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-version 1.34, 2014/12/24 15:55:32
+version 1.48, 2014/12/26 20:00:44
  Line 152  Therefore, this HOWTO recommends running
  xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the
  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 163  NetBSD, which is not yet a dom0, and the
+ Line 181  NetBSD, which is not yet a dom0, and the
  NetBSD install to a dom0 install by just changing the kernel and boot
  configuration.
+ For experimenting with Xen, a machine with as little as 1G of RAM and
+G of disk can work.  For running many domUs in productions, far
+ more will be needed.
  Styles of dom0 operation
  ------------------------
- Line 251  beginning of your root filesystem, /boot
+ Line 273  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
- Line 277  is using xm or xl.  Note that xend is fo
+ Line 305  is using xm or xl.  Note that xend is fo
  only be used if you plan on using "xm".  Do NOT enable xend if you
  plan on using "xl" as it will cause problems.
+ 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).
  For 3.3 (and thus xm), add to rc.conf (but note that you should have
- Line 305  For 4.2 with xl (preferred), add to rc.c
+ Line 338  For 4.2 with xl (preferred), add to rc.c
  TODO: Recommend for/against xen-watchdog.
- After you have configured the daemons and rebooted, run the following
+ After you have configured the daemons and either started them or
- to inspect Xen's boot messages, available resources, and running
+ rebooted, run the following (or use xl) to inspect Xen's boot
- domains:
+ messages, available resources, and running domains:
-         xm dmesg
+         # xm dmesg
-         xm info
+         [xen's boot info]
-         xm list
+         # xm info
+         [available memory, etc.]
+         # xm list
+         Name              Id  Mem(MB)  CPU  State  Time(s)  Console
+         Domain-0           0       64    0  r----     58.1
+ anita (for testing NetBSD)
+ --------------------------
+ With the setup so far, one should be able to run anita (see
+ pkgsrc/sysutils/py-anita) to test NetBSD releases, by doing (as root,
+ because anita must create a domU):
+         anita --vmm=xm test file:///usr/obj/i386/
+ Alternatively, one can use --vmm=xl to use xl-based domU creation instead.
+ TODO: check this.
+ Xen-specific NetBSD issues
+ --------------------------
+ There are (at least) two additional things different about NetBSD as a
+ dom0 kernel compared to hardware.
+ One is that modules are not usable in DOM0 kernels, so one must
+ compile in what's needed.  It's not really that modules cannot work,
+ but that modules must be built for XEN3_DOM0 because some of the
+ defines change and the normal module builds don't do this.  Basically,
+ enabling Xen changes the kernel ABI, and the module build system
+ doesn't cope with this.
+ 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
+ bug, users should be aware of this and can simply add missing config
+ items if desired.
  Updating NetBSD in a dom0
  -------------------------
- Line 358  mediated by Xen, and configured in the d
+ Line 425  mediated by Xen, and configured in the d
  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.
+ Config files
+ ------------
+ There is no good order to present config files and the concepts
+ surrounding what is being configured.  We first show an example config
+ file, and then in the various sections give details.
+ See (at least in xentools41) /usr/pkg/share/examples/xen/xmexample*,
+ for a large number of well-commented examples, mostly for running
+ GNU/Linux.
+ The following is an example minimal domain configuration file
+ "/usr/pkg/etc/xen/foo".  It is (with only a name change) an actual
+ known working config file on Xen 4.1 (NetBSD 5 amd64 dom0 and NetBSD 5
+ i386 domU).  The domU serves as a network file server.
+         # -*- mode: python; -*-
+         kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
+         memory = 1024
+         vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
+         disk = [ 'file:/n0/xen/foo-wd0,0x0,w',
+                  'file:/n0/xen/foo-wd1,0x1,w' ]
+ The domain will have the same name as the file.  The kernel has the
+ host/domU name in it, so that on the dom0 one can update the various
+ domUs independently.  The vif line causes an interface to be provided,
+ with a specific mac address (do not reuse MAC addresses!), in bridge
+ 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
+ dom0 on domain creation.  The system treates xbd0 as the boot device
+ without needing explicit configuration.
+ By default xm looks for domain config files in /usr/pkg/etc/xen.  Note
+ that "xm create" takes the name of a config file, while other commands
+ take the name of a domain.  To create the domain, connect to the
+ console, create the domain while attaching the console, shutdown the
+ domain, and see if it has finished stopping, do (or xl with Xen >=
+.2):
+         xm create foo
+         xm console foo
+         xm create -c foo
+         xm shutdown foo
+         xm list
+ Typing ^] will exit the console session.  Shutting down a domain is
+ equivalent to pushing the power button; a NetBSD domU will receive a
+ power-press event and do a clean shutdown.  Shutting down the dom0
+ will trigger controlled shutdowns of all configured domUs.
+ domU kernels
+ ------------
+ 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
+ filesystem.  With Xen domUs, the process is totally different.  The
+ 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
+ new domU instance and starts execution.  While domU kernels can be
+ 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
+ config files), or in /u0/xen (where the vdisks are).
+ See the VPS section near the end for discussion of alternate ways to
+ obtain domU kernels.
  CPU and memory
  --------------
- A domain is provided with some number of vcpus, less than the
+ A domain is provided with some number of vcpus, less than the number
- number of cpus seen by the hypervisor.  For a dom0, this is controlled
+ of cpus seen by the hypervisor.  (For a dom0, this is controlled by
- 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.
+ from the config file by the "vcpus = N" directive.
- A domain is provided with memory, In the straightforward case, the sum
+ A domain is provided with memory; this is controlled in the config
- of the the memory allocated to the dom0 and all domUs must be less
+ file by "memory = N" (in megabytes).  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
- Line 387  improves performance.  The other is that
+ Line 522  improves performance.  The other is that
  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.
