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version 1.95, 2015/03/05 14:04:55	version 1.123, 2016/12/20 16:53:40
Line 27 code for Xen and need not be aware that	Line 27 code for Xen and need not be aware that
Attempts to access hardware registers are trapped and emulated. This	Attempts to access hardware registers are trapped and emulated. This
style is less efficient but can run unmodified guests.	style is less efficient but can run unmodified guests.

Generally any amd64 machine will work with Xen and PV guests. In	Generally any machine that runs NetBSD/amd64 will work with Xen and PV
theory i386 computers without amd64 support can be used for Xen <=	guests. In theory i386 computers (without x86_64/amd64 support) can
4.2, but we have no recent reports of this working (this is a hint).	be used for Xen <= 4.2, but we have no recent reports of this working
For HVM guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT	(this is a hint). For HVM guests, hardware support is needed, but it
(amd64) is needed; "cpuctl identify 0" will show this. TODO: Clean up	is common on recent machines. For Intel CPUs, one needs the VT-x
and check the above features.	extension, shown in "cpuctl identify 0" as VMX. For AMD CPUs, one
	needs the AMD-V extensions, shown in "cpuctl identify 0" as SVM.
	There are further features for IOMMU virtualization, Intel's VT-d and
	AMD's AMD-Vi. TODO: Explain whether Xen on NetBSD makes use of these
	features. TODO: Review by someone who really understands this.

	Note that a FreeBSD dom0 requires VT-x and VT-d (or equivalent); this
	is because the FreeBSD dom0 does not run in PV mode.

At boot, the dom0 kernel is loaded as a module with Xen as the kernel.	At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
The dom0 can start one or more domUs. (Booting is explained in detail	The dom0 can start one or more domUs. (Booting is explained in detail
Line 44 attempts to address both the case of run	Line 51 attempts to address both the case of run
and running domUs under it (NetBSD and other), and also running NetBSD	and running domUs under it (NetBSD and other), and also running NetBSD
as a domU in a VPS.	as a domU in a VPS.

Some versions of Xen support "PCI passthrough", which means that	Xen 3.1 in pkgsrc supports "PCI passthrough", which means that
specific PCI devices can be made available to a specific domU instead	specific PCI devices can be made available to a specific domU instead
of the dom0. This can be useful to let a domU run X11, or access some	of the dom0. This can be useful to let a domU run X11, or access some
network interface or other peripheral.	network interface or other peripheral.

NetBSD used to support Xen2; this has been removed.	NetBSD 6 and earlier supported Xen 2; support was removed from NetBSD
	7. Xen 2 has been removed from pkgsrc.

Prerequisites	Prerequisites
-------------	-------------
Line 61 things must be done, guiding the reader	Line 69 things must be done, guiding the reader
path when there are no known good reasons to stray.	path when there are no known good reasons to stray.

This HOWTO presumes a basic familiarity with the Xen system	This HOWTO presumes a basic familiarity with the Xen system
architecture. This HOWTO presumes familiarity with installing NetBSD	architecture, with installing NetBSD on i386/amd64 hardware, and with
on i386/amd64 hardware and installing software from pkgsrc.	installing software from pkgsrc. See also the [Xen
See also the [Xen website](http://www.xenproject.org/).	website](http://www.xenproject.org/).

Versions of Xen and NetBSD	Versions of Xen and NetBSD
==========================	==========================
Line 76 versions of NetBSD are intentionally ign	Line 84 versions of NetBSD are intentionally ign
Xen	Xen
---	---

In NetBSD, xen is provided in pkgsrc, via matching pairs of packages	In NetBSD, Xen is provided in pkgsrc, via matching pairs of packages
xenkernel and xentools. We will refer only to the kernel versions,	xenkernel and xentools. We will refer only to the kernel versions,
but note that both packages must be installed together and must have	but note that both packages must be installed together and must have
matching versions.	matching versions.

xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3. These no longer	xenkernel3 provides Xen 3.1. It is no longer maintained by Xen, and the last applied security patch was in
receive security patches and should not be used. Xen 3.1 supports PCI	2011. Thus, it should not be used. It supports PCI passthrough,
passthrough. Xen 3.1 supports non-PAE on i386.	which is why people use it anyway. Xen 3.1 supports i386, both PAE and
	non-PAE.
xenkernel41 provides Xen 4.1. This is no longer maintained by Xen,
but as of 2014-12 receives backported security patches. It is a	xenkernel33 provides Xen 3.3. It is no longer maintained by Xen, and
reasonable although trailing-edge choice.	the last applied security patch was in 2012. Thus, it should not be
	used. Xen 3.3 supports i386, but only in PAE mode. There are no good
	reasons to run this version.

	xenkernel41 provides Xen 4.1. It is no longer maintained by Xen, but
	as of 2016-12 received backported security patches. Xen 4.1 supports
	i386, but only in PAE mode. There are no good reasons to run this
	version.

