Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.57 and 1.75

version 1.57, 2014/12/27 00:33:45 version 1.75, 2015/01/17 01:32:12
Line 4  Introduction Line 4  Introduction
 [![[Xen  [![[Xen
 screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](http://www.netbsd.org/gallery/in-Action/hubertf-xen.png)  screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](http://www.netbsd.org/gallery/in-Action/hubertf-xen.png)
   
 Xen is a virtual machine monitor or hypervisor for x86 hardware  Xen is a hypervisor (or virtual machine monitor) for x86 hardware
 (i686-class or higher), which supports running multiple guest  (i686-class or higher), which supports running multiple guest
 operating systems on a single physical machine.  With Xen, one uses  operating systems on a single physical machine.  Xen is a Type 1 or
 the Xen kernel to control the CPU, memory and console, a dom0  bare-metal hypervisor; one uses the Xen kernel to control the CPU,
 operating system which mediates access to other hardware (e.g., disks,  memory and console, a dom0 operating system which mediates access to
 network, USB), and one or more domU operating systems which operate in  other hardware (e.g., disks, network, USB), and one or more domU
 an unprivileged virtualized environment.  IO requests from the domU  operating systems which operate in an unprivileged virtualized
 systems are forwarded by the hypervisor (Xen) to the dom0 to be  environment.  IO requests from the domU systems are forwarded by the
 fulfilled.  hypervisor (Xen) to the dom0 to be fulfilled.
   
 Xen supports two styles of guests.  The original is Para-Virtualized  Xen supports two styles of guests.  The original is Para-Virtualized
 (PV) which means that the guest OS does not attempt to access hardware  (PV) which means that the guest OS does not attempt to access hardware
Line 151  Build problems Line 151  Build problems
 Ideally, all versions of Xen in pkgsrc would build on all versions of  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  NetBSD on both i386 and amd64.  However, that isn't the case.  Besides
 aging code and aging compilers, qemu (included in xentools for HVM  aging code and aging compilers, qemu (included in xentools for HVM
 support) is difficult to build.  The following are known to fail:  support) is difficult to build.  The following are known to work or FAIL:
   
         xenkernel3 netbsd-6 i386  
         xentools42 netbsd-6 i386   
   
 The following are known to work:  
   
           xenkernel3 netbsd-5 amd64
           xentools3 netbsd-5 amd64
           xentools3=hvm netbsd-5 amd64 ????
           xenkernel33 netbsd-5 amd64
           xentools33 netbsd-5 amd64
         xenkernel41 netbsd-5 amd64          xenkernel41 netbsd-5 amd64
         xentools41 netbsd-5 amd64          xentools41 netbsd-5 amd64
           xenkernel42 netbsd-5 amd64
           xentools42 netbsd-5 amd64
   
           xenkernel3 netbsd-6 i386 FAIL
           xentools3 netbsd-6 i386
           xentools3-hvm netbsd-6 i386 FAIL (dependencies fail)
           xenkernel33 netbsd-6 i386
           xentools33 netbsd-6 i386
         xenkernel41 netbsd-6 i386          xenkernel41 netbsd-6 i386
         xentools41 netbsd-6 i386          xentools41 netbsd-6 i386
           xenkernel42 netbsd-6 i386
           xentools42 netbsd-6 i386 *MIXED
   
           (all 3 and 33 seem to FAIL)
           xenkernel41 netbsd-7 i386
           xentools41 netbsd-7 i386
           xenkernel42 netbsd-7 i386
           xentools42 netbsd-7 i386 ??FAIL
   
   (*On netbsd-6 i386, there is a xentools42 in the 2014Q3 official builds,
   but it does not build for gdt.)
   
 NetBSD as a dom0  NetBSD as a dom0
 ================  ================
Line 255  For debugging, one may copy xen-debug.gz Line 274  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 comunicate 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
Line 283  See boot.cfg(5) for an example.  The bas Line 294  See boot.cfg(5) for an example.  The bas
         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 In an attempt to add performance, one can
 add  also add
   
         dom0_max_vcpus=1 dom0_vcpus_pin          dom0_max_vcpus=1 dom0_vcpus_pin
   
Line 457  Unprivileged domains (domU) Line 468  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.  The  address specific domU operating systems or how to install them.  The
 config files for domUs are typically in /usr/pkg/etc/xen, and are  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  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
Line 531  anyplace, reasonable places to store dom Line 542  anyplace, reasonable places to store dom
 (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
 config files), or in /u0/xen (where the vdisks are).  config files), or in /u0/xen (where the vdisks are).
   
