Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.83 and 1.95

version 1.83, 2015/01/17 13:14:32 version 1.95, 2015/03/05 14:04:55
Line 92  reasonable although trailing-edge choice Line 92  reasonable although trailing-edge choice
 xenkernel42 provides Xen 4.2.  This is maintained by Xen, but old as  xenkernel42 provides Xen 4.2.  This is maintained by Xen, but old as
 of 2014-12.  of 2014-12.
   
   xenkernel45 provides Xen 4.5.  This is new to pkgsrc as of 2015-01 and
   not yet recommended for other than experimental/testing use.
   
 Ideally newer versions of Xen will be added to pkgsrc.  Ideally newer versions of Xen will be added to pkgsrc.
   
 Note that NetBSD support is called XEN3.  It works with 3.1 through  Note that NetBSD support is called XEN3.  It works with Xen 3 and Xen
 4.2 because the hypercall interface has been stable.  4 because the hypercall interface has been stable.
   
 Xen command program  Xen command program
 -------------------  -------------------
Line 139  running an i386 NetBSD kernel as a domU, Line 142  running an i386 NetBSD kernel as a domU,
 (Note that emacs (at least) fails if run on i386 with PAE when built  (Note that emacs (at least) fails if run on i386 with PAE when built
 without, and vice versa, presumably due to bugs in the undump code.)  without, and vice versa, presumably due to bugs in the undump code.)
   
   Stability
   ---------
   
   Mostly, NetBSD as a dom0 or domU is quite stable.
   However, there are some open PRs indicating problems.
   
    - [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
   these are not about Xen.
   
 Recommendation  Recommendation
 --------------  --------------
   
Line 211  dom0 is what the computer would have bee Line 226  dom0 is what the computer would have bee
 desktop or laptop.  Then, one can run domUs at will.  Purists will  desktop or laptop.  Then, one can run domUs at will.  Purists will
 deride this as less secure than the previous approach, and for a  deride this as less secure than the previous approach, and for a
 computer whose purpose is to run domUs, they are right.  But Xen and a  computer whose purpose is to run domUs, they are right.  But Xen and a
 dom0 (without domUs) is not meaingfully less secure than the same  dom0 (without domUs) is not meaningfully less secure than the same
 things running without Xen.  One can boot Xen or boot regular NetBSD  things running without Xen.  One can boot Xen or boot regular NetBSD
 alternately with little problems, simply refraining from starting the  alternately with little problems, simply refraining from starting the
 Xen daemons when not running Xen.  Xen daemons when not running Xen.
Line 236  over a RAID1 header to find /boot from a Line 251  over a RAID1 header to find /boot from a
 partition; this is no different when booting Xen.  partition; this is no different when booting Xen.
   
 There are 4 styles of providing backing storage for the virtual disks  There are 4 styles of providing backing storage for the virtual disks
 used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN,  used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN.
   
 With raw partitions, one has a disklabel (or gpt) partition sized for  With raw partitions, one has a disklabel (or gpt) partition sized for
 each virtual disk to be used by the domU.  (If you are able to predict  each virtual disk to be used by the domU.  (If you are able to predict
Line 309  starting at 0).  In an attempt to add pe Line 324  starting at 0).  In an attempt to add pe
 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.  TODO: benchmark this.  more) and to pin that vcpu to a physical cpu.  TODO: benchmark this.
   
   Xen has [many boot
   options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html),
   and other tham dom0 memory and max_vcpus, they are generally not
   necessary.
   
