Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.19 and 1.155

version 1.19, 2014/12/24 00:41:04 version 1.155, 2018/08/01 13:19:43
Line 1 Line 1
   [[!meta title="Xen HowTo"]]
   
 Introduction  Introduction
 ============  ============
   
 [![[Xen  Xen is a hypervisor for x86 hardware, which supports running multiple guest
 screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](../../gallery/in-Action/hubertf-xen.png)  operating systems on a single physical machine.  Xen is a Type 1 or
   bare-metal hypervisor; one uses the Xen kernel to control the CPU,
 Xen is a virtual machine monitor or hypervisor for x86 hardware  memory and console, a dom0 operating system which mediates access to
 (i686-class or higher), which supports running multiple guest  other hardware (e.g., disks, network, USB), and one or more domU
 operating systems on a single physical machine.  With Xen, one uses  operating systems which operate in an unprivileged virtualized
 the Xen kernel to control the CPU, memory and console, a dom0  environment.  IO requests from the domU systems are forwarded by the
 operating system which mediates access to other hardware (e.g., disks,  Xen hypervisor to the dom0 to be fulfilled.
 network, USB), and one or more domU operating systems which operate in  
 an unprivileged virtualized environment.  IO requests from the domU  Xen supports different styles of guest:
 systems are forwarded by the hypervisor (Xen) to the dom0 to be  
 fulfilled.  [[!table data="""
   Style of guest  |Supported by NetBSD
 Xen supports two styles of guests.  The original is Para-Virtualized  PV              |Yes (dom0, domU)
 (PV) which means that the guest OS does not attempt to access hardware  HVM             |Yes (domU)
 directly, but instead makes hypercalls to the hypervisor.  This is  PVHVM           |No
 analogous to a user-space program making system calls.  (The dom0  PVH             |No
 operating system uses PV calls for some functions, such as updating  """]]
 memory mapping page tables, but has direct hardware access for disk  
 and network.)   PV guests must be specifically coded for Xen.  In Para-Virtualized (PV) mode, the guest OS does not attempt to access
   hardware directly, but instead makes hypercalls to the hypervisor; PV
 The more recent style is HVM, which means that the guest does not have  guests must be specifically coded for Xen. In HVM mode, no guest
 code for Xen and need not be aware that it is running under Xen.  modification is required; however, hardware support is required, such
 Attempts to access hardware registers are trapped and emulated.  This  as VT-x on Intel CPUs and SVM on AMD CPUs.
 style is less efficient but can run unmodified guests.  
   
 Generally any amd64 machine will work with Xen and PV guests.  For HVM  
 guests, the VMX cpu feature (Intel) or VT?? (amd64) is needed.  TODO:  
 Explain if i386 (non-amd64) machines can still be used - I think that  
 witthe requirement to use PAE kernels is about the hypervisor being  
 amd64 only.  
   
 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  The dom0 can start one or more domUs.  (Booting is explained in detail
 in the dom0 section.)  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.  
   
 Prerequisites  
 -------------  
   
 Installing NetBSD/Xen is not extremely difficult, but it is more  
 complex than a normal installation of NetBSD.  
 In general, this HOWTO is occasionally overly restrictive about how  
 things must be done, guiding the reader to stay on the established  
 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.xen.org/).  website](http://www.xenproject.org/).
   
 History  This HOWTO attempts to address both the case of running a NetBSD dom0
 -------  on hardware and running domUs under it (NetBSD and other), and also
   running NetBSD as a domU in a VPS.
 NetBSD used to support Xen2; this has been removed.  
   
 Before NetBSD's native bootloader could support Xen, the use of  
 grub was recommended.  If necessary, see the  
 [old grub information](/xen/howto-grub/).  
   
 Versions of Xen and NetBSD  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.
   
   The term "amd64" is used to refer to both the NetBSD port and to the
   hardware architecture on which it runs.  Such hardware is generally
   made by both Intel and AMD, and common on PC computers.
   
 Xen  Xen versions
 ---  ------------
   
 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  Versions available in pkgsrc:
 receive security patches and should not be used.  
   
 xenkernel41 provides Xen 4.1.  This is no longer maintained by Xen,  [[!table data="""
 but as of 2014-12 receives backported security patches.  It is a  Xen Version     |Package Name   |Xen CPU Support        |EOL'ed By Upstream
 reasonable although trailing-edge choice.  4.2             |xenkernel42    |32bit, 64bit           |Yes
   4.5             |xenkernel45    |64bit                  |Yes
   4.6             |xenkernel46    |64bit                  |Partially
   4.8             |xenkernel48    |64bit                  |No
   4.11            |xenkernel411   |64bit                  |No
   """]]
   
 xenkernel42 provides Xen 4.2.  This is maintained by Xen, but old as  See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
 of 2014-12.  
   
 Ideally newer versions of Xen will be added to pkgsrc.  Note: Xen 4.2 was the last version to support 32bit CPUs.
   
 Xen command program  
 -------------------  
   
 Early Xen used a program called "xm" to manipulate the system from the  NetBSD versions
 dom0.  Starting in 4.1, a replacement program with similar behavior  ---------------
 called "xl" is provided.  In 4.2, "xm" is no longer available.  
   
 NetBSD  NetBSD 8 is recommended as the stable version of the most recent
 ------  release for production use.
   
 The netbsd-5, netbsd-6, netbsd-7, and -current branches are all  For developing Xen, netbsd-current may be appropriate.
 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.  
   
 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.)
   
   Note: NetBSD support is called XEN3. However, it does support Xen 4,
   because the hypercall interface has remained identical.
   
 Architecture  Architecture
 ------------  ------------
   
 Xen is basically amd64 only at this point.  One can either run i386  Xen itself runs on amd64 hardware. Practically, almost any computer
 domains or amd64 domains.  If running i386, PAE versions are required,  where one would want to run Xen today supports amd64.
 for both dom0 and domU.  These versions are built by default in NetBSD  
 releases.  While i386 dom0 works fine, amd64 is recommended as more  
 normal.  (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  The dom0 system, plus each domU, can be either i386PAE or amd64.
 --------------  i386 without PAE is not supported.
   
 Therefore, this HOWTO recommends running xenkernel42 (and xentools42),  The standard approach is to use NetBSD/amd64 for the dom0.  For domUs,
 xl, the NetBSD 6 stable branch, and to use amd64 as the dom0.  Either  NetBSD/i386 (PAE) and NetBSD/amd64 are in widespread use, and there is
 the i386 or amd64 of NetBSD may be used as domUs.  little to no Xen-specific reason to prefer one over the other.
   
