Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.75 and 1.100

version 1.75, 2015/01/17 01:32:12 version 1.100, 2015/03/12 21:29:11
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.
   
   See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
   
 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
 -------------------  -------------------
   
 Early Xen used a program called "xm" to manipulate the system from the  Early Xen used a program called xm to manipulate the system from the
 dom0.  Starting in 4.1, a replacement program with similar behavior  dom0.  Starting in 4.1, a replacement program with similar behavior
 called "xl" is provided.  In 4.2 and later, "xl" is preferred.  4.4 is  called xl is provided, but it does not work well in 4.1.  In 4.2, both
 the last version that has "xm".  xm and xl work fine.  4.4 is the last version that has xm.  You must
   choose one or the other, because it affects which daemons you run.
   
 NetBSD  NetBSD
 ------  ------
Line 124  Architecture Line 130  Architecture
 ------------  ------------
   
 Xen itself can run on i386 or amd64 machines.  (Practically, almost  Xen itself can run on i386 or amd64 machines.  (Practically, almost
 any computer where one would want to run Xen supports amd64.)  If  any computer where one would want to run Xen today supports amd64.)
 using an i386 NetBSD kernel for the dom0, PAE is required (PAE  
 versions are built by default).  While i386 dom0 works fine, amd64 is  Xen, the dom0 kernel, and each domU kernel can be either i386 or
 recommended as more normal.  amd64.  When building a xenkernel package, one obtains i386 on an i386
   host, and amd64 on an amd64 host.  If 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 work, and an i386 dom0 kernel
   should in theory work.  An amd64 xen/dom0 is known to support both
   i386 and amd64 domUs.
   
   Except for an odd case with Xen 3.1, i386 dom0 and domU kernels must
   be PAE; these are built by default.  (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.)
   
   Because of the above, the standard approach is to use amd64 for the
   dom0.
   
 Xen 4.2 is the last version to support i386 as a host.  TODO: Clarify  Xen 4.2 is the last version to support i386 as a host.  TODO: Clarify
 if this is about the CPU having to be amd64, or about the dom0 kernel  if this is about the CPU, the xen kernel, or the dom0 kernel having to
 having to be amd64.  be amd64.
   
   
   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)
   
 One can then run i386 domUs and amd64 domUs, in any combination.  If  Note also that there are issues with sparse vnd(4) instances, but
 running an i386 NetBSD kernel as a domU, the PAE version is required.  these are not about Xen.
 (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.)  
   
 Recommendation  Recommendation
 --------------  --------------
Line 210  dom0 is what the computer would have bee Line 237  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 235  over a RAID1 header to find /boot from a Line 262  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 289  with an MBR bootblock, either bootxx_ffs Line 316  with an MBR bootblock, either bootxx_ffs
 beginning of your root filesystem, /boot present, and likely  beginning of your root filesystem, /boot present, and likely
 /boot.cfg.  (If not, fix before continuing!)  /boot.cfg.  (If not, fix before continuing!)
   
 See boot.cfg(5) for an example.  The basic line is  Add a line to to /boot.cfg to boot Xen.  See boot.cfg(5) for an
   example.  The basic line is
   
         menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M          menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
   
 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 In an attempt to add performance, one can  allocated for domUs.  To use a serial console, use
 also add  
           menu=Xen:load /netbsd-XEN3_DOM0.gz console=com0;multiboot /xen.gz dom0_mem=256M console=com1 com1=9600,8n1
   
   which will use the first serial port for Xen (which counts starting
   from 1), forcing speed/parity, and also for NetBSD (which counts
   starting at 0).  In an attempt to add performance, one can also add
   
         dom0_max_vcpus=1 dom0_vcpus_pin          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.  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.
   
   Now, reboot so that you are running a DOM0 kernel under Xen, rather
   than GENERIC without Xen.
   
 Using grub (historic)  Using grub (historic)
 ---------------------  ---------------------
   
Line 324  Configuring Xen Line 365  Configuring Xen
   
 Xen logs will be in /var/log/xen.  Xen logs will be in /var/log/xen.
   
