--- wikisrc/ports/xen/howto.mdwn 2013/11/01 12:27:37 1.5 +++ wikisrc/ports/xen/howto.mdwn 2015/03/05 14:04:55 1.95 @@ -1,461 +1,799 @@ - - - - - - - -

Table Of Contents

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  • Introduction
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  • Installing NetBSD as privileged domain (Dom0)
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  • Creating an unprivileged NetBSD domain (DomU)
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  • Creating an unprivileged Linux domain (DomU)
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  • Creating an unprivileged Solaris domain (DomU)
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  • Using PCI devices in guest domains
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  • Links and further information
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- Introduction ------------- +============ [![[Xen -screenshot]](../../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 for x86 hardware (requires i686-class -CPUs), which supports running multiple guest operating systems on a -single machine. Guest OSes (also called “domains”) require a modified -kernel which supports Xen hypercalls in replacement to access to the -physical hardware. At boot, the Xen kernel (also known as the Xen -hypervisor) is loaded (via the bootloader) along with the guest kernel -for the first domain (called *domain0*). The Xen kernel has to be loaded -using the multiboot protocol. You would use the NetBSD boot loader for -this, or alternatively the `grub` boot loader (`grub` has some -limitations, detailed below). *domain0* has special privileges to access -the physical hardware (PCI and ISA devices), administrate other domains -and provide virtual devices (disks and network) to other domains that -lack those privileges. For more details, see [](http://www.xen.org/). - -NetBSD can be used for both *domain0 (Dom0)* and further, unprivileged -(DomU) domains. (Actually there can be multiple privileged domains -accessing different parts of the hardware, all providing virtual devices -to unprivileged domains. We will only talk about the case of a single -privileged domain, *domain0*). *domain0* will see physical devices much -like a regular i386 or amd64 kernel, and will own the physical console -(VGA or serial). Unprivileged domains will only see a character-only -virtual console, virtual disks (`xbd`) and virtual network interfaces -(`xennet`) provided by a privileged domain (usually *domain0*). xbd -devices are connected to a block device (i.e., a partition of a disk, -raid, ccd, ... device) in the privileged domain. xennet devices are -connected to virtual devices in the privileged domain, named -xvif\.\, e.g., xvif1.0. Both -xennet and xvif devices are seen as regular Ethernet devices (they can -be seen as a crossover cable between 2 PCs) and can be assigned -addresses (and be routed or NATed, filtered using IPF, etc ...) or be -added as part of a bridge. +Xen is a hypervisor (or virtual machine monitor) for x86 hardware +(i686-class or higher), which supports running multiple guest +operating systems on a single physical machine. Xen is a Type 1 or +bare-metal hypervisor; one uses the Xen kernel to control the CPU, +memory and console, a dom0 operating system which mediates access to +other hardware (e.g., disks, network, USB), and one or more domU +operating systems which operate in an unprivileged virtualized +environment. IO requests from the domU systems are forwarded by the +hypervisor (Xen) to the dom0 to be fulfilled. + +Xen supports two styles of guests. The original is Para-Virtualized +(PV) which means that the guest OS does not attempt to access hardware +directly, but instead makes hypercalls to the hypervisor. This is +analogous to a user-space program making system calls. (The dom0 +operating system uses PV calls for some functions, such as updating +memory mapping page tables, but has direct hardware access for disk +and network.) PV guests must be specifically coded for Xen. + +The more recent style is HVM, which means that the guest does not have +code for Xen and need not be aware that it is running under Xen. +Attempts to access hardware registers are trapped and emulated. This +style is less efficient but can run unmodified guests. + +Generally any amd64 machine will work with Xen and PV guests. In +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). +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 +and check the above features. + +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 +in the dom0 section.) + +NetBSD supports Xen in that it can serve as dom0, be used as a domU, +and that Xen kernels and tools are available in pkgsrc. This HOWTO +attempts