 As with non-Xen systems, you should have a line to boot /netbsd (a  As with non-Xen systems, you should have a line to boot /netbsd (a
 kernel that works without Xen) and fallback versions of the non-Xen  kernel that works without Xen) and fallback versions of the non-Xen
 kernel, Xen, and the dom0 kernel.  kernel, Xen, and the dom0 kernel.
Line 341  to configure the dom0 tools.  The daemon Line 361  to configure the dom0 tools.  The daemon
 with Xen version and with whether one is using xm or xl.  Note that  with Xen version and with whether one is using xm or xl.  Note that
 xend is for supporting "xm", and should only be used if you plan on  xend is for supporting "xm", and should only be used if you plan on
 using "xm".  Do NOT enable xend if you plan on using "xl" as it will  using "xm".  Do NOT enable xend if you plan on using "xl" as it will
 cause problems.  cause problems.  Running xl without xencommons=YES (and starting it)
   will result in a hang (so don't do that; follow the HOWTO!).
   
 The installation of NetBSD should already have created devices for xen  The installation of NetBSD should already have created devices for xen
 (xencons, xenevt), but if they are not present, create them:  (xencons, xenevt), but if they are not present, create them:
Line 374  For 4.2 with xl, add to rc.conf: Line 395  For 4.2 with xl, add to rc.conf:
         xencommons=YES          xencommons=YES
         TODO: explain if there is a xend replacement          TODO: explain if there is a xend replacement
   
   For 4.5 (and thus with xl), add to rc.conf:
   
           xencommons=YES
           TODO: explain if there is a xend replacement
   
 TODO: Recommend for/against xen-watchdog.  TODO: Recommend for/against xen-watchdog.
   
 After you have configured the daemons and either started them (in the  After you have configured the daemons and either started them (in the
Line 392  With xl, the commands are the same, and  Line 418  With xl, the commands are the same, and 
 different.  TODO: add example output for xl before the xm example,  different.  TODO: add example output for xl before the xm example,
 after confirming on 4.2 and resolving the TODO about rc.conf.  after confirming on 4.2 and resolving the TODO about rc.conf.
   
   ### Issues with xencommons
   
   xencommons starts xenstored, which stores data on behalf of dom0 and
   domUs.  It does not currently work to stop and start xenstored.
   Certainly all domUs should be shutdown first, following the sort order
   of the rc.d scripts.  However, the dom0 sets up state with xenstored,
   and is not notified when xenstored exits, leading to not recreating
   the state when the new xenstored starts.  Until there's a mechanism to
   make this work, one should not expect to be able to restart xenstored
   (and thus xencommons).  There is currently no reason to expect that
   this will get fixed any time soon.
   
 anita (for testing NetBSD)  anita (for testing NetBSD)
 --------------------------  --------------------------
   
Line 485  However, it can be useful to run Xen und Line 523  However, it can be useful to run Xen und
 version of NetBSD as a dom0 does not run on the hardware in use, or to  version of NetBSD as a dom0 does not run on the hardware in use, or to
 generate automated test cases involving Xen.  generate automated test cases involving Xen.
   
 In 2015-01, the following combination was reported to work:  In 2015-01, the following combination was reported to mostly work:
   
         host OS: NetBSD/amd64 6.1.4          host OS: NetBSD/amd64 6.1.4
         qemu: 2.2.0 from pkgsrc          qemu: 2.2.0 from pkgsrc
Line 493  In 2015-01, the following combination wa Line 531  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
   shutdown.
   
 Unprivileged domains (domU)  Unprivileged domains (domU)
 ===========================  ===========================
   
Line 553  domain, and see if it has finished stopp Line 594  domain, and see if it has finished stopp
         xm console foo          xm console foo
         xm create -c foo          xm create -c foo
         xm shutdown foo          xm shutdown foo
         xm list          xm list
   
 Typing ^] will exit the console session.  Shutting down a domain is  Typing ^] will exit the console session.  Shutting down a domain is
 equivalent to pushing the power button; a NetBSD domU will receive a  equivalent to pushing the power button; a NetBSD domU will receive a
Line 613  create an empty 4G virtual disk, simply  Line 654  create an empty 4G virtual disk, simply 
   
         dd if=/dev/zero of=foo-xbd0 bs=1m count=4096          dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
   
   Do not use qemu-img-xen, because this will create sparse file.  There
   have been recent (2015) reports of sparse vnd(4) devices causing
   lockups, but there is apparently no PR.
   
