Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.181 and 1.189

version 1.181, 2020/11/15 14:37:20 version 1.189, 2020/11/19 13:55:58
Line 8  systems which operate in an unprivileged Line 8  systems which operate in an unprivileged
 from the domU systems are forwarded by the Xen hypervisor to the dom0 to be  from the domU systems are forwarded by the Xen hypervisor to the dom0 to be
 fulfilled.  fulfilled.
   
 Xen supports different styles of guests; see [PV on HVM](https://wiki.xen.org/wiki/PV_on_HVM) and [PVH(v2)](https://wiki.xenproject.org/wiki/PVH_(v2\)_Domu) for upstream documentation.  This HOWTO presumes a basic familiarity with the Xen system
   architecture, with installing NetBSD on amd64 hardware, and with
   installing software from pkgsrc.  See also the [Xen
   website](http://www.xenproject.org/).
   
   [[!toc]]
   
   # Overview
   
   The basic concept of Xen is that the hypervisor (xenkernel) runs on
   the hardware, and runs a privileged domain ("dom0") that can access
   disks/networking/etc.  One then runs additonal unprivileged domains
   (each a "domU"), presumably to do something useful.
   
   This HOWTO addresses how to run a NetBSD dom0 (and hence also build
   xen itself).  It also addresses how to run domUs in that environment,
   and how to deal with having a domU in a Xen environment run by someone
   else and/or not running NetBSD.
   
   There are many choices one can make; the HOWTO recommends the standard
   approach and limits discussion of alternatives in many cases.
   
   ## Guest Styles
   
   Xen supports different styles of guests.
   
 [[!table data="""  [[!table data="""
 Style of guest  |Supported by NetBSD  Style of guest  |Supported by NetBSD
Line 21  PVH  |current-only (domU, dom0 not yet) Line 45  PVH  |current-only (domU, dom0 not yet)
 In Para-Virtualized (PV) mode, the guest OS does not attempt to access  In Para-Virtualized (PV) mode, the guest OS does not attempt to access
 hardware directly, but instead makes hypercalls to the hypervisor; PV  hardware directly, but instead makes hypercalls to the hypervisor; PV
 guests must be specifically coded for Xen.  guests must be specifically coded for Xen.
   See [PV](https://wiki.xen.org/wiki/Paravirtualization_(PV\)).
   
 In HVM mode, no guest modification is required; however, hardware  In HVM mode, no guest modification is required; however, hardware
 support is required, such as VT-x on Intel CPUs and SVM on AMD CPUs.  support is required, such as VT-x on Intel CPUs and SVM on AMD CPUs.
Line 28  The dom0 runs qemu to emulate hardware. Line 53  The dom0 runs qemu to emulate hardware.
   
 In PVHVM mode, the guest runs as HVM, but additionally can use PV  In PVHVM mode, the guest runs as HVM, but additionally can use PV
 drivers for efficiency.  drivers for efficiency.
   See [PV on HVM](https://wiki.xen.org/wiki/PV_on_HVM).
   
 There have been two PVH modes: original PVH and PVHv2.  Original PVH  There have been two PVH modes: original PVH and PVHv2.  Original PVH
 was based on PV mode and is no longer relevant at all.  PVHv2 is  was based on PV mode and is no longer relevant at all.  PVHv2 is
 basically lightweight HVM with PV drivers.  A critical feature of it  basically lightweight HVM with PV drivers.  A critical feature of it
 is that qemu is not needed; the hypervisor can do the emulation that  is that qemu is not needed; the hypervisor can do the emulation that
 is required.  Thus, a dom0 can be PVHv2.  is required.  Thus, a dom0 can be PVHv2.
   
 The source code uses PVH and config files use pvh; this refers to PVHv2.  The source code uses PVH and config files use pvh; this refers to PVHv2.
   See [PVH(v2)](https://wiki.xenproject.org/wiki/PVH_(v2\)_Domu).
   
 At boot, the dom0 kernel is loaded as a module with Xen as the kernel.  At system 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.)
   
 This HOWTO presumes a basic familiarity with the Xen system  ## CPU Architecture
 architecture, with installing NetBSD on i386/amd64 hardware, and with  
 installing software from pkgsrc.  See also the [Xen  
 website](http://www.xenproject.org/).  
   
