1.111 wiz 518: file system. However, various programs (e.g. netstat) will use that
1.92 gdt 519: kernel to look up symbols to read from kernel virtual memory. If
520: /netbsd is not the running kernel, those lookups will fail. (This is
521: not really a Xen-specific issue, but because the domU kernel is
522: obtained from the dom0, it is far more likely to be out of sync or
523: missing with Xen.)
524:
1.158 maxv 525: Creating a Linux domU
526: ---------------------
1.1 mspo 527:
528: Creating unprivileged Linux domains isn't much different from
529: unprivileged NetBSD domains, but there are some details to know.
530:
531: First, the second parameter passed to the disk declaration (the '0x1' in
532: the example below)
533:
1.3 mspo 534: disk = [ 'phy:/dev/wd0e,0x1,w' ]
1.1 mspo 535:
536: does matter to Linux. It wants a Linux device number here (e.g. 0x300
1.49 gdt 537: for hda). Linux builds device numbers as: (major \<\< 8 + minor).
538: So, hda1 which has major 3 and minor 1 on a Linux system will have
539: device number 0x301. Alternatively, devices names can be used (hda,
540: hdb, ...) as xentools has a table to map these names to devices
541: numbers. To export a partition to a Linux guest we can use:
1.1 mspo 542:
1.49 gdt 543: disk = [ 'phy:/dev/wd0e,0x300,w' ]
544: root = "/dev/hda1 ro"
1.1 mspo 545:
546: and it will appear as /dev/hda on the Linux system, and be used as root
547: partition.
548:
1.49 gdt 549: To install the Linux system on the partition to be exported to the
550: guest domain, the following method can be used: install
551: sysutils/e2fsprogs from pkgsrc. Use mke2fs to format the partition
552: that will be the root partition of your Linux domain, and mount it.
553: Then copy the files from a working Linux system, make adjustments in
554: `/etc` (fstab, network config). It should also be possible to extract
555: binary packages such as .rpm or .deb directly to the mounted partition
556: using the appropriate tool, possibly running under NetBSD's Linux
1.111 wiz 557: emulation. Once the file system has been populated, umount it. If
558: desirable, the file system can be converted to ext3 using tune2fs -j.
1.49 gdt 559: It should now be possible to boot the Linux guest domain, using one of
560: the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
1.1 mspo 561:
1.111 wiz 562: To get the Linux console right, you need to add:
1.1 mspo 563:
1.3 mspo 564: extra = "xencons=tty1"
1.1 mspo 565:
1.111 wiz 566: to your configuration since not all Linux distributions auto-attach a
1.1 mspo 567: tty to the xen console.
568:
1.180 gdt 569: ## Creating a NetBSD HVM domU
570:
571: Use type='hmv', probably. Use a GENERIC kernel within the disk image.
572:
573: ## Creating a NetBSD PVH domU
574:
575: Use type='pvh'.
576:
577: \todo Explain where the kernel comes from.
578:
579:
1.158 maxv 580: Creating a Solaris domU
581: -----------------------
1.1 mspo 582:
1.50 gdt 583: See possibly outdated
584: [Solaris domU instructions](/ports/xen/howto-solaris/).
1.5 mspo 585:
1.1 mspo 586:
1.52 gdt 587: PCI passthrough: Using PCI devices in guest domains
588: ---------------------------------------------------
1.1 mspo 589:
1.180 gdt 590: NB: PCI passthrough only works on some Xen versions and as of 2020 it
591: is not clear that it works on any version in pkgsrc. Reports
592: confirming or denying this notion should be sent to port-xen@.
593:
1.53 gdt 594: The dom0 can give other domains access to selected PCI
1.52 gdt 595: devices. This can allow, for example, a non-privileged domain to have
596: access to a physical network interface or disk controller. However,
597: keep in mind that giving a domain access to a PCI device most likely
598: will give the domain read/write access to the whole physical memory,
599: as PCs don't have an IOMMU to restrict memory access to DMA-capable
1.53 gdt 600: device. Also, it's not possible to export ISA devices to non-dom0
1.52 gdt 601: domains, which means that the primary VGA adapter can't be exported.