to address both the case of running a NetBSD dom0 on hardware +and running domUs under it (NetBSD and other), and also running NetBSD +as a domU in a VPS. + +Some versions of Xen support "PCI passthrough", which means that +specific PCI devices can be made available to a specific domU instead +of the dom0. This can be useful to let a domU run X11, or access some +network interface or other peripheral. + +NetBSD used to support Xen2; this has been removed. + +Prerequisites +------------- + +Installing NetBSD/Xen is not extremely difficult, but it is more +complex than a normal installation of NetBSD. +In general, this HOWTO is occasionally overly restrictive about how +things must be done, guiding the reader to stay on the established +path when there are no known good reasons to stray. + +This HOWTO presumes a basic familiarity with the Xen system +architecture. This HOWTO presumes familiarity with installing NetBSD +on i386/amd64 hardware and installing software from pkgsrc. +See also the [Xen website](http://www.xenproject.org/). + +Versions of Xen and NetBSD +========================== + +Most of the installation concepts and instructions are independent +of Xen version and NetBSD version. This section gives advice on +which version to choose. Versions not in pkgsrc and older unsupported +versions of NetBSD are intentionally ignored. + +Xen +--- + +In NetBSD, xen is provided in pkgsrc, via matching pairs of packages +xenkernel and xentools. We will refer only to the kernel versions, +but note that both packages must be installed together and must have +matching versions. + +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 +passthrough. Xen 3.1 supports non-PAE on i386. + +xenkernel41 provides Xen 4.1. This is no longer maintained by Xen, +but as of 2014-12 receives backported security patches. It is a +reasonable although trailing-edge choice. + +xenkernel42 provides Xen 4.2. This is maintained by Xen, but old as +of 2014-12. + +xenkernel45 provides Xen 4.5. This is new to pkgsrc as of 2015-01 and +not yet recommended for other than experimental/testing use. + +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. + +Xen command program +------------------- + +Early Xen used a program called xm to manipulate the system from the +dom0. Starting in 4.1, a replacement program with similar behavior +called xl is provided, but it does not work well in 4.1. In 4.2, both +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. + +NetBSD +------ + +The netbsd-5, netbsd-6, netbsd-7, and -current branches are all +reasonable choices, with more or less the same considerations for +non-Xen use. Therefore, netbsd-6 is recommended as the stable version +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 +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 +a normal computer.) -Installing NetBSD as privileged domain (Dom0) ---------------------------------------------- +Architecture +------------ + +Xen itself can run on i386 or amd64 machines. (Practically, almost +any computer where one would want to run Xen supports amd64.) If +using an i386 NetBSD kernel for the dom0, PAE is required (PAE +versions are built by default). While i386 dom0 works fine, amd64 is +recommended as more normal. + +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.) + +Stability +--------- + +Mostly, NetBSD as a dom0 or domU is quite stable. +However, there are some open PRs indicating problems. + + - [PR 48125](http://gnats.netbsd.org/48125) + - [PR 47720](http://gnats.netbsd.org/47720) + +Note also that there are issues with sparse vnd(4) instances, but +these are not about Xen. + +Recommendation +-------------- + +Therefore, this HOWTO recommends running xenkernel42 (and xentools42), +xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the +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 work or FAIL: + + 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 + 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 + 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 can be used as a dom0 and works very well. The following +sections address installation, updating NetBSD, and updating Xen. +Note that it doesn't make sense to talk about installing a dom0 OS +without also installing Xen itself. We first address installing +NetBSD, which is not yet a dom0, and then adding Xen, pivoting the +NetBSD install to a dom0 install by just changing the kernel and boot +configuration. + +For experimenting with Xen, a machine with as little as 1G of RAM and +100G of disk can work. For running many domUs in productions, far +more will be needed. + +Styles of dom0 operation +------------------------ + +There are two basic ways to use Xen. The traditional method is for +the dom0 to do absolutely nothing other