Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.133 and 1.140

version 1.133, 2016/12/20 20:59:49 version 1.140, 2017/12/15 16:39:33
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 109  as of 2016-12 received backported securi Line 109  as of 2016-12 received backported securi
 i386 PAE and amd64 hardware.  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  It is no longer maintained by Xen, but  xenkernel42 provides Xen 4.2.  It is no longer maintained by Xen, but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 runs on  as of 2016-12 received backported security patches.  Xen 4.2 runs on
 i386 PAE and amd64 hardware.  The only reason to run this is if you  i386 PAE and amd64 hardware.  The only reason to run this is if you
Line 126  xenkernel46 provides Xen 4.6.  It is new Line 130  xenkernel46 provides Xen 4.6.  It is new
 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 runs on amd64 hardware only For new installations,  pkgsrc.  Xen 4.6 runs on amd64 hardware only For new installations,
 4.6 is probably the appropriate choice and it will likely soon be the  4.6 is probably the appropriate choice and it will likely soon be the
 standard approach.  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 150  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
Line 190  run Xen today supports amd64.) Line 195  run Xen today supports amd64.)
   
 Xen, the dom0 system, and each domU system 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 an i386 Xen  amd64.  When building a xenkernel package, one obtains an i386 Xen
 kernel on an i386 host, and anamd64 Xen kernel on an amd64 host.  If  kernel on an i386 host, and an amd64 Xen kernel on an amd64 host.  If
 the Xen kernel is i386, then the dom0 kernel and all domU kernels must  the Xen kernel is i386, then the dom0 kernel and all domU kernels must
 be i386.  With an amd64 Xen kernel, an amd64 dom0 kernel is known to  be i386.  With an amd64 Xen kernel, an amd64 dom0 kernel is known to
 work, and an i386 dom0 kernel should in theory work.  An amd64  work, and an i386 dom0 kernel should in theory work.  An amd64
 Xen/dom0 is known to support both i386 and amd64 domUs.  Xen/dom0 is known to support both i386 and amd64 domUs.
   
 i386 dom0 and domU kernels must be PAE (except for an i386 Xen 3.1  i386 dom0 and domU kernels must be PAE (except for an i386 Xen 3.1
 kernel, where one can use non-PAE for dom0 and all domUs); PAE  kernel, where one can use non-PAE for dom0 and all domUs); PAE kernels
 versions are included in the NetBSD default build.  (Note that emacs  are included in the NetBSD default build.  (Note that emacs (at least)
 (at least) fails if run on i386 with PAE when built without, and vice  fails if run on i386 with PAE when built without, and vice versa,
 versa, presumably due to bugs in the undump code.)  presumably due to bugs in the undump code.)
   
 Because of the above, the standard approach is to use NetBSD/amd64 for  Because of the above, the standard approach is to use an amd64 Xen
 the dom0 and therefore an amd64 Xen kernel, and to use PAE kernels for  kernel and NetBSD/amd64 for the dom0.  For domUs, NetBSD/i386 (with
 i386 domUs.  the PAE kernel) and NetBSD/amd64 are in widespread use, and there is
   little to no Xen-specific reason to prefer one over the other.
   
 Note that to use an i386 dom0 with Xen 4.5 or higher, one must build  Note that to use an i386 dom0 with Xen 4.5 or higher, one must build
 an amd64 Xen kernel and install that on the system.  One must also use  (or obtain from pre-built packages) an amd64 Xen kernel and install
 a PAE i386 kernel.  There is no good reason to undertake these  that on the system.  (One must also use a PAE i386 kernel, but this is
 contortions; you should use a NetBSD/amd64 dom0 system.  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 232  xl, the NetBSD 7 stable branch, and to u Line 248  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 247  The following table gives status, with t Line 271  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
Line 303  configuration. Line 328  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 326  Xen daemons when not running Xen. Line 354  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 369  Installation of Xen Line 397  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 390  releasedir/i386/binary/kernel/netbsd-XEN Line 418  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 407  example.  The basic line is Line 435  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 441  Using grub (historic) Line 474  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 643  In 2015-01, the following combination wa Line 677  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 1138  DOMU kernel. Line 1172  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 1153  TODO items for improving NetBSD/xen Line 1187  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

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