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version 1.127, 2016/12/20 19:25:35 version 1.141, 2017/12/15 16:40:59
Line 2  Introduction Line 2  Introduction
 ============  ============
   
 [![[Xen  [![[Xen
 screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](http://www.netbsd.org/gallery/in-Action/hubertf-xen.png)  screenshot]](https://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](https://www.netbsd.org/gallery/in-Action/hubertf-xen.png)
   
 Xen is a hypervisor (or virtual machine monitor) for x86 hardware  Xen is a hypervisor (or virtual machine monitor) for x86 hardware
 (i686-class or higher), which supports running multiple guest  (i686-class or higher), which supports running multiple guest
Line 81  of Xen version and NetBSD version.  This Line 81  of Xen version and NetBSD version.  This
 which version to choose.  Versions not in pkgsrc and older unsupported  which version to choose.  Versions not in pkgsrc and older unsupported
 versions of NetBSD are intentionally ignored.  versions of NetBSD are intentionally ignored.
   
   The term "amd64" is used to refer to both the NetBSD port and to the
   hardware architecture on which it runs.  (Such hardware is made by
   both Intel and AMD, and in 2016 a normal PC has this CPU
   architecture.)
   
 Xen  Xen
 ---  ---
   
Line 89  xenkernel and xentools.  We will refer o Line 94  xenkernel and xentools.  We will refer o
 but note that both packages must be installed together and must have  but note that both packages must be installed together and must have
 matching versions.  matching versions.
   
 xenkernel3 provides Xen 3.1.  It is no longer maintained by Xen, and the last applied security patch was in  xenkernel3 provides Xen 3.1.  It is no longer maintained by Xen, and
 2011. Thus, it should not be used.  It supports PCI passthrough,  the last applied security patch was in 2011. Thus, it should not be
 which is why people use it anyway. Xen 3.1 supports i386, both PAE and  used.  It supports PCI passthrough, which is why people use it anyway.
 non-PAE.  Xen 3.1 runs on i386 (both non-PAE and PAE) and amd64 hardware.
   
 xenkernel33 provides Xen 3.3.  It is no longer maintained by Xen, and  xenkernel33 provides Xen 3.3.  It is no longer maintained by Xen, and
 the last applied security patch was in 2012.  Thus, it should not be  the last applied security patch was in 2012.  Thus, it should not be
 used.  Xen 3.3 supports i386, but only in PAE mode.  There are no good  used.  Xen 3.3 runs on i386 PAE and amd64 hardware.  There are no good
 reasons to run this version.  reasons to run this version.
   
 xenkernel41 provides Xen 4.1.  It is no longer maintained by Xen, but  xenkernel41 provides Xen 4.1.  It is no longer maintained by Xen, but
 as of 2016-12 received backported security patches.  Xen 4.1 supports  as of 2016-12 received backported security patches.  Xen 4.1 runs on
 i386, but only in PAE mode.  There are no good reasons to run this  i386 PAE and amd64 hardware.  There are no good reasons to run this
 version.  version.
   
   Note that 3.1, 3.3 and 4.1 have been removed from pkgsrc-current, but
   are in 2016Q4.  They will be removed from this HOWTO sometime after
   2017Q1.
   
 xenkernel42 provides Xen 4.2.  It is no longer maintained by Xen, but  xenkernel42 provides Xen 4.2.  It is no longer maintained by Xen, but
 as of 2016-12 received backported security patches.  Xen 4.2 supports  as of 2016-12 received backported security patches.  Xen 4.2 runs on
 i386, but only in PAE mode.  The only reason to run this is if you  i386 PAE and amd64 hardware.  The only reason to run this is if you
 need to use xm instead of xl, or if you need to run an i386 dom0  need to use xm instead of xl, or if you need to run on hardware that
 (because your hardware is i386 only).  supports i386 but not amd64.  (This might also be useful if you need
   an i386 dom0, if it turns out that an amd64 Xen kernel and an i386
   dom0 is problematic.)
   
