Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.202 and 1.203

version 1.202, 2021/03/09 13:57:53 version 1.203, 2021/03/15 00:11:52
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 [[!meta title="Xen HowTo and Status"]]  [[!meta title="Xen Status and HowTo"]]
   
 Xen is a Type 1 hypervisor which supports running multiple guest operating  Xen is a Type 1 hypervisor which supports running multiple guest operating
 systems on a single physical machine. One uses the Xen kernel to control the  systems on a single physical machine. One uses the Xen kernel to control the
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.
   
 This HOWTO presumes a basic familiarity with the Xen system  This document provides status on what Xen things work on NetBSD
 architecture, with installing NetBSD on amd64 hardware, and with  
 installing software from pkgsrc.  See also the [Xen  
 website](http://www.xenproject.org/).  
   
 This document also provides status on what Xen things work on NetBSD  
 (upstream documentation might say something works if it works on some  (upstream documentation might say something works if it works on some
 particular Linux system).  particular Linux system).
   
   This document is also a HOWTO that 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/).
   
   If this document says that something works, and you find that it does
   not, it is best to ask on port-xen and if you are correct to file a
   PR.
   
 [[!toc]]  [[!toc]]
   
 # Overview  # Overview
Line 39  approach and limits discussion of altern Line 43  approach and limits discussion of altern
 Xen supports different styles of guests.  Xen supports different styles of guests.
   
 [[!table data="""  [[!table data="""
 Style of guest  |Supported by NetBSD  Style of guest  |description                            |NetBSD dom0?   |NetBSD domU?
 PV              |Yes (dom0, domU)  PV              |Paravirtualization (hypercalls)        |yes            |yes
 HVM             |Yes (domU)  HVM             |unmodified guest - domU perceives HW   |N/A            |yes
 PVHVM           |current-only (domU)  PVHVM           |Like HVM but also PV drivers           |N/A            |current only
 PVH             |current-only (domU, dom0 not yet)  PVH             |                                       |not yet        |current only
 """]]  """]]
   
 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
Line 61  drivers for efficiency.  Therefore it is Line 65  drivers for efficiency.  Therefore it is
 PVHVM dom0.  See [PV on HVM](https://wiki.xen.org/wiki/PV_on_HVM).  PVHVM dom0.  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.  Therefore
 basically lightweight HVM with PV drivers.  A critical feature of it  PVHv2 is abreviated PVH.  PVHv2 is basically lightweight HVM with PV
 is that qemu is not needed; the hypervisor can do the emulation that  drivers.  A critical feature of it is that qemu is not needed; the
 is required.  Thus, a dom0 can be PVHv2.  hypervisor can do the emulation that is required.  Thus, a dom0 can be
 The source code uses PVH and config files use pvh; this refers to PVHv2.  PVHv2.  The source code uses PVH and config files use pvh, but NB that
 See [PVH(v2)](https://wiki.xenproject.org/wiki/PVH_(v2\)_Domu).  this refers to PVHv2.  See
   [PVH(v2)](https://wiki.xenproject.org/wiki/PVH_(v2\)_Domu).
   
 At system 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
Line 108  by xl. Line 113  by xl.
 Xen has been supported in NetBSD for a long time, at least since 2005.  Xen has been supported in NetBSD for a long time, at least since 2005.
 Initially Xen was PV only.  Initially Xen was PV only.
   
 NetBSD 8 and up support PV and HVM modes.  NetBSD has supported PV for a very long time, in both dom0 and domU.
   NetBSD >=8 supports HVM mode as a domU (HVM as a dom0 does not make
 Support for PVHVM and PVH is available only in NetBSD-current.  sense).
   
 NetBSD up to and including NetBSD 9 as a dom0 does not run SMP,  Support for PVHVM and PVH is available only in NetBSD-current; this is
 because some drivers are not yet safe for this.  NetBSD-current  currently somewhat experimental, although PVHVM appears reasonably
 supports SMP in dom0.  solid.
   
 NetBSD, when run as a domU, can and does typically run SMP.  NetBSD up to and including NetBSD 9 as a dom0 cannot safely run SMP.
   Even if one added "options MULTIPROCESSOR" and configured multiple
   vcpus, the kernel is likely to crash because of drivers without
   adequate locking.
   
   NetBSD-current supports SMP in dom0, and XEN3_DOM0 includes "options
   MULTIPROCESSOR".
   
   NetBSD (since NetBSD 6), when run as a domU, can run SMP, using
   multiple CPUs if provided.  The XEN3_DOMU kernel is built
   with "options MULITPROCESSOR".
   
 Note that while Xen 4.13 is current, the kernel support is still  Note that while Xen 4.13 is current, the kernel support is still
 called XEN3, because the hypercall interface has not changed  called XEN3, because the hypercall interface has not changed

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