Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.177 and 1.180

version 1.177, 2020/11/13 20:41:56 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 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.  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           |current-only (domU)  PVHVM           |current-only (domU)
 PVHv2           |current-only (domU, dom0 not yet)  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
Line 29  The dom0 runs qemu to emulate hardware. Line 29  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.
   
 In PVHv2H mode, operation is similar to PVHVM, except that qemu is not  There have been two PVH modes: original PVH and PVHv2.  Original PVH
 run and thus the PV interfaces for console, disks, networking are the  was based on PV mode and is no longer relevant at all.  PVHv2 is
 only way to access these resources.  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 105  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 145  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.
   
Line 196  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 427  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).
Line 549  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 559  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 660  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.
   
   ## Complexities due to Xen changes
   
   Xen has many security advisories and people running Xen systems make
   different choices.
   
   ### 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
 ------  ------
   

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