Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.158 and 1.180

version 1.158, 2018/09/05 09:16:10 version 1.180, 2020/11/15 14:31:58
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 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  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. 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.
   The dom0 runs qemu to emulate hardware.
   
   In PVHVM mode, the guest runs as HVM, but additionally can use PV
   drivers for efficiency.
   
   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
   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 required.  Thus, a dom0 can be PVHv2.
   
   The source code uses PVH and config files use pvh; this refers to PVHv2.
   
 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 33  architecture, with installing NetBSD on  Line 46  architecture, with installing NetBSD on 
 installing software from pkgsrc.  See also the [Xen  installing software from pkgsrc.  See also the [Xen
 website](http://www.xenproject.org/).  website](http://www.xenproject.org/).
   
 This HOWTO attempts to address both the case of running a NetBSD dom0  [[!toc]]
 on hardware and running domUs under it (NetBSD and other), and also  
 running NetBSD as a domU in a VPS.  
   
 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 48  matching versions. Line 58  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 66  dom0  |No Line 73  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.  The dom0 system should be amd64.  (Instructions for i386PAE dom0 have been removed from the HOWTO.)
 i386 without PAE is not supported.  
   
 The standard approach is to use NetBSD/amd64 for the dom0.  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.
   
 To use an i386PAE dom0, one must build or obtain a 64bit Xen kernel and  # Creating a dom0
 install it on the system.  
   
 For domUs, i386PAE is considered as  
 [faster](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html)  
 than amd64.  
   
 NetBSD as 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 106  just as you would if you were not using  Line 109  just as you would if you were not using 
 Installation of Xen  Installation of Xen
 -------------------  -------------------
   
 We will consider that you chose to use Xen 4.8, with NetBSD/amd64 as  We will consider that you chose to use Xen 4.13, with NetBSD/amd64 as
 dom0. In the dom0, install xenkernel48 and xentools48 from pkgsrc.  dom0. In the dom0, install xenkernel48 and xentools48 from pkgsrc.
   
 Once this is done, install the Xen kernel itself:  Once this is done, install the Xen kernel itself:
Line 115  Once this is done, install the Xen kerne Line 118  Once this is done, install the Xen kerne
 # cp /usr/pkg/xen48-kernel/xen.gz /  # cp /usr/pkg/xen48-kernel/xen.gz /
 """]]  """]]
   
 Then, place a NetBSD XEN3_DOM0 kernel in the `/` directory, copied from  Then, place a NetBSD XEN3_DOM0 kernel in the `/` directory. Such kernel
 `releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz` of a NetBSD build.  can either be compiled manually, or downloaded from the NetBSD FTP, for
   example at:
   
   [[!template id=programlisting text="""
   ftp.netbsd.org/pub/NetBSD/NetBSD-8.0/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 124  Add a line to /boot.cfg to boot Xen: Line 132  Add a line to /boot.cfg to boot Xen:
 menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M  menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M
 """]]  """]]
   
 which 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.  To use a serial console, use:
   
 [[!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 141  itself uses (in this case, the serial po Line 149  itself uses (in this case, the serial po
 In an attempt to add performance, one can also add `dom0_max_vcpus=1 dom0_vcpus_pin`,  In an attempt to add performance, one can also add `dom0_max_vcpus=1 dom0_vcpus_pin`,
 to force only one vcpu to be provided (since NetBSD dom0 can't use  to force only one vcpu to be provided (since NetBSD dom0 can't use
 more) and to pin that vcpu to a physical CPU. Xen has  more) and to pin that vcpu to a physical CPU. Xen has
 [many boot options](http://xenbits.xenproject.org/docs/4.8-testing/misc/xen-command-line.html),  [many boot options](http://xenbits.xenproject.org/docs/4.13-testing/misc/xen-command-line.html),
 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`:
   
   [[!template id=programlisting text="""
   # cp /usr/pkg/share/examples/rc.d/xen* /etc/rc.d/
   """]]
   
 Enable `xencommons`:  Enable `xencommons`:
   
 [[!template id=filecontent name="/etc/rc.conf" text="""  [[!template id=filecontent name="/etc/rc.conf" text="""
Line 186  this will get fixed any time soon. Line 200  this will get fixed any time soon.
 anita (for testing NetBSD)  anita (for testing NetBSD)
 --------------------------  --------------------------
   