	xenkernel42 provides Xen 4.2. It is no longer maintained by Xen, but
	as of 2016-12 received backported security patches. Xen 4.2 supports
	i386, but only in PAE mode. The only reason to run this is if you
	need to use xm instead of xl, or if you need to run an i386 dom0
	(because your hardware is i386 only).

	xenkernel45 provides Xen 4.5. As of 2016-12, security patches were
	released by Xen and applied to pkgsrc. Xen 4.5 requires using a dom0
	running NetBSD's amd64 port (Intel or AMD hardware is fine), but domUs
	can be amd64 or i386 PAE. TODO: It is either a conservative choice or
	somewhat old.

	xenkernel46 provides Xen 4.6. It is new to pkgsrc as of 2016-05. As
	of 2016-12, security patches were released by Xen and applied to
	pkgsrc. Xen 4.6 similarly requires a NetBSD/amd64 dom0, but domUs can
	be amd64 or i386 PAE. TODO: It is either a somewhat aggressive choice
	or the standard choice.

xenkernel42 provides Xen 4.2. This is maintained by Xen, but old as	Xen 4.7 (released 2016-06) and 4.8 (released 2016-12) are not yet in
of 2014-12.	pkgsrc.

xenkernel45 provides Xen 4.5. This is new to pkgsrc as of 2015-01 and	See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
not yet recommended for other than experimental/testing use.

Ideally newer versions of Xen will be added to pkgsrc.

Note that NetBSD support is called XEN3. It works with Xen 3 and Xen	Note that NetBSD support is called XEN3. It works with Xen 3 and Xen
4 because the hypercall interface has been stable.	4 because the hypercall interface has been stable.
Line 108 dom0. Starting in 4.1, a replacement pr	Line 138 dom0. Starting in 4.1, a replacement pr
called xl is provided, but it does not work well in 4.1. In 4.2, both	called xl is provided, but it does not work well in 4.1. In 4.2, both
xm and xl work fine. 4.4 is the last version that has xm. You must	xm and xl work fine. 4.4 is the last version that has xm. You must
choose one or the other, because it affects which daemons you run.	choose one or the other, because it affects which daemons you run.
	However, the rc.d scripts provided by xentools packages expect a
	particular version, and you should use the version used by the
	scripts.

NetBSD	NetBSD
------	------

The netbsd-5, netbsd-6, netbsd-7, and -current branches are all	The netbsd-6, netbsd-7, and -current branches are all reasonable
reasonable choices, with more or less the same considerations for	choices, with more or less the same considerations for non-Xen use.
non-Xen use. Therefore, netbsd-6 is recommended as the stable version	Therefore, netbsd-7 is recommended as the stable version of the most
of the most recent release for production use. For those wanting to	recent release for production use. In addition, netbsd-7 and -current
learn Xen or without production stability concerns, netbsd-7 is likely	have a important scheduler fix (in November of 2015) affecting
most appropriate.	contention between dom0 and domUs; see
	https://releng.netbsd.org/cgi-bin/req-7.cgi?show=1040 for a
	description. For those wanting to learn Xen or without production
	stability concerns, netbsd-7 is still likely most appropriate, but
	-current is also a reasonable choice. (Xen runs ok on netbsd-5, but
	the xentools packages are likely difficult to build, and netbsd-5 is
	not supported.)

As of NetBSD 6, a NetBSD domU will support multiple vcpus. There is	As of NetBSD 6, a NetBSD domU will support multiple vcpus. There is
no SMP support for NetBSD as dom0. (The dom0 itself doesn't really	no SMP support for NetBSD as dom0. (The dom0 itself doesn't really
need SMP; the lack of support is really a problem when using a dom0 as	need SMP for dom0 functions; the lack of support is really a problem
a normal computer.)	when using a dom0 as a normal computer.)

Architecture	Architecture
------------	------------

Xen itself can run on i386 or amd64 machines. (Practically, almost	Xen itself can run on i386 (Xen < 3.1) or amd64 machines (all Xen
any computer where one would want to run Xen supports amd64.) If	versions). (Practically, almost any computer where one would want to
using an i386 NetBSD kernel for the dom0, PAE is required (PAE	run Xen today supports amd64.)
versions are built by default). While i386 dom0 works fine, amd64 is
recommended as more normal.	Xen, the dom0 kernel, and each domU kernel can be either i386 or
	amd64. When building a xenkernel package, one obtains i386 on an i386
	host, and amd64 on an amd64 host. If the Xen kernel is i386, then the
	dom0 kernel and all domU kernels must be i386. With an amd64 Xen
	kernel, an amd64 dom0 kernel is known to work, and an i386PAE dom0
	kernel should in theory work. An amd64 Xen/dom0 is known to support
	both i386PAE and amd64 domUs.

	i386 dom0 and domU kernels must be PAE (except for Xen 3.1); these are
	built by default. (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.)

