Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.74 and 1.115

version 1.74, 2015/01/04 02:18:47 version 1.115, 2016/12/20 13:16:43
Line 30  style is less efficient but can run unmo Line 30  style is less efficient but can run unmo
 Generally any amd64 machine will work with Xen and PV guests.  In  Generally any amd64 machine will work with Xen and PV guests.  In
 theory i386 computers without amd64 support can be used for Xen <=  theory i386 computers without amd64 support can be used for Xen <=
 4.2, but we have no recent reports of this working (this is a hint).  4.2, but we have no recent reports of this working (this is a hint).
 For HVM guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT  For HVM guests, the VT or VMX CPU feature (Intel) or SVM/HVM/VT
 (amd64) is needed; "cpuctl identify 0" will show this.  TODO: Clean up  (amd64) is needed; "cpuctl identify 0" will show this.  TODO: Clean up
 and check the above features.  and check the above features.
   
Line 49  specific PCI devices can be made availab Line 49  specific PCI devices can be made availab
 of the dom0.  This can be useful to let a domU run X11, or access some  of the dom0.  This can be useful to let a domU run X11, or access some
 network interface or other peripheral.  network interface or other peripheral.
   
 NetBSD used to support Xen2; this has been removed.  NetBSD 6 and earlier supported Xen 2; support was removed from NetBSD
   7.  Xen 2 has been removed from pkgsrc.
   
 Prerequisites  Prerequisites
 -------------  -------------
Line 76  versions of NetBSD are intentionally ign Line 77  versions of NetBSD are intentionally ign
 Xen  Xen
 ---  ---
   
 In NetBSD, xen is provided in pkgsrc, via matching pairs of packages  In NetBSD, Xen is provided in pkgsrc, via matching pairs of packages
 xenkernel and xentools.  We will refer only to the kernel versions,  xenkernel and xentools.  We will refer only to the kernel versions,
 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 and xenkernel33 provide Xen 3.1 and 3.3.  These no longer  xenkernel3 provides Xen 3.1.  It is no longer maintained by Xen, and the last applied security patch was in
 receive security patches and should not be used.  Xen 3.1 supports PCI  2011. Thus, it should not be used.  It supports PCI passthrough,
 passthrough.  Xen 3.1 supports non-PAE on i386.  which is why people use it anyway. Xen 3.1 supports i386, both PAE and
   non-PAE.
   
   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
   used.  Xen 3.3 supports i386, but only in PAE mode.  There are no good
   reasons to run this version.
   
   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
   i386, but only in PAE mode.  There are no good reasons to run this
   version.
   
   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
   i386, but only in PAE mode.  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
   (because your hardware is i386 only).
   
   xenkernel45 provides Xen 4.5.  As of 2016-12, security patches were
   released by Xen and applied to pkgsrc.  Xen 4.5 requires an amd64
   dom0, but domUs can be amd64 or i386 PAE.  TODO: It is either a
   conservative choice or somewhat old.
   
   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
   pkgsrc.  Xen 4.6 requires an amd64 dom0, but domUs can be amd64 or
   i386 PAE.  TODO: It is either a somewhat aggressive choice or the
   standard choice
   
 xenkernel41 provides Xen 4.1.  This is no longer maintained by Xen,  Xen 4.7 (released 2016-06) and 4.8 (released 2016-12) are not yet in
 but as of 2014-12 receives backported security patches.  It is a  pkgsrc.
 reasonable although trailing-edge choice.  
   
 xenkernel42 provides Xen 4.2.  This is maintained by Xen, but old as  See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/).
 of 2014-12.  
   
 Ideally newer versions of Xen will be added to pkgsrc.  Note that NetBSD support is called XEN3.  It works with Xen 3 and Xen
   4 because the hypercall interface has been stable.
 Note that NetBSD support is called XEN3.  It works with 3.1 through  
 4.2 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.
   However, the rc.d scripts provided by xentools packages expect a
   particular version, and you should use the version used by the
   scripts.
   