than providing support to some +number of domUs. Such a system was probably installed for the sole +purpose of hosting domUs, and sits in a server room on a UPS. + +The other way is to put Xen under a normal-usage computer, so that the +dom0 is what the computer would have been without Xen, perhaps a +desktop or laptop. Then, one can run domUs at will. Purists will +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 +dom0 (without domUs) is not meaningfully less secure than the same +things running without Xen. One can boot Xen or boot regular NetBSD +alternately with little problems, simply refraining from starting the +Xen daemons when not running Xen. + +Note that NetBSD as dom0 does not support multiple CPUs. This will +limit the performance of the Xen/dom0 workstation approach. In theory +the only issue is that the "backend drivers" are not yet MPSAFE: + http://mail-index.netbsd.org/netbsd-users/2014/08/29/msg015195.html + +Installation of NetBSD +---------------------- + +First, +[install NetBSD/amd64](/guide/inst/) +just as you would if you were not using Xen. +However, the partitioning approach is very important. + +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 +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 +partition; this is no different when booting Xen. + +There are 4 styles of providing backing storage for the virtual disks +used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN. + +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 +how domU usage will evolve, please add an explanation to the HOWTO. +Seriously, needs tend to change over time.) + +One can use [lvm(8)](/guide/lvm/) to create logical devices to use +for domU disks. This is almost as efficient as raw disk partitions +and more flexible. Hence raw disk partitions should typically not +be used. + +One can use files in the dom0 filesystem, typically created by dd'ing +/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 +between dom0 hosts. + +Finally, in theory one can place the files backing the domU disks in a +SAN. (This is an invitation for someone who has done this to add a +HOWTO page.) + +Installation of Xen +------------------- + +In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from +pkgsrc (or another matching pair). +See [the pkgsrc +documentation](http://www.NetBSD.org/docs/pkgsrc/) for help with pkgsrc. + +For Xen 3.1, support for HVM guests is in sysutils/xentool3-hvm. More +recent versions have HVM support integrated in the main xentools +package. It is entirely reasonable to run only PV guests. + +Next you need to install the selected Xen kernel itself, which is +installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz". Copy it to /. +For debugging, one may copy xen-debug.gz; this is conceptually similar +to DIAGNOSTIC and DEBUG in NetBSD. xen-debug.gz is basically only +useful with a serial console. Then, place a NetBSD XEN3_DOM0 kernel +in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz +of a NetBSD build. If using i386, use +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 +should not use Xen 3.1.) Both xen and the NetBSD kernel may be (and +typically are) left compressed. + +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 +with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the +beginning of your root filesystem, /boot present, and likely +/boot.cfg. (If not, fix before continuing!) + +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 + +which specifies that the dom0 should have 256M, leaving the rest to be +allocated for domUs. To use a serial console, use + + 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 + +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. + +Xen has [many boot +options](http://xenbits.xenproject.org/docs/4.5-testing/misc/xen-command-line.html), +and other tham dom0 memory and max_vcpus, they are generally not +necessary. + +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, 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) +--------------------- + +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 +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 +NetBSD's RAIDframe. (This is obsolete with the use of NetBSD's native +boot.) + +Configuring Xen +--------------- + +Xen logs will be in /var/log/xen. + +Now, you have a system that will boot Xen and the dom0 kernel, but not +do anything else special. Make sure that you have rebooted into Xen. +There will be no domUs, and none can be 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. Running xl without xencommons=YES (and starting it) +will result in a hang (so don't do that; follow the HOWTO!). + +The installation of NetBSD should already have created devices for xen +(xencons, xenevt), but if they are not present, create