	Because of the above, the standard approach is to use amd64 for the
	dom0.

Xen 4.2 is the last version to support i386 as a host. TODO: Clarify	Xen 4.2 is the last version to support i386 as a host. TODO: Clarify
if this is about the CPU having to be amd64, or about the dom0 kernel	if this is about the CPU, the Xen kernel, or the dom0 kernel having to
having to be amd64.	be amd64.

One can then run i386 domUs and amd64 domUs, in any combination. If
running an i386 NetBSD kernel as a domU, the PAE version is required.
(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.)

Stability	Stability
---------	---------
Line 152 However, there are some open PRs indicat	Line 201 However, there are some open PRs indicat
- [PR 47720](http://gnats.netbsd.org/47720)	- [PR 47720](http://gnats.netbsd.org/47720)

Note also that there are issues with sparse vnd(4) instances, but	Note also that there are issues with sparse vnd(4) instances, but
these are not about Xen.	these are not about Xen -- they just are noticed with sparse vnd(4)
	instances in support of virtual disks in a dom0.

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

Therefore, this HOWTO recommends running xenkernel42 (and xentools42),	Therefore, this HOWTO recommends running xenkernel45 or xenkernel46,
xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the	xl, the NetBSD 7 stable branch, and to use an amd64 kernel as the
dom0. Either the i386 or amd64 of NetBSD may be used as domUs.	dom0. Either the i386PAE or amd64 version of NetBSD may be used as
	domUs.

Build problems	Build problems
--------------	--------------

Ideally, all versions of Xen in pkgsrc would build on all versions of	Ideally, all versions of Xen in pkgsrc would build on all supported
NetBSD on both i386 and amd64. However, that isn't the case. Besides	versions of NetBSD/amd64, to the point where this section would be
aging code and aging compilers, qemu (included in xentools for HVM	silly. However, that has not always been the case. Besides aging
support) is difficult to build. The following are known to work or FAIL:	code and aging compilers, qemu (included in xentools for HVM support)
	is difficult to build. The following are known to be ok or FAIL, with
xenkernel3 netbsd-5 amd64	the date last checked:
xentools3 netbsd-5 amd64
xentools3=hvm netbsd-5 amd64 ????	xenkernel3 netbsd-6 i386 FAIL 201412
xenkernel33 netbsd-5 amd64	xenkernel33 netbsd-6 i386 ok 201412
xentools33 netbsd-5 amd64	xenkernel41 netbsd-6 i386 ok 201412
xenkernel41 netbsd-5 amd64	xenkernel42 netbsd-6 i386 ok 201412
xentools41 netbsd-5 amd64	xentools3 netbsd-6 i386 ok 201412
xenkernel42 netbsd-5 amd64	xentools3-hvm netbsd-6 i386 FAIL 201412
xentools42 netbsd-5 amd64	xentools33 netbsd-6 i386 ok 201412
	xentools41 netbsd-6 i386 ok 201412
xenkernel3 netbsd-6 i386 FAIL	xentools42 netbsd-6 i386 mixed 201412
xentools3 netbsd-6 i386
xentools3-hvm netbsd-6 i386 FAIL (dependencies fail)
xenkernel33 netbsd-6 i386
xentools33 netbsd-6 i386
xenkernel41 netbsd-6 i386
xentools41 netbsd-6 i386
xenkernel42 netbsd-6 i386
xentools42 netbsd-6 i386 *MIXED

(all 3 and 33 seem to FAIL)	(all 3 and 33 seem to FAIL)
xenkernel41 netbsd-7 i386	xenkernel41 netbsd-7 i386 ok 201412
xentools41 netbsd-7 i386	xenkernel42 netbsd-7 i386 ok 201412
xenkernel42 netbsd-7 i386	xentools41 netbsd-7 i386 ok 201412
xentools42 netbsd-7 i386 ??FAIL	xentools42 netbsd-7 i386 ??FAIL 201412

(*On netbsd-6 i386, there is a xentools42 in the 2014Q3 official builds,	xenkernel33 netbsd-6 amd64 ok 201612
but it does not build for gdt.)	xenkernel42 netbsd-6 amd64 ok 201612
	xenkernel45 netbsd-6 amd64 ok 201612
	xenkernel46 netbsd-6 amd64 ok 201612
	xentools42 netbsd-6 amd64 ok 201612
	xentools45 netbsd-6 amd64 ok 201612

	xenkernel3 netbsd-7 amd64 ok 201612
	xenkernel33 netbsd-7 amd64 ok 201612
	xenkernel41 netbsd-7 amd64 ok 201612
	xenkernel42 netbsd-7 amd64 ok 201612
	xenkernel45 netbsd-7 amd64 ok 201612
	xenkernel46 netbsd-7 amd64 ok 201612
	xentools3 netbsd-7 amd64 ok 201612
	xentools3-hvm netbsd-7 amd64 ok 201612
	xentools33 netbsd-7 amd64 FAIL 201612
	xentools41 netbsd-7 amd64 ok 201612
	xentools42 netbsd-7 amd64 ok 201612
	xentools45 netbsd-7 amd64 ok 201612
	xentools46 netbsd-7 amd64 ok 201612