 xenkernel45 provides Xen 4.5.  As of 2016-12, security patches were  xenkernel45 provides Xen 4.5.  As of 2016-12, security patches were
 released by Xen and applied to pkgsrc.  Xen 4.5 requires using a dom0  released by Xen and applied to pkgsrc.  Xen 4.5 runs on amd64 hardware
 running NetBSD's amd64 port (Intel or AMD hardware is fine), but domUs  only.  While slightly old, 4.5 has been tested and run by others, so
 can be amd64 or i386 PAE.  TODO: It is either a conservative choice or  it is the conservative choice.
 somewhat old.  
   
 xenkernel46 provides Xen 4.6.  It is new to pkgsrc as of 2016-05.  As  xenkernel46 provides Xen 4.6.  It is new to pkgsrc as of 2016-05.  As
 of 2016-12, security patches were released by Xen and applied to  of 2016-12, security patches were released by Xen and applied to
 pkgsrc.  Xen 4.6 similarly requires a NetBSD/amd64 dom0, but domUs can  pkgsrc.  Xen 4.6 runs on amd64 hardware only For new installations,
 be amd64 or i386 PAE.  TODO: It is either a somewhat aggressive choice  4.6 is probably the appropriate choice and it will likely soon be the
 or the standard choice.  standard approach.  (If using Ubuntu guests, be sure to have the
   xentools46 from December, 2016).
   
 Xen 4.7 (released 2016-06) and 4.8 (released 2016-12) are not yet in  Xen 4.7 (released 2016-06) and 4.8 (released 2016-12) are not yet in
 pkgsrc.  pkgsrc.
Line 144  only which command you use, but the comm Line 155  only which command you use, but the comm
 xentools packages provide xm for 3.1, 3.3 and 4.1 and xl for 4.2 and up.  xentools packages provide xm for 3.1, 3.3 and 4.1 and xl for 4.2 and up.
   
 In 4.2, you can choose to use xm by simply changing the ctl_command  In 4.2, you can choose to use xm by simply changing the ctl_command
 variable.  variable and setting xend=YES in rc.conf.
   
 With xl, virtual devices are configured in parallel, which can cause  With xl, virtual devices are configured in parallel, which can cause
 problems if they are written assuming serial operation (e.g., updating  problems if they are written assuming serial operation (e.g., updating
 firewall rules without explicit locking).  firewall rules without explicit locking).  There is now locking for
   the provided scripts, which works for normal casses (e.g, file-backed
 There is now locking for xl startup, but as of 201612 it has not been  xbd, where a vnd must be allocated).  But, as of 201612, it has not
 adequately tested.  been adequately tested for a complex custom setup with a large number
   of interfaces.
   
 NetBSD  NetBSD
 ------  ------
Line 177  when using a dom0 as a normal computer.) Line 189  when using a dom0 as a normal computer.)
 Architecture  Architecture
 ------------  ------------
   
 Xen itself can run on i386 (Xen < 3.1) or amd64 machines (all Xen  Xen itself can run on i386 (Xen < 4.2) or amd64 hardware (all Xen
 versions).  (Practically, almost any computer where one would want to  versions).  (Practically, almost any computer where one would want to
 run Xen today supports amd64.)  run Xen today supports amd64.)
   
 Xen, the dom0 kernel, and each domU kernel can be either i386 or  Xen, the dom0 system, and each domU system can be either i386 or
 amd64.  When building a xenkernel package, one obtains i386 on an i386  amd64.  When building a xenkernel package, one obtains an i386 Xen
 host, and amd64 on an amd64 host.  If the Xen kernel is i386, then the  kernel on an i386 host, and an amd64 Xen kernel on an amd64 host.  If
 dom0 kernel and all domU kernels must be i386.  With an amd64 Xen  the Xen kernel is i386, then the dom0 kernel and all domU kernels must
 kernel, an amd64 dom0 kernel is known to work, and an i386PAE dom0  be i386.  With an amd64 Xen kernel, an amd64 dom0 kernel is known to
 kernel should in theory work.  An amd64 Xen/dom0 is known to support  work, and an i386 dom0 kernel should in theory work.  An amd64
 both i386PAE and amd64 domUs.  Xen/dom0 is known to support both i386 and amd64 domUs.
   