   Note that loading the domU kernel from the dom0 implies that boot
   blocks, /boot, /boot.cfg, and so on are all ignored in the domU.
 See the VPS section near the end for discussion of alternate ways to  See the VPS section near the end for discussion of alternate ways to
 obtain domU kernels.  obtain domU kernels.
   
Line 854  NetBSD as a domU in a VPS Line 867  NetBSD as a domU in a VPS
 The bulk of the HOWTO is about using NetBSD as a dom0 on your own  The bulk of the HOWTO is about using NetBSD as a dom0 on your own
 hardware.  This section explains how to deal with Xen in a domU as a  hardware.  This section explains how to deal with Xen in a domU as a
 virtual private server where you do not control or have access to the  virtual private server where you do not control or have access to the
 dom0.  dom0.  This is not intended to be an exhaustive list of VPS providers;
   only a few are mentioned that specifically support NetBSD.
   
 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 filesystem (to
 which VPS users do not normally have acesss).  which VPS users do not normally have acesss).  A second issue is how
   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 adminstrative interface to upload a kernel,
 or to select from a prepopulated list.  or to select from a prepopulated list.  Other approaches are pygrub
   (deprecated) and pvgrub, which are ways to have a bootloader obtain a
   kernel from the domU filesystem.  This is closer to a regular physical
   computer, where someone who controls a machine can replace the kernel.
   
   A second issue is multiple CPUs.  With NetBSD 6, domUs support
   multiple vcpus, and it is typical for VPS providers to enable multiple
   CPUs for NetBSD domUs.
   
   pygrub
   -------
   
   pygrub runs in the dom0 and looks into the domU filesystem.  This
   implies that the domU must have a kernel in a filesystem in a format
   known to pygrub.  As of 2014, pygrub seems to be of mostly historical
   interest.
   
   pvgrub
   ------
   
 Otehr approaches are pvgrub and py-grub, which are ways to start a  pvgrub is a version of grub that uses PV operations instead of BIOS
 bootloader from the dom0 instead of the actual domU kernel, and for  calls.  It is booted from the dom0 as the domU kernel, and then reads
 that loader to then load a kernel from the domU filesystem.  This is  /grub/menu.lst and loads a kernel from the domU filesystem.
 closer to a regular physical computer, where someone who controls a  
 machine can replace the kernel.  [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
   (and hence with defaults from "newfs -O 2").  See [Panix's pvgrub
   page](http://www.panix.com/v-colo/grub.html), which describes only
   Linux but should be updated to cover NetBSD :-).
   
   [prgmr.com](http://prgmr.com/) also lets users with pvgrub to boot
   their own kernel.  See then [prgmr.com NetBSD
   HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU)
   (which is in need of updating).
   
   It appears that [grub's FFS
   code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
   does not support all aspects of modern FFS, but there are also reports
   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,
   which leads to /netbsd not being the actual kernel.  One must remember
   to update the special boot partiion.
   
 prmgr and pvgrub  Amazon
 ----------------  ------
   
 TODO: Perhaps reference panix, prmgr, amazon as interesting examples.  TODO: add link to NetBSD amazon howto.
 Explain what prmgr does.  
   
 Using npf  Using npf
 ---------  ---------
Line 886  Using npf Line 934  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 loadeed in a
 DOMU kernel.  DOMU kernel.
   
 TODO: explain how to compile npf into a custom kernel, answering:  TODO: explain how to compile npf into a custom kernel, answering (but
   note that the problem was caused by not booting the right kernel):
 http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html  http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html
   
   TODO items for improving NetBSD/xen
   ===================================
   
   * Package Xen 4.4.
   * Get PCI passthrough working on Xen 4.2 (or 4.4).
   * Get pvgrub into pkgsrc, either via xentools or separately.
   * grub
     * Check/add support to pkgsrc grub2 for UFS2 and arbitrary
       fragsize/blocksize (UFS2 support may be present; the point is to
       make it so that with any UFS1/UFS2 filesystem setup that works
       with NetBSD grub will also work).
       See [pkg/40258](http://gnats.netbsd.org/40258).
     * Push patches upstream.
     * Get UFS2 patches into pvgrub.
   * Add support for PV ops to a version of /boot, and make it usable as
     a kernel in Xen, similar to pvgrub.

Removed from v.1.57  
changed lines
  Added in v.1.75


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