NetBSD as a dom0	NetBSD as a dom0
================	================
Line 247 However, the partitioning approach is ve	Line 308 However, the partitioning approach is ve
If you want to use RAIDframe for the dom0, there are no special issues	If you want to use RAIDframe for the dom0, there are no special issues
for Xen. Typically one provides RAID storage for the dom0, and the	for Xen. Typically one provides RAID storage for the dom0, and the
domU systems are unaware of RAID. The 2nd-stage loader bootxx_* skips	domU systems are unaware of RAID. The 2nd-stage loader bootxx_* skips
over a RAID1 header to find /boot from a filesystem within a RAID	over a RAID1 header to find /boot from a file system within a RAID
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
Line 263 for domU disks. This is almost as effic	Line 324 for domU disks. This is almost as effic
and more flexible. Hence raw disk partitions should typically not	and more flexible. Hence raw disk partitions should typically not
be used.	be used.

One can use files in the dom0 filesystem, typically created by dd'ing	One can use files in the dom0 file system, typically created by dd'ing
/dev/zero to create a specific size. This is somewhat less efficient,	/dev/zero to create a specific size. This is somewhat less efficient,
but very convenient, as one can cp the files for backup, or move them	but very convenient, as one can cp the files for backup, or move them
between dom0 hosts.	between dom0 hosts.
Line 296 releasedir/i386/binary/kernel/netbsd-XEN	Line 357 releasedir/i386/binary/kernel/netbsd-XEN
should not use Xen 3.1.) Both xen and the NetBSD kernel may be (and	should not use Xen 3.1.) Both xen and the NetBSD kernel may be (and
typically are) left compressed.	typically are) left compressed.

In a dom0 kernel, kernfs is mandatory for xend to comunicate with the	In a dom0 kernel, kernfs is mandatory for xend to communicate with the
kernel, so ensure that /kern is in fstab. TODO: Say this is default,	kernel, so ensure that /kern is in fstab. TODO: Say this is default,
or file a PR and give a reference.	or file a PR and give a reference.

Because you already installed NetBSD, you have a working boot setup	Because you already installed NetBSD, you have a working boot setup
with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the	with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
beginning of your root filesystem, /boot present, and likely	beginning of your root file system, /boot present, and likely
/boot.cfg. (If not, fix before continuing!)	/boot.cfg. (If not, fix before continuing!)

Add a line to to /boot.cfg to boot Xen. See boot.cfg(5) for an	Add a line to to /boot.cfg to boot Xen. See boot.cfg(5) for an
Line 322 starting at 0). In an attempt to add pe	Line 383 starting at 0). In an attempt to add pe
dom0_max_vcpus=1 dom0_vcpus_pin	dom0_max_vcpus=1 dom0_vcpus_pin

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	Xen has [many boot
options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html),	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	and other than dom0 memory and max_vcpus, they are generally not
necessary.	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
Line 357 Xen logs will be in /var/log/xen.	Line 418 Xen logs will be in /var/log/xen.
Now, you have a system that will boot Xen and the dom0 kernel, but not	Now, you have a system that will boot Xen and the dom0 kernel, but not
do anything else special. Make sure that you have rebooted into Xen.	do anything else special. Make sure that you have rebooted into Xen.
There will be no domUs, and none can be started because you still have	There will be no domUs, and none can be started because you still have
to configure the dom0 tools. The daemons which should be run vary	to configure the dom0 daemons.
with Xen version and with whether one is using xm or xl. Note that
xend is for supporting "xm", and should only be used if you plan on
using "xm". Do NOT enable xend if you plan on using "xl" as it will
cause problems. Running xl without xencommons=YES (and starting it)
will result in a hang (so don't do that; follow the HOWTO!).

The installation of NetBSD should already have created devices for xen
(xencons, xenevt), but if they are not present, create them:

cd /dev && sh MAKEDEV xen

TODO: Give 3.1 advice (or remove it from pkgsrc).	The daemons which should be run vary with Xen version and with whether
	one is using xm or xl. The Xen 3.1 and 3.3 packages use xm. Xen 4.1
	and higher packages use xl. While is is possible to use xm with some
	4.x versions (TODO: 4.1 and 4.2?), the pkgsrc-provided rc.d scripts do
	not support this as of 2014-12-26, and thus the HOWTO does not support
	it either. (Make sure your packages are reasonably recent.)