 i386 dom0 and domU kernels must be PAE (except for Xen 3.1); these are  i386 dom0 and domU kernels must be PAE (except for an i386 Xen 3.1
 built by default.  (Note that emacs (at least) fails if run on i386  kernel, where one can use non-PAE for dom0 and all domUs); PAE kernels
 with PAE when built without, and vice versa, presumably due to bugs in  are included in the NetBSD default build.  (Note that emacs (at least)
 the undump code.)  fails if run on i386 with PAE when built without, and vice versa,
   presumably due to bugs in the undump code.)
 Because of the above, the standard approach is to use amd64 for the  
 dom0.  Because of the above, the standard approach is to use an amd64 Xen
   kernel and NetBSD/amd64 for the dom0.  For domUs, NetBSD/i386 (with
 Xen 4.2 is the last version to support i386 as a host.  TODO: Clarify  the PAE kernel) and NetBSD/amd64 are in widespread use, and there is
 if this is about the CPU, the Xen kernel, or the dom0 kernel having to  little to no Xen-specific reason to prefer one over the other.
 be amd64.  
   Note that to use an i386 dom0 with Xen 4.5 or higher, one must build
   (or obtain from pre-built packages) an amd64 Xen kernel and install
   that on the system.  (One must also use a PAE i386 kernel, but this is
   also required with an i386 Xen kernel.).  Almost no one in the
   NetBSD/Xen community does this, and the standard, well-tested,
   approach is to use an amd64 dom0.
   
   A [posting on
   xen-devel](https://lists.xen.org/archives/html/xen-devel/2012-07/msg00085.html)
   explained that PV system call overhead was higher on amd64, and thus
   there is some notion that i386 guests are faster.  It goes on to
   caution that the total situation is complex and not entirely
   understood. On top of that caution, the post is about Linux, not
   NetBSD.  TODO: Include link to benchmarks, if someone posts them.
   
 Stability  Stability
 ---------  ---------
Line 209  Mostly, NetBSD as a dom0 or domU is quit Line 234  Mostly, NetBSD as a dom0 or domU is quit
 However, there are some open PRs indicating problems.  However, there are some open PRs indicating problems.
   
  - [PR 48125](http://gnats.netbsd.org/48125)   - [PR 48125](http://gnats.netbsd.org/48125)
  - [PR 47720](http://gnats.netbsd.org/47720)  
   
 Note also that there are issues with sparse vnd(4) instances, but  Note also that there are issues with sparse vnd(4) instances, but
 these are not about Xen -- they just are noticed with sparse vnd(4)  these are not about Xen -- they just are noticed with sparse vnd(4)
Line 223  xl, the NetBSD 7 stable branch, and to u Line 247  xl, the NetBSD 7 stable branch, and to u
 dom0.  Either the i386PAE or amd64 version of NetBSD may be used as  dom0.  Either the i386PAE or amd64 version of NetBSD may be used as
 domUs.  domUs.
   
   Because bugs are fixed quite often, and because of Xen security
   advisories, it is good to stay up to date with NetBSD (tracking a
   stable branch), with the Xen kernel (tracking a Xen version via
   pkgsrc), and with the Xen tools.  Specifically, NetBSD (-7 and
   -current) got an important fix affecting dom0/domU timesharing in
   November, 2015, and xentools46 got a fix to enable Ubuntu guests to
   boot in December, 2016.
   
