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Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.87 and 1.95

version 1.87, 2015/01/28 19:27:11	version 1.95, 2015/03/05 14:04:55
Line 142 running an i386 NetBSD kernel as a domU,	Line 142 running an i386 NetBSD kernel as a domU,
(Note that emacs (at least) fails if run on i386 with PAE when built	(Note that emacs (at least) fails if run on i386 with PAE when built
without, and vice versa, presumably due to bugs in the undump code.)	without, and vice versa, presumably due to bugs in the undump code.)

	Stability
	---------

	Mostly, NetBSD as a dom0 or domU is quite stable.
	However, there are some open PRs indicating problems.

	- [PR 48125](http://gnats.netbsd.org/48125)
	- [PR 47720](http://gnats.netbsd.org/47720)

	Note also that there are issues with sparse vnd(4) instances, but
	these are not about Xen.

Recommendation	Recommendation
--------------	--------------

Line 214 dom0 is what the computer would have bee	Line 226 dom0 is what the computer would have bee
desktop or laptop. Then, one can run domUs at will. Purists will	desktop or laptop. Then, one can run domUs at will. Purists will
deride this as less secure than the previous approach, and for a	deride this as less secure than the previous approach, and for a
computer whose purpose is to run domUs, they are right. But Xen and a	computer whose purpose is to run domUs, they are right. But Xen and a
dom0 (without domUs) is not meaingfully less secure than the same	dom0 (without domUs) is not meaningfully less secure than the same
things running without Xen. One can boot Xen or boot regular NetBSD	things running without Xen. One can boot Xen or boot regular NetBSD
alternately with little problems, simply refraining from starting the	alternately with little problems, simply refraining from starting the
Xen daemons when not running Xen.	Xen daemons when not running Xen.
Line 239 over a RAID1 header to find /boot from a	Line 251 over a RAID1 header to find /boot from a
partition; this is no different when booting Xen.	partition; this is no different when booting Xen.

There are 4 styles of providing backing storage for the virtual disks	There are 4 styles of providing backing storage for the virtual disks
used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN,	used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN.

With raw partitions, one has a disklabel (or gpt) partition sized for	With raw partitions, one has a disklabel (or gpt) partition sized for
each virtual disk to be used by the domU. (If you are able to predict	each virtual disk to be used by the domU. (If you are able to predict
Line 312 starting at 0). In an attempt to add pe	Line 324 starting at 0). In an attempt to add pe
to force only one vcpu to be provided (since NetBSD dom0 can't use	to force only one vcpu to be provided (since NetBSD dom0 can't use
more) and to pin that vcpu to a physical cpu. TODO: benchmark this.	more) and to pin that vcpu to a physical cpu. TODO: benchmark this.

	Xen has [many boot
	options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html),
	and other tham dom0 memory and max_vcpus, they are generally not
	necessary.

As with non-Xen systems, you should have a line to boot /netbsd (a	As with non-Xen systems, you should have a line to boot /netbsd (a
kernel that works without Xen) and fallback versions of the non-Xen	kernel that works without Xen) and fallback versions of the non-Xen
kernel, Xen, and the dom0 kernel.	kernel, Xen, and the dom0 kernel.
Line 401 With xl, the commands are the same, and	Line 418 With xl, the commands are the same, and
different. TODO: add example output for xl before the xm example,	different. TODO: add example output for xl before the xm example,
after confirming on 4.2 and resolving the TODO about rc.conf.	after confirming on 4.2 and resolving the TODO about rc.conf.

	### Issues with xencommons

	xencommons starts xenstored, which stores data on behalf of dom0 and
	domUs. It does not currently work to stop and start xenstored.
	Certainly all domUs should be shutdown first, following the sort order
	of the rc.d scripts. However, the dom0 sets up state with xenstored,
	and is not notified when xenstored exits, leading to not recreating
	the state when the new xenstored starts. Until there's a mechanism to
	make this work, one should not expect to be able to restart xenstored
	(and thus xencommons). There is currently no reason to expect that
	this will get fixed any time soon.

anita (for testing NetBSD)	anita (for testing NetBSD)
--------------------------	--------------------------

Line 502 In 2015-01, the following combination wa	Line 531 In 2015-01, the following combination wa
dom0 kernel: NetBSD/amd64 6.1.5	dom0 kernel: NetBSD/amd64 6.1.5
Xen tools: xentools42-4.2.5 from pkgsrc	Xen tools: xentools42-4.2.5 from pkgsrc

See http://gnats.netbsd.org/47720 for a problem with dom0 shutdown.	See [PR 47720](http://gnats.netbsd.org/47720) for a problem with dom0
	shutdown.