For 3.3 (and thus xm), add to rc.conf (but note that you should have	For "xm" (3.1 and 3.3), you should enable xend and xenbackendd (but
installed 4.1 or 4.2):	note that you should be using 4.x):

xend=YES	xend=YES
xenbackendd=YES	xenbackendd=YES

For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:	For "xl" (4.x), you should enabled xend and xencommons (xenstored).
	Trying to boot 4.x without xencommons=YES will result in a hang; it is
xencommons=YES	necessary to hit ^C on the console to let the machine finish booting.
xend=YES	TODO: explain why xend is installed by the package.

(If you are using xentools41 from before 2014-12-26, change
rc.d/xendomains to use xm rather than xl.)

For 4.2 with xm, add to rc.conf

xencommons=YES	xencommons=YES
xend=YES

For 4.2 with xl, add to rc.conf:	The installation of NetBSD should already have created devices for xen
	(xencons, xenevt), but if they are not present, create them:
xencommons=YES
TODO: explain if there is a xend replacement

For 4.5 (and thus with xl), add to rc.conf:

xencommons=YES	cd /dev && sh MAKEDEV xen
TODO: explain if there is a xend replacement

TODO: Recommend for/against xen-watchdog.	TODO: Recommend for/against xen-watchdog.

After you have configured the daemons and either started them (in the	After you have configured the daemons and either started them (in the
order given) or rebooted, use xm or xl to inspect Xen's boot messages,	order given) or rebooted, use xm or xl to inspect Xen's boot messages,
available resources, and running domains. An example with xm follows:	available resources, and running domains. An example with xl follows:

# xm dmesg	# xl dmesg
[xen's boot info]	[xen's boot info]
# xm info	# xl info
[available memory, etc.]	[available memory, etc.]
# xm list	# xl list
Name Id Mem(MB) CPU State Time(s) Console	Name Id Mem(MB) CPU State Time(s) Console
Domain-0 0 64 0 r---- 58.1	Domain-0 0 64 0 r---- 58.1

With xl, the commands are the same, and the output may be slightly
different. TODO: add example output for xl before the xm example,
after confirming on 4.2 and resolving the TODO about rc.conf.

### Issues with xencommons	### Issues with xencommons

xencommons starts xenstored, which stores data on behalf of dom0 and	xencommons starts xenstored, which stores data on behalf of dom0 and
Line 448 Xen-specific NetBSD issues	Line 489 Xen-specific NetBSD issues
There are (at least) two additional things different about NetBSD as a	There are (at least) two additional things different about NetBSD as a
dom0 kernel compared to hardware.	dom0 kernel compared to hardware.

One is that modules are not usable in DOM0 kernels, so one must	One is that the module ABI is different because some of the #defines
compile in what's needed. It's not really that modules cannot work,	change, so one must build modules for Xen. As of netbsd-7, the build
but that modules must be built for XEN3_DOM0 because some of the	system does this automatically. TODO: check this. (Before building
defines change and the normal module builds don't do this. Basically,	Xen modules was added, it was awkward to use modules to the point
enabling Xen changes the kernel ABI, and the module build system	where it was considered that it did not work.)
doesn't cope with this.

The other difference is that XEN3_DOM0 does not have exactly the same	The other difference is that XEN3_DOM0 does not have exactly the same
options as GENERIC. While it is debatable whether or not this is a	options as GENERIC. While it is debatable whether or not this is a
Line 481 over time. Before these commands, it wa	Line 521 over time. Before these commands, it wa
4.1 and grub, much like the message linked earlier in the grub	4.1 and grub, much like the message linked earlier in the grub
section.	section.

# Install mbr bootblocks on both disks.	# Install MBR bootblocks on both disks.
fdisk -i /dev/rwd0d	fdisk -i /dev/rwd0d
fdisk -i /dev/rwd1d	fdisk -i /dev/rwd1d
# Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.	# Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
Line 489 section.	Line 529 section.
installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1	installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
# Install secondary boot loader	# Install secondary boot loader
cp -p /usr/mdec/boot /	cp -p /usr/mdec/boot /
# Create boog.cfg following earlier guidance:	# Create boot.cfg following earlier guidance:
menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M	menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=256M	menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=256M
menu=GENERIC:boot	menu=GENERIC:boot
Line 502 section.	Line 542 section.

TODO: actually do this and fix it if necessary.	TODO: actually do this and fix it if necessary.

Updating Xen versions	Upgrading Xen versions
---------------------	---------------------

Updating Xen is conceptually not difficult, but can run into all the	Minor version upgrades are trivial. Just rebuild/replace the
issues found when installing Xen. Assuming migration from 4.1 to 4.2,	xenkernel version and copy the new xen.gz to / (where /boot.cfg
remove the xenkernel41 and xentools41 packages and install the	references it), and reboot.
xenkernel42 and xentools42 packages. Copy the 4.2 xen.gz to /.
	Major version upgrades are conceptually not difficult, but can run
Ensure that the contents of /etc/rc.d/xen* are correct. Enable the	into all the issues found when installing Xen. Assuming migration
correct set of daemons. Ensure that the domU config files are valid	from 4.1 to 4.2, remove the xenkernel41 and xentools41 packages and
for the new version.	install the xenkernel42 and xentools42 packages. Copy the 4.2 xen.gz
	to /.