 NetBSD  NetBSD
 ------  ------
   
 The netbsd-5, netbsd-6, netbsd-7, and -current branches are all  The netbsd-6, netbsd-7, and -current branches are all reasonable
 reasonable choices, with more or less the same considerations for  choices, with more or less the same considerations for non-Xen use.
 non-Xen use.  Therefore, netbsd-6 is recommended as the stable version  Therefore, netbsd-7 is recommended as the stable version of the most
 of the most recent release for production use.  For those wanting to  recent release for production use.  For those wanting to learn Xen or
 learn Xen or without production stability concerns, netbsd-7 is likely  without production stability concerns, netbsd-7 is still likely most
 most appropriate.  appropriate, but -current is also a reasonable choice.  Xen runs fine
   on netbsd-5, but the xentools packages are likely difficult to build.
   
 As of NetBSD 6, a NetBSD domU will support multiple vcpus.  There is  As of NetBSD 6, a NetBSD domU will support multiple vcpus.  There is
 no SMP support for NetBSD as dom0.  (The dom0 itself doesn't really  no SMP support for NetBSD as dom0.  (The dom0 itself doesn't really
 need SMP; the lack of support is really a problem when using a dom0 as  need SMP for dom0 functions; the lack of support is really a problem
 a normal computer.)  when using a dom0 as a normal computer.)
   
 Architecture  Architecture
 ------------  ------------
   
 Xen itself can run on i386 or amd64 machines.  (Practically, almost  Xen itself can run on i386 (Xen < 3.1) or amd64 machines (all Xen
 any computer where one would want to run Xen supports amd64.)  If  versions).  (Practically, almost any computer where one would want to
 using an i386 NetBSD kernel for the dom0, PAE is required (PAE  run Xen today supports amd64.)
 versions are built by default).  While i386 dom0 works fine, amd64 is  
 recommended as more normal.  Xen, the dom0 kernel, and each domU kernel can be either i386 or
   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 i386PAE dom0
   kernel should in theory work.  An amd64 Xen/dom0 is known to support
   both i386PAE and amd64 domUs.
   
   i386 dom0 and domU kernels must be PAE (except for Xen 3.1); 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.
   
 One can then run i386 domUs and amd64 domUs, in any combination.  If   - [PR 48125](http://gnats.netbsd.org/48125)
 running an i386 NetBSD kernel as a domU, the PAE version is required.   - [PR 47720](http://gnats.netbsd.org/47720)
 (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.)  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)
   instances in support of virtual disks in a dom0.
   
 Recommendation  Recommendation
 --------------  --------------
   
 Therefore, this HOWTO recommends running xenkernel42 (and xentools42),  Therefore, this HOWTO recommends running xenkernel45 or xenkernel46,
 xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the  xl, the NetBSD 7 stable branch, and to use an amd64 kernel as the
 dom0.  Either the i386 or amd64 of NetBSD may be used as domUs.  dom0.  Either the i386PAE or amd64 version of NetBSD may be used as
   domUs.
   
 Build problems  Build problems
 --------------  --------------
Line 210  dom0 is what the computer would have bee Line 264  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 231  However, the partitioning approach is ve Line 285  However, the partitioning approach is ve
 If you want to use RAIDframe for the dom0, there are no special issues  If you want to use RAIDframe for the dom0, there are no special issues
 for Xen.  Typically one provides RAID storage for the dom0, and the  for Xen.  Typically one provides RAID storage for the dom0, and the
 domU systems are unaware of RAID.  The 2nd-stage loader bootxx_* skips  domU systems are unaware of RAID.  The 2nd-stage loader bootxx_* skips
 over a RAID1 header to find /boot from a filesystem within a RAID  over a RAID1 header to find /boot from a file system within a RAID
 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 247  for domU disks.  This is almost as effic Line 301  for domU disks.  This is almost as effic
 and more flexible.  Hence raw disk partitions should typically not  and more flexible.  Hence raw disk partitions should typically not
 be used.  be used.
   