   Note that to use an i386 dom0 with Xen 4.5 or higher, one must build
   (or obtain from pre-built packages) an amd64 Xen kernel and install
   that on the system.  Almost no one in the NetBSD/Xen community does
   this, and the standard, well-tested, approach is to use an amd64 dom0.
   
   A [posting on
   xen-devel](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html)
   explained that PV system call overhead was higher on amd64, and thus
   there is some notion that i386 guests are faster.  It goes on to
   caution that the total situation is complex and not entirely
   understood. On top of that caution, the post is about Linux, not
   NetBSD.
   
 NetBSD as a dom0  NetBSD as a dom0
 ================  ================
Line 142  NetBSD, which is not yet a dom0, and the Line 129  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; e.g. 4-8G and 1T of disk is reasonable for a
   half-dozen domUs of 512M and 32G each.  Basically, the RAM and disk
   have to be bigger than the sum of the RAM/disk needs of the dom0 and
   all the domUs.
   
   In 2018-05, trouble booting a dom0 was reported with 256M of RAM: with
   512M it worked reliably.  This does not make sense, but if you see
   "not ELF" after Xen boots, try increasing dom0 RAM.
   
 Styles of dom0 operation  Styles of dom0 operation
 ------------------------  ------------------------
   
Line 155  dom0 is what the computer would have bee Line 153  dom0 is what the computer would have bee
 desktop or laptop.  Then, one can run domUs at will.  Purists will  desktop or laptop.  Then, one can run domUs at will.  Purists will
 deride this as less secure than the previous approach, and for a  deride this as less secure than the previous approach, and for a
 computer whose purpose is to run domUs, they are right.  But Xen and a  computer whose purpose is to run domUs, they are right.  But Xen and a
 dom0 (without domUs) is not meaingfully less secure than the same  dom0 (without domUs) is not meaningfully less secure than the same
 things running without Xen.  One can boot Xen or boot regular NetBSD  things running without Xen.  One can boot Xen or boot regular NetBSD
 alternately with little problems, simply refraining from starting the  alternately with little problems, simply refraining from starting the
 Xen daemons when not running Xen.  Xen daemons when not running Xen.
   
 Note that NetBSD as dom0 does not support multiple CPUs.  This will  Note that NetBSD as dom0 does not support multiple CPUs.  This will
 limit the performance of the Xen/dom0 workstation approach.  limit the performance of the Xen/dom0 workstation approach.  In theory
   the only issue is that the "backend drivers" are not yet MPSAFE:
     https://mail-index.netbsd.org/netbsd-users/2014/08/29/msg015195.html
   
 Installation of NetBSD  Installation of NetBSD
 ----------------------  ----------------------
   
 First,  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.  just as you would if you were not using Xen.
 However, the partitioning approach is very important.  However, the partitioning approach is very important.
   
 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.  domU systems are unaware of RAID.  The 2nd-stage loader bootxx_* skips
   over a RAID1 header to find /boot from a file system within a RAID
   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
 used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN,  used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN.
   
 With raw partitions, one has a disklabel (or gpt) partition sized for  With raw partitions, one has a disklabel (or gpt) partition sized for
 each virtual disk to be used by the domU.  (If you are able to predict  each virtual disk to be used by the domU.  (If you are able to predict
 how domU usage will evolve, please add an explanation to the HOWTO.  how domU usage will evolve, please add an explanation to the HOWTO.
 Seriously, needs tend to change over time.)  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  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 199  HOWTO page.) Line 202  HOWTO page.)
 Installation of Xen  Installation of Xen
 -------------------  -------------------
   
 Next step is to install the Xen packages via pkgsrc or from binary  We will consider that you chose to use Xen 4.8, with NetBSD/amd64 as
 packages. See [the pkgsrc  dom0. In the dom0, install xenkernel48 and xentools48 from pkgsrc.
 documentation](http://www.NetBSD.org/docs/pkgsrc/) if you are unfamiliar  Ensure that your packages are recent.
 with pkgsrc and/or handling of binary packages. Xen 3.1, 3.3, 4.1 and  
 4.2 are available. 3.1 supports PCI pass-through while other versions do  Once this is done, install the Xen kernel itself:
 not. You'll need either `sysutils/xentools3` and `sysutils/xenkernel3`  
 for Xen 3.1, `sysutils/xentools33` and `sysutils/xenkernel33` for Xen  [[!template id=programlisting text="""
 3.3, `sysutils/xentools41` and `sysutils/xenkernel41` for Xen 4.1. or  # cp /usr/pkg/xen48-kernel/xen.gz /
 `sysutils/xentools42` and `sysutils/xenkernel42` for Xen 4.2. You'll  """]]
 also need `sysutils/grub` if you plan do use the grub boot loader. If  
 using Xen 3.1, you may also want to install `sysutils/xentools3-hvm`  Then, place a NetBSD XEN3_DOM0 kernel in /, copied from
 which contains the utilities to run unmodified guests OSes using the  releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz of a NetBSD build.
 *HVM* support (for later versions this is included in  
 `sysutils/xentools`). Note that your CPU needs to support this. Intel  Add a line to /boot.cfg to boot Xen:
 CPUs must have the 'VT' instruction, AMD CPUs the 'SVM' instruction. You  
 can easily find out if your CPU support HVM by using NetBSD's cpuctl  [[!template id=programlisting text="""
 command:  menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
   """]]
     # cpuctl identify 0  
     cpu0: Intel Core 2 (Merom) (686-class), id 0x6f6  which specifies that the dom0 should have 512MB of ram, leaving the rest
     cpu0: features 0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>  to be allocated for domUs.  To use a serial console, use
     cpu0: features 0xbfebfbff<PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX>  
     cpu0: features 0xbfebfbff<FXSR,SSE,SSE2,SS,HTT,TM,SBF>  [[!template id=programlisting text="""
     cpu0: features2 0x4e33d<SSE3,DTES64,MONITOR,DS-CPL,,TM2,SSSE3,CX16,xTPR,PDCM,DCA>  menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
     cpu0: features3 0x20100800<SYSCALL/SYSRET,XD,EM64T>  """]]
     cpu0: "Intel(R) Xeon(R) CPU            5130  @ 2.00GHz"  
     cpu0: I-cache 32KB 64B/line 8-way, D-cache 32KB 64B/line 8-way  which will use the first serial port for Xen (which counts starting
     cpu0: L2 cache 4MB 64B/line 16-way  from 1, unlike NetBSD which counts starting from 0), forcing
     cpu0: ITLB 128 4KB entries 4-way  speed/parity.  Because the NetBSD command line lacks a
     cpu0: DTLB 256 4KB entries 4-way, 32 4MB entries 4-way  "console=pc" argument, it will use the default "xencons" console device,
     cpu0: Initial APIC ID 0  which directs the console I/O through Xen to the same console device Xen
     cpu0: Cluster/Package ID 0  itself uses (in this case, the serial port).
     cpu0: Core ID 0  
     cpu0: family 06 model 0f extfamily 00 extmodel 00  In an attempt to add performance, one can also add:
   