 [[!toc]]  Xen runs on x86_64 hardware (the NetBSD amd64 port).
   
   There is a concept of Xen running on ARM, but there are no reports of this working with NetBSD.
   
   The dom0 system should be amd64.  (Instructions for i386PAE dom0 have been removed from the HOWTO.)
   
 # Versions and Support  The domU can be i386PAE or amd64.
   i386PAE at one point was considered as [faster](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html) than amd64.
   
   ## 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,
Line 58  matching versions. Line 88  matching versions.
 Versions available in pkgsrc:  Versions available in pkgsrc:
   
 [[!table data="""  [[!table data="""
 Xen Version     |Package Name   |Xen CPU Support        |xm?    |EOL'ed By Upstream  Xen Version     |Package Name   |Xen CPU Support        |EOL'ed By Upstream
 4.11            |xenkernel411   |x86_64                 |       |No  4.11            |xenkernel411   |x86_64                 |No
 4.13            |xenkernel413   |x86_64                 |       |No  4.13            |xenkernel413   |x86_64                 |No
 """]]  """]]
   
 See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).  See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
   
 Multiprocessor (SMP) support in NetBSD differs depending on the domain:  Older Xen had a python-based management tool called xm, now replaced
   by xl.
   
 [[!table data="""  ## NetBSD versions
 Domain          |Supports SMP  
 dom0            |No  
 domU            |Yes  
 """]]  
   
 Note: NetBSD support is called XEN3.  However, it does support Xen 4,  Xen has been supported in NetBSD for a long time, at least since 2005.
 because the hypercall interface has remained identical.  Initially Xen was PV only.
   
 Older Xen had a python-based management tool called xm, now replaced  NetBSD 8 and up support PV and HVM modes.
 by xl.  
   
 ## Architecture  Support for PVHVM and PVH is available only in NetBSD-current.
   
 Xen 4.5 and later runs on x86_64 hardware (the NetBSD amd64 port).  NetBSD as a dom0 does not run SMP, because some drivers are not yet
 There is a concept of Xen running on ARM, but there are no reports of this working with NetBSD.  safe for this.  \todo Link to more information about what needs work.
   
 The dom0 system should be amd64.  (Instructions for i386PAE dom0 have been removed from the HOWTO.)  NetBSD, when run as a domU, can and does typically run SMP.
   
 The domU can be i386PAE or amd64.  Note: NetBSD support is called XEN3.  However, it does support Xen 4,
 i386PAE at one point was considered as [faster](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html) than amd64.  because the hypercall interface has remained identical.
   
 # Creating a dom0  # Creating a NetBSD dom0
   
 In order to install a NetBSD as a dom0, one must first install a normal  In order to install a NetBSD as a dom0, one must first install a normal
 NetBSD system, and then pivot the install to a dom0 install by changing  NetBSD system, and then pivot the install to a dom0 install by changing
Line 103  In 2018-05, trouble booting a dom0 was r Line 129  In 2018-05, trouble booting a dom0 was r
   
 [Install NetBSD/amd64](/guide/inst/)  [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.
   Therefore, use the most recent release, or a build from the most recent stable branch.
   
 ## Installation of Xen  ## Installation of Xen
   
 We will consider that you chose to use Xen 4.13, with NetBSD/amd64 as  Use the most recent version of Xen in pkgsrc, unless the DESCR says that it is not suitable.
 dom0. In the dom0, install xenkernel48 and xentools48 from pkgsrc.  Therefore, choose 4.13.
   In the dom0, install xenkernel413 and xentools413 from pkgsrc.
   