	Ensure that the contents of /etc/rc.d/xen* are correct. Specifically,
	they must match the package you just installed and not be left over
	from some previous installation.

	Enable the correct set of daemons; see the configuring section above.
	(Upgrading from 3.x to 4.x without doing this will result in a hang.)

	Ensure that the domU config files are valid for the new version.
	Specifically, for 4.x remove autorestart=True, and ensure that disks
	are specified with numbers as the second argument, as the examples
	above show, and not NetBSD device names.

	Hardware known to work
	----------------------

	Arguably, this section is misplaced, and there should be a page of
	hardware that runs NetBSD/amd64 well, with the mostly-well-founded
	assumption that NetBSD/xen runs fine on any modern hardware that
	NetBSD/amd64 runs well on. Until then, we give motherboard/CPU/RAM
	triples to aid those choosing a motherboard. Note that Xen systems
	usually do not run X, so a listing here does not imply that X works at
	all.

	Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC
	Supermicro ??, Atom C2758 (8 core), 32 GiB ECC
	ASUS M5A78L-M/USB3 AM3+ microATX, AMD Piledriver X8 4000MHz, 16 GiB ECC

	Older hardware:

	Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2

Running Xen under qemu	Running Xen under qemu
----------------------	----------------------
Line 543 config files for domUs are typically in	Line 614 config files for domUs are typically in
typically named so that the file name, domU name and the domU's host	typically named so that the file name, domU name and the domU's host
name match.	name match.

The domU is provided with cpu and memory by Xen, configured by the	The domU is provided with CPU and memory by Xen, configured by the
dom0. The domU is provided with disk and network by the dom0,	dom0. The domU is provided with disk and network by the dom0,
mediated by Xen, and configured in the dom0.	mediated by Xen, and configured in the dom0.

Line 580 domUs independently. The vif line cause	Line 651 domUs independently. The vif line cause
with a specific mac address (do not reuse MAC addresses!), in bridge	with a specific mac address (do not reuse MAC addresses!), in bridge
mode. Two disks are provided, and they are both writable; the bits	mode. Two disks are provided, and they are both writable; the bits
are stored in files and Xen attaches them to a vnd(4) device in the	are stored in files and Xen attaches them to a vnd(4) device in the
dom0 on domain creation. The system treates xbd0 as the boot device	dom0 on domain creation. The system treats xbd0 as the boot device
without needing explicit configuration.	without needing explicit configuration.

By default xm looks for domain config files in /usr/pkg/etc/xen. Note	By default xm looks for domain config files in /usr/pkg/etc/xen. Note
Line 606 domU kernels	Line 677 domU kernels

On a physical computer, the BIOS reads sector 0, and a chain of boot	On a physical computer, the BIOS reads sector 0, and a chain of boot
loaders finds and loads a kernel. Normally this comes from the root	loaders finds and loads a kernel. Normally this comes from the root
filesystem. With Xen domUs, the process is totally different. The	file system. With Xen domUs, the process is totally different. The
normal path is for the domU kernel to be a file in the dom0's	normal path is for the domU kernel to be a file in the dom0's
filesystem. At the request of the dom0, Xen loads that kernel into a	file system. At the request of the dom0, Xen loads that kernel into a
new domU instance and starts execution. While domU kernels can be	new domU instance and starts execution. While domU kernels can be
anyplace, reasonable places to store domU kernels on the dom0 are in /	anyplace, reasonable places to store domU kernels on the dom0 are in /
(so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the	(so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
Line 623 CPU and memory	Line 694 CPU and memory
--------------	--------------

A domain is provided with some number of vcpus, less than the number	A domain is provided with some number of vcpus, less than the number
of cpus seen by the hypervisor. (For a dom0, this is controlled by	of CPUs seen by the hypervisor. (For a dom0, this is controlled by
the boot argument "dom0_max_vcpus=1".) For a domU, it is controlled	the boot argument "dom0_max_vcpus=1".) For a domU, it is controlled
from the config file by the "vcpus = N" directive.	from the config file by the "vcpus = N" directive.

Line 687 disks.	Line 758 disks.
Virtual Networking	Virtual Networking
------------------	------------------

Xen provides virtual ethernets, each of which connects the dom0 and a	Xen provides virtual Ethernets, each of which connects the dom0 and a
domU. For each virtual network, there is an interface "xvifN.M" in	domU. For each virtual network, there is an interface "xvifN.M" in
the dom0, and in domU index N, a matching interface xennetM (NetBSD	the dom0, and in domU index N, a matching interface xennetM (NetBSD
name). The interfaces behave as if there is an Ethernet with two	name). The interfaces behave as if there is an Ethernet with two
adaptors connected. From this primitive, one can construct various	adapters connected. From this primitive, one can construct various
configurations. We focus on two common and useful cases for which	configurations. We focus on two common and useful cases for which
there are existing scripts: bridging and NAT.	there are existing scripts: bridging and NAT.