 Depending on your CPU, the feature you are looking for is called HVM,  [[!template id=programlisting text="""
 SVM or VMX.  dom0_max_vcpus=1 dom0_vcpus_pin
   """]]
 Next you need to copy the selected Xen kernel itself. pkgsrc installed  
 them under `/usr/pkg/xen*-kernel/`. The file you're looking for is  to force only one vcpu to be provided (since NetBSD dom0 can't use
 `xen.gz`. Copy it to your root file system. `xen-debug.gz` is a kernel  more) and to pin that vcpu to a physical CPU.
 with more consistency checks and more details printed on the serial  
 console. It is useful for debugging crashing guests if you use a serial  Xen has [many boot
 console. It is not useful with a VGA console.  options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html),
   and other than dom0 memory and max_vcpus, they are generally not
 You'll then need a NetBSD/Xen kernel for *domain0* on your root file  necessary.
 system. The XEN3PAE\_DOM0 kernel or XEN3\_DOM0 provided as part of the  
 i386 or amd64 binaries is suitable for this, but you may want to  As with non-Xen systems, you should have a line to boot /netbsd (a
 customize it. Keep your native kernel around, as it can be useful for  kernel that works without Xen).
 recovery. *Note:* the *domain0* kernel must support KERNFS and `/kern`  
 must be mounted because *xend* needs access to `/kern/xen/privcmd`.  Now, reboot so that you are running a DOM0 kernel under Xen, rather
   than GENERIC without Xen.
 Next you need to get a bootloader to load the `xen.gz` kernel, and the  
 NetBSD *domain0* kernel as a module. This can be `grub` or NetBSD's boot  Using grub (historic)
 loader. Below is a detailled example for grub, see the boot.cfg(5)  ---------------------
 manual page for an example using the latter.  
   Before NetBSD's native bootloader could support Xen, the use of
 This is also where you'll specify the memory allocated to *domain0*, the  grub was recommended.  If necessary, see the
 console to use, etc ...  [old grub information](/ports/xen/howto-grub).
   
 Here is a commented `/grub/menu.lst` file:  The [HowTo on Installing into
   RAID-1](https://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
     #Grub config file for NetBSD/xen. Copy as /grub/menu.lst and run  explains how to set up booting a dom0 with Xen using grub with
     # grub-install /dev/rwd0d (assuming your boot device is wd0).  NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
     #  boot.  Now, just create a system with RAID-1, and alter /boot.cfg as
     # The default entry to load will be the first one  described above.)
     default=0  
   Configuring Xen
     # boot the default entry after 10s if the user didn't hit keyboard  ---------------
     timeout=10  
   Now, you have a system that will boot Xen and the dom0 kernel, but not
     # Configure serial port to use as console. Ignore if you'll use VGA only  do anything else special.  Make sure that you have rebooted into Xen.
     serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1  There will be no domUs, and none can be started because you still have
   to configure the dom0 daemons.
     # Let the user select which console to use (serial or VGA), default  
     # to serial after 10s  The daemons which should be run vary with Xen version and with whether
     terminal --timeout=10 serial console  one is using xm or xl. Xen 4.2 and up packages use xl. To use xm with 4.2,
   edit xendomains to use xm instead.
     # An entry for NetBSD/xen, using /netbsd as the domain0 kernel, and serial  
     # console. Domain0 will have 64MB RAM allocated.  For 4.1 and up, you should enable xencommons.  Not enabling xencommons
     # Assume NetBSD is installed in the first MBR partition.  will result in a hang; it is necessary to hit ^C on the console to let
     title Xen 3 / NetBSD (hda0, serial)  the machine finish booting.  If you are using xm (default in 4.1, or
       root(hd0,0)  if you changed xendomains in 4.2), you should also enable xend:
       kernel (hd0,a)/xen.gz dom0_mem=65536 com1=115200,8n1  
       module (hd0,a)/netbsd bootdev=wd0a ro console=ttyS0  [[!template id=programlisting text="""
   xend=YES # only if using xm, and only installed <= 4.2
     # Same as above, but using VGA console  xencommons=YES
     # We can use console=tty0 (Linux syntax) or console=pc (NetBSD syntax)  """]]
     title Xen 3 / NetBSD (hda0, vga)  
       root(hd0,0)  TODO: Recommend for/against xen-watchdog.
       kernel (hd0,a)/xen.gz dom0_mem=65536  
       module (hd0,a)/netbsd bootdev=wd0a ro console=tty0  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,
     # NetBSD/xen using a backup domain0 kernel (in case you installed a  available resources, and running domains.  An example with xl follows:
     # nonworking kernel as /netbsd  
     title Xen 3 / NetBSD (hda0, backup, serial)  [[!template id=programlisting text="""
       root(hd0,0)  # xl dmesg
       kernel (hd0,a)/xen.gz dom0_mem=65536 com1=115200,8n1  ... xen's boot info ...
       module (hd0,a)/netbsd.backup bootdev=wd0a ro console=ttyS0  # xl info
     title Xen 3 / NetBSD (hda0, backup, VGA)  ... available memory, etc ...
       root(hd0,0)  # xl list
       kernel (hd0,a)/xen.gz dom0_mem=65536  Name              Id  Mem(MB)  CPU  State  Time(s)  Console
       module (hd0,a)/netbsd.backup bootdev=wd0a ro console=tty0  Domain-0           0       64    0  r----     58.1
   """]]
     #Load a regular NetBSD/i386 kernel. Can be useful if you end up with a  
     #nonworking /xen.gz  Xen logs will be in /var/log/xen.
     title NetBSD 5.1  
       root (hd0,a)  ### Issues with xencommons
       kernel --type=netbsd /netbsd-GENERIC  
   xencommons starts xenstored, which stores data on behalf of dom0 and
     #Load the NetBSD bootloader, letting it load the NetBSD/i386 kernel.  domUs.  It does not currently work to stop and start xenstored.
     #May be better than the above, as grub can't pass all required infos  Certainly all domUs should be shutdown first, following the sort order
     #to the NetBSD/i386 kernel (e.g. console, root device, ...)  of the rc.d scripts.  However, the dom0 sets up state with xenstored,
     title NetBSD chain  and is not notified when xenstored exits, leading to not recreating
       root        (hd0,0)  the state when the new xenstored starts.  Until there's a mechanism to
       chainloader +1  make this work, one should not expect to be able to restart xenstored
   (and thus xencommons).  There is currently no reason to expect that
     ## end of grub config file.  this will get fixed any time soon.
             
