Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.33 and 1.48

version 1.33, 2014/12/24 15:54:50 version 1.48, 2014/12/26 20:00:44
Line 152  Therefore, this HOWTO recommends running Line 152  Therefore, this HOWTO recommends running
 xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the  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.  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  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  NetBSD install to a dom0 install by just changing the kernel and boot
 configuration.  configuration.
   
   For experimenting with Xen, a machine with as little as 1G of RAM and
   100G of disk can work.  For running many domUs in productions, far
   more will be needed.
   
 Styles of dom0 operation  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  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  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  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
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  only be used if you plan on using "xm".  Do NOT enable xend if you
 plan on using "xl" as it will cause problems.  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).  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  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.  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 info          # xm dmesg
         xm list          [xen's boot info]
           # 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  Updating NetBSD in a dom0
 -------------------------  -------------------------
Line 357  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  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.  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 >=
   4.2):
   
           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  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.  than the available memory.
   
 Xen also provides a "balloon" driver, which can be used to let domains  Xen also provides a "balloon" driver, which can be used to let domains
Line 386  improves performance.  The other is that Line 522  improves performance.  The other is that
 failed to work.  TODO: give working/notworking NetBSD versions for  failed to work.  TODO: give working/notworking NetBSD versions for
 sparse vnd.  Note that the use of file/vnd for Xen is not really  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  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  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  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.  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  Sizing domains
 --------------  --------------
Line 419  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  just like updating physical disks, but without having to be there and
 without those pesky connectors.  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  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 specific unprivileged domains (domU)
 =============================================  =============================================
   
 Creating domUs is almost entirely independent of operating system.  We  Creating domUs is almost entirely independent of operating system.  We
 first explain NetBSD, and then differences for Linux and Solaris.  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)  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  '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  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  `/usr/pkg/etc/xen/`. On creation, a kernel has to be specified, which
Line 583  working vif-bridge is also provided with Line 735  working vif-bridge is also provided with
   
     #!/bin/sh      #!/bin/sh
     #============================================================================      #============================================================================
     # $NetBSD: howto.mdwn,v 1.32 2014/12/24 15:31:36 gdt Exp $      # $NetBSD: howto.mdwn,v 1.47 2014/12/26 18:35:45 gdt Exp $
     #      #
     # /usr/pkg/etc/xen/vif-bridge      # /usr/pkg/etc/xen/vif-bridge
     #      #
Line 973  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  TODO: Somewhere, discuss pvgrub and py-grub to load the domU kernel
 from the domU filesystem.  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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