Diff for /wikisrc/ports/xen/howto.mdwn between versions 1.52 and 1.67

version 1.52, 2014/12/26 23:46:22 version 1.67, 2014/12/30 18:25:46
Line 2  Introduction Line 2  Introduction
 ============  ============
   
 [![[Xen  [![[Xen
 screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](../../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 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.
   
 Prerequisites  Prerequisites
 -------------  -------------
   
Line 63  architecture.  This HOWTO presumes famil Line 65  architecture.  This HOWTO presumes famil
 on i386/amd64 hardware and installing software from pkgsrc.  on i386/amd64 hardware and installing software from pkgsrc.
 See also the [Xen website](http://www.xenproject.org/).  See also the [Xen website](http://www.xenproject.org/).
   
 History  
 -------  
   
 NetBSD used to support Xen2; this has been removed.  
   
 Before NetBSD's native bootloader could support Xen, the use of  
 grub was recommended.  If necessary, see the  
 [old grub information](/ports/xen/howto-grub/).  
   
 Versions of Xen and NetBSD  Versions of Xen and NetBSD
 ==========================  ==========================
   
Line 158  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
   
   (*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 302  As with non-Xen systems, you should have Line 308  As with non-Xen systems, you should have
 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.
   
   Using grub (historic)
   ---------------------
   
   Before NetBSD's native bootloader could support Xen, the use of
   grub was recommended.  If necessary, see the
   [old grub information](/ports/xen/howto-grub/).
   
 The [HowTo on Installing into  The [HowTo on Installing into
 RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)  RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
 explains how to set up booting a dom0 with Xen using grub with  explains how to set up booting a dom0 with Xen using grub with
Line 311  boot.) Line 324  boot.)
 Configuring Xen  Configuring 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, 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.  The  started because you still have to configure the dom0 tools.  The
Line 334  installed 4.1 or 4.2): Line 349  installed 4.1 or 4.2):
   
 For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:  For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:
   
         xend=YES  
         xencommons=YES          xencommons=YES
           xend=YES
   
 TODO: Explain why if xm is preferred on 4.1, rc.d/xendomains has xl.  (If you are using xentools41 from before 2014-12-26, change
 Or fix the package.  rc.d/xendomains to use xm rather than xl.)
   
 For 4.2 with xm, add to rc.conf  For 4.2 with xm, add to rc.conf
   
         xend=YES  
         xencommons=YES          xencommons=YES
           xend=YES
   
 For 4.2 with xl (preferred), add to rc.conf:  For 4.2 with xl (preferred), add to rc.conf:
   
         TODO: explain if there is a xend replacement  
         xencommons=YES          xencommons=YES
           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 or  After you have configured the daemons and either started them (in the
 rebooted, run the following (or use xl) to inspect Xen's boot  order given) or rebooted, run the following (or use xl) to inspect
 messages, available resources, and running domains:  Xen's boot messages, available resources, and running domains:
   
         # xm dmesg          # xm dmesg
         [xen's boot info]          [xen's boot info]
Line 405  and adjusts /etc. Line 420  and adjusts /etc.
 Note that one must update both the non-Xen kernel typically used for  Note that one must update both the non-Xen kernel typically used for
 rescue purposes and the DOM0 kernel used with Xen.  rescue purposes and the DOM0 kernel used with Xen.
   
 To convert from grub to /boot, install an mbr bootblock with fdisk,  Converting from grub to /boot
 bootxx_ with installboot, /boot and /boot.cfg.  This really should be  -----------------------------
 no different than completely reinstalling boot blocks on a non-Xen  
 system.  These instructions were [TODO: will be] used to convert a system from
   grub to /boot.  The system was originally installed in February of
   2006 with a RAID1 setup and grub to boot Xen 2, and has been updated
   over time.  Before these commands, it was running NetBSD 6 i386, Xen
   4.1 and grub, much like the message linked earlier in the grub
   section.
   
           # Install mbr bootblocks on both disks. 
           fdisk -i /dev/rwd0d
           fdisk -i /dev/rwd1d
           # Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components.
           installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1
           installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1
           # Install secondary boot loader
           cp -p /usr/mdec/boot /
           # Create boog.cfg following earlier guidance:
           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=GENERIC:boot
           menu=GENERIC single-user:boot -s
           menu=GENERIC.ok:boot netbsd.ok
           menu=GENERIC.ok single-user:boot netbsd.ok -s
           menu=Drop to boot prompt:prompt
           default=1
           timeout=30
   
   TODO: actually do this and fix it if necessary.
   