 Once this is done, install the Xen kernel itself:  Once this is done, copy the Xen kernel from where pkgsrc puts it to
   where the boot process will be able to find it:
   
 [[!template id=programlisting text="""  [[!template id=programlisting text="""
 # cp /usr/pkg/xen48-kernel/xen.gz /  # cp -p /usr/pkg/xen413-kernel/xen.gz /
 """]]  """]]
   
 Then, place a NetBSD XEN3_DOM0 kernel in the `/` directory. Such kernel  Then, place a NetBSD XEN3_DOM0 kernel in the `/` directory. Such kernel
Line 120  can either be compiled manually, or down Line 149  can either be compiled manually, or down
 example at:  example at:
   
 [[!template id=programlisting text="""  [[!template id=programlisting text="""
 ftp.netbsd.org/pub/NetBSD/NetBSD-8.0/amd64/binary/kernel/netbsd-XEN3_DOM0.gz  ftp.netbsd.org/pub/NetBSD/NetBSD-9.1/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
 """]]  """]]
   
 Add a line to /boot.cfg to boot Xen:  Add a line to /boot.cfg to boot Xen:
Line 130  menu=Xen:load /netbsd-XEN3_DOM0.gz conso Line 159  menu=Xen:load /netbsd-XEN3_DOM0.gz conso
 """]]  """]]
   
 This specifies that the dom0 should have 512MB of ram, leaving the rest  This specifies that the dom0 should have 512MB of ram, leaving the rest
 to be allocated for domUs.  To use a serial console, use:  to be allocated for domUs.
   
   NB: This says add, not replace, so that you will be able to boot a
   NetBSD kernel without Xen.  Once Xen boots ok, you may want to set it
   as default.
   
   To use a serial console, add settings as follows:
   
 [[!template id=filecontent name="/boot.cfg" text="""  [[!template id=filecontent name="/boot.cfg" text="""
 menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1  menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1
Line 150  more) and to pin that vcpu to a physical Line 185  more) and to pin that vcpu to a physical
 and other than dom0 memory and max_vcpus, they are generally not  and other than dom0 memory and max_vcpus, they are generally not
 necessary.  necessary.
   
 Copy the boot scripts into `/etc/rc.d`:  Ensure that the boot scripts installed in
   `/usr/pkg/share/examples/rc.d` are in `/etc/rc.d`, either because you
 [[!template id=programlisting text="""  have `PKG_RCD_SCRIPTS=yes`, or manually.  (This is not special to Xen,
 # cp /usr/pkg/share/examples/rc.d/xen* /etc/rc.d/  but a normal part of pkgsrc usage.)
 """]]  
   
 Enable `xencommons`:  Set `xencommons=YES` in rc.conf:
   
 [[!template id=filecontent name="/etc/rc.conf" text="""  [[!template id=filecontent name="/etc/rc.conf" text="""
 xencommons=YES  xencommons=YES
 """]]  """]]
   
   \todo Recommend for/against xen-watchdog.
   
 Now, reboot so that you are running a DOM0 kernel under Xen, rather  Now, reboot so that you are running a DOM0 kernel under Xen, rather
 than GENERIC without Xen.  than GENERIC without Xen.
   
 TODO: Recommend for/against xen-watchdog.  
   
 Once the reboot is done, use `xl` to inspect Xen's boot messages,  Once the reboot is done, use `xl` to inspect Xen's boot messages,
 available resources, and running domains.  For example:  available resources, and running domains.  For example:
   
Line 193  the state when the new xenstored starts. Line 227  the state when the new xenstored starts.
 make this work, one should not expect to be able to restart xenstored  make this work, one should not expect to be able to restart xenstored
 (and thus xencommons).  There is currently no reason to expect that  (and thus xencommons).  There is currently no reason to expect that
 this will get fixed any time soon.  this will get fixed any time soon.
   \todo Confirm if this is still true in 2020.
 ## anita (for testing NetBSD)  
   
 With the setup so far, one should be able to run  
 anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as  
 root, because anita must create a domU):  
   
 [[!template id=programlisting text="""  
 anita --vmm=xl test file:///usr/obj/i386/  
 """]]  
   
 ## Xen-specific NetBSD issues  ## Xen-specific NetBSD issues
   
Line 218  options as GENERIC.  While it is debatab Line 243  options as GENERIC.  While it is debatab
 bug, users should be aware of this and can simply add missing config  bug, users should be aware of this and can simply add missing config
 items if desired.  items if desired.
   
   Finally, there have been occasional reports of trouble with X11
   servers in NetBSD as a dom0.
   
