Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.28 and 1.33

version 1.28, 2014/12/24 14:35:23 version 1.33, 2014/12/24 15:54:50
Line 27  code for Xen and need not be aware that  Line 27  code for Xen and need not be aware that 
 Attempts to access hardware registers are trapped and emulated.  This  Attempts to access hardware registers are trapped and emulated.  This
 style is less efficient but can run unmodified guests.  style is less efficient but can run unmodified guests.
   
 Generally any amd64 machine will work with Xen and PV guests.  For  Generally any amd64 machine will work with Xen and PV guests.  In
 HVM guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT (amd64)  theory i386 computers without amd64 support can be used for Xen <=
 is needed; "cpuctl identify 0" will show this.  Xen 4.2 is the last  4.2, but we have no recent reports of this working (this is a hint).
 version for support for using i386 as a host.  TODO: Clean up and  For HVM guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT
 check the above features.  (amd64) is needed; "cpuctl identify 0" will show this.  TODO: Clean up
   and check the above features.
   
 At boot, the dom0 kernel is loaded as a module with Xen as the kernel.  At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
 The dom0 can start one or more domUs.  (Booting is explained in detail  The dom0 can start one or more domUs.  (Booting is explained in detail
Line 89  matching versions. Line 90  matching versions.
   
 xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3.  These no longer  xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3.  These no longer
 receive security patches and should not be used.  Xen 3.1 supports PCI  receive security patches and should not be used.  Xen 3.1 supports PCI
 passthrough.  passthrough.  Xen 3.1 supports non-PAE on i386.
   
 xenkernel41 provides Xen 4.1.  This is no longer maintained by Xen,  xenkernel41 provides Xen 4.1.  This is no longer maintained by Xen,
 but as of 2014-12 receives backported security patches.  It is a  but as of 2014-12 receives backported security patches.  It is a
Line 117  NetBSD Line 118  NetBSD
 The netbsd-5, netbsd-6, netbsd-7, and -current branches are all  The netbsd-5, netbsd-6, netbsd-7, and -current branches are all
 reasonable choices, with more or less the same considerations for  reasonable choices, with more or less the same considerations for
 non-Xen use.  Therefore, netbsd-6 is recommended as the stable version  non-Xen use.  Therefore, netbsd-6 is recommended as the stable version
 of the most recent release.  of the most recent release for production use.  For those wanting to
   learn Xen or without production stability concerns, netbsd-7 is likely
   most appropriate.
   
 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
Line 127  a normal computer.) Line 130  a normal computer.)
 Architecture  Architecture
 ------------  ------------
   
 Xen is basically amd64 only at this point.  One can either run i386  Xen itself can run on i386 or amd64 machines.  (Practically, almost
 domains or amd64 domains.  If running i386, PAE versions are required,  any computer where one would want to run Xen supports amd64.)  If
 for both dom0 and domU.  These versions are built by default in NetBSD  using an i386 NetBSD kernel for the dom0, PAE is required (PAE
 releases.  While i386 dom0 works fine, amd64 is recommended as more  versions are built by default).  While i386 dom0 works fine, amd64 is
 normal.  (Note that emacs (at least) fails if run on i386 with PAE when  recommended as more normal.
 built without, and vice versa, presumably due to bugs in the undump  
 code.)  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
   having to be amd64.
   
   One can then run i386 domUs and amd64 domUs, in any combination.  If
   running an i386 NetBSD kernel as a domU, the PAE version is required.
   (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
 --------------  --------------
   
 Therefore, this HOWTO recommends running xenkernel42 (and xentools42),  Therefore, this HOWTO recommends running xenkernel42 (and xentools42),
 xl, the NetBSD 6 stable branch, and to use amd64 as the dom0.  Either  xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the
 the i386 or amd64 of NetBSD may be used as domUs.  dom0.  Either the i386 or amd64 of NetBSD may be used as domUs.
   
 NetBSD as a dom0  NetBSD as a dom0
 ================  ================
Line 261  Configuring Xen Line 271  Configuring 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, and
 just run the dom0 kernel.  There will be no domUs, and none can be  just run the dom0 kernel.  There will be no domUs, and none can be
 started because you still have to configure the dom0 tools.  started because you still have to configure the dom0 tools.  The
   daemons which should be run vary 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 using "xm".  Do NOT enable xend if you
   plan on using "xl" as it will cause problems.
   
