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-version 1.22, 2014/12/24 01:27:36
+version 1.37, 2014/12/24 16:06:38
  Line 27  code for Xen and need not be aware that
  Attempts to access hardware registers are trapped and emulated.  This
  style is less efficient but can run unmodified guests.
- Generally any amd64 machine will work with Xen and PV guests.  For HVM
+ Generally any amd64 machine will work with Xen and PV guests.  In
- guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT (amd64) is
+ theory i386 computers without amd64 support can be used for Xen <=
- needed; "cpuctl identify 0" will show this.  TODO: Clean up and check
+.2, but we have no recent reports of this working (this is a hint).
- the above features.  TODO: Explain if i386 (non-amd64) machines can
+ For HVM guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT
- still be used - I think that witthe requirement to use PAE kernels is
+ (amd64) is needed; "cpuctl identify 0" will show this.  TODO: Clean up
- about the hypervisor being amd64 only.
+ and check the above features.
- At boot, the dom0 kernel is loaded as 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
  in the dom0 section.)
  NetBSD supports Xen in that it can serve as dom0, be used as a domU,
  and that Xen kernels and tools are available in pkgsrc.  This HOWTO
  attempts to address both the case of running a NetBSD dom0 on hardware
- and running NetBSD as a domU in a VPS.
+ and running domUs under it (NetBSD and other), and also running NetBSD
+ as a domU in a VPS.
  Some versions of Xen support "PCI passthrough", which means that
  specific PCI devices can be made available to a specific domU instead
- Line 60  path when there are no known good reason
+ Line 61  path when there are no known good reason
  This HOWTO presumes a basic familiarity with the Xen system
  architecture.  This HOWTO presumes familiarity with installing NetBSD
  on i386/amd64 hardware and installing software from pkgsrc.
- See also the [Xen website](http://www.xen.org/).
+ See also the [Xen website](http://www.xenproject.org/).
  History
  -------
- Line 69  NetBSD used to support Xen2; this has be
+ Line 70  NetBSD used to support Xen2; this has be
  Before NetBSD's native bootloader could support Xen, the use of
  grub was recommended.  If necessary, see the
- [old grub information](/xen/howto-grub/).
+ [old grub information](/ports/xen/howto-grub/).
  Versions of Xen and NetBSD
  ==========================
- Most of the installation concepts and instructions are independent of
+ Most of the installation concepts and instructions are independent
- Xen version.  This section gives advice on which version to choose.
+ of Xen version and NetBSD version.  This section gives advice on
- Versions not in pkgsrc and older unsupported versions of NetBSD are
+ which version to choose.  Versions not in pkgsrc and older unsupported
- inentionally ignored.
+ versions of NetBSD are intentionally ignored.
  Xen
  ---
- Line 89  matching versions.
+ Line 90  matching versions.
  xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3.  These no longer
  receive security patches and should not be used.  Xen 3.1 supports PCI
- passthrough.
+ passthrough.  Xen 3.1 supports non-PAE on i386.
  xenkernel41 provides Xen 4.1.  This is no longer maintained by Xen,
  but as of 2014-12 receives backported security patches.  It is a
- Line 100  of 2014-12.
+ Line 101  of 2014-12.
  Ideally newer versions of Xen will be added to pkgsrc.
- Note that NetBSD support is called XEN3; it works with 3.1 through
+ Note that NetBSD support is called XEN3.  It works with 3.1 through
-.2, because the hypercall interface has been stable.
+.2 because the hypercall interface has been stable.
  Xen command program
  -------------------
  Early Xen used a program called "xm" to manipulate the system from the
  dom0.  Starting in 4.1, a replacement program with similar behavior
- called "xl" is provided.  In 4.2, "xm" is no longer available.
+ called "xl" is provided.  In 4.2 and later, "xl" is preferred.  4.4 is
+ the last version that has "xm".