 One can use files in the dom0 filesystem, typically created by dd'ing  One can use files in the dom0 file system, typically created by dd'ing
 /dev/zero to create a specific size.  This is somewhat less efficient,  /dev/zero to create a specific size.  This is somewhat less efficient,
 but very convenient, as one can cp the files for backup, or move them  but very convenient, as one can cp the files for backup, or move them
 between dom0 hosts.  between dom0 hosts.
Line 274  For debugging, one may copy xen-debug.gz Line 328  For debugging, one may copy xen-debug.gz
 to DIAGNOSTIC and DEBUG in NetBSD.  xen-debug.gz is basically only  to DIAGNOSTIC and DEBUG in NetBSD.  xen-debug.gz is basically only
 useful with a serial console.  Then, place a NetBSD XEN3_DOM0 kernel  useful with a serial console.  Then, place a NetBSD XEN3_DOM0 kernel
 in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz  in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
 of a NetBSD build.  Both xen and NetBSD may be left compressed.  (If  of a NetBSD build.  If using i386, use
 using i386, use releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.)  releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.  (If using Xen
   3.1 and i386, you may use XEN3_DOM0 with the non-PAE Xen.  But you
 With Xen as the kernel, you must provide a dom0 NetBSD kernel to be  should not use Xen 3.1.)  Both xen and the NetBSD kernel may be (and
 used as a module; place this in /.  Suitable kernels are provided in  typically are) left compressed.
 releasedir/binary/kernel:  
   In a dom0 kernel, kernfs is mandatory for xend to communicate with the
         i386 XEN3_DOM0  kernel, so ensure that /kern is in fstab.  TODO: Say this is default,
         i386 XEN3PAE_DOM0  or file a PR and give a reference.
         amd64 XEN3_DOM0  
   
 The first one is only for use with Xen 3.1 and i386-mode Xen (and you  
 should not do this).  Current Xen always uses PAE on i386, but you  
 should generally use amd64 for the dom0.  In a dom0 kernel, kernfs is  
 mandatory for xend to comunicate with the kernel, so ensure that /kern  
 is in fstab.  TODO: Say this is default, or file a PR and give a  
 reference.  
   
 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 filesystem, /boot present, and likely  beginning of your root file system, /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.  In an attempt to add performance, one can also  allocated for domUs.  To use a serial console, use
 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 than 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 332  Configuring Xen Line 392  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 daemons.
 is using xm or xl.  Note that xend is for supporting "xm", and should  
 only be used if you plan on using "xm".  Do NOT enable xend if you  The daemons which should be run vary with Xen version and with whether
 plan on using "xl" as it will cause problems.  one is using xm or xl.  The Xen 3.1 and 3.3 packages use xm.  Xen 4.1
   and higher packages use xl.  While is is possible to use xm with some
   4.x versions (TODO: 4.1 and 4.2?), the pkgsrc-provided rc.d scripts do
   not support this as of 2014-12-26, and thus the HOWTO does not support
   it either.  (Make sure your packages are reasonably recent.)
   
 The installation of NetBSD should already have created devices for xen  For "xm" (3.1 and 3.3), you should enable xend and xenbackendd (but
 (xencons, xenevt), but if they are not present, create them:  note that you should be using 4.x):
   
         cd /dev && sh MAKEDEV xen  
   
 TODO: Give 3.1 advice (or remove it from pkgsrc).  
   
 For 3.3 (and thus xm), add to rc.conf (but note that you should have  
 installed 4.1 or 4.2):  
   
         xend=YES          xend=YES
         xenbackendd=YES          xenbackendd=YES
   
 For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:  For "xl" (4.x), you should enabled xend and xencommons (xenstored).
   Trying to boot 4.x without xencommons=YES will result in a hang; it is
   necessary to hit ^C on the console to let the machine finish booting.
   TODO: explain why xend is installed by the package.
   
         xencommons=YES          xencommons=YES
         xend=YES  
   
 (If you are using xentools41 from before 2014-12-26, change  
 rc.d/xendomains to use xm rather than xl.)  
   