Line 735 shutdown, in rc.conf add:	Line 806 shutdown, in rc.conf add:

xendomains="foo bar"	xendomains="foo bar"

Note that earlier versions of the xentools41 xendomains rc.d scripth	Note that earlier versions of the xentools41 xendomains rc.d script
usd xl, when one should use xm with 4.1.	used xl, when one should use xm with 4.1.

Creating specific unprivileged domains (domU)	Creating specific unprivileged domains (domU)
=============================================	=============================================
Line 752 Creating an unprivileged NetBSD domain (	Line 823 Creating an unprivileged NetBSD domain (
See the earlier config file, and adjust memory. Decide on how much	See the earlier config file, and adjust memory. Decide on how much
storage you will provide, and prepare it (file or lvm).	storage you will provide, and prepare it (file or lvm).

While the kernel will be obtained from the dom0 filesystem, the same	While the kernel will be obtained from the dom0 file system, the same
file should be present in the domU as /netbsd so that tools like	file should be present in the domU as /netbsd so that tools like
savecore(8) can work. (This is helpful but not necessary.)	savecore(8) can work. (This is helpful but not necessary.)

Line 815 in rc.conf. This way, the domain will be	Line 886 in rc.conf. This way, the domain will be
`xm shutdown -R` or `xm shutdown -H` is used on the dom0.	`xm shutdown -R` or `xm shutdown -H` is used on the dom0.

It is not strictly necessary to have a kernel (as /netbsd) in the domU	It is not strictly necessary to have a kernel (as /netbsd) in the domU
filesystem. However, various programs (e.g. netstat) will use that	file system. However, various programs (e.g. netstat) will use that
kernel to look up symbols to read from kernel virtual memory. If	kernel to look up symbols to read from kernel virtual memory. If
/netbsd is not the running kernel, those lookups will fail. (This is	/netbsd is not the running kernel, those lookups will fail. (This is
not really a Xen-specific issue, but because the domU kernel is	not really a Xen-specific issue, but because the domU kernel is
Line 854 Then copy the files from a working Linux	Line 925 Then copy the files from a working Linux
`/etc` (fstab, network config). It should also be possible to extract	`/etc` (fstab, network config). It should also be possible to extract
binary packages such as .rpm or .deb directly to the mounted partition	binary packages such as .rpm or .deb directly to the mounted partition
using the appropriate tool, possibly running under NetBSD's Linux	using the appropriate tool, possibly running under NetBSD's Linux
emulation. Once the filesystem has been populated, umount it. If	emulation. Once the file system has been populated, umount it. If
desirable, the filesystem can be converted to ext3 using tune2fs -j.	desirable, the file system can be converted to ext3 using tune2fs -j.
It should now be possible to boot the Linux guest domain, using one of	It should now be possible to boot the Linux guest domain, using one of
the vmlinuz-\*-xenU kernels available in the Xen binary distribution.	the vmlinuz-\*-xenU kernels available in the Xen binary distribution.

To get the linux console right, you need to add:	To get the Linux console right, you need to add:

extra = "xencons=tty1"	extra = "xencons=tty1"

to your configuration since not all linux distributions auto-attach a	to your configuration since not all Linux distributions auto-attach a
tty to the xen console.	tty to the xen console.

Creating an unprivileged Solaris domain (domU)	Creating an unprivileged Solaris domain (domU)
Line 907 the domU's config file, with the format	Line 978 the domU's config file, with the format
pci = [ '0000:00:06.0', '0000:00:0a.0' ]	pci = [ '0000:00:06.0', '0000:00:0a.0' ]

In the domU an "xpci" device will show up, to which one or more pci	In the domU an "xpci" device will show up, to which one or more pci
busses will attach. Then the PCI drivers will attach to PCI busses as	buses will attach. Then the PCI drivers will attach to PCI buses as
usual. Note that the default NetBSD DOMU kernels do not have "xpci"	usual. Note that the default NetBSD DOMU kernels do not have "xpci"
or any PCI drivers built in by default; you have to build your own	or any PCI drivers built in by default; you have to build your own
kernel to use PCI devices in a domU. Here's a kernel config example;	kernel to use PCI devices in a domU. Here's a kernel config example;
Line 915 note that only the "xpci" lines are unus	Line 986 note that only the "xpci" lines are unus

include "arch/i386/conf/XEN3_DOMU"	include "arch/i386/conf/XEN3_DOMU"

# Add support for PCI busses to the XEN3_DOMU kernel	# Add support for PCI buses to the XEN3_DOMU kernel
xpci* at xenbus ?	xpci* at xenbus ?
pci* at xpci ?	pci* at xpci ?