  NetBSD
  ------
- Line 116  NetBSD
+ Line 118  NetBSD
  The netbsd-5, netbsd-6, netbsd-7, and -current branches are all
  reasonable choices, with more or less the same considerations for
  non-Xen use.  Therefore, netbsd-6 is recommended as the stable version
- of the most recent release.
+ of the most recent release for production use.  For those wanting to
+ learn Xen or without production stability concerns, netbsd-7 is likely
+ most appropriate.
  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
- Line 126  a normal computer.)
+ Line 130  a normal computer.)
  Architecture
  ------------
- Xen is basically amd64 only at this point.  One can either run i386
+ Xen itself can run on i386 or amd64 machines.  (Practically, almost
- domains or amd64 domains.  If running i386, PAE versions are required,
+ any computer where one would want to run Xen supports amd64.)  If
- for both dom0 and domU.  These versions are built by default in NetBSD
+ using an i386 NetBSD kernel for the dom0, PAE is required (PAE
- releases.  While i386 dom0 works fine, amd64 is recommended as more
+ versions are built by default).  While i386 dom0 works fine, amd64 is
- normal.  (Note that emacs (at least) fails if run on i386 with PAE when
+ recommended as more normal.
- built without, and vice versa, presumably due to bugs in the undump
- code.)
+ 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
+ having to 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.)
  Recommendation
  --------------
  Therefore, this HOWTO recommends running xenkernel42 (and xentools42),
- xl, the NetBSD 6 stable branch, and to use amd64 as the dom0.  Either
+ xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the
- the i386 or amd64 of NetBSD may be used as domUs.
+ dom0.  Either the i386 or amd64 of NetBSD may be used as domUs.
+ Build problems
+ --------------
+ Ideally, all versions of Xen in pkgsrc would build on all versions of
+ NetBSD on both i386 and amd64.  However, that isn't the case.  Besides
+ aging code and aging compilers, qemu (included in xentools for HVM
+ support) is difficult to build.  The following are known to fail:
+         xenkernel3 netbsd-6 i386
+         xentools42 netbsd-6 i386
+ The following are known to work:
+         xenkernel41 netbsd-5 amd64
+         xentools41 netbsd-5 amd64
+         xenkernel41 netbsd-6 i386
+         xentools41 netbsd-6 i386
  NetBSD as a dom0
  ================
- Line 177  Installation of NetBSD
+ Line 206  Installation of NetBSD
  ----------------------
  First,
- [install NetBSD/amd64](../../docs/guide/en/chap-inst.html)
+ [install NetBSD/amd64](/guide/inst/)
  just as you would if you were not using Xen.
  However, the partitioning approach is very important.
- Line 195  each virtual disk to be used by the domU
+ Line 224  each virtual disk to be used by the domU
  how domU usage will evolve, please add an explanation to the HOWTO.
  Seriously, needs tend to change over time.)
- One can use lvm(8) to create logical devices to use for domU disks.
+ One can use [lvm(8)](/guide/lvm/) to create logical devices to use
- This is almost as efficient sa raw disk partitions and more flexible.
+ for domU disks.  This is almost as efficient as raw disk partitions
- Hence raw disk partitions should typically not be used.
+ and more flexible.  Hence raw disk partitions should typically not
+ be used.
  One can use files in the dom0 filesystem, typically created by dd'ing
  /dev/zero to create a specific size.  This is somewhat less efficient,
- Line 239  beginning of your root filesystem, /boot
+ Line 269  beginning of your root filesystem, /boot
  See boot.cfg(5) for an example.  The basic line is
- "menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M"
+         menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
  which specifies that the dom0 should have 256M, leaving the rest to be
- allocated for domUs.
+ allocated for domUs.  In an attempt to add performance, one can also
+ add
+         dom0_max_vcpus=1 dom0_vcpus_pin
+ 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.
  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, Xen, and the dom0 kernel.