602: A guest domain trying to access the VGA registers will panic.
603:
1.53 gdt 604: If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
1.52 gdt 605: not been ported to later versions at this time.
606:
607: For a PCI device to be exported to a domU, is has to be attached to
608: the "pciback" driver in dom0. Devices passed to the dom0 via the
609: pciback.hide boot parameter will attach to "pciback" instead of the
610: usual driver. The list of devices is specified as "(bus:dev.func)",
1.5 mspo 611: where bus and dev are 2-digit hexadecimal numbers, and func a
612: single-digit number:
1.1 mspo 613:
1.52 gdt 614: pciback.hide=(00:0a.0)(00:06.0)
1.1 mspo 615:
1.52 gdt 616: pciback devices should show up in the dom0's boot messages, and the
1.5 mspo 617: devices should be listed in the `/kern/xen/pci` directory.
1.1 mspo 618:
1.52 gdt 619: PCI devices to be exported to a domU are listed in the "pci" array of
620: the domU's config file, with the format "0000:bus:dev.func".
1.1 mspo 621:
1.52 gdt 622: pci = [ '0000:00:06.0', '0000:00:0a.0' ]
1.1 mspo 623:
1.52 gdt 624: In the domU an "xpci" device will show up, to which one or more pci
1.111 wiz 625: buses will attach. Then the PCI drivers will attach to PCI buses as
1.52 gdt 626: usual. Note that the default NetBSD DOMU kernels do not have "xpci"
627: or any PCI drivers built in by default; you have to build your own
628: kernel to use PCI devices in a domU. Here's a kernel config example;
629: note that only the "xpci" lines are unusual.
630:
631: include "arch/i386/conf/XEN3_DOMU"
632:
1.111 wiz 633: # Add support for PCI buses to the XEN3_DOMU kernel
1.52 gdt 634: xpci* at xenbus ?
635: pci* at xpci ?
636:
637: # PCI USB controllers
638: uhci* at pci? dev ? function ? # Universal Host Controller (Intel)
639:
640: # USB bus support
641: usb* at uhci?
642:
643: # USB Hubs
644: uhub* at usb?
645: uhub* at uhub? port ? configuration ? interface ?
646:
647: # USB Mass Storage
648: umass* at uhub? port ? configuration ? interface ?
649: wd* at umass?
650: # SCSI controllers
651: ahc* at pci? dev ? function ? # Adaptec [23]94x, aic78x0 SCSI
652:
653: # SCSI bus support (for both ahc and umass)
654: scsibus* at scsi?
655:
656: # SCSI devices
657: sd* at scsibus? target ? lun ? # SCSI disk drives
658: cd* at scsibus? target ? lun ? # SCSI CD-ROM drives
1.1 mspo 659:
660:
1.173 gdt 661: # Specific Issues
662:
663: ## domU
664:
1.176 gdt 665: [NetBSD 5 is known to panic.](http://mail-index.netbsd.org/port-xen/2018/04/17/msg009181.html)
1.175 gdt 666: (However, NetBSD 5 systems should be updated to a supported version.)
1.173 gdt 667:
668: # NetBSD as a domU in a VPS
1.28 gdt 669:
670: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
671: hardware. This section explains how to deal with Xen in a domU as a
672: virtual private server where you do not control or have access to the
1.70 gdt 673: dom0. This is not intended to be an exhaustive list of VPS providers;
674: only a few are mentioned that specifically support NetBSD.
1.28 gdt 675:
1.52 gdt 676: VPS operators provide varying degrees of access and mechanisms for
677: configuration. The big issue is usually how one controls which kernel
1.111 wiz 678: is booted, because the kernel is nominally in the dom0 file system (to
679: which VPS users do not normally have access). A second issue is how
1.70 gdt 680: to install NetBSD.