them: + + 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 + xenbackendd=YES + +For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf: + + 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 + xend=YES + +For 4.2 with xl, add to rc.conf: + + xencommons=YES + TODO: explain if there is a xend replacement + +For 4.5 (and thus with xl), add to rc.conf: + + xencommons=YES + TODO: explain if there is a xend replacement + +TODO: Recommend for/against xen-watchdog. + +After you have configured the daemons and either started them (in the +order given) or rebooted, use xm or xl to inspect Xen's boot messages, +available resources, and running domains. An example with xm follows: + + # xm dmesg + [xen's boot info] + # xm info + [available memory, etc.] + # xm list + Name Id Mem(MB) CPU State Time(s) Console + Domain-0 0 64 0 r---- 58.1 + +With xl, the commands are the same, and the output may be slightly +different. TODO: add example output for xl before the xm example, +after confirming on 4.2 and resolving the TODO about rc.conf. + +### Issues with xencommons + +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. + +anita (for testing NetBSD) +-------------------------- + +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 +-------------------------- + +There are (at least) two additional things different about NetBSD as a +dom0 kernel compared to hardware. + +One is that modules are not usable in DOM0 kernels, so one must +compile in what's needed. It's not really that modules cannot work, +but that modules must be built for XEN3_DOM0 because some of the +defines change and the normal module builds don't do this. Basically, +enabling Xen changes the kernel ABI, and the module build system +doesn't cope with this. + +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 +bug, users should be aware of this and can simply add missing config +items if desired. + +Updating NetBSD in a dom0 +------------------------- + +This is just like updating NetBSD on bare hardware, assuming the new +version supports the version of Xen you are running. Generally, one +replaces the kernel and reboots, and then overlays userland binaries +and adjusts /etc. + +Note that one must update both the non-Xen kernel typically used for +rescue purposes and the DOM0 kernel used with Xen. + +Converting from grub to /boot +----------------------------- + +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 is conceptually not difficult, but can run into all the +issues found when installing Xen. Assuming migration from 4.1 to 4.2, +remove the xenkernel41 and xentools41 packages and install the +xenkernel42 and xentools42 packages. Copy the 4.2 xen.gz to /. + +Ensure that the contents of /etc/rc.d/xen* are correct. Enable the +correct set of daemons. Ensure that the domU config files are valid +for the new version. + + +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) +=========================== + +This section describes general concepts about domUs. It does not +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 name, 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. + +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. + +Config files +------------ + +There is no good order to present config files and the concepts +surrounding what is being configured. We first show an example config +file, and then in the various sections give details. + +See (at least in xentools41) /usr/pkg/share/examples/xen/xmexample*, +for a large number of well-commented examples, mostly for running +GNU/Linux. + +The following is an example minimal domain configuration file +"/usr/pkg/etc/xen/foo". It is (with only a name change) an actual +known working config file on Xen 4.1 (NetBSD 5 amd64 dom0 and NetBSD 5 +i386 domU). The domU serves as a network file server. + + # -*- mode: python; -*- + + kernel = "/netbsd-XEN3PAE_DOMU-i386-foo.gz" + memory = 1024 + vif = [ 'mac=aa:00:00:d1:00:09,bridge=bridge0' ] + disk = [ 'file:/n0/xen/foo-wd0,0x0,w', + 'file:/n0/xen/foo-wd1,0x1,w' ] + +The domain will have the same name as the file. The kernel has the +host/domU name in it, so that on the dom0 one can update the various +domUs independently. The vif line causes an interface to be provided, +with a specific mac address (do not reuse MAC addresses!), in bridge +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 +dom0 on domain creation. The system treates xbd0 as the boot device +without needing explicit configuration. + +By default xm looks for domain config files in /usr/pkg/etc/xen. Note +that "xm create" takes the name of a config file, while other commands +take the name of a domain. To create the domain, connect to the +console, create the domain while attaching the console, shutdown the +domain, and see if