 With the setup so far (assuming 4.8/xl), one should be able to run  With the setup so far, one should be able to run
 anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as  anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
 root, because anita must create a domU):  root, because anita must create a domU):
   
Line 258  Minor version upgrades are trivial.  Jus Line 272  Minor version upgrades are trivial.  Jus
 xenkernel version and copy the new xen.gz to `/` (where `/boot.cfg`  xenkernel version and copy the new xen.gz to `/` (where `/boot.cfg`
 references it), and reboot.  references it), and reboot.
   
 Unprivileged domains (domU)  #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 277  the dom0.  NetBSD's /dev/random system w Line 290  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 302  are stored in files and Xen attaches the Line 315  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 324  will trigger controlled shutdowns of all Line 337  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 342  Virtual disks Line 355  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 418  down cleanly on dom0 shutdown, add the f Line 431  down cleanly on dom0 shutdown, add the f
 xendomains="domU-netbsd domU-linux"  xendomains="domU-netbsd domU-linux"
 """]]  """]]
   
 Creating a domU  # Creating a domU
 ===============  
   
 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.  Note that you must
 have already completed the dom0 setup so that "xl list" works.  have already completed the dom0 setup so that "xl list" works.
   
 Creating a NetBSD 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).
   
 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 452  kernel to / and change the kernel line i Line 464  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 541  To get the Linux console right, you need Line 553  To get the Linux console right, you need
 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 a NetBSD HVM domU
   
   Use type='hmv', probably.  Use a GENERIC kernel within the disk image.
   
   ## Creating a NetBSD PVH domU
   
   Use type='pvh'.
   
   \todo Explain where the kernel comes from.
   
   
 Creating a Solaris domU  Creating a Solaris domU
 -----------------------  -----------------------
   
Line 551  See possibly outdated Line 574  See possibly outdated
 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
   is not clear that it works on any version in pkgsrc.  Reports
   confirming or denying this notion should be sent to port-xen@.
   
 The dom0 can give other domains access to selected PCI  The dom0 can give other domains access to selected PCI
 devices. This can allow, for example, a non-privileged domain to have  devices. This can allow, for example, a non-privileged domain to have
 access to a physical network interface or disk controller.  However,  access to a physical network interface or disk controller.  However,
Line 618  note that only the "xpci" lines are unus Line 645  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 646  A second issue is multiple CPUs.  With N Line 679  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  ## Complexities due to Xen changes
 -------  
   
 pygrub runs in the dom0 and looks into the domU file system.  This  Xen has many security advisories and people running Xen systems make
 implies that the domU must have a kernel in a file system in a format  different choices.
 known to pygrub.  As of 2014, pygrub seems to be of mostly historical  
 interest.  ### stub domains
   
   Some (Linux only?) dom0 systems use something called "stub domains" to
   isolate qemu from the dom0 system, as a security and reliabilty
   mechanism when running HVM domUs.  Somehow, NetBSD's GENERIC kernel
   ends up using PIO for disks rather than DMA.  Of course, all of this
   is emulated, but emulated PIO is unusably slow.  This problem is not
   currently understood.
   
   ### Grant tables
   
   There are multiple versions of using grant tables, and some security
   advisories have suggested disabling some versions.  Some versions of
   NetBSD apparently only use specific versions and this can lead to
   "NetBSD current doesn't run on hosting provider X" situations.
   
   \todo Explain better.
   
 pvgrub  pvgrub
 ------  ------
Line 680  partition for the kernel with the intent Line 728  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.
   
 Amazon  pygrub
 ------  -------
   
 See the [Amazon EC2 page](/amazon_ec2/).  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.
   
 Random pointers  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.
   
 This section contains links from elsewhere not yet integrated into the  As of 2014, pygrub seems to be of mostly historical
 HOWTO, and other guides.  interest. New DomUs should use pvgrub.
   
 * http://www.lumbercartel.ca/library/xen/  Amazon
 * http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html  ------
 * https://gmplib.org/~tege/xen.html  
   See the [Amazon EC2 page](/amazon_ec2/).

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