 For 4.2 with xm, add to rc.conf  
   
         xencommons=YES  The installation of NetBSD should already have created devices for xen
         xend=YES  (xencons, xenevt), but if they are not present, create them:
   
 For 4.2 with xl (preferred), add to rc.conf:  
   
         xencommons=YES          cd /dev && sh MAKEDEV xen
         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
 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 xl follows:
   
         # xm dmesg          # xl dmesg
         [xen's boot info]          [xen's boot info]
         # xm info          # xl info
         [available memory, etc.]          [available memory, etc.]
         # xm list          # xl list
         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
   
 anita (for testing NetBSD)  ### Issues with xencommons
 --------------------------  
   
 With the setup so far, one should be able to run anita (see  
 pkgsrc/sysutils/py-anita) to test NetBSD releases, by doing (as root,  
 because anita must create a domU):  
   
         anita --vmm=xm test file:///usr/obj/i386/  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.
   
 Alternatively, one can use --vmm=xl to use xl-based domU creation instead.  anita (for testing NetBSD)
 TODO: check this.  --------------------------
   
   With the setup so far (assuming 4.2/xl), one should be able to run
   anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as
   root, because anita must create a domU):
   
           anita --vmm=xl test file:///usr/obj/i386/
   
   Alternatively, one can use --vmm=xm to use xm-based domU creation
   instead (and must, on Xen <= 4.1).   TODO: confirm that anita xl really works.
       
 Xen-specific NetBSD issues  Xen-specific NetBSD issues
 --------------------------  --------------------------
   
 There are (at least) two additional things different about NetBSD as a  There are (at least) two additional things different about NetBSD as a
 dom0 kernel compared to hardware.  dom0 kernel compared to hardware.
   
 One is that modules are not usable in DOM0 kernels, so one must  One is that the module ABI is different because some of the #defines
 compile in what's needed.  It's not really that modules cannot work,  change, so one must build modules for Xen.  As of netbsd-7, the build
 but that modules must be built for XEN3_DOM0 because some of the  system does this automatically.  TODO: check this.  (Before building
 defines change and the normal module builds don't do this.  Basically,  Xen modules was added, it was awkward to use modules to the point
 enabling Xen changes the kernel ABI, and the module build system  where it was considered that it did not work.)
 doesn't cope with this.  
   
 The other difference is that XEN3_DOM0 does not have exactly the same  The other difference is that XEN3_DOM0 does not have exactly the same
 options as GENERIC.  While it is debatable whether or not this is a  options as GENERIC.  While it is debatable whether or not this is a
Line 436  over time.  Before these commands, it wa Line 498  over time.  Before these commands, it wa
 4.1 and grub, much like the message linked earlier in the grub  4.1 and grub, much like the message linked earlier in the grub
 section.  section.
   
         # Install mbr bootblocks on both disks.           # Install MBR bootblocks on both disks. 
         fdisk -i /dev/rwd0d          fdisk -i /dev/rwd0d
         fdisk -i /dev/rwd1d          fdisk -i /dev/rwd1d
         # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.          # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
Line 444  section. Line 506  section.
         installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1          installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
         # Install secondary boot loader          # Install secondary boot loader
         cp -p /usr/mdec/boot /          cp -p /usr/mdec/boot /
         # Create boog.cfg following earlier guidance:          # Create boot.cfg following earlier guidance:
         menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M          menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
         menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=256M          menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=256M
         menu=GENERIC:boot          menu=GENERIC:boot
Line 457  section. Line 519  section.
   
 TODO: actually do this and fix it if necessary.  TODO: actually do this and fix it if necessary.
   