it has finished stopping, do (or xl with Xen >= +4.2): + + xm create foo + xm console foo + xm create -c foo + xm shutdown foo + xm list + +Typing ^] will exit the console session. Shutting down a domain is +equivalent to pushing the power button; a NetBSD domU will receive a +power-press event and do a clean shutdown. Shutting down the dom0 +will trigger controlled shutdowns of all configured domUs. + +domU kernels +------------ -First do a NetBSD/i386 or NetBSD/amd64 -[installation](../../docs/guide/en/chap-inst.html) of the 5.1 release -(or newer) as you usually do on x86 hardware. The binary releases are -available from [](ftp://ftp.NetBSD.org/pub/NetBSD/). Binary snapshots -for current and the stable branches are available on daily autobuilds. -If you plan to use the `grub` boot loader, when partitioning the disk -you have to make the root partition smaller than 512Mb, and formatted as -FFSv1 with 8k block/1k fragments. If the partition is larger than this, -uses FFSv2 or has different block/fragment sizes, grub may fail to load -some files. Also keep in mind that you'll probably want to provide -virtual disks to other domains, so reserve some partitions for these -virtual disks. Alternatively, you can create large files in the file -system, map them to vnd(4) devices and export theses vnd devices to -other domains. - -Next step is to install the Xen packages via pkgsrc or from binary -packages. See [the pkgsrc -documentation](http://www.NetBSD.org/docs/pkgsrc/) if you are unfamiliar -with pkgsrc and/or handling of binary packages. Xen 3.1, 3.3, 4.1 and -4.2 are available. 3.1 supports PCI pass-through while other versions do -not. You'll need either `sysutils/xentools3` and `sysutils/xenkernel3` -for Xen 3.1, `sysutils/xentools33` and `sysutils/xenkernel33` for Xen -3.3, `sysutils/xentools41` and `sysutils/xenkernel41` for Xen 4.1. or -`sysutils/xentools42` and `sysutils/xenkernel42` for Xen 4.2. You'll -also need `sysutils/grub` if you plan do use the grub boot loader. If -using Xen 3.1, you may also want to install `sysutils/xentools3-hvm` -which contains the utilities to run unmodified guests OSes using the -*HVM* support (for later versions this is included in -`sysutils/xentools`). Note that your CPU needs to support this. Intel -CPUs must have the 'VT' instruction, AMD CPUs the 'SVM' instruction. You -can easily find out if your CPU support HVM by using NetBSD's cpuctl -command: - - # cpuctl identify 0 - cpu0: Intel Core 2 (Merom) (686-class), id 0x6f6 - cpu0: features 0xbfebfbff - cpu0: features 0xbfebfbff - cpu0: features 0xbfebfbff - cpu0: features2 0x4e33d - cpu0: features3 0x20100800 - cpu0: "Intel(R) Xeon(R) CPU 5130 @ 2.00GHz" - cpu0: I-cache 32KB 64B/line 8-way, D-cache 32KB 64B/line 8-way - cpu0: L2 cache 4MB 64B/line 16-way - cpu0: ITLB 128 4KB entries 4-way - cpu0: DTLB 256 4KB entries 4-way, 32 4MB entries 4-way - cpu0: Initial APIC ID 0 - cpu0: Cluster/Package ID 0 - cpu0: Core ID 0 - cpu0: family 06 model 0f extfamily 00 extmodel 00 - -Depending on your CPU, the feature you are looking for is called HVM, -SVM or VMX. - -Next you need to copy the selected Xen kernel itself. pkgsrc installed -them under `/usr/pkg/xen*-kernel/`. The file you're looking for is -`xen.gz`. Copy it to your root file system. `xen-debug.gz` is a kernel -with more consistency checks and more details printed on the serial -console. It is useful for debugging crashing guests if you use a serial -console. It is not useful with a VGA console. - -You'll then need a NetBSD/Xen kernel for *domain0* on your root file -system. The XEN3PAE\_DOM0 kernel or XEN3\_DOM0 provided as part of the -i386 or amd64 binaries is suitable for this, but you may want to -customize it. Keep your native kernel around, as it can be useful for -recovery. *Note:* the *domain0* kernel must support KERNFS and `/kern` -must be mounted because *xend* needs access to `/kern/xen/privcmd`. - -Next you need to get a bootloader to load the `xen.gz` kernel, and the -NetBSD *domain0* kernel as a module. This can be `grub` or NetBSD's boot -loader. Below is a detailled example for grub, see the boot.cfg(5) -manual page for an example using the latter. - -This is also where you'll specify the memory allocated to *domain0*, the -console to use, etc ... - -Here is a commented `/grub/menu.lst` file: - - #Grub config file for NetBSD/xen. Copy as /grub/menu.lst and run - # grub-install /dev/rwd0d (assuming your boot device is wd0). - # - # The default entry to load will be the first one - default=0 - - # boot the default entry after 10s if the user didn't hit keyboard - timeout=10 - - # Configure serial port to use as console. Ignore if you'll use VGA only - serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1 - - # Let the