 Status  Status
 ------  ------
   
Line 238  The following table gives status, with t Line 270  The following table gives status, with t
 (generally on the most recent quarterly branch).  The first code is  (generally on the most recent quarterly branch).  The first code is
 "builds" if it builds ok, and "FAIL" for a failure to build.  The  "builds" if it builds ok, and "FAIL" for a failure to build.  The
 second code/date only appears for xenkernel* and is "works" if it runs  second code/date only appears for xenkernel* and is "works" if it runs
 ok as a dom0, and "FAIL" if it won't boot or run a domU.  ok as a dom0 and can support a domU, and "FAIL" if it won't boot or
   run a domU.
   
         xenkernel3 netbsd-6 i386 FAIL 201612          xenkernel3 netbsd-6 i386 FAIL 201612
         xenkernel33 netbsd-6 i386 FAIL 201612          xenkernel33 netbsd-6 i386 FAIL 201612
         xenkernel41 netbsd-6 i386 builds 201612          xenkernel41 netbsd-6 i386 builds 201612
         xenkernel42 netbsd-6 i386 builds 201612          xenkernel42 netbsd-6 i386 builds 201612
         xentools3 netbsd-6 i386 FAIL 201612          xentools3 netbsd-6 i386 FAIL 201612
         xentools3-hvm netbsd-6 i386 FAIL 201412          xentools33 netbsd-6 i386 FAIL 201612
         xentools33 netbsd-6 i386 builds 201412  
         xentools41 netbsd-6 i386 builds 201612          xentools41 netbsd-6 i386 builds 201612
         xentools42 netbsd-6 i386 FAIL 201612          xentools42 netbsd-6 i386 FAIL 201612
   
Line 295  configuration. Line 327  configuration.
   
 For experimenting with Xen, a machine with as little as 1G of RAM and  For experimenting with Xen, a machine with as little as 1G of RAM and
 100G of disk can work.  For running many domUs in productions, far  100G of disk can work.  For running many domUs in productions, far
 more will be needed.  more will be needed; e.g. 4-8G and 1T of disk is reasonable for a
   half-dozen domUs of 512M and 32G each.  Basically, the RAM and disk
   have to be bigger than the sum of the RAM/disk needs of the dom0 and
   all the domUs.
   
 Styles of dom0 operation  Styles of dom0 operation
 ------------------------  ------------------------
Line 318  Xen daemons when not running Xen. Line 353  Xen daemons when not running Xen.
 Note that NetBSD as dom0 does not support multiple CPUs.  This will  Note that NetBSD as dom0 does not support multiple CPUs.  This will
 limit the performance of the Xen/dom0 workstation approach.  In theory  limit the performance of the Xen/dom0 workstation approach.  In theory
 the only issue is that the "backend drivers" are not yet MPSAFE:  the only issue is that the "backend drivers" are not yet MPSAFE:
   http://mail-index.netbsd.org/netbsd-users/2014/08/29/msg015195.html    https://mail-index.netbsd.org/netbsd-users/2014/08/29/msg015195.html
   
 Installation of NetBSD  Installation of NetBSD
 ----------------------  ----------------------
Line 361  Installation of Xen Line 396  Installation of Xen
   
 In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from  In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from
 pkgsrc (or another matching pair).  See [the pkgsrc  pkgsrc (or another matching pair).  See [the pkgsrc
 documentation](http://www.NetBSD.org/docs/pkgsrc/) for help with  documentation](https://www.NetBSD.org/docs/pkgsrc/) for help with
 pkgsrc.  Ensure that your packages are recent; the HOWTO does not  pkgsrc.  Ensure that your packages are recent; the HOWTO does not
 contemplate old builds.  contemplate old builds.
   
Line 382  releasedir/i386/binary/kernel/netbsd-XEN Line 417  releasedir/i386/binary/kernel/netbsd-XEN
 should not use Xen 3.1.)  Both xen and the NetBSD kernel may be (and  should not use Xen 3.1.)  Both xen and the NetBSD kernel may be (and
 typically are) left compressed.  typically are) left compressed.
   