   ### No-longer needed advice about devices
 Install grub with the following command:  
   The installation of NetBSD should already have created devices for xen
     # grub --no-floppy  (xencons, xenevt, xsd_kva), but if they are not present, create them:
   
     grub> root (hd0,a)  [[!template id=programlisting text="""
      Filesystem type is ffs, partition type 0xa9  cd /dev && sh MAKEDEV xen
   """]]
     grub> setup (hd0)  
      Checking if "/boot/grub/stage1" exists... no  anita (for testing NetBSD)
      Checking if "/grub/stage1" exists... yes  --------------------------
      Checking if "/grub/stage2" exists... yes  
      Checking if "/grub/ffs_stage1_5" exists... yes  With the setup so far (assuming 4.2/xl), one should be able to run
      Running "embed /grub/ffs_stage1_5 (hd0)"...  14 sectors are embedded.  anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
     succeeded  root, because anita must create a domU):
      Running "install /grub/stage1 (hd0) (hd0)1+14 p (hd0,0,a)/grub/stage2 /grub/menu.lst"...  
      succeeded  [[!template id=programlisting text="""
     Done.  anita --vmm=xl test file:///usr/obj/i386/
             """]]
   
   Alternatively, one can use --vmm=xm to use xm-based domU creation
   instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
       
   Xen-specific NetBSD issues
   --------------------------
   
   There are (at least) two additional things different about NetBSD as a
   dom0 kernel compared to hardware.
   
   One is that the module ABI is different because some of the #defines
   change, so one must build modules for Xen.  As of netbsd-7, the build
   system does this automatically.  TODO: check this.  (Before building
   Xen modules was added, it was awkward to use modules to the point
   where it was considered that it did not work.)
   
   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 349  and adjusts /etc. Line 372  and adjusts /etc.
 Note that one must update both the non-Xen kernel typically used for  Note that one must update both the non-Xen kernel typically used for
 rescue purposes and the DOM0 kernel used with Xen.  rescue purposes and the DOM0 kernel used with Xen.
   
 Updating Xen versions  Converting from grub to /boot
   -----------------------------
   
   These instructions were [TODO: will be] used to convert a system from
   grub to /boot.  The system was originally installed in February of
   2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
   over time.  Before these commands, it was running NetBSD 6 i386, Xen
   4.1 and grub, much like the message linked earlier in the grub
   section.
   
           # Install MBR bootblocks on both disks. 
           fdisk -i /dev/rwd0d
           fdisk -i /dev/rwd1d
           # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
           installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
           installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
           # Install secondary boot loader
           cp -p /usr/mdec/boot /
           # Create boot.cfg following earlier guidance:
           menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
           menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=512M
           menu=GENERIC:boot
           menu=GENERIC single-user:boot -s
           menu=GENERIC.ok:boot netbsd.ok
           menu=GENERIC.ok single-user:boot netbsd.ok -s
           menu=Drop to boot prompt:prompt
           default=1
           timeout=30
   
   TODO: actually do this and fix it if necessary.
   
   Upgrading Xen versions
 ---------------------  ---------------------
   
 TODO: write  Minor version upgrades are trivial.  Just rebuild/replace the
   xenkernel version and copy the new xen.gz to / (where /boot.cfg
   references it), and reboot.
   
   Major version upgrades are conceptually not difficult, but can run
   into all the issues found when installing Xen.  Assuming migration
   from 4.1 to 4.2, remove the xenkernel41 and xentools41 packages and
   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.
   
   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 name, 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.
   
   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 treats 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
   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
   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
   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).
   
   Note that loading the domU kernel from the dom0 implies that boot
   blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
   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 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 by the "vcpus = N" directive.
   
   A domain is provided with memory; this is controlled in the config
   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
   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 and gnats reference.  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
   
   Do not use qemu-img-xen, because this will create sparse file.  There
   have been recent (2015) reports of sparse vnd(4) devices causing
   lockups, but there is apparently no PR.
   
   With the lvm style, one creates logical devices.  They are then used
   similarly to vnds.  TODO: Add an example with lvm.
   
   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
   calling stat(2) on the name in /dev and this is passed to the domU.
   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.  For a GNU/Linux
   guest, one can create /dev/hda1 in /dev, or to pass 0x301 for
   /dev/hda1.
   
   The third element is "w" for writable disks, and "r" for read-only
   disks.
   
   Note that NetBSD by default creates only vnd[0123].  If you need more
   than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the
   dom0.
   
   Note that NetBSD by default creates only xbd[0123].  If you need more
   virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU.
   
   Virtual Networking
   ------------------
   
   Xen provides virtual Ethernets, each of which connects the dom0 and a
   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
   adapters 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 = [ '' ]".
   
   The MAC address specified is the one used for the interface in the new
   domain.  The interface in dom0 will use this address XOR'd with
   00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
   
   Sizing domains
   --------------
   
   Modern x86 hardware has vast amounts of resources.  However, many
   virtual servers can function just fine on far less.  A system with
   512M 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.
   
   Starting domains automatically
   ------------------------------
   
   To start domains foo at bar at boot and shut them down cleanly on dom0
   shutdown, in rc.conf add:
   
           xendomains="foo bar"
   
   Note that earlier versions of the xentools41 xendomains rc.d script
   used xl, when one should use xm with 4.1.
   
 Creating 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.  have already presented the basics of config files.  Note that you must
   have already completed the dom0 setup so that "xl list" (or "xm 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  See the earlier config file, and adjust memory.  Decide on how much
 (`/usr/pkg/share/examples/rc.d/xend start`) and the xen backend daemon  storage you will provide, and prepare it (file or lvm).
 (`/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  
 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  
 provided as part of the i386 and amd64 binary sets: XEN3\_DOMU.  
   
 Here is an /usr/pkg/etc/xen/nbsd example config file:  
   
     #  -*- mode: python; -*-  
     #============================================================================  
     # Python defaults setup for 'xm create'.  
     # Edit this file to reflect the configuration of your system.  
     #============================================================================  
   
     #----------------------------------------------------------------------------  
     # Kernel image file. This kernel will be loaded in the new domain.  
     kernel = "/home/bouyer/netbsd-XEN3_DOMU"  
     #kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"  
   
     # Memory allocation (in megabytes) for the new domain.  
     memory = 128  
   
     # A handy name for your new domain. This will appear in 'xm list',  
     # and you can use this as parameters for xm in place of the domain  
     # number. All domains must have different names.  
     #  
     name = "nbsd"  
   
     # The number of virtual CPUs this domain has.  
     #  
     vcpus = 1  
   
     #----------------------------------------------------------------------------  
     # Define network interfaces for the new domain.  
   