1.52 gdt 681: A VPS user may want to compile a kernel for security updates, to run
682: npf, run IPsec, or any other reason why someone would want to change
683: their kernel.
684:
1.111 wiz 685: One approach is to have an administrative interface to upload a kernel,
1.68 gdt 686: or to select from a prepopulated list. Other approaches are pygrub
1.59 gdt 687: (deprecated) and pvgrub, which are ways to have a bootloader obtain a
1.111 wiz 688: kernel from the domU file system. This is closer to a regular physical
1.59 gdt 689: computer, where someone who controls a machine can replace the kernel.
1.52 gdt 690:
1.74 gdt 691: A second issue is multiple CPUs. With NetBSD 6, domUs support
692: multiple vcpus, and it is typical for VPS providers to enable multiple
693: CPUs for NetBSD domUs.
694:
1.180 gdt 695: ## Complexities due to Xen changes
696:
697: Xen has many security advisories and people running Xen systems make
698: different choices.
699:
700: ### stub domains
701:
702: Some (Linux only?) dom0 systems use something called "stub domains" to
703: isolate qemu from the dom0 system, as a security and reliabilty
704: mechanism when running HVM domUs. Somehow, NetBSD's GENERIC kernel
705: ends up using PIO for disks rather than DMA. Of course, all of this
706: is emulated, but emulated PIO is unusably slow. This problem is not
707: currently understood.
708:
709: ### Grant tables
710:
711: There are multiple versions of using grant tables, and some security
712: advisories have suggested disabling some versions. Some versions of
713: NetBSD apparently only use specific versions and this can lead to
714: "NetBSD current doesn't run on hosting provider X" situations.
715:
716: \todo Explain better.
717:
1.181 gdt 718: ## Boot methods
719:
720: ### pvgrub
1.59 gdt 721:
722: pvgrub is a version of grub that uses PV operations instead of BIOS
723: calls. It is booted from the dom0 as the domU kernel, and then reads
1.111 wiz 724: /grub/menu.lst and loads a kernel from the domU file system.
1.59 gdt 725:
1.70 gdt 726: [Panix](http://www.panix.com/) lets users use pvgrub. Panix reports
1.71 gdt 727: that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
728: (and hence with defaults from "newfs -O 2"). See [Panix's pvgrub
1.70 gdt 729: page](http://www.panix.com/v-colo/grub.html), which describes only
1.74 gdt 730: Linux but should be updated to cover NetBSD :-).
1.70 gdt 731:
732: [prgmr.com](http://prgmr.com/) also lets users with pvgrub to boot
733: their own kernel. See then [prgmr.com NetBSD
1.74 gdt 734: HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU)
735: (which is in need of updating).
1.59 gdt 736:
1.70 gdt 737: It appears that [grub's FFS
738: code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
739: does not support all aspects of modern FFS, but there are also reports
1.72 gdt 740: that FFSv2 works fine. At prgmr, typically one has an ext2 or FAT
1.70 gdt 741: partition for the kernel with the intent that grub can understand it,
742: which leads to /netbsd not being the actual kernel. One must remember
1.111 wiz 743: to update the special boot partition.
1.59 gdt 744:
1.181 gdt 745: ### pygrub
1.168 wiki 746:
747: pygrub runs in the dom0 and looks into the domU file system. This
748: implies that the domU must have a kernel in a file system in a format
749: known to pygrub.
750:
751: pygrub doesn't seem to work to load Linux images under NetBSD dom0,
752: and is inherently less secure than pvgrub due to running inside dom0. For both these
753: reasons, pygrub should not be used, and is only still present so that
754: historical DomU images using it still work.
755:
756: As of 2014, pygrub seems to be of mostly historical
757: interest. New DomUs should use pvgrub.
758:
1.181 gdt 759: ## Specific Providers
760:
761: ### Amazon
1.59 gdt 762:
1.143 wiki 763: See the [Amazon EC2 page](/amazon_ec2/).
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