 In a dom0 kernel, kernfs is mandatory for xend to communicate with the  In a dom0, kernfs is mandatory for xend to communicate with the
 kernel, so ensure that /kern is in fstab.  TODO: Say this is default,  kernel, so ensure that /kern is in fstab.  (A standard NetBSD install
 or file a PR and give a reference.  should already mount /kern.)
   
 Because you already installed NetBSD, you have a working boot setup  Because you already installed NetBSD, you have a working boot setup
 with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the  with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
 beginning of your root file system, /boot present, and likely  beginning of your root file system, have /boot, and likely also
 /boot.cfg.  (If not, fix before continuing!)  /boot.cfg.  (If not, fix before continuing!)
   
 Add a line to to /boot.cfg to boot Xen.  See boot.cfg(5) for an  Add a line to to /boot.cfg to boot Xen.  See boot.cfg(5) for an
Line 399  example.  The basic line is Line 434  example.  The basic line is
 which specifies that the dom0 should have 256M, leaving the rest to be  which specifies that the dom0 should have 256M, leaving the rest to be
 allocated for domUs.  To use a serial console, use  allocated for domUs.  To use a serial console, use
   
         menu=Xen:load /netbsd-XEN3_DOM0.gz console=com0;multiboot /xen.gz dom0_mem=256M console=com1 com1=9600,8n1          menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=256M console=com1 com1=9600,8n1
   
 which will use the first serial port for Xen (which counts starting  which will use the first serial port for Xen (which counts starting
 from 1), forcing speed/parity, and also for NetBSD (which counts  from 1, unlike NetBSD which counts starting from 0), forcing
 starting at 0).  In an attempt to add performance, one can also add  speed/parity.  Because the NetBSD command line lacks a
   "console=pc" argument, it will use the default "xencons" console device,
   which directs the console I/O through Xen to the same console device Xen
   itself uses (in this case, the serial port).
   
   In an attempt to add performance, one can also add
   
         dom0_max_vcpus=1 dom0_vcpus_pin          dom0_max_vcpus=1 dom0_vcpus_pin
   
Line 433  Using grub (historic) Line 473  Using grub (historic)
   
 Before NetBSD's native bootloader could support Xen, the use of  Before NetBSD's native bootloader could support Xen, the use of
 grub was recommended.  If necessary, see the  grub was recommended.  If necessary, see the
 [old grub information](/ports/xen/howto-grub/).  [old grub information](/ports/xen/howto-grub).
   
 The [HowTo on Installing into  The [HowTo on Installing into
 RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)  RAID-1](https://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
 explains how to set up booting a dom0 with Xen using grub with  explains how to set up booting a dom0 with Xen using grub with
 NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native  NetBSD's RAIDframe.  (This is obsolete with the use of NetBSD's native
 boot.)  boot.  Now, just create a system with RAID-1, and alter /boot.cfg as
   described above.)
   
 Configuring Xen  Configuring Xen
 ---------------  ---------------
Line 456  one is using xm or xl.  The Xen 3.1, 3.3 Line 497  one is using xm or xl.  The Xen 3.1, 3.3
 4.2 and up packages use xl.  To use xm with 4.2, edit xendomains to  4.2 and up packages use xl.  To use xm with 4.2, edit xendomains to
 use xm instead.  use xm instead.
   
   For 3.1 and 3.3, you should enable xend and xenbackendd:
 For "xm", you should enable xend and xenbackendd:  
   
         xend=YES          xend=YES
         xenbackendd=YES          xenbackendd=YES
   
 For "xl", you should enable xend and xencommons (xenstored).  Trying  For 4.1 and up, you should enable xencommons.  Not enabling xencommons
 to use xl without xencommons=YES will result in a hang; it is  will result in a hang; it is necessary to hit ^C on the console to let
 necessary to hit ^C on the console to let the machine finish booting.  the machine finish booting.  If you are using xm (default in 4.1, or
 TODO: Check if xend really should be used, and if not why it is  if you changed xendomains in 4.2), you should also enable xend:
 installed.  
   