Line 954 only a few are mentioned that specifical	Line 1025 only a few are mentioned that specifical

VPS operators provide varying degrees of access and mechanisms for	VPS operators provide varying degrees of access and mechanisms for
configuration. The big issue is usually how one controls which kernel	configuration. The big issue is usually how one controls which kernel
is booted, because the kernel is nominally in the dom0 filesystem (to	is booted, because the kernel is nominally in the dom0 file system (to
which VPS users do not normally have acesss). A second issue is how	which VPS users do not normally have access). A second issue is how
to install NetBSD.	to install NetBSD.
A VPS user may want to compile a kernel for security updates, to run	A VPS user may want to compile a kernel for security updates, to run
npf, run IPsec, or any other reason why someone would want to change	npf, run IPsec, or any other reason why someone would want to change
their kernel.	their kernel.

One approach is to have an adminstrative interface to upload a kernel,	One approach is to have an administrative interface to upload a kernel,
or to select from a prepopulated list. Other approaches are pygrub	or to select from a prepopulated list. Other approaches are pygrub
(deprecated) and pvgrub, which are ways to have a bootloader obtain a	(deprecated) and pvgrub, which are ways to have a bootloader obtain a
kernel from the domU filesystem. This is closer to a regular physical	kernel from the domU file system. This is closer to a regular physical
computer, where someone who controls a machine can replace the kernel.	computer, where someone who controls a machine can replace the kernel.

A second issue is multiple CPUs. With NetBSD 6, domUs support	A second issue is multiple CPUs. With NetBSD 6, domUs support
Line 974 CPUs for NetBSD domUs.	Line 1045 CPUs for NetBSD domUs.
pygrub	pygrub
-------	-------

pygrub runs in the dom0 and looks into the domU filesystem. This	pygrub runs in the dom0 and looks into the domU file system. This
implies that the domU must have a kernel in a filesystem in a format	implies that the domU must have a kernel in a file system in a format
known to pygrub. As of 2014, pygrub seems to be of mostly historical	known to pygrub. As of 2014, pygrub seems to be of mostly historical
interest.	interest.

Line 984 pvgrub	Line 1055 pvgrub

pvgrub is a version of grub that uses PV operations instead of BIOS	pvgrub is a version of grub that uses PV operations instead of BIOS
calls. It is booted from the dom0 as the domU kernel, and then reads	calls. It is booted from the dom0 as the domU kernel, and then reads
/grub/menu.lst and loads a kernel from the domU filesystem.	/grub/menu.lst and loads a kernel from the domU file system.

[Panix](http://www.panix.com/) lets users use pvgrub. Panix reports	[Panix](http://www.panix.com/) lets users use pvgrub. Panix reports
that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes	that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
Line 1003 does not support all aspects of modern F	Line 1074 does not support all aspects of modern F
that FFSv2 works fine. At prgmr, typically one has an ext2 or FAT	that FFSv2 works fine. At prgmr, typically one has an ext2 or FAT
partition for the kernel with the intent that grub can understand it,	partition for the kernel with the intent that grub can understand it,
which leads to /netbsd not being the actual kernel. One must remember	which leads to /netbsd not being the actual kernel. One must remember
to update the special boot partiion.	to update the special boot partition.

Amazon	Amazon
------	------
Line 1032 TODO items for improving NetBSD/xen	Line 1103 TODO items for improving NetBSD/xen
* grub	* grub
* Check/add support to pkgsrc grub2 for UFS2 and arbitrary	* Check/add support to pkgsrc grub2 for UFS2 and arbitrary
fragsize/blocksize (UFS2 support may be present; the point is to	fragsize/blocksize (UFS2 support may be present; the point is to
make it so that with any UFS1/UFS2 filesystem setup that works	make it so that with any UFS1/UFS2 file system setup that works
with NetBSD grub will also work).	with NetBSD grub will also work).
See [pkg/40258](http://gnats.netbsd.org/40258).	See [pkg/40258](http://gnats.netbsd.org/40258).
* Push patches upstream.	* Push patches upstream.
Line 1045 TODO items for improving NetBSD/xen	Line 1116 TODO items for improving NetBSD/xen
Random pointers	Random pointers
===============	===============

TODO: This section contains links from elsewhere not yet integrated	This section contains links from elsewhere not yet integrated into the
into the HOWTO.	HOWTO, and other guides.

* http://www.lumbercartel.ca/library/xen/	* http://www.lumbercartel.ca/library/xen/
* http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html	* http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html
	* https://gmplib.org/~tege/xen.html

CVSweb for NetBSD wikisrc <wikimaster@NetBSD.org> software: FreeBSD-CVSweb

Removed from v.1.95
changed lines
	Added in v.1.123