Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.160 and 1.176

version 1.160, 2018/09/05 09:37:37 version 1.176, 2020/11/13 20:40:04
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 guest:  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.
   
 [[!table data="""  [[!table data="""
 Style of guest  |Supported by NetBSD  Style of guest  |Supported by NetBSD
 PV              |Yes (dom0, domU)  PV              |Yes (dom0, domU)
 HVM             |Yes (domU)  HVM             |Yes (domU)
 PVHVM           |No  PVHVM           |current-only (domU)
 PVH             |No  PVHv2           |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. In HVM mode, no guest  guests must be specifically coded for Xen.
 modification is required; however, hardware support is required, such  
 as VT-x on Intel CPUs and SVM on AMD CPUs.  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.
   
   In PVHVM mode, the guest runs as HVM, but additionally can use PV
   drivers for efficiency.
   
   In PVHv2H mode, operation is similar to PVHVM, except that qemu is not
   run and thus the PV interfaces for console, disks, networking are the
   only way to access these resources.
   
 At boot, the dom0 kernel is loaded as a 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
Line 35  website](http://www.xenproject.org/). Line 43  website](http://www.xenproject.org/).
   
 [[!toc]]  [[!toc]]
   
 #Versions and Support  # Versions and Support
   
 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 45  matching versions. Line 53  matching versions.
 Versions available in pkgsrc:  Versions available in pkgsrc:
   
 [[!table data="""  [[!table data="""
 Xen Version     |Package Name   |Xen CPU Support        |EOL'ed By Upstream  Xen Version     |Package Name   |Xen CPU Support        |xm?    |EOL'ed By Upstream
 4.2             |xenkernel42    |32bit, 64bit           |Yes  4.11            |xenkernel411   |x86_64                 |       |No
 4.5             |xenkernel45    |64bit                  |Yes  4.13            |xenkernel413   |x86_64                 |       |No
 4.6             |xenkernel46    |64bit                  |Partially  
 4.8             |xenkernel48    |64bit                  |No  
 4.11            |xenkernel411   |64bit                  |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/).
Line 63  dom0  |No Line 68  dom0  |No
 domU            |Yes  domU            |Yes
 """]]  """]]
   
 Note: NetBSD support is called XEN3. However, it does support Xen 4,  Note: NetBSD support is called XEN3.  However, it does support Xen 4,
 because the hypercall interface has remained identical.  because the hypercall interface has remained identical.
   
   Older Xen had a python-based management tool called xm, now replaced
   by xl.
   
 Architecture  Architecture
 ------------  ------------
   
 Xen itself runs on x86_64 hardware.  Xen 4.5 and later 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, plus each domU, can be either i386PAE or amd64.  
 i386 without PAE is not supported.  
   
 The standard approach is to use NetBSD/amd64 for the dom0.  
   
 To use an i386PAE dom0, one must build or obtain a 64bit Xen kernel and  The dom0 system should be amd64.  (Instructions for i386PAE dom0 have been removed from the HOWTO.)
 install it on the system.  
   
 For domUs, i386PAE is considered as  The domU can be i386PAE or amd64.
 [faster](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html)  i386PAE at one point was considered as [faster](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html) than amd64.
 than amd64.  
   
 #NetBSD as a dom0  # Creating a 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 283  the dom0.  NetBSD's /dev/random system w Line 285  the dom0.  NetBSD's /dev/random system w
 Config files  Config files
 ------------  ------------
   
 See /usr/pkg/share/examples/xen/xlexample*,  See /usr/pkg/share/examples/xen/xlexample*
 for a large number of well-commented examples, mostly for running  for a small number of well-commented examples, mostly for running
 GNU/Linux.  GNU/Linux.
   
 The following is an example minimal domain configuration file. The domU  The following is an example minimal domain configuration file. The domU
Line 308  are stored in files and Xen attaches the Line 310  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.
   
 By default, `xl` looks for domain config files 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.
   
 Examples of commands:  Examples of commands:
   
 [[!template id=programlisting text="""  [[!template id=programlisting text="""
 xl create foo  xl create /usr/pkg/etc/xen/foo
 xl console foo  xl console domU-id
 xl create -c foo  xl create -c /usr/pkg/etc/xen/foo
 xl shutdown foo  xl shutdown domU-id
 xl list  xl list
 """]]  """]]
   
Line 330  will trigger controlled shutdowns of all Line 332  will trigger controlled shutdowns of all
 CPU and memory  CPU and memory
 --------------  --------------
   
 A domain is provided with some number of vcpus, less than the number  A domain is provided with some number of vcpus, up to the number
 of CPUs seen by the hypervisor. For a domU, it is controlled  of CPUs seen by the hypervisor. For a domU, it is controlled
 from the config file by the "vcpus = N" directive.  from the config file by the "vcpus = N" directive.
   
Line 348  Virtual disks Line 350  Virtual disks
 In domU config files, the disks are defined as a sequence of 3-tuples:  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   * The first element is "method:/path/to/disk". Common methods are
    "file:" for file-backed vnd, and "phy:" for something that is already     "file:" for a file-backed vnd, and "phy:" for something that is already
    a device.     a device, such as an LVM logical volume.
   
  * The second element is an artifact of how virtual disks are passed to   * 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     Linux, and a source of confusion with NetBSD Xen usage.  Linux domUs
Line 434  Creating a NetBSD domU Line 436  Creating a NetBSD 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).
   
 While the kernel will be obtained from the dom0 file system, the same  While the kernel will be obtained from the dom0 file system, the same
 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
Line 457  kernel to / and change the kernel line i Line 459  kernel to / and change the kernel line i
   
         kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"          kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
   
 Then, start the domain as "xl create -c configname".  Then, start the domain as "xl create -c configfile".
   
 Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following  Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following
 line should be used in the config file.  line should be used in the config file.
Line 623  note that only the "xpci" lines are unus Line 625  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
   
   
 #NetBSD as a domU in a VPS  # Specific Issues
   
   ## domU
   
   [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.)
   
   # NetBSD as a domU in a VPS
   
 The bulk of the HOWTO is about using NetBSD as a dom0 on your own  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  hardware.  This section explains how to deal with Xen in a domU as a
Line 650  A second issue is multiple CPUs.  With N Line 659  A second issue is multiple CPUs.  With N
 multiple vcpus, and it is typical for VPS providers to enable multiple  multiple vcpus, and it is typical for VPS providers to enable multiple
 CPUs for NetBSD domUs.  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
 ------  ------
   
Line 684  partition for the kernel with the intent Line 685  partition for the kernel with the intent
 which leads to /netbsd not being the actual kernel.  One must remember  which leads to /netbsd not being the actual kernel.  One must remember
 to update the special boot partition.  to update the special boot partition.
   
   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.
   
   pygrub doesn't seem to work to load Linux images under NetBSD dom0,
   and is inherently less secure than pvgrub due to running inside dom0. For both these
   reasons, pygrub should not be used, and is only still present so that
   historical DomU images using it still work.
   
   As of 2014, pygrub seems to be of mostly historical
   interest. New DomUs should use pvgrub.
   
 Amazon  Amazon
 ------  ------
   

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