Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.29 and 1.38

version 1.29, 2014/12/24 15:17:25 version 1.38, 2014/12/24 16:07:32
Line 149  Recommendation Line 149  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.
   
   Build problems
   --------------
   
   Ideally, all versions of Xen in pkgsrc would build on all versions of
   NetBSD on both i386 and amd64.  However, that isn't the case.  Besides
   aging code and aging compilers, qemu (included in xentools for HVM
   support) is difficult to build.  The following are known to fail:
   
           xenkernel3 netbsd-6 i386
           xentools42 netbsd-6 i386 
   
   The following are known to work:
   
           xenkernel41 netbsd-5 amd64
           xentools41 netbsd-5 amd64
           xenkernel41 netbsd-6 i386
           xentools41 netbsd-6 i386
   
 NetBSD as a dom0  NetBSD as a dom0
 ================  ================
Line 251  beginning of your root filesystem, /boot Line 269  beginning of your root filesystem, /boot
   
 See boot.cfg(5) for an example.  The basic line is  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.  allocated for domUs.  In an attempt to add performance, one can also
   add
   
           dom0_max_vcpus=1 dom0_vcpus_pin
   
   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.
   
 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
Line 271  Configuring Xen Line 295  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.
   
   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
           xenbackendd=YES
   
   For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:
   
           xend=YES
           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
   
 For 3.3 (and probably 3.1), add to rc.conf (but note that you should          xend=YES
 have installed 4.2):          xencommons=YES
   xend=YES  
   xenbackendd=YES  For 4.2 with xl (preferred), add to rc.conf:
   
 For 4.1 and 4.2, add to rc.conf:          TODO: explain if there is a xend replacement
   xend=YES          xencommons=YES
   xencommons=YES  
   TODO: Recommend for/against xen-watchdog.
 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  After you have configured the daemons and rebooted, run the following
 "xl" as it will cause problems.  (or use xl) 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 319  Unprivileged domains (domU) Line 370  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.
   
 TODO: Explain that domUs get cpu, memory, disk and network.  CPU and memory
 Explain that randomness can be an issue.  --------------
   
   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 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 349  dom0.  This is often appropriate when ru Line 432  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 513  working vif-bridge is also provided with Line 608  working vif-bridge is also provided with
   
     #!/bin/sh      #!/bin/sh
     #============================================================================      #============================================================================
     # $NetBSD: howto.mdwn,v 1.28 2014/12/24 14:35:23 gdt Exp $      # $NetBSD: howto.mdwn,v 1.37 2014/12/24 16:06:38 gdt Exp $
     #      #
     # /usr/pkg/etc/xen/vif-bridge      # /usr/pkg/etc/xen/vif-bridge
     #      #

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