+ The [HowTo on Installing into
+ RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
+ explains how to set up booting a dom0 with Xen using grub with
+ NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
+ boot.)
  Configuring Xen
  ---------------
  Now, you have a system that will boot Xen and the dom0 kernel, and
  just run the dom0 kernel.  There will be no domUs, and none can be
- started because you still have to configure the dom0 tools.
+ started because you still have to configure the dom0 tools.  The
+ daemons which should be run vary 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.
+ TODO: Give 3.1 advice (or remove it from pkgsrc).
+ For 3.3 (and thus xm), add to rc.conf (but note that you should have
+ installed 4.1 or 4.2):
+         xend=YES
+         xenbackendd=YES
+ For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:
+         xend=YES
+         xencommons=YES
- For 3.3 (and probably 3.1), add to rc.conf (but note that you should
+ TODO: Explain why if xm is preferred on 4.1, rc.d/xendomains has xl.
- have installed 4.2):
+ Or fix the package.
-   xend=YES
-   xenbackendd=YES
+ For 4.2 with xm, add to rc.conf
- For 4.1 and 4.2, add to rc.conf:
+         xend=YES
-   xend=YES
+         xencommons=YES
-   xencommons=YES
+ For 4.2 with xl (preferred), add to rc.conf:
+         TODO: explain if there is a xend replacement
+         xencommons=YES
+ TODO: Recommend for/against xen-watchdog.
+ After you have configured the daemons and rebooted, run the following
+ to inspect Xen's boot messages, available resources, and running
+ domains:
+         xm dmesg
+         xm info
+         xm list
  Updating NetBSD in a dom0
  -------------------------
- Line 292  Ensure that the contents of /etc/rc.d/xe
+ Line 365  Ensure that the contents of /etc/rc.d/xe
  correct set of daemons.  Ensure that the domU config files are valid
  for the new version.
- Creating unprivileged domains (domU)
- ====================================
+ Unprivileged domains (domU)
+ ===========================
+ This section describes general concepts about domUs.  It does not
+ address specific domU operating systems or how to install them.  The
+ config files for domUs are typically in /usr/pkg/etc/xen, and are
+ typically named so that the file anme, domU name and the domU's host
+ name match.
+ 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,
+ mediated by Xen, and configured in the dom0.
+ Entropy in domUs can be an issue; physical disks and network are on
+ the dom0.  NetBSD's /dev/random system works, but is often challenged.
+ CPU and memory
+ --------------
+ 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 the boot argument "dom0_max_vcpus=1".  For a domU, it is controlled
+ from the config file.
+ A domain is provided with memory, In the straightforward case, the sum
+ of the the memory allocated to the dom0 and all domUs must be less
+ than the available memory.
+ Xen also provides a "balloon" driver, which can be used to let domains
+ use more memory temporarily.  TODO: Explain better, and explain how
+ well it works with NetBSD.
+ Virtual disks
+ -------------
+ With the file/vnd style, typically one creates a directory,
+ e.g. /u0/xen, on a disk large enough to hold virtual disks for all
+ domUs.  Then, for each domU disk, one writes zeros to a file that then
+ serves to hold the virtual disk's bits; a suggested name is foo-xbd0
+ for the first virtual disk for the domU called foo.  Writing zeros to
+ the file serves two purposes.  One is that preallocating the contents
+ improves performance.  The other is that vnd on sparse files has
+ failed to work.  TODO: give working/notworking NetBSD versions for
+ sparse vnd.  Note that the use of file/vnd for Xen is not really
+ different than creating a file-backed virtual disk for some other
+ purpose, except that xentools handles the vnconfig commands.
+ With the lvm style, one creates logical devices.  They are then used
+ similarly to vnds.
+ Virtual Networking
+ ------------------
+ TODO: explain xvif concept, and that it's general.
+ There are two normal styles: bridging and NAT.