 For 3.3 (and probably 3.1), add to rc.conf (but note that you should  TODO: Give 3.1 advice (or remove it from pkgsrc).
 have installed 4.2):  
   xend=YES  For 3.3 (and thus xm), add to rc.conf (but note that you should have
   xenbackendd=YES  installed 4.1 or 4.2):
   
 For 4.1 and 4.2, add to rc.conf:          xend=YES
   xend=YES          xenbackendd=YES
   xencommons=YES  
   For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:
 Note that 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          xend=YES
 "xl" as it will cause problems.          xencommons=YES
   
   TODO: Explain why if xm is preferred on 4.1, rc.d/xendomains has xl.
   Or fix the package.
   
   For 4.2 with xm, add to rc.conf
   
           xend=YES
           xencommons=YES
   
   For 4.2 with xl (preferred), add to rc.conf:
   
           TODO: explain if there is a xend replacement
           xencommons=YES
   
   TODO: Recommend for/against xen-watchdog.
   
   After you have configured the daemons and rebooted, run the following
   to inspect Xen's boot messages, available resources, and running
   domains:
           xm dmesg
           xm info
           xm list
   
 Updating NetBSD in a dom0  Updating NetBSD in a dom0
 -------------------------  -------------------------
Line 309  Unprivileged domains (domU) Line 345  Unprivileged domains (domU)
 ===========================  ===========================
   
 This section describes general concepts about domUs.  It does not  This section describes general concepts about domUs.  It does not
 address specific domU operating systems or how to install them.  address specific domU operating systems or how to install them.  The
   config files for domUs are typically in /usr/pkg/etc/xen, and are
   typically named so that the file anme, domU name and the domU's host
   name match.
   
   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,
   mediated by Xen, and configured in the dom0.
   
 Provided Resources for PV domains  Entropy in domUs can be an issue; physical disks and network are on
 ---------------------------------  the dom0.  NetBSD's /dev/random system works, but is often challenged.
   
   CPU and memory
   --------------
   
 TODO: Explain that domUs get cpu, memory, disk and network.  A domain is provided with some number of vcpus, less than the
 Explain that randomness can be an issue.  number 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
   from the config file.
   
   A domain is provided with memory, In the straightforward case, the sum
   of the the memory allocated to the dom0 and all domUs must be less
   than the available memory.
   
   Xen also provides a "balloon" driver, which can be used to let domains
   use more memory temporarily.  TODO: Explain better, and explain how
   well it works with NetBSD.
   
 Virtual disks  Virtual disks
 -------------  -------------
   
 TODO: Explain how to set up files for vnd and that one should write all zeros to preallocate.  With the file/vnd style, typically one creates a directory,
 TODO: Explain in what NetBSD versions sparse vnd files do and don't work.  e.g. /u0/xen, on a disk large enough to hold virtual disks for all
   domUs.  Then, for each domU disk, one writes zeros to a file that then
   serves to hold the virtual disk's bits; a suggested name is foo-xbd0
   for the first virtual disk for the domU called foo.  Writing zeros to
   the file serves two purposes.  One is that preallocating the contents
   improves performance.  The other is that vnd on sparse files has
   failed to work.  TODO: give working/notworking NetBSD versions for
   sparse vnd.  Note that the use of file/vnd for Xen is not really
   different than creating a file-backed virtual disk for some other
   purpose, except that xentools handles the vnconfig commands.
   
   With the lvm style, one creates logical devices.  They are then used
   similarly to vnds.
   
 Virtual Networking  Virtual Networking
 ------------------  ------------------
Line 339  dom0.  This is often appropriate when ru Line 407  dom0.  This is often appropriate when ru
 One can construct arbitrary other configurations, but there is no  One can construct arbitrary other configurations, but there is no
 script support.  script support.
   
   Sizing domains
   --------------
   
   Modern x86 hardware has vast amounts of resources.  However, many
   virtual servers can function just fine on far less.  A system with
   256M of RAM and a 4G disk can be a reasonable choice.  Note that it is
   far easier to adjust virtual resources than physical ones.  For
   memory, it's just a config file edit and a reboot.  For disk, one can
   create a new file and vnconfig it (or lvm), and then dump/restore,
   just like updating physical disks, but without having to be there and
   without those pesky connectors.
   
 Config files  Config files
 ------------  ------------
   
Line 503  working vif-bridge is also provided with Line 583  working vif-bridge is also provided with
   
     #!/bin/sh      #!/bin/sh
     #============================================================================      #============================================================================
     # $NetBSD: howto.mdwn,v 1.27 2014/12/24 08:32:49 jnemeth Exp $      # $NetBSD: howto.mdwn,v 1.32 2014/12/24 15:31:36 gdt Exp $
     #      #
     # /usr/pkg/etc/xen/vif-bridge      # /usr/pkg/etc/xen/vif-bridge
     #      #

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  Added in v.1.33


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