   ## Updating Xen in a dom0
   
   Basically, update the xenkernel and xentools packages and copy the new
   Xen kernel into place, and reboot.  This procedure should be usable to
   update to a new Xen release, but the reader is reminded that having a
   non-Xen boot methods was recommended earlier.
   
 ## Updating NetBSD in a dom0  ## Updating NetBSD in a dom0
   
 This is just like updating NetBSD on bare hardware, assuming the new  This is just like updating NetBSD on bare hardware, assuming the new
Line 228  and adjusts `/etc`. Line 263  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.
   
 ## Converting from grub to /boot  ## anita (for testing NetBSD)
   
   With a NetBSD dom0, even without any domUs, one should be able to run
   anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
   root, because anita must create a domU):
   
   [[!template id=programlisting text="""
   anita --vmm=xl test file:///usr/obj/i386/
   """]]
   
   ## Converting from grub to /boot (historical note)
   
   These instructions are provided only to help people using grub, which
   used to be the normal approach.
   
 These instructions were used to convert a system from  These instructions were used to convert a system from
 grub to /boot.  The system was originally installed in February of  grub to /boot.  The system was originally installed in February of
Line 258  default=1 Line 306  default=1
 timeout=30  timeout=30
 """]]  """]]
   
 ## Upgrading Xen versions  # Unprivileged domains (domU)
   
 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.  
   
 #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.  The  address specific domU operating systems or how to install them.  The
Line 306  are stored in files and Xen attaches the Line 348  are stored in files and Xen attaches the
 dom0 on domain creation.  The system treats xbd0 as the boot device  dom0 on domain creation.  The system treats xbd0 as the boot device
 without needing explicit configuration.  without needing explicit configuration.
   
   There is not type line; that implicitly defines a pv domU.
   
 By convention, domain config files are kept in `/usr/pkg/etc/xen`.  Note  By convention, domain config files are kept in `/usr/pkg/etc/xen`.  Note
 that "xl create" takes the name of a config file, while other commands  that "xl create" takes the name of a config file, while other commands
 take the name of a domain.  take the name of a domain.
Line 374  Note that NetBSD by default creates only Line 418  Note that NetBSD by default creates only
 than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the  than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the
 dom0.  dom0.
   
 Note that NetBSD by default creates only xbd[0123].  If you need more  ## Virtual Networking
 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  Xen provides virtual Ethernets, each of which connects the dom0 and a
 domU.  For each virtual network, there is an interface "xvifN.M" in  domU.  For each virtual network, there is an interface "xvifN.M" in
Line 410  The MAC address specified is the one use Line 450  The MAC address specified is the one use
 domain.  The interface in dom0 will use this address XOR'd with  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.  00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
   
 Starting domains automatically  ## Starting domains automatically
 ------------------------------  
   
 To start domains `domU-netbsd` and `domU-linux` at boot and shut them  To start domains `domU-netbsd` and `domU-linux` at boot and shut them
 down cleanly on dom0 shutdown, add the following in rc.conf:  down cleanly on dom0 shutdown, add the following in rc.conf:
Line 420  down cleanly on dom0 shutdown, add the f Line 459  down cleanly on dom0 shutdown, add the f
 xendomains="domU-netbsd domU-linux"  xendomains="domU-netbsd domU-linux"
 """]]  """]]
   
 # Creating a domU  # domU setup for specific systems
   
 Creating domUs is almost entirely independent of operating system.  We  Creating domUs is almost entirely independent of operating system.  We
 have already presented the basics of config files.  Note that you must  have already presented the basics of config files in the previous system.
 have already completed the dom0 setup so that "xl list" works.  
   Of course, this section presumes that you have a working dom0.
   
 Creating a NetBSD PV domU  ## Creating a NetBSD PV domU
 --------------------------  
   
 See the earlier config file, and adjust memory.  Decide on how much  See the earlier config file, and adjust memory.  Decide on how much
 storage you will provide, and prepare it (file or LVM).  storage you will provide, and prepare it (file or LVM).
Line 436  While the kernel will be obtained from t Line 475  While the kernel will be obtained from t
 file should be present in the domU as /netbsd so that tools like  file should be present in the domU as /netbsd so that tools like
 savecore(8) can work.   (This is helpful but not necessary.)  savecore(8) can work.   (This is helpful but not necessary.)
   