     # Number of network interfaces (must be at least 1). Default is 1.  
     nics = 1  
   
     # Define MAC and/or bridge for the network interfaces.  
     #  
     # The MAC address specified in ``mac'' is the one used for the interface  
     # in the new domain. The interface in domain0 will use this address XOR'd  
     # with 00:00:00:01:00:00 (i.e. aa:00:00:51:02:f0 in our example). Random  
     # MACs are assigned if not given.  
     #  
     # ``bridge'' is a required parameter, which will be passed to the  
     # vif-script called by xend(8) when a new domain is created to configure  
     # the new xvif interface in domain0.  
     #  
     # In this example, the xvif is added to bridge0, which should have been  
     # set up prior to the new domain being created -- either in the  
     # ``network'' script or using a /etc/ifconfig.bridge0 file.  
     #  
     vif = [ 'mac=aa:00:00:50:02:f0, bridge=bridge0' ]  
   
     #----------------------------------------------------------------------------  
     # Define the disk devices you want the domain to have access to, and  
     # what you want them accessible as.  
     #  
     # Each disk entry is of the form:  
     #  
     #   phy:DEV,VDEV,MODE  
     #  
     # where DEV is the device, VDEV is the device name the domain will see,  
     # and MODE is r for read-only, w for read-write.  You can also create  
     # file-backed domains using disk entries of the form:  
     #  
     #   file:PATH,VDEV,MODE  
     #  
     # where PATH is the path to the file used as the virtual disk, and VDEV  
     # and MODE have the same meaning as for ``phy'' devices.  
     #  
     # VDEV doesn't really matter for a NetBSD guest OS (it's just used as an index),  
     # but it does for Linux.  
     # Worse, the device has to exist in /dev/ of domain0, because xm will  
     # try to stat() it. This means that in order to load a Linux guest OS  
     # from a NetBSD domain0, you'll have to create /dev/hda1, /dev/hda2, ...  
     # on domain0, with the major/minor from Linux :(  
     # Alternatively it's possible to specify the device number in hex,  
     # e.g. 0x301 for /dev/hda1, 0x302 for /dev/hda2, etc ...  
   
     disk = [ 'phy:/dev/wd0e,0x1,w' ]  While the kernel will be obtained from the dom0 file system, the same
     #disk = [ 'file:/var/xen/nbsd-disk,0x01,w' ]  file should be present in the domU as /netbsd so that tools like
     #disk = [ 'file:/var/xen/nbsd-disk,0x301,w' ]  savecore(8) can work.   (This is helpful but not necessary.)
   
   The kernel must be specifically for Xen and for use as a domU.  The
   i386 and amd64 provide the following kernels:
   
           i386 XEN3PAE_DOMU
           amd64 XEN3_DOMU
   
   This will boot NetBSD, but this is not that useful if the disk is
   empty.  One approach is to unpack sets onto the disk outside of xen
   (by mounting it, just as you would prepare a physical disk for a
   system you can't run the installer on).
   
   A second approach is to run an INSTALL kernel, which has a miniroot
   and can load sets from the network.  To do this, copy the INSTALL
   kernel to / and change the kernel line in the config file to:
   
     #----------------------------------------------------------------------------          kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
     # Set the kernel command line for the new domain.  
   
     # Set root device. This one does matter for NetBSD  Then, start the domain as "xl create -c configname".
     root = "xbd0"  
     # extra parameters passed to the kernel  
     # this is where you can set boot flags like -s, -a, etc ...  
     #extra = ""  
   
     #----------------------------------------------------------------------------  
     # Set according to whether you want the domain restarted when it exits.  
     # The default is False.  
     #autorestart = True  
   
     # end of nbsd config file ====================================================  
   
 When a new domain is created, xen calls the  
 `/usr/pkg/etc/xen/vif-bridge` script for each virtual network interface  
 created in *domain0*. This can be used to automatically configure the  
 xvif?.? interfaces in *domain0*. In our example, these will be bridged  
 with the bridge0 device in *domain0*, but the bridge has to exist first.  
 To do this, create the file `/etc/ifconfig.bridge0` and make it look  
 like this:  
   
     create  
     !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.  
   
 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 1.18 2014/12/24 00:11:15 gdt Exp $  
     #  
     # /usr/pkg/etc/xen/vif-bridge  
     #  
     # Script for configuring a vif in bridged mode with a dom0 interface.  
     # The xend(8) daemon calls a vif script when bringing a vif up or down.  
     # The script name to use is defined in /usr/pkg/etc/xen/xend-config.sxp  
     # in the ``vif-script'' field.  
     #  
     # Usage: vif-bridge up|down [var=value ...]  
     #  
     # Actions:  
     #    up     Adds the vif interface to the bridge.  
     #    down   Removes the vif interface from the bridge.  
     #  
     # Variables:  
     #    domain name of the domain the interface is on (required).  
     #    vifq   vif interface name (required).  
     #    mac    vif MAC address (required).  
     #    bridge bridge to add the vif to (required).  
     #  
     # Example invocation:  
     #  
     # vif-bridge up domain=VM1 vif=xvif1.0 mac="ee:14:01:d0:ec:af" bridge=bridge0  
     #  
     #============================================================================  
   
     # Exit if anything goes wrong  
     set -e  
   
     echo "vif-bridge $*"  
   
     # Operation name.  
     OP=$1; shift  
   
     # Pull variables in args into environment  
     for arg ; do export "${arg}" ; done  
   
     # Required parameters. Fail if not set.  
     domain=${domain:?}  
     vif=${vif:?}  
     mac=${mac:?}  
     bridge=${bridge:?}  
   
     # Optional parameters. Set defaults.  
     ip=${ip:-''}   # default to null (do nothing)  
   
     # Are we going up or down?  
     case $OP in  
     up) brcmd='add' ;;  
     down)   brcmd='delete' ;;  
     *)  
         echo 'Invalid command: ' $OP  
         echo 'Valid commands are: up, down'  
         exit 1  
         ;;  
     esac  
   
     # Don't do anything if the bridge is "null".  
     if [ "${bridge}" = "null" ] ; then  
         exit  
     fi  
   
     # Don't do anything if the bridge doesn't exist.  
     if ! ifconfig -l | grep "${bridge}" >/dev/null; then  
         exit  
     fi  
   