Unprivileged domains (domU)	Unprivileged domains (domU)
===========================	===========================
Line 564 domain, and see if it has finished stopp	Line 594 domain, and see if it has finished stopp
xm console foo	xm console foo
xm create -c foo	xm create -c foo
xm shutdown foo	xm shutdown foo
xm list	xm list

Typing ^] will exit the console session. Shutting down a domain is	Typing ^] will exit the console session. Shutting down a domain is
equivalent to pushing the power button; a NetBSD domU will receive a	equivalent to pushing the power button; a NetBSD domU will receive a
Line 624 create an empty 4G virtual disk, simply	Line 654 create an empty 4G virtual disk, simply

dd if=/dev/zero of=foo-xbd0 bs=1m count=4096	dd if=/dev/zero of=foo-xbd0 bs=1m count=4096

	Do not use qemu-img-xen, because this will create sparse file. There
	have been recent (2015) reports of sparse vnd(4) devices causing
	lockups, but there is apparently no PR.

With the lvm style, one creates logical devices. They are then used	With the lvm style, one creates logical devices. They are then used
similarly to vnds. TODO: Add an example with lvm.	similarly to vnds. TODO: Add an example with lvm.

Line 727 i386 and amd64 provide the following ker	Line 761 i386 and amd64 provide the following ker

i386 XEN3_DOMU	i386 XEN3_DOMU
i386 XEN3PAE_DOMU	i386 XEN3PAE_DOMU
amd64 XEN3_DOMU	amd64 XEN3_DOMU

Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must	Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must
use the PAE version of the i386 kernel.	use the PAE version of the i386 kernel.
Line 780 It is also desirable to add	Line 814 It is also desirable to add
in rc.conf. This way, the domain will be properly shut down if	in rc.conf. This way, the domain will be properly shut down if
`xm shutdown -R` or `xm shutdown -H` is used on the dom0.	`xm shutdown -R` or `xm shutdown -H` is used on the dom0.

Your domain should be now ready to work, enjoy.	It is not strictly necessary to have a kernel (as /netbsd) in the domU
	filesystem. However, various programs (e.g. netstat) will use that
	kernel to look up symbols to read from kernel virtual memory. If
	/netbsd is not the running kernel, those lookups will fail. (This is
	not really a Xen-specific issue, but because the domU kernel is
	obtained from the dom0, it is far more likely to be out of sync or
	missing with Xen.)

Creating an unprivileged Linux domain (domU)	Creating an unprivileged Linux domain (domU)
--------------------------------------------	--------------------------------------------
Line 968 to update the special boot partiion.	Line 1008 to update the special boot partiion.
Amazon	Amazon
------	------

TODO: add link to NetBSD amazon howto.	See the [Amazon EC2 page](../amazon_ec2/).

Using npf	Using npf
---------	---------
Line 976 Using npf	Line 1016 Using npf
In standard kernels, npf is a module, and thus cannot be loaded in a	In standard kernels, npf is a module, and thus cannot be loaded in a
DOMU kernel.	DOMU kernel.

TODO: explain how to compile npf into a custom kernel, answering (but	TODO: Explain how to compile npf into a custom kernel, answering (but
note that the problem was caused by not booting the right kernel):	note that the problem was caused by not booting the right kernel)
http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html	[this email to
	netbsd-users](http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html).

TODO items for improving NetBSD/xen	TODO items for improving NetBSD/xen
===================================	===================================

* Package Xen 4.4.	* Make the NetBSD dom0 kernel work with SMP.
* Get PCI passthrough working on Xen 4.2 (or 4.4).	* Test the Xen 4.5 packages adequately to be able to recommend them as
	the standard approach.
	* Get PCI passthrough working on Xen 4.5
* Get pvgrub into pkgsrc, either via xentools or separately.	* Get pvgrub into pkgsrc, either via xentools or separately.
* grub	* grub
* Check/add support to pkgsrc grub2 for UFS2 and arbitrary	* Check/add support to pkgsrc grub2 for UFS2 and arbitrary
Line 996 TODO items for improving NetBSD/xen	Line 1039 TODO items for improving NetBSD/xen
* Get UFS2 patches into pvgrub.	* Get UFS2 patches into pvgrub.
* Add support for PV ops to a version of /boot, and make it usable as	* Add support for PV ops to a version of /boot, and make it usable as
a kernel in Xen, similar to pvgrub.	a kernel in Xen, similar to pvgrub.
	* Solve somehow the issue with modules for GENERIC not being loadable
	in a Xen dom0 or domU kernel.

	Random pointers
	===============

	TODO: This section contains links from elsewhere not yet integrated
	into the HOWTO.

	* http://www.lumbercartel.ca/library/xen/
	* http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html

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