 Now, you have a system that will boot Xen and the dom0 kernel, and  Now, you have a system that will boot Xen and the dom0 kernel, but not
 just run the dom0 kernel.  There will be no domUs, and none can be  do anything else special.  Make sure that you have rebooted into Xen.
 started because you still have to configure the dom0 tools.  The  There will be no domUs, and none can be started because you still have
 daemons which should be run vary with Xen version and with whether one  to configure the dom0 tools.  The daemons which should be run vary
 is using xm or xl.  Note that xend is for supporting "xm", and should  with Xen version and with whether one is using xm or xl.  Note that
 only be used if you plan on using "xm".  Do NOT enable xend if you  xend is for supporting "xm", and should only be used if you plan on
 plan on using "xl" as it will cause problems.  using "xm".  Do NOT enable xend if you plan on using "xl" as it will
   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 358  For 4.2 with xm, add to rc.conf Line 401  For 4.2 with xm, add to rc.conf
         xencommons=YES          xencommons=YES
         xend=YES          xend=YES
   
 For 4.2 with xl (preferred), add to rc.conf:  For 4.2 with xl, add to rc.conf:
   
           xencommons=YES
           TODO: explain if there is a xend replacement
   
   For 4.5 (and thus 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
Line 366  For 4.2 with xl (preferred), add to rc.c Line 414  For 4.2 with xl (preferred), add to rc.c
 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
 order given) or rebooted, run the following (or use xl) to inspect  order given) or rebooted, use xm or xl to inspect Xen's boot messages,
 Xen's boot messages, available resources, and running domains:  available resources, and running domains.  An example with xm follows:
   
         # xm dmesg          # xm dmesg
         [xen's boot info]          [xen's boot info]
Line 377  Xen's boot messages, available resources Line 425  Xen's boot messages, available resources
         Name              Id  Mem(MB)  CPU  State  Time(s)  Console          Name              Id  Mem(MB)  CPU  State  Time(s)  Console
         Domain-0           0       64    0  r----     58.1          Domain-0           0       64    0  r----     58.1
   
   With xl, the commands are the same, and the output may be slightly
   different.  TODO: add example output for xl before the xm example,
   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)
 --------------------------  --------------------------
   
 With the setup so far, one should be able to run anita (see  With the setup so far (assuming 4.2/xl), one should be able to run
 pkgsrc/sysutils/py-anita) to test NetBSD releases, by doing (as root,  anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
 because anita must create a domU):  root, because anita must create a domU):
   
         anita --vmm=xm test file:///usr/obj/i386/          anita --vmm=xl test file:///usr/obj/i386/
   
 Alternatively, one can use --vmm=xl to use xl-based domU creation instead.  Alternatively, one can use --vmm=xm to use xm-based domU creation
 TODO: check this.  instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
       
 Xen-specific NetBSD issues  Xen-specific NetBSD issues
 --------------------------  --------------------------
   
Line 461  Ensure that the contents of /etc/rc.d/xe Line 525  Ensure that the contents of /etc/rc.d/xe
 correct set of daemons.  Ensure that the domU config files are valid  correct set of daemons.  Ensure that the domU config files are valid
 for the new version.  for the new version.
   
   Hardware known to work
   ----------------------
   
   Arguably, this section is misplaced, and there should be a page of
   hardware that runs NetBSD/amd64 well, with the mostly-well-founded
   assumption that NetBSD/xen runs fine on any modern hardware that
   NetBSD/amd64 runs well on.  Until then, we give motherboard/CPU/RAM
   triples to aid those choosing a motherboard.  Note that Xen systems
   usually do not run X, so a listing here does not imply that X works at
   all.
   
           Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC
           Supermicro ??, Atom C2758 (8 core), 32 GiB ECC
           ASUS M5A78L-M/USB3 AM3+ microATX, AMD Piledriver X8 4000MHz, 16 GiB ECC
   
   Older hardware:
   
           Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2
   
   Running Xen under qemu
   ----------------------
   
   The astute reader will note that this section is somewhat twisted.
   However, it can be useful to run Xen under qemu either because the
   version of NetBSD as a dom0 does not run on the hardware in use, or to
   generate automated test cases involving Xen.
   
   In 2015-01, the following combination was reported to mostly work:
   
           host OS: NetBSD/amd64 6.1.4
           qemu: 2.2.0 from pkgsrc
           Xen kernel: xenkernel42-4.2.5nb1 from pkgsrc
           dom0 kernel: NetBSD/amd64 6.1.5
           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 522  domain, and see if it has finished stopp Line 623  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 582  create an empty 4G virtual disk, simply  Line 683  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 659  shutdown, in rc.conf add: Line 764  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 685  i386 and amd64 provide the following ker Line 790  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 738  It is also desirable to add Line 843  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 926  to update the special boot partiion. Line 1037  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
 ---------  ---------
   
 In standard kernels, npf is a module, and thus cannot be loadeed 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 954  TODO items for improving NetBSD/xen Line 1068  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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