+ purpose, except that xentools handles the vnconfig commands.  To
+ create an empty 4G virtual disk, simply do
+         dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
  With the lvm style, one creates logical devices.  They are then used
- similarly to vnds.
+ similarly to vnds.  TODO: Add an example with lvm.
- Virtual Networking
+ In domU config files, the disks are defined as a sequence of 3-tuples.
- ------------------
+ The first element is "method:/path/to/disk".  Common methods are
+ "file:" for file-backed vnd. and "phy:" for something that is already
+ a (TODO: character or block) device.
+ The second element is an artifact of how virtual disks are passed to
+ Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
+ are given a device name to associate with the disk, and values like
+ "hda1" or "sda1" are common.  In a NetBSD domU, the first disk appears
+ as xbd0, the second as xbd1, and so on.  However, xm/xl demand a
+ second argument.  The name given is converted to a major/minor by
+ consulting /dev and this is passed to the domU (TODO: check this).  In
+ the general case, the dom0 and domU can be different operating
+ systems, and it is an unwarranted assumption that they have consistent
+ numbering in /dev, or even that the dom0 OS has a /dev.  With NetBSD
+ as both dom0 and domU, using values of 0x0 for the first disk and 0x1
+ for the second works fine and avoids this issue.
- TODO: explain xvif concept, and that it's general.
+ The third element is "w" for writable disks, and "r" for read-only
+ disks.
- There are two normal styles: bridging and NAT.
+ Virtual Networking
+ ------------------
- With bridging, the domU perceives itself to be on the same network as
+ Xen provides virtual ethernets, each of which connects the dom0 and a
- the dom0.  For server virtualization, this is usually best.
+ domU.  For each virtual network, there is an interface "xvifN.M" in
+ the dom0, and in domU index N, a matching interface xennetM (NetBSD
+ name).  The interfaces behave as if there is an Ethernet with two
+ adaptors connected.  From this primitive, one can construct various
+ configurations.  We focus on two common and useful cases for which
+ there are existing scripts: bridging and NAT.
+ With bridging (in the example above), the domU perceives itself to be
+ on the same network as the dom0.  For server virtualization, this is
+ usually best.  Bridging is accomplished by creating a bridge(4) device
+ and adding the dom0's physical interface and the various xvifN.0
+ interfaces to the bridge.  One specifies "bridge=bridge0" in the domU
+ config file.  The bridge must be set up already in the dom0; an
+ example /etc/ifconfig.bridge0 is:
+         create
+         up
+         !brconfig bridge0 add wm0
  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.
+ TODO: NAT appears to be configured by "vif = [ '' ]".
- One can construct arbitrary other configurations, but there is no
- script support.
  Sizing domains
  --------------
- Line 420  create a new file and vnconfig it (or lv
+ Line 590  create a new file and vnconfig it (or lv
  just like updating physical disks, but without having to be there and
  without those pesky connectors.
- Config files
+ Starting domains automatically
- ------------
+ ------------------------------
- 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
+ To start domains foo at bar at boot and shut them down cleanly on dom0
- ----------------
+ shutdown, in rc.conf add:
- TODO: Explain "xm start" and "xl start".  Explain rc.d/xendomains.
+         xendomains="foo bar"
  TODO: Explain why 4.1 rc.d/xendomains has xl, when one should use xm
- on 4.1.
+ on 4.1.  Or fix the xentools41 package to have xm
  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.
+ Note that you must have already completed the dom0 setup so that "xm
+ list" (or "xl list") works.
  Creating an unprivileged NetBSD domain (domU)
  ---------------------------------------------
- Once you have *domain0* running, you need to start the xen tool daemon
- (`/usr/pkg/share/examples/rc.d/xend start`) and the xen backend daemon
- (`/usr/pkg/share/examples/rc.d/xenbackendd start` for Xen3\*,
- `/usr/pkg/share/examples/rc.d/xencommons start` for Xen4.\*). Make sure
- that `/dev/xencons` and `/dev/xenevt` exist before starting `xend`. You
- can create them with this command:
-     # cd /dev && sh MAKEDEV xen
- xend will write logs to `/var/log/xend.log` and
- `/var/log/xend-debug.log`. You can then control xen with the xm tool.
- 'xm list' will show something like:
-     # xm list
-     Name              Id  Mem(MB)  CPU  State  Time(s)  Console
-     Domain-0           0       64    0  r----     58.1
  'xm create' allows you to create a new domain. It uses a config file in
  PKG\_SYSCONFDIR for its parameters. By default, this file will be in
  `/usr/pkg/etc/xen/`. On creation, a kernel has to be specified, which
- Line 584  working vif-bridge is also provided with
+ Line 735  working vif-bridge is also provided with
      #!/bin/sh
      #============================================================================
-     # $NetBSD: howto.mdwn,v 1.33 2014/12/24 15:54:50 gdt Exp $
+     # $NetBSD: howto.mdwn,v 1.47 2014/12/26 18:35:45 gdt Exp $
      #
      # /usr/pkg/etc/xen/vif-bridge
      #
- Line 974  TODO: Perhaps reference panix, prmgr, am
+ Line 1125  TODO: Perhaps reference panix, prmgr, am
  TODO: Somewhere, discuss pvgrub and py-grub to load the domU kernel
  from the domU filesystem.
+ Using npf
+ ---------
+ In standard kernels, npf is a module, and thus cannot be loadeed in a
+ DOMU kernel.
+ TODO: explain how to compile npf into a custom kernel, answering:
+ http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html

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