 Updating Xen versions  Upgrading Xen versions
 ---------------------  ---------------------
   
 Updating Xen is conceptually not difficult, but can run into all the  Minor version upgrades are trivial.  Just rebuild/replace the
 issues found when installing Xen.  Assuming migration from 4.1 to 4.2,  xenkernel version and copy the new xen.gz to / (where /boot.cfg
 remove the xenkernel41 and xentools41 packages and install the  references it), and reboot.
 xenkernel42 and xentools42 packages.  Copy the 4.2 xen.gz to /.  
   Major version upgrades are conceptually not difficult, but can run
 Ensure that the contents of /etc/rc.d/xen* are correct.  Enable the  into all the issues found when installing Xen.  Assuming migration
 correct set of daemons.  Ensure that the domU config files are valid  from 4.1 to 4.2, remove the xenkernel41 and xentools41 packages and
 for the new version.  install the xenkernel42 and xentools42 packages.  Copy the 4.2 xen.gz
   to /.
   
   Ensure that the contents of /etc/rc.d/xen* are correct.  Specifically,
   they must match the package you just installed and not be left over
   from some previous installation.
   
   Enable the correct set of daemons; see the configuring section above.
   (Upgrading from 3.x to 4.x without doing this will result in a hang.)
   
   Ensure that the domU config files are valid for the new version.
   Specifically, for 4.x remove autorestart=True, and ensure that disks
   are specified with numbers as the second argument, as the examples
   above show, and not NetBSD device names.
   
   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 479  config files for domUs are typically in  Line 591  config files for domUs are typically in 
 typically named so that the file name, domU name and the domU's host  typically named so that the file name, domU name and the domU's host
 name match.  name match.
   
 The domU is provided with cpu and memory by Xen, configured by the  The domU is provided with CPU and memory by Xen, configured by the
 dom0.  The domU is provided with disk and network by the dom0,  dom0.  The domU is provided with disk and network by the dom0,
 mediated by Xen, and configured in the dom0.  mediated by Xen, and configured in the dom0.
   
Line 516  domUs independently.  The vif line cause Line 628  domUs independently.  The vif line cause
 with a specific mac address (do not reuse MAC addresses!), in bridge  with a specific mac address (do not reuse MAC addresses!), in bridge
 mode.  Two disks are provided, and they are both writable; the bits  mode.  Two disks are provided, and they are both writable; the bits
 are stored in files and Xen attaches them to a vnd(4) device in the  are stored in files and Xen attaches them to a vnd(4) device in the
 dom0 on domain creation.  The system treates xbd0 as the boot device  dom0 on domain creation.  The system treats xbd0 as the boot device
 without needing explicit configuration.  without needing explicit configuration.
   
 By default xm looks for domain config files in /usr/pkg/etc/xen.  Note  By default xm looks for domain config files in /usr/pkg/etc/xen.  Note
Line 530  domain, and see if it has finished stopp Line 642  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 542  domU kernels Line 654  domU kernels
   
 On a physical computer, the BIOS reads sector 0, and a chain of boot  On a physical computer, the BIOS reads sector 0, and a chain of boot
 loaders finds and loads a kernel.  Normally this comes from the root  loaders finds and loads a kernel.  Normally this comes from the root
 filesystem.  With Xen domUs, the process is totally different.  The  file system.  With Xen domUs, the process is totally different.  The
 normal path is for the domU kernel to be a file in the dom0's  normal path is for the domU kernel to be a file in the dom0's
 filesystem.  At the request of the dom0, Xen loads that kernel into a  file system.  At the request of the dom0, Xen loads that kernel into a
 new domU instance and starts execution.  While domU kernels can be  new domU instance and starts execution.  While domU kernels can be
 anyplace, reasonable places to store domU kernels on the dom0 are in /  anyplace, reasonable places to store domU kernels on the dom0 are in /
 (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the  (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
Line 559  CPU and memory Line 671  CPU and memory
 --------------  --------------
   
 A domain is provided with some number of vcpus, less than the number  A domain is provided with some number of vcpus, less than the number
 of cpus seen by the hypervisor.  (For a dom0, this is controlled by  of CPUs seen by the hypervisor.  (For a dom0, this is controlled by
 the boot argument "dom0_max_vcpus=1".)  For a domU, it is controlled  the boot argument "dom0_max_vcpus=1".)  For a domU, it is controlled
 from the config file by the "vcpus = N" directive.  from the config file by the "vcpus = N" directive.
   