 The kernel must be specifically for Xen and for use as a domU.  The  The kernel must be specifically built for Xen, to use PV interfacesas
 i386 and amd64 provide the following kernels:  a domU.  NetBSD release builds provide the following kernels:
   
         i386 XEN3PAE_DOMU          i386 XEN3PAE_DOMU
         amd64 XEN3_DOMU          amd64 XEN3_DOMU
   
 This will boot NetBSD, but this is not that useful if the disk is  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  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  (by mounting it, just as you would prepare a physical disk for a
 system you can't run the installer on).  system you can't run the installer on).
   
Line 463  line should be used in the config file. Line 502  line should be used in the config file.
 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,  Once done installing, "halt -p" the new domain (don't reboot or halt:
 it 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,  config file), switch the config file back to the XEN3_DOMU kernel,
 and start the new domain again. Now it should be able to use "root on  and start the new domain again. Now it should be able to use "root on
 xbd0a" and you should have a, functional NetBSD domU.  xbd0a" and you should have a functional NetBSD domU.
   
 TODO: check if this is still accurate.  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*
Line 488  It is also desirable to add Line 527  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 dom0.  `xl shutdown -R` or `xl shutdown -H` is used on the dom0.
   \todo Check the translation to xl.
   
 It is not strictly necessary to have a kernel (as /netbsd) in the domU  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  file system.  However, various programs (e.g. netstat) will use that
Line 498  not really a Xen-specific issue, but bec Line 538  not really a Xen-specific issue, but bec
 obtained from the dom0, it is far more likely to be out of sync or  obtained from the dom0, it is far more likely to be out of sync or
 missing with Xen.)  missing with Xen.)
   
 Creating a Linux domU  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.
   
   ## Creating a Linux domU
   
 Creating unprivileged Linux domains isn't much different from  Creating unprivileged Linux domains isn't much different from
 unprivileged NetBSD domains, but there are some details to know.  unprivileged NetBSD domains, but there are some details to know.
Line 553  Use type='pvh'. Line 595  Use type='pvh'.
 \todo Explain where the kernel comes from.  \todo Explain where the kernel comes from.
   
   
 Creating a Solaris domU  ## Creating a Solaris domU
 -----------------------  
   
 See possibly outdated  See possibly outdated
 [Solaris domU instructions](/ports/xen/howto-solaris/).  [Solaris domU instructions](/ports/xen/howto-solaris/).
   
   
 PCI passthrough: Using PCI devices in guest domains  ## PCI passthrough: Using PCI devices in guest domains
 ---------------------------------------------------  
   
 NB: PCI passthrough only works on some Xen versions and as of 2020 it  NB: PCI passthrough only works on some Xen versions and as of 2020 it
 is not clear that it works on any version in pkgsrc.  Reports  is not clear that it works on any version in pkgsrc.  Reports
Line 634  note that only the "xpci" lines are unus Line 674  note that only the "xpci" lines are unus
         cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives          cd*     at scsibus? target ? lun ?      # SCSI CD-ROM drives
   
   
 # Specific Issues  # Miscellaneous Information
   
   ## Nesting under Linux KVM
   
   It is possible to run a Xen and a NetBSD dom0 under Linux KVM.  One
   can enable virtio in the dom0 for greater speed.
   
   ## Other nesting
   
   In theory, any full emulation should be able to run Xen and a NetBSD
   dom0.  The HOWTO does not currently have information about Xen XVM
   mode, nvmm, qemu, Virtualbox, etc.
   
 ## domU  ## NetBSD 5 as domU
   
 [NetBSD 5 is known to panic.](http://mail-index.netbsd.org/port-xen/2018/04/17/msg009181.html)  [NetBSD 5 is known to panic.](http://mail-index.netbsd.org/port-xen/2018/04/17/msg009181.html)
 (However, NetBSD 5 systems should be updated to a supported version.)  (However, NetBSD 5 systems should be updated to a supported version.)

Removed from v.1.181  
changed lines
  Added in v.1.189


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