user select which console to use (serial or VGA), default - # to serial after 10s - terminal --timeout=10 serial console - - # An entry for NetBSD/xen, using /netbsd as the domain0 kernel, and serial - # console. Domain0 will have 64MB RAM allocated. - # Assume NetBSD is installed in the first MBR partition. - title Xen 3 / NetBSD (hda0, serial) - root(hd0,0) - kernel (hd0,a)/xen.gz dom0_mem=65536 com1=115200,8n1 - module (hd0,a)/netbsd bootdev=wd0a ro console=ttyS0 - - # Same as above, but using VGA console - # We can use console=tty0 (Linux syntax) or console=pc (NetBSD syntax) - title Xen 3 / NetBSD (hda0, vga) - root(hd0,0) - kernel (hd0,a)/xen.gz dom0_mem=65536 - module (hd0,a)/netbsd bootdev=wd0a ro console=tty0 - - # NetBSD/xen using a backup domain0 kernel (in case you installed a - # nonworking kernel as /netbsd - title Xen 3 / NetBSD (hda0, backup, serial) - root(hd0,0) - kernel (hd0,a)/xen.gz dom0_mem=65536 com1=115200,8n1 - module (hd0,a)/netbsd.backup bootdev=wd0a ro console=ttyS0 - title Xen 3 / NetBSD (hda0, backup, VGA) - root(hd0,0) - kernel (hd0,a)/xen.gz dom0_mem=65536 - module (hd0,a)/netbsd.backup bootdev=wd0a ro console=tty0 - - #Load a regular NetBSD/i386 kernel. Can be useful if you end up with a - #nonworking /xen.gz - title NetBSD 5.1 - root (hd0,a) - kernel --type=netbsd /netbsd-GENERIC - - #Load the NetBSD bootloader, letting it load the NetBSD/i386 kernel. - #May be better than the above, as grub can't pass all required infos - #to the NetBSD/i386 kernel (e.g. console, root device, ...) - title NetBSD chain - root (hd0,0) - chainloader +1 - - ## end of grub config file. - - -Install grub with the following command: - - # grub --no-floppy - - grub> root (hd0,a) - Filesystem type is ffs, partition type 0xa9 - - grub> setup (hd0) - Checking if "/boot/grub/stage1" exists... no - Checking if "/grub/stage1" exists... yes - Checking if "/grub/stage2" exists... yes - Checking if "/grub/ffs_stage1_5" exists... yes - Running "embed /grub/ffs_stage1_5 (hd0)"... 14 sectors are embedded. - succeeded - Running "install /grub/stage1 (hd0) (hd0)1+14 p (hd0,0,a)/grub/stage2 /grub/menu.lst"... - succeeded - Done. - +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 +filesystem. With Xen domUs, the process is totally different. The +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 +new domU instance and starts execution. While domU kernels can be +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 +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 +obtain domU kernels. + +CPU and memory +-------------- + +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 by the "vcpus = N" directive. + +A domain is provided with memory; this is controlled in the config +file by "memory = N" (in megabytes). 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 +------------- + +With the file/vnd style, typically one creates a directory, +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. To +create an empty 4G virtual disk, simply do + + 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 +similarly to vnds. TODO: Add an example with lvm. + +In domU config files, the disks are defined as a sequence of 3-tuples. +The first element is "method:/path/to/disk". Common methods are +"file:" for file-backed vnd. and "phy:" for something that is already +a (TODO: character or block) device. + +The second element is an artifact of how virtual disks are passed to +Linux, and a source of confusion with NetBSD Xen usage. Linux domUs +are given a device name to associate with the disk, and values like +"hda1" or "sda1" are common. In a NetBSD domU, the first disk appears +as xbd0, the second as xbd1, and so on. However, xm/xl demand a +second argument. The name given is converted to a major/minor by +calling stat(2) on the name in /dev and this is passed to the domU. +In the general case, the dom0 and domU can be different operating +systems, and it is an unwarranted assumption that they have consistent +numbering in /dev, or even that the dom0 OS has a /dev. With NetBSD +as both dom0 and domU, using values of 0x0 for the first disk and 0x1 +for the second works fine and avoids this issue. For a GNU/Linux +guest, one can create /dev/hda1 in /dev, or to pass 0x301 for +/dev/hda1. + +The third element is "w" for writable disks, and "r" for read-only +disks. + +Virtual Networking +------------------ + +Xen provides virtual ethernets, each of which connects the dom0 and a +domU. For each virtual network, there is an interface "xvifN.M" in +the dom0, and in domU index N, a matching interface xennetM (NetBSD +name). The interfaces behave as if there is an Ethernet with two +adaptors connected. From this primitive, one can construct various +configurations. We focus on two common and