Line 590  create an empty 4G virtual disk, simply  Line 702  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 619  disks. Line 735  disks.
 Virtual Networking  Virtual Networking
 ------------------  ------------------
   
 Xen provides virtual ethernets, each of which connects the dom0 and a  Xen provides virtual Ethernets, each of which connects the dom0 and a
 domU.  For each virtual network, there is an interface "xvifN.M" in  domU.  For each virtual network, there is an interface "xvifN.M" in
 the dom0, and in domU index N, a matching interface xennetM (NetBSD  the dom0, and in domU index N, a matching interface xennetM (NetBSD
 name).  The interfaces behave as if there is an Ethernet with two  name).  The interfaces behave as if there is an Ethernet with two
 adaptors connected.  From this primitive, one can construct various  adapters connected.  From this primitive, one can construct various
 configurations.  We focus on two common and useful cases for which  configurations.  We focus on two common and useful cases for which
 there are existing scripts: bridging and NAT.  there are existing scripts: bridging and NAT.
   
Line 667  shutdown, in rc.conf add: Line 783  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 script
 on 4.1.  Or fix the xentools41 package to have xm  used xl, when one should use xm with 4.1.
   
 Creating specific unprivileged domains (domU)  Creating specific unprivileged domains (domU)
 =============================================  =============================================
Line 684  Creating an unprivileged NetBSD domain ( Line 800  Creating an unprivileged NetBSD domain (
 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).
   
 While the kernel will be obtained from the dom0 filesystem, the same  While the kernel will be obtained from the dom0 file system, the same
 file should be present in the domU as /netbsd so that tools like  file should be present in the domU as /netbsd so that tools like
 savecore(8) can work.   (This is helpful but not necessary.)  savecore(8) can work.   (This is helpful but not necessary.)
   
Line 693  i386 and amd64 provide the following ker Line 809  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 746  It is also desirable to add Line 862  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
   file system.  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 780  Then copy the files from a working Linux Line 902  Then copy the files from a working Linux
 `/etc` (fstab, network config).  It should also be possible to extract  `/etc` (fstab, network config).  It should also be possible to extract
 binary packages such as .rpm or .deb directly to the mounted partition  binary packages such as .rpm or .deb directly to the mounted partition
 using the appropriate tool, possibly running under NetBSD's Linux  using the appropriate tool, possibly running under NetBSD's Linux
 emulation.  Once the filesystem has been populated, umount it.  If  emulation.  Once the file system has been populated, umount it.  If
 desirable, the filesystem can be converted to ext3 using tune2fs -j.  desirable, the file system can be converted to ext3 using tune2fs -j.
 It should now be possible to boot the Linux guest domain, using one of  It should now be possible to boot the Linux guest domain, using one of
 the vmlinuz-\*-xenU kernels available in the Xen binary distribution.  the vmlinuz-\*-xenU kernels available in the Xen binary distribution.
   
 To get the linux console right, you need to add:  To get the Linux console right, you need to add:
   
     extra = "xencons=tty1"      extra = "xencons=tty1"
   
 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 an unprivileged Solaris domain (domU)  Creating an unprivileged Solaris domain (domU)
Line 833  the domU's config file, with the format  Line 955  the domU's config file, with the format 
         pci = [ '0000:00:06.0', '0000:00:0a.0' ]          pci = [ '0000:00:06.0', '0000:00:0a.0' ]
   
 In the domU an "xpci" device will show up, to which one or more pci  In the domU an "xpci" device will show up, to which one or more pci
 busses will attach.  Then the PCI drivers will attach to PCI busses as  buses will attach.  Then the PCI drivers will attach to PCI buses as
 usual.  Note that the default NetBSD DOMU kernels do not have "xpci"  usual.  Note that the default NetBSD DOMU kernels do not have "xpci"
 or any PCI drivers built in by default; you have to build your own  or any PCI drivers built in by default; you have to build your own
 kernel to use PCI devices in a domU.  Here's a kernel config example;  kernel to use PCI devices in a domU.  Here's a kernel config example;
Line 841  note that only the "xpci" lines are unus Line 963  note that only the "xpci" lines are unus
   
         include         "arch/i386/conf/XEN3_DOMU"          include         "arch/i386/conf/XEN3_DOMU"
   
         # Add support for PCI busses to the XEN3_DOMU kernel          # Add support for PCI buses to the XEN3_DOMU kernel
         xpci* at xenbus ?          xpci* at xenbus ?
         pci* at xpci ?          pci* at xpci ?
   