     # Add/remove vif to/from bridge.  
     ifconfig x${vif} $OP  
     brconfig ${bridge} ${brcmd} x${vif}  
   
 Now, running  
   
     xm create -c /usr/pkg/etc/xen/nbsd  
   
 should create a domain and load a NetBSD kernel in it. (Note: `-c`  
 causes xm to connect to the domain's console once created.) The kernel  
 will try to find its root file system on xbd0 (i.e., wd0e) which hasn't  
 been created yet. wd0e will be seen as a disk device in the new domain,  
 so it will be 'sub-partitioned'. We could attach a ccd to wd0e in  
 *domain0* and partition it, newfs and extract the NetBSD/i386 or amd64  
 tarballs there, but there's an easier way: load the  
 `netbsd-INSTALL_XEN3_DOMU` kernel provided in the NetBSD binary sets.  
 Like other install kernels, it contains a ramdisk with sysinst, so you  
 can install NetBSD using sysinst on your new domain.  
   
 If you want to install NetBSD/Xen with a CDROM image, the following line  Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
 should be used in the `/usr/pkg/etc/xen/nbsd` file:  line should be used in the config file.
   
     disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]      disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
   
 After booting the domain, the option to install via CDROM may be  After booting the domain, the option to install via CDROM may be
 selected. The CDROM device should be changed to `xbd1d`.  selected.  The CDROM device should be changed to `xbd1d`.
   
 Once done installing, `halt -p` the new domain (don't reboot or halt, it  Once done installing, "halt -p" the new domain (don't reboot or halt,
 would reload the INSTALL\_XEN3\_DOMU kernel even if you changed the  it would reload the INSTALL_XEN3_DOMU kernel even if you changed the
 config file), switch the config file back to the XEN3\_DOMU kernel, and  config file), switch the config file back to the XEN3_DOMU kernel,
 start the new domain again. Now it should be able to use `root on xbd0a`  and start the new domain again. Now it should be able to use "root on
 and you should have a second, functional NetBSD system on your xen  xbd0a" and you should have a, functional NetBSD domU.
 installation.  
   
   TODO: check if this is still accurate.
 When the new domain is booting you'll see some warnings about *wscons*  When the new domain is booting you'll see some warnings about *wscons*
 and the pseudo-terminals. These can be fixed by editing the files  and the pseudo-terminals. These can be fixed by editing the files
 `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in  `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
Line 620  Finally, all screens must be commented o Line 706  Finally, all screens must be commented o
   
 It is also desirable to add  It is also desirable to add
   
     powerd=YES          powerd=YES
   
 in rc.conf. This way, the domain will be properly shut down if  in rc.conf. This way, the domain will be properly shut down if
 `xm shutdown -R` or `xm shutdown -H` is used on the domain0.  `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
   
 Your domain should be now ready to work, enjoy.  It is not strictly necessary to have a kernel (as /netbsd) in the domU
   file system.  However, various programs (e.g. netstat) will use that
   kernel to look up symbols to read from kernel virtual memory.  If
   /netbsd is not the running kernel, those lookups will fail.  (This is
   not really a Xen-specific issue, but because the domU kernel is
   obtained from the dom0, it is far more likely to be out of sync or
   missing with Xen.)
   
 Creating an unprivileged Linux domain (domU)  Creating an unprivileged Linux domain (domU)
 --------------------------------------------  --------------------------------------------
Line 639  the example below) Line 731  the example below)
     disk = [ 'phy:/dev/wd0e,0x1,w' ]      disk = [ 'phy:/dev/wd0e,0x1,w' ]
   
 does matter to Linux. It wants a Linux device number here (e.g. 0x300  does matter to Linux. It wants a Linux device number here (e.g. 0x300
 for hda). Linux builds device numbers as: (major \<\< 8 + minor). So,  for hda).  Linux builds device numbers as: (major \<\< 8 + minor).
 hda1 which has major 3 and minor 1 on a Linux system will have device  So, hda1 which has major 3 and minor 1 on a Linux system will have
 number 0x301. Alternatively, devices names can be used (hda, hdb, ...)  device number 0x301.  Alternatively, devices names can be used (hda,
 as xentools has a table to map these names to devices numbers. To export  hdb, ...)  as xentools has a table to map these names to devices
 a partition to a Linux guest we can use:  numbers.  To export a partition to a Linux guest we can use:
   
     disk = [ 'phy:/dev/wd0e,0x300,w' ]          disk = [ 'phy:/dev/wd0e,0x300,w' ]
     root = "/dev/hda1 ro"          root = "/dev/hda1 ro"
   
 and it will appear as /dev/hda on the Linux system, and be used as root  and it will appear as /dev/hda on the Linux system, and be used as root
 partition.  partition.
   
 To install the Linux system on the partition to be exported to the guest  To install the Linux system on the partition to be exported to the
 domain, the following method can be used: install sysutils/e2fsprogs  guest domain, the following method can be used: install
 from pkgsrc. Use mke2fs to format the partition that will be the root  sysutils/e2fsprogs from pkgsrc.  Use mke2fs to format the partition
 partition of your Linux domain, and mount it. Then copy the files from a  that will be the root partition of your Linux domain, and mount it.
 working Linux system, make adjustments in `/etc` (fstab, network  Then copy the files from a working Linux system, make adjustments in
 config). It should also be possible to extract binary packages such as  `/etc` (fstab, network config).  It should also be possible to extract
 .rpm or .deb directly to the mounted partition using the appropriate  binary packages such as .rpm or .deb directly to the mounted partition
 tool, possibly running under NetBSD's Linux emulation. Once the  using the appropriate tool, possibly running under NetBSD's Linux
 filesystem has been populated, umount it. If desirable, the filesystem  emulation.  Once the file system has been populated, umount it.  If
 can be converted to ext3 using tune2fs -j. It should now be possible to  desirable, the file system can be converted to ext3 using tune2fs -j.
 boot the Linux guest domain, using one of the vmlinuz-\*-xenU kernels  It should now be possible to boot the Linux guest domain, using one of
 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)
 ----------------------------------------------  ----------------------------------------------
   
