Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.31 and 1.47

version 1.31, 2014/12/24 15:30:45 version 1.47, 2014/12/26 18:35:45
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
 installed 4.1 or 4.2):  installed 4.1 or 4.2):
   
         xend=YES          xend=YES
         xenbackendd=YES          xenbackendd=YES
   
 For 4.1 (and thus xm), add to rc.conf:  For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:
   
         xend=YES          xend=YES
         xencommons=YES          xencommons=YES
   
 TODO: Explain why if xm is preferred on 4.1, rc.d/xendomains has xl.  TODO: Explain why if xm is preferred on 4.1, rc.d/xendomains has xl.
   Or fix the package.
   
 For 4.2 with xl, add to rc.conf:  For 4.2 with xm, add to rc.conf
   
           xend=YES
           xencommons=YES
   
   For 4.2 with xl (preferred), add to rc.conf:
   
         TODO: explain if there is a xend replacement          TODO: explain if there is a xend replacement
         xencommons=YES          xencommons=YES
   
 TODO: Recommend for/against xen-watchdog.  TODO: Recommend for/against xen-watchdog.
   
   After you have configured the daemons and either started them or
   rebooted, run the following (or use xl) to inspect Xen's boot
   messages, available resources, and running domains:
   
           # xm dmesg
           [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 332  Unprivileged domains (domU) Line 413  Unprivileged domains (domU)
 ===========================  ===========================
   
 This section describes general concepts about domUs.  It does not  This section describes general concepts about domUs.  It does not
 address specific domU operating systems or how to install them.  address specific domU operating systems or how to install them.  The
   config files for domUs are typically in /usr/pkg/etc/xen, and are
 Provided Resources for PV domains  typically named so that the file anme, domU name and the domU's host
 ---------------------------------  name match.
   
 TODO: Explain that domUs get cpu, memory, disk and network.  The domU is provided with cpu and memory by Xen, configured by the
 Explain that randomness can be an issue.  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  Virtual disks
 -------------  -------------
   
 TODO: Explain how to set up files for vnd and that one should write all zeros to preallocate.  With the file/vnd style, typically one creates a directory,
 TODO: Explain in what NetBSD versions sparse vnd files do and don't work.  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.  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.
   
 Virtual Networking  Virtual Networking
 ------------------  ------------------
   
 TODO: explain xvif concept, and that it's general.  Xen provides virtual ethernets, each of which connects the dom0 and a
   domU.  For each virtual network, there is an interface "xvifN.M" in
 There are two normal styles: bridging and NAT.  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, the domU perceives itself to be on the same network as  With bridging, the domU perceives itself to be on the same network as
 the dom0.  For server virtualization, this is usually best.  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.
   
 One can construct arbitrary other configurations, but there is no  Sizing domains
 script support.  --------------
   
   Modern x86 hardware has vast amounts of resources.  However, many
   virtual servers can function just fine on far less.  A system with
   256M 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.
   
   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.
   
 Config files  Config files
 ------------  ------------
   
 TODO: give example config files.   Use both lvm and vnd.  The following is an example domain configuration file
   "/usr/pkg/etc/xen/foo", lightly sanitized from a known working on Xen
   4.1 (NetBSD 5 amd64 dom0 and NetBSD 6 i386 domU):
   
           # -*- mode: python; -*-
   
           kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz"
           memory = 1024
           #cpu = -1
           vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ]
           disk = [ 'file:/n0/xen/foo-wd0,0x1,w',
                    'file:/n0/xen/foo-wd1,0x2,w' ]
           root = "xbd0"
           autorestart = True
   
   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 writable.
   
   TODO: explain if the root line is really necessary.
   TODO: explain or remove autorestart.
   
 TODO: explain the mess with 3 arguments for disks and how to cope (0x1).  TODO: Add an example with lvm
   
   TODO: explain, someplace the mess with 3 arguments for disks and how to cope (0x1).
   
 Starting domains  Starting domains
 ----------------  ----------------
Line 382  Creating specific unprivileged domains ( Line 560  Creating specific unprivileged domains (
   
 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 526  working vif-bridge is also provided with Line 689  working vif-bridge is also provided with
   
     #!/bin/sh      #!/bin/sh
     #============================================================================      #============================================================================
     # $NetBSD: howto.mdwn,v 1.30 2014/12/24 15:21:41 gdt Exp $      # $NetBSD: howto.mdwn,v 1.46 2014/12/26 16:43:51 gdt Exp $
     #      #
     # /usr/pkg/etc/xen/vif-bridge      # /usr/pkg/etc/xen/vif-bridge
     #      #
Line 916  TODO: Perhaps reference panix, prmgr, am Line 1079  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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