Line 880  only a few are mentioned that specifical Line 1002  only a few are mentioned that specifical
   
 VPS operators provide varying degrees of access and mechanisms for  VPS operators provide varying degrees of access and mechanisms for
 configuration.  The big issue is usually how one controls which kernel  configuration.  The big issue is usually how one controls which kernel
 is booted, because the kernel is nominally in the dom0 filesystem (to  is booted, because the kernel is nominally in the dom0 file system (to
 which VPS users do not normally have acesss).  A second issue is how  which VPS users do not normally have access).  A second issue is how
 to install NetBSD.  to install NetBSD.
 A VPS user may want to compile a kernel for security updates, to run  A VPS user may want to compile a kernel for security updates, to run
 npf, run IPsec, or any other reason why someone would want to change  npf, run IPsec, or any other reason why someone would want to change
 their kernel.  their kernel.
   
 One approach is to have an adminstrative interface to upload a kernel,  One approach is to have an administrative interface to upload a kernel,
 or to select from a prepopulated list.  Other approaches are pygrub  or to select from a prepopulated list.  Other approaches are pygrub
 (deprecated) and pvgrub, which are ways to have a bootloader obtain a  (deprecated) and pvgrub, which are ways to have a bootloader obtain a
 kernel from the domU filesystem.  This is closer to a regular physical  kernel from the domU file system.  This is closer to a regular physical
 computer, where someone who controls a machine can replace the kernel.  computer, where someone who controls a machine can replace the kernel.
   
 A second issue is multiple CPUs.  With NetBSD 6, domUs support  A second issue is multiple CPUs.  With NetBSD 6, domUs support
Line 900  CPUs for NetBSD domUs. Line 1022  CPUs for NetBSD domUs.
 pygrub  pygrub
 -------  -------
   
 pygrub runs in the dom0 and looks into the domU filesystem.  This  pygrub runs in the dom0 and looks into the domU file system.  This
 implies that the domU must have a kernel in a filesystem in a format  implies that the domU must have a kernel in a file system in a format
 known to pygrub.  As of 2014, pygrub seems to be of mostly historical  known to pygrub.  As of 2014, pygrub seems to be of mostly historical
 interest.  interest.
   
Line 910  pvgrub Line 1032  pvgrub
   
 pvgrub is a version of grub that uses PV operations instead of BIOS  pvgrub is a version of grub that uses PV operations instead of BIOS
 calls.  It is booted from the dom0 as the domU kernel, and then reads  calls.  It is booted from the dom0 as the domU kernel, and then reads
 /grub/menu.lst and loads a kernel from the domU filesystem.  /grub/menu.lst and loads a kernel from the domU file system.
   
 [Panix](http://www.panix.com/) lets users use pvgrub.  Panix reports  [Panix](http://www.panix.com/) lets users use pvgrub.  Panix reports
 that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes  that pvgrub works with FFsv2 with 16K/2K and 32K/4K block/frag sizes
Line 929  does not support all aspects of modern F Line 1051  does not support all aspects of modern F
 that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT  that FFSv2 works fine.  At prgmr, typically one has an ext2 or FAT
 partition for the kernel with the intent that grub can understand it,  partition for the kernel with the intent that grub can understand it,
 which leads to /netbsd not being the actual kernel.  One must remember  which leads to /netbsd not being the actual kernel.  One must remember
 to update the special boot partiion.  to update the special boot partition.
   
 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
     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 filesystem 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](http://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
   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

Removed from v.1.74  
changed lines
  Added in v.1.115


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