 Updating Xen versions  Updating Xen versions
 ---------------------  ---------------------
Line 429  Unprivileged domains (domU) Line 470  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 503  anyplace, reasonable places to store dom Line 544  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 595  dom0.  This is often appropriate when ru Line 638  dom0.  This is often appropriate when ru
 TODO: NAT appears to be configured by "vif = [ '' ]".  TODO: NAT appears to be configured by "vif = [ '' ]".
   
 The MAC address specified is the one used for the interface in the new  The MAC address specified is the one used for the interface in the new
 domain.  The interface in domain0 will use this address XOR'd with  domain.  The interface in dom0 will use this address XOR'd with
 00:00:00:01:00:00.  Random MAC addresses are assigned if not given.  00:00:00:01:00:00.  Random MAC addresses are assigned if not given.
   
 Sizing domains  Sizing domains
Line 695  It is also desirable to add Line 738  It is also desirable to add
         powerd=YES          powerd=YES
   
 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 domain0.  `xm shutdown -R` or `xm shutdown -H` is used on the dom0.
   
 Your domain should be now ready to work, enjoy.  Your domain should be now ready to work, enjoy.
   
Line 753  See possibly outdated Line 796  See possibly outdated
 PCI passthrough: Using PCI devices in guest domains  PCI passthrough: Using PCI devices in guest domains
 ---------------------------------------------------  ---------------------------------------------------
   
 The domain0 can give other domains access to selected PCI  The dom0 can give other domains access to selected PCI
 devices. This can allow, for example, a non-privileged domain to have  devices. This can allow, for example, a non-privileged domain to have
 access to a physical network interface or disk controller.  However,  access to a physical network interface or disk controller.  However,
 keep in mind that giving a domain access to a PCI device most likely  keep in mind that giving a domain access to a PCI device most likely
 will give the domain read/write access to the whole physical memory,  will give the domain read/write access to the whole physical memory,
 as PCs don't have an IOMMU to restrict memory access to DMA-capable  as PCs don't have an IOMMU to restrict memory access to DMA-capable
 device.  Also, it's not possible to export ISA devices to non-domain0  device.  Also, it's not possible to export ISA devices to non-dom0
 domains, which means that the primary VGA adapter can't be exported.  domains, which means that the primary VGA adapter can't be exported.
 A guest domain trying to access the VGA registers will panic.  A guest domain trying to access the VGA registers will panic.
   
 If the domain0 is NetBSD, it has to be running Xen 3.1, as support has  If the dom0 is NetBSD, it has to be running Xen 3.1, as support has
 not been ported to later versions at this time.  not been ported to later versions at this time.
   
 For a PCI device to be exported to a domU, is has to be attached to  For a PCI device to be exported to a domU, is has to be attached to
Line 838  npf, run IPsec, or any other reason why  Line 881  npf, run IPsec, or any other reason why 
 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 py-grub
   (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.
   
 Otehr approaches are pvgrub and py-grub, which are ways to start a  py-grub
 bootloader from the dom0 instead of the actual domU kernel, and for  -------
 that loader to then load a kernel from the domU filesystem.  This is  
 closer to a regular physical computer, where someone who controls a  
 machine can replace the kernel.  
   
 prmgr and pvgrub  py-grub 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 py-grub.  As of 2014, py-grub seems to be of mostly historical interest.
   
 TODO: Perhaps reference panix, prmgr, amazon as interesting examples.  pvgrub
 Explain what prmgr does.  ------
   
   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
   /grub/menu.lst and loads a kernel from the domU filesystem.
   
   [prgmr.com](http://prgmr.com/) uses this approach to let users choose
   their own operating system and kernel.  See then [prgmr.com NetBSD
   HOWTO](http://wiki.prgmr.com/mediawiki/index.php/NetBSD_as_a_DomU).
   
   Because [grub's FFS code](http://xenbits.xensource.com/hg/xen-unstable.hg/file/bca284f67702/tools/libfsimage/ufs/fsys_ufs.c)
   appears not to support all aspects of modern FFS,
   typically one has an ext2 or FAT partition for the kernel, so that
   grub can understand it, which leads to /netbsd not being the actual
   kernel.  One must remember to update the special boot partiion.
   
   Amazon
   ------
   
   TODO: add link to NetBSD amazon howto.
   
 Using npf  Using npf
 ---------  ---------
Line 858  Using npf Line 921  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
     * 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).
     * 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.

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