useful cases for which +there are existing scripts: bridging and NAT. + +With bridging (in the example above), the domU perceives itself to be +on the same network as the dom0. For server virtualization, this is +usually best. Bridging is accomplished by creating a bridge(4) device +and adding the dom0's physical interface and the various xvifN.0 +interfaces to the bridge. One specifies "bridge=bridge0" in the domU +config file. The bridge must be set up already in the dom0; an +example /etc/ifconfig.bridge0 is: + + create + up + !brconfig bridge0 add wm0 + +With NAT, the domU perceives itself to be behind a NAT running on the +dom0. This is often appropriate when running Xen on a workstation. +TODO: NAT appears to be configured by "vif = [ '' ]". + +The MAC address specified is the one used for the interface in the new +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. + +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. + +Starting domains automatically +------------------------------ + +To start domains foo at bar at boot and shut them down cleanly on dom0 +shutdown, in rc.conf add: + + xendomains="foo bar" + +Note that earlier versions of the xentools41 xendomains rc.d scripth +usd xl, when one should use xm with 4.1. + +Creating specific unprivileged domains (domU) +============================================= + +Creating domUs is almost entirely independent of operating system. We +have already presented the basics of config files. Note that you must +have already completed the dom0 setup so that "xl list" (or "xm list") +works. -Creating an unprivileged NetBSD domain (DomU) +Creating an unprivileged NetBSD domain (domU) --------------------------------------------- -Once you have *domain0* running, you need to start the xen tool daemon -(`/usr/pkg/share/examples/rc.d/xend start`) and the xen backend daemon -(`/usr/pkg/share/examples/rc.d/xenbackendd start` for Xen3\*, -`/usr/pkg/share/examples/rc.d/xencommons start` for Xen4.\*). Make sure -that `/dev/xencons` and `/dev/xenevt` exist before starting `xend`. You -can create them with this command: - - # cd /dev && sh MAKEDEV xen - -xend will write logs to `/var/log/xend.log` and -`/var/log/xend-debug.log`. You can then control xen with the xm tool. -'xm list' will show something like: - - # xm list - Name Id Mem(MB) CPU State Time(s) Console - Domain-0 0 64 0 r---- 58.1 - -'xm create' allows you to create a new domain. It uses a config file in -PKG\_SYSCONFDIR for its parameters. By default, this file will be in -`/usr/pkg/etc/xen/`. On creation, a kernel has to be specified, which -will be executed in the new domain (this kernel is in the *domain0* file -system, not on the new domain virtual disk; but please note, you should -install the same kernel into *domainU* as `/netbsd` in order to make -your system tools, like MAN.SAVECORE.8, work). A suitable kernel is -provided as part of the i386 and amd64 binary sets: XEN3\_DOMU. - -Here is an /usr/pkg/etc/xen/nbsd example config file: - - # -*- mode: python; -*- - #============================================================================ - # Python defaults setup for 'xm create'. - # Edit this file to reflect the configuration of your system. - #============================================================================ - - #---------------------------------------------------------------------------- - # Kernel image file. This kernel will be loaded in the new domain. - kernel = "/home/bouyer/netbsd-XEN3_DOMU" - #kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU" - - # Memory allocation (in megabytes) for the new domain. - memory = 128 - - # A handy name for your new domain. This will appear in 'xm list', - # and you can use this as parameters for xm in place of the domain - # number. All domains must have different names. - # - name = "nbsd" - - # The number of virtual CPUs this domain has. - # - vcpus = 1 - - #---------------------------------------------------------------------------- - # Define network interfaces for the new domain. - - # Number of network interfaces (must be at least 1). Default is 1. - nics = 1 - - # Define MAC and/or bridge for the network interfaces. - # - # The MAC address specified in ``mac'' is the one used for the interface - # in the new domain. The interface in domain0 will use this address XOR'd - # with 00:00:00:01:00:00 (i.e. aa:00:00:51:02:f0 in our example). Random - # MACs are assigned if not given. - # - # ``bridge'' is a required parameter, which will be passed to the - # vif-script called by xend(8) when a new domain is created to configure - # the new xvif interface in domain0. - # - # In this example, the xvif is added to bridge0, which should have been - # set up prior to the new domain being created -- either in the - # ``network'' script or using a /etc/ifconfig.bridge0 file. - # - vif = [ 'mac=aa:00:00:50:02:f0, bridge=bridge0' ] - - #---------------------------------------------------------------------------- - # Define the disk devices you want the domain to have access to, and - # what you want them accessible as. - # - # Each disk entry is of the form: - # - # phy:DEV,VDEV,MODE - # - # where DEV is the device, VDEV is the device name the domain will see, - # and MODE is r for read-only, w for read-write. You can also create - # file-backed domains using disk entries of the form: - # - # file:PATH,VDEV,MODE - # - # where PATH is the path to the file used as the virtual disk, and VDEV - # and MODE have the same meaning as for ``phy'' devices. - # - # VDEV doesn't really matter for a NetBSD guest OS (it's just used as an index), - # but it does for Linux. - # Worse, the device has to exist in /dev/ of domain0, because xm will - # try to stat() it. This means that in order to load a Linux guest OS - # from a NetBSD domain0, you'll have to create /dev/hda1, /dev/hda2, ... - # on domain0, with the major/minor from Linux :( - # Alternatively it's possible to specify the device number in hex, - # e.g. 0x301 for /dev/hda1, 0x302 for /dev/hda2, etc ... +See the earlier config file, and adjust memory. Decide on how much +storage you will provide, and prepare it (file or lvm). - disk = [ 'phy:/dev/wd0e,0x1,w' ] - #disk = [ 'file:/var/xen/nbsd-disk,0x01,w' ] - #disk = [ 'file:/var/xen/nbsd-disk,0x301,w' ] +While the kernel will be obtained from the dom0 filesystem, the same +file should be present in the domU as /netbsd so that tools like +savecore(8) can work. (This is helpful but not necessary.) + +The kernel must be specifically for Xen and for use as a domU. The +i386 and amd64 provide the following kernels: + + i386 XEN3_DOMU + i386 XEN3PAE_DOMU + amd64 XEN3_DOMU + +Unless using Xen 3.1 (and you shouldn't) with i386-mode Xen, you must +use the PAE version of the i386 kernel. + +This will boot NetBSD, but this is not that useful if the disk is +empty. One approach is to unpack sets onto the disk outside of xen +(by mounting it, just as you would prepare a physical disk for a +system you can't run the installer on). + +A second approach is to run an INSTALL kernel, which has a miniroot +and can load sets from the network. To do this, copy the INSTALL +kernel to / and change the kernel line in the config file to: - #---------------------------------------------------------------------------- - # Set the kernel command line for the new domain. + kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU" - # Set root device. This one does matter for NetBSD - root = "xbd0" - # extra parameters passed to the kernel - # this is where you can set boot flags like -s, -a, etc ... - #extra = "" - - #---------------------------------------------------------------------------- - # Set according to whether you want the domain restarted when it exits. - # The default is False. - #autorestart = True - - # end of nbsd config file ==================================================== - -When a new domain is created, xen calls the -`/usr/pkg/etc/xen/vif-bridge` script for each virtual network interface -created in *domain0*. This can be used to automatically configure the -xvif?.? interfaces in *domain0*. In our example, these will be bridged -with the bridge0 device in *domain0*, but the bridge has to exist first. -To do this, create the file `/etc/ifconfig.bridge0` and make it look -like this: - - create - !brconfig $int add ex0 up - -(replace `ex0` with the name of your physical interface). Then bridge0 -will be created on boot. See the MAN.BRIDGE.4 man page for details. - -So, here is a suitable `/usr/pkg/etc/xen/vif-bridge` for xvif?.? (a -working vif-bridge is also provided with xentools20) configuring: - - #!/bin/sh - #============================================================================ - # $NetBSD: vif-bridge-nbsd,v 1.3 2005/11/08 00:47:35 jlam Exp $ - # - # /usr/pkg/etc/xen/vif-bridge - # - # Script for configuring a vif in bridged mode with a dom0 interface. - # The xend(8) daemon calls a vif script when bringing a vif up or down. - # The script name to use is defined in /usr/pkg/etc/xen/xend-config.sxp - # in the ``vif-script'' field. - # - # Usage: vif-bridge up|down [var=value ...] - # - # Actions: - # up Adds the vif interface to the bridge. - # down Removes the vif interface from the bridge. - # - # Variables: - # domain name of the domain the interface is on (required). - # vifq vif interface name (required). - # mac vif MAC address (required). - # bridge bridge to add the vif to (required). - # - # Example invocation: - # - # vif-bridge up domain=VM1 vif=xvif1.0 mac="ee:14:01:d0:ec:af" bridge=