 With the lvm style, one creates logical devices.  They are then used  With the lvm style, one creates logical devices.  They are then used
 similarly to vnds.  TODO: Add an example with lvm.  similarly to vnds.  TODO: Add an example with lvm.
   
Line 690  shutdown, in rc.conf add: Line 735  shutdown, in rc.conf add:
   
         xendomains="foo bar"          xendomains="foo bar"
   
 TODO: Explain why 4.1 rc.d/xendomains has xl, when one should use xm  Note that earlier versions of the xentools41 xendomains rc.d scripth
 on 4.1.  Or fix the xentools41 package to have xm  usd xl, when one should use xm with 4.1.
   
 Creating specific unprivileged domains (domU)  Creating specific unprivileged domains (domU)
 =============================================  =============================================
Line 716  i386 and amd64 provide the following ker Line 761  i386 and amd64 provide the following ker
   
         i386 XEN3_DOMU          i386 XEN3_DOMU
         i386 XEN3PAE_DOMU          i386 XEN3PAE_DOMU
         amd64 XEN3_DOMU          amd64 XEN3_DOMU
   
 Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must  Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must
 use the PAE version of the i386 kernel.  use the PAE version of the i386 kernel.
Line 769  It is also desirable to add Line 814  It is also desirable to add
 in rc.conf. This way, the domain will be properly shut down if  in rc.conf. This way, the domain will be properly shut down if
 `xm shutdown -R` or `xm shutdown -H` is used on the dom0.  `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
   
 Your domain should be now ready to work, enjoy.  It is not strictly necessary to have a kernel (as /netbsd) in the domU
   filesystem.  However, various programs (e.g. netstat) will use that
   kernel to look up symbols to read from kernel virtual memory.  If
   /netbsd is not the running kernel, those lookups will fail.  (This is
   not really a Xen-specific issue, but because the domU kernel is
   obtained from the dom0, it is far more likely to be out of sync or
   missing with Xen.)
   
 Creating an unprivileged Linux domain (domU)  Creating an unprivileged Linux domain (domU)
 --------------------------------------------  --------------------------------------------
Line 957  to update the special boot partiion. Line 1008  to update the special boot partiion.
 Amazon  Amazon
 ------  ------
   
 TODO: add link to NetBSD amazon howto.  See the [Amazon EC2 page](../amazon_ec2/).
   
 Using npf  Using npf
 ---------  ---------
Line 965  Using npf Line 1016  Using npf
 In standard kernels, npf is a module, and thus cannot be loaded in a  In standard kernels, npf is a module, and thus cannot be loaded in a
 DOMU kernel.  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)
 http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html  [this email to
   netbsd-users](http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html).
   
 TODO items for improving NetBSD/xen  TODO items for improving NetBSD/xen
 ===================================  ===================================
   
 * Package Xen 4.4.  * Make the NetBSD dom0 kernel work with SMP.
 * Get PCI passthrough working on Xen 4.2 (or 4.4).  * Test the Xen 4.5 packages adequately to be able to recommend them as
     the standard approach.
   * Get PCI passthrough working on Xen 4.5
 * Get pvgrub into pkgsrc, either via xentools or separately.  * Get pvgrub into pkgsrc, either via xentools or separately.
 * grub  * grub
   * Check/add support to pkgsrc grub2 for UFS2 and arbitrary    * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
Line 985  TODO items for improving NetBSD/xen Line 1039  TODO items for improving NetBSD/xen
   * 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
   a kernel in Xen, similar to pvgrub.    a kernel in Xen, similar to pvgrub.
   * Solve somehow the issue with modules for GENERIC not being loadable
     in a Xen dom0 or domU kernel.
   
   Random pointers
   ===============
   
   TODO: This section contains links from elsewhere not yet integrated
   into the HOWTO.
   
   * http://www.lumbercartel.ca/library/xen/
   * http://pbraun.nethence.com/doc/sysutils/xen_netbsd_dom0.html

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