 Download an Opensolaris [release](http://opensolaris.org/os/downloads/)  See possibly outdated
 or [development snapshot](http://genunix.org/) DVD image. Attach the DVD  [Solaris domU instructions](/ports/xen/howto-solaris/).
 image to a MAN.VND.4 device. Copy the kernel and ramdisk filesystem  
 image to your dom0 filesystem.  
   PCI passthrough: Using PCI devices in guest domains
     dom0# mkdir /root/solaris  ---------------------------------------------------
     dom0# vnconfig vnd0 osol-1002-124-x86.iso  
     dom0# mount /dev/vnd0a /mnt  The dom0 can give other domains access to selected PCI
   devices. This can allow, for example, a non-privileged domain to have
     ## for a 64-bit guest  access to a physical network interface or disk controller.  However,
     dom0# cp /mnt/boot/amd64/x86.microroot /root/solaris  keep in mind that giving a domain access to a PCI device most likely
     dom0# cp /mnt/platform/i86xpv/kernel/amd64/unix /root/solaris  will give the domain read/write access to the whole physical memory,
   as PCs don't have an IOMMU to restrict memory access to DMA-capable
     ## for a 32-bit guest  device.  Also, it's not possible to export ISA devices to non-dom0
     dom0# cp /mnt/boot/x86.microroot /root/solaris  domains, which means that the primary VGA adapter can't be exported.
     dom0# cp /mnt/platform/i86xpv/kernel/unix /root/solaris  A guest domain trying to access the VGA registers will panic.
   
     dom0# umount /mnt  If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
             not been ported to later versions at this time.
   
 Keep the MAN.VND.4 configured. For some reason the boot process stalls  For a PCI device to be exported to a domU, is has to be attached to
 unless the DVD image is attached to the guest as a "phy" device. Create  the "pciback" driver in dom0.  Devices passed to the dom0 via the
 an initial configuration file with the following contents. Substitute  pciback.hide boot parameter will attach to "pciback" instead of the
 */dev/wd0k* with an empty partition at least 8 GB large.  usual driver.  The list of devices is specified as "(bus:dev.func)",
   
     memory = 640  
     name = 'solaris'  
     disk = [ 'phy:/dev/wd0k,0,w' ]  
     disk += [ 'phy:/dev/vnd0d,6:cdrom,r' ]  
     vif = [ 'bridge=bridge0' ]  
     kernel = '/root/solaris/unix'  
     ramdisk = '/root/solaris/x86.microroot'  
     # for a 64-bit guest  
     extra = '/platform/i86xpv/kernel/amd64/unix - nowin -B install_media=cdrom'  
     # for a 32-bit guest  
     #extra = '/platform/i86xpv/kernel/unix - nowin -B install_media=cdrom'  
             
   
 Start the guest.  
   
     dom0# xm create -c solaris.cfg  
     Started domain solaris  
                           v3.3.2 chgset 'unavailable'  
     SunOS Release 5.11 Version snv_124 64-bit  
     Copyright 1983-2009 Sun Microsystems, Inc.  All rights reserved.  
     Use is subject to license terms.  
     Hostname: opensolaris  
     Remounting root read/write  
     Probing for device nodes ...  
     WARNING: emlxs: ddi_modopen drv/fct failed: err 2  
     Preparing live image for use  
     Done mounting Live image  
             
   
 Make sure the network is configured. Note that it can take a minute for  
 the xnf0 interface to appear.  
   
     opensolaris console login: jack  
     Password: jack  
     Sun Microsystems Inc.   SunOS 5.11      snv_124 November 2008  
     jack@opensolaris:~$ pfexec sh  
     sh-3.2# ifconfig -a  
     sh-3.2# exit  
             
   
 Set a password for VNC and start the VNC server which provides the X11  
 display where the installation program runs.  
   
     jack@opensolaris:~$ vncpasswd  
     Password: solaris  
     Verify: solaris  
     jack@opensolaris:~$ cp .Xclients .vnc/xstartup  
     jack@opensolaris:~$ vncserver :1  
             
   
 From a remote machine connect to the VNC server. Use `ifconfig xnf0` on  
 the guest to find the correct IP address to use.  
   
     remote$ vncviewer 172.18.2.99:1  
             
   
 It is also possible to launch the installation on a remote X11 display.  
   
     jack@opensolaris:~$ export DISPLAY=172.18.1.1:0  
     jack@opensolaris:~$ pfexec gui-install  
              
   
 After the GUI installation is complete you will be asked to reboot.  
 Before that you need to determine the ZFS ID for the new boot filesystem  
 and update the configuration file accordingly. Return to the guest  
 console.  
   
     jack@opensolaris:~$ pfexec zdb -vvv rpool | grep bootfs  
                     bootfs = 43  
     ^C  
     jack@opensolaris:~$  
              
   
 The final configuration file should look like this. Note in particular  
 the last line.  
   
     memory = 640  
     name = 'solaris'  
     disk = [ 'phy:/dev/wd0k,0,w' ]  
     vif = [ 'bridge=bridge0' ]  
     kernel = '/root/solaris/unix'  
     ramdisk = '/root/solaris/x86.microroot'  
     extra = '/platform/i86xpv/kernel/amd64/unix -B zfs-bootfs=rpool/43,bootpath="/xpvd/xdf@0:a"'  
              
   
 Restart the guest to verify it works correctly.  
   
     dom0# xm destroy solaris  
     dom0# xm create -c solaris.cfg  
     Using config file "./solaris.cfg".  
     v3.3.2 chgset 'unavailable'  
     Started domain solaris  
     SunOS Release 5.11 Version snv_124 64-bit  
     Copyright 1983-2009 Sun Microsystems, Inc.  All rights reserved.  
     Use is subject to license terms.  
     WARNING: emlxs: ddi_modopen drv/fct failed: err 2  
     Hostname: osol  
     Configuring devices.  
     Loading smf(5) service descriptions: 160/160  
     svccfg import warnings. See /var/svc/log/system-manifest-import:default.log .  
     Reading ZFS config: done.  
     Mounting ZFS filesystems: (6/6)  
     Creating new rsa public/private host key pair  
     Creating new dsa public/private host key pair  
   
     osol console login:  
              
   
 Using PCI devices in guest domains  
 ----------------------------------  
   
 The domain0 can give other domains access to selected PCI devices. This  
 can allow, for example, a non-privileged domain to have access to a  
 physical network interface or disk controller. However, keep in mind  
 that giving a domain access to a PCI device most likely will give the  
 domain read/write access to the whole physical memory, as PCs don't have  
 an IOMMU to restrict memory access to DMA-capable device. Also, it's not  
 possible to export ISA devices to non-domain0 domains (which means that  
 the primary VGA adapter can't be exported. A guest domain trying to  
 access the VGA registers will panic).  
   
 This functionality is only available in NetBSD-5.1 (and later) domain0  
 and domU. If the domain0 is NetBSD, it has to be running Xen 3.1, as  
 support has not been ported to later versions at this time.  
   