         xend=YES          xend=YES # only if using xm, and only installed <= 4.2
         xencommons=YES          xencommons=YES
   
 TODO: Recommend for/against xen-watchdog.  TODO: Recommend for/against xen-watchdog.
Line 606  Hardware known to work Line 645  Hardware known to work
 Arguably, this section is misplaced, and there should be a page of  Arguably, this section is misplaced, and there should be a page of
 hardware that runs NetBSD/amd64 well, with the mostly-well-founded  hardware that runs NetBSD/amd64 well, with the mostly-well-founded
 assumption that NetBSD/xen runs fine on any modern hardware that  assumption that NetBSD/xen runs fine on any modern hardware that
 NetBSD/amd64 runs well on.  Until then, we give motherboard/CPU/RAM  NetBSD/amd64 runs well on.  Until then, we give motherboard/CPU (and
 triples to aid those choosing a motherboard.  Note that Xen systems  sometimes RAM) pairs/triples to aid those choosing a motherboard.
 usually do not run X, so a listing here does not imply that X works at  Note that Xen systems usually do not run X, so a listing here does not
 all.  imply that X works at all.
   
         Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC          Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC
         Supermicro ??, Atom C2758 (8 core), 32 GiB ECC          Supermicro ??, Atom C2758 (8 core), 32 GiB ECC
Line 618  all. Line 657  all.
 Older hardware:  Older hardware:
   
         Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2          Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2
           INTEL DG33FB, "Intel(R) Core(TM)2 Duo CPU     E6850  @ 3.00GHz"
           INTEL DG33FB, "Intel(R) Core(TM)2 Duo CPU     E8400  @ 3.00GHz"
   
 Running Xen under qemu  Running Xen under qemu
 ----------------------  ----------------------
Line 635  In 2015-01, the following combination wa Line 676  In 2015-01, the following combination wa
         dom0 kernel: NetBSD/amd64 6.1.5          dom0 kernel: NetBSD/amd64 6.1.5
         Xen tools: xentools42-4.2.5 from pkgsrc          Xen tools: xentools42-4.2.5 from pkgsrc
   
 See [PR 47720](http://gnats.netbsd.org/47720) for a problem with dom0  See [PR 47720](https://gnats.netbsd.org/47720) for a problem with dom0
 shutdown.  shutdown.
   
 Unprivileged domains (domU)  Unprivileged domains (domU)
Line 1130  DOMU kernel. Line 1171  DOMU kernel.
 TODO: Explain how to compile npf into a custom kernel, answering (but  TODO: Explain how to compile npf into a custom kernel, answering (but
 note that the problem was caused by not booting the right kernel)  note that the problem was caused by not booting the right kernel)
 [this email to  [this email to
 netbsd-users](http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html).  netbsd-users](https://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html).
   
 TODO items for improving NetBSD/xen  TODO items for improving NetBSD/xen
 ===================================  ===================================
Line 1145  TODO items for improving NetBSD/xen Line 1186  TODO items for improving NetBSD/xen
     fragsize/blocksize (UFS2 support may be present; the point is to      fragsize/blocksize (UFS2 support may be present; the point is to
     make it so that with any UFS1/UFS2 file system setup that works      make it so that with any UFS1/UFS2 file system setup that works
     with NetBSD grub will also work).      with NetBSD grub will also work).
     See [pkg/40258](http://gnats.netbsd.org/40258).      See [pkg/40258](https://gnats.netbsd.org/40258).
   * Push patches upstream.    * Push patches upstream.
   * Get UFS2 patches into pvgrub.    * Get UFS2 patches into pvgrub.
 * Add support for PV ops to a version of /boot, and make it usable as  * Add support for PV ops to a version of /boot, and make it usable as
Removed from v.1.127  
changed lines
  Added in v.1.141

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