Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.181 and 1.185

version 1.181, 2020/11/15 14:37:20 version 1.185, 2020/11/15 14:59:54
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.
   
   ## 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 42  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 50  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 85  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 dom0
   
Line 488  It is also desirable to add Line 511  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

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