 For a PCI device to be exported to a domU, is has to be attached to the  
 `pciback` driver in domain0. Devices passed to the domain0 via the  
 pciback.hide boot parameter will attach to `pciback` instead of the  
 usual driver. The list of devices is specified as `(bus:dev.func)`,  
 where bus and dev are 2-digit hexadecimal numbers, and func a  where bus and dev are 2-digit hexadecimal numbers, and func a
 single-digit number:  single-digit number:
   
     pciback.hide=(00:0a.0)(00:06.0)          pciback.hide=(00:0a.0)(00:06.0)
   
 pciback devices should show up in the domain0's boot messages, and the  pciback devices should show up in the dom0's boot messages, and the
 devices should be listed in the `/kern/xen/pci` directory.  devices should be listed in the `/kern/xen/pci` directory.
   
 PCI devices to be exported to a domU are listed in the `pci` array of  PCI devices to be exported to a domU are listed in the "pci" array of
 the domU's config file, with the format `'0000:bus:dev.func'`  the domU's config file, with the format "0000:bus:dev.func".
   
           pci = [ '0000:00:06.0', '0000:00:0a.0' ]
   
   In the domU an "xpci" device will show up, to which one or more pci
   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"
   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;
   note that only the "xpci" lines are unusual.
   
           include         "arch/i386/conf/XEN3_DOMU"
   
           # Add support for PCI buses to the XEN3_DOMU kernel
           xpci* at xenbus ?
           pci* at xpci ?
   
           # PCI USB controllers
           uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)
   
           # USB bus support
           usb*    at uhci?
   
           # USB Hubs
           uhub*   at usb?
           uhub*   at uhub? port ? configuration ? interface ?
   
           # USB Mass Storage
           umass*  at uhub? port ? configuration ? interface ?
           wd*     at umass?
           # SCSI controllers
           ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI
   
           # SCSI bus support (for both ahc and umass)
           scsibus* at scsi?
   
           # SCSI devices
           sd*     at scsibus? target ? lun ?      # SCSI disk drives
           cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
   
   
   NetBSD as a domU in a VPS
   =========================
   
   The bulk of the HOWTO is about using NetBSD as a dom0 on your own
   hardware.  This section explains how to deal with Xen in a domU as a
   virtual private server where you do not control or have access to the
   dom0.  This is not intended to be an exhaustive list of VPS providers;
   only a few are mentioned that specifically support NetBSD.
   
   VPS operators provide varying degrees of access and mechanisms for
   configuration.  The big issue is usually how one controls which kernel
   is booted, because the kernel is nominally in the dom0 file system (to
   which VPS users do not normally have access).  A second issue is how
   to install NetBSD.
   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
   their kernel.
   
   One approach is to have an administrative interface to upload a kernel,
   or to select from a prepopulated list.  Other approaches are pygrub
   (deprecated) and pvgrub, which are ways to have a bootloader obtain a
   kernel from the domU file system.  This is closer to a regular physical
   computer, where someone who controls a machine can replace the kernel.
   
   A second issue is multiple CPUs.  With NetBSD 6, domUs support
   multiple vcpus, and it is typical for VPS providers to enable multiple
   CPUs for NetBSD domUs.
   
   pygrub
   -------
   
   pygrub runs in the dom0 and looks into the domU file system.  This
   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
   interest.
   
   pvgrub
   ------
   
   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
   /grub/menu.lst and loads a kernel from the domU file system.
   
   [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
   (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
   page](http://www.panix.com/v-colo/grub.html), which describes only
   Linux but should be updated to cover NetBSD :-).
   
   [prgmr.com](http://prgmr.com/) also lets users with pvgrub to boot
   their own kernel.  See then [prgmr.com NetBSD
   HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU)
   (which is in need of updating).
   
   It appears that [grub's FFS
   code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
   does not support all aspects of modern FFS, but there are also reports
   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,
   which leads to /netbsd not being the actual kernel.  One must remember
   to update the special boot partition.
   
   Amazon
   ------
   
   See the [Amazon EC2 page](/amazon_ec2/).
   
     pci = [ '0000:00:06.0', '0000:00:0a.0' ]  TODO items for improving NetBSD/xen
   ===================================
   
 In the domU an `xpci` device will show up, to which one or more pci  * Make the NetBSD dom0 kernel work with SMP.
 busses will attach. Then the PCI drivers will attach to PCI busses as  * Test the Xen 4.5 packages adequately to be able to recommend them as
 usual. Note that the default NetBSD DOMU kernels do not have `xpci` or    the standard approach.
 any PCI drivers built in by default; you have to build your own kernel  * Get PCI passthrough working on Xen 4.5
 to use PCI devices in a domU. Here's a kernel config example:  * Get pvgrub into pkgsrc, either via xentools or separately.
   * grub
     include         "arch/i386/conf/XEN3_DOMU"    * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
     #include         "arch/i386/conf/XENU"           # in NetBSD 3.0      fragsize/blocksize (UFS2 support may be present; the point is to
       make it so that with any UFS1/UFS2 file system setup that works
     # Add support for PCI busses to the XEN3_DOMU kernel      with NetBSD grub will also work).
     xpci* at xenbus ?      See [pkg/40258](https://gnats.netbsd.org/40258).
     pci* at xpci ?    * Push patches upstream.
     * Get UFS2 patches into pvgrub.
     # Now add PCI and related devices to be used by this domain  * Add support for PV ops to a version of /boot, and make it usable as
     # USB Controller and Devices    a kernel in Xen, similar to pvgrub.
   
     # PCI USB controllers  Random pointers
     uhci*   at pci? dev ? function ?        # Universal Host Controller (Intel)  ===============
   
     # USB bus support  This section contains links from elsewhere not yet integrated into the
     usb*    at uhci?  HOWTO, and other guides.
   
     # USB Hubs  * http://www.lumbercartel.ca/library/xen/
     uhub*   at usb?  * http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html
     uhub*   at uhub? port ? configuration ? interface ?  * https://gmplib.org/~tege/xen.html
   
     # USB Mass Storage  
     umass*  at uhub? port ? configuration ? interface ?  
     wd*     at umass?  
     # SCSI controllers  
     ahc*    at pci? dev ? function ?        # Adaptec [23]94x, aic78x0 SCSI  
   
     # SCSI bus support (for both ahc and umass)  
     scsibus* at scsi?  
   
     # SCSI devices  
     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)  
     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.)  
 -   An example of how to use NetBSD's native bootloader to load  
     NetBSD/Xen instead of Grub can be found in the i386/amd64 boot(8)  
     and boot.cfg(5) manpages.  

Removed from v.1.19  
changed lines
  Added in v.1.155


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