+ With bridging, the domU perceives itself to be on the same network as
+ the dom0.  For server virtualization, this is usually best.
+ With NAT, the domU perceives itself to be behind a NAT running on the
+ dom0.  This is often appropriate when running Xen on a workstation.
+ One can construct arbitrary other configurations, but there is no
+ script support.
+ Sizing domains
+ --------------
+ Modern x86 hardware has vast amounts of resources.  However, many
+ virtual servers can function just fine on far less.  A system with
+M of RAM and a 4G disk can be a reasonable choice.  Note that it is
+ far easier to adjust virtual resources than physical ones.  For
+ memory, it's just a config file edit and a reboot.  For disk, one can
+ create a new file and vnconfig it (or lvm), and then dump/restore,
+ just like updating physical disks, but without having to be there and
+ without those pesky connectors.
+ Config files
+ ------------
+ TODO: give example config files.   Use both lvm and vnd.
+ TODO: explain the mess with 3 arguments for disks and how to cope (0x1).
+ Starting domains
+ ----------------
+ TODO: Explain "xm start" and "xl start".  Explain rc.d/xendomains.
+ TODO: Explain why 4.1 rc.d/xendomains has xl, when one should use xm
+ on 4.1.
+ Creating specific unprivileged domains (domU)
+ =============================================
  Creating domUs is almost entirely independent of operating system.  We
  first explain NetBSD, and then differences for Linux and Solaris.
- Line 324  PKG\_SYSCONFDIR for its parameters. By d
+ Line 491  PKG\_SYSCONFDIR for its parameters. By d
  will be executed in the new domain (this kernel is in the *domain0* file
  system, not on the new domain virtual disk; but please note, you should
  install the same kernel into *domainU* as `/netbsd` in order to make
- your system tools, like MAN.SAVECORE.8, work). A suitable kernel is
+ your system tools, like savecore(8), work). A suitable kernel is
  provided as part of the i386 and amd64 binary sets: XEN3\_DOMU.
  Here is an /usr/pkg/etc/xen/nbsd example config file:
- Line 434  like this:
+ Line 601  like this:
      !brconfig $int add ex0 up
  (replace `ex0` with the name of your physical interface). Then bridge0
- will be created on boot. See the MAN.BRIDGE.4 man page for details.
+ will be created on boot. See the bridge(4) man page for details.
  So, here is a suitable `/usr/pkg/etc/xen/vif-bridge` for xvif?.? (a
  working vif-bridge is also provided with xentools20) configuring:
      #!/bin/sh
      #============================================================================
-     # $NetBSD: howto.mdwn,v 1.21 2014/12/24 01:12:49 gdt Exp $
+     # $NetBSD: howto.mdwn,v 1.36 2014/12/24 16:02:49 gdt Exp $
      #
      # /usr/pkg/etc/xen/vif-bridge
      #
- Line 818  to use PCI devices in a domU. Here's a k
+ Line 985  to use PCI devices in a domU. Here's a k
      sd*     at scsibus? target ? lun ?      # SCSI disk drives
      cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
- Links and further information
- =============================
- -   The [HowTo on Installing into RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
+ NetBSD as a domU in a VPS
-     explains how to set up booting a dom0 with Xen using grub
+ =========================
-     with NetBSD's RAIDframe.  (This is obsolete with the use of
-     NetBSD's native boot.)
+ The bulk of the HOWTO is about using NetBSD as a dom0 on your own
- -   An example of how to use NetBSD's native bootloader to load
+ hardware.  This section explains how to deal with Xen in a domU as a
-     NetBSD/Xen instead of Grub can be found in the i386/amd64 boot(8)
+ virtual private server where you do not control or have access to the
-     and boot.cfg(5) manpages.
+ dom0.
+ TODO: Perhaps reference panix, prmgr, amazon as interesting examples.
+ TODO: Somewhere, discuss pvgrub and py-grub to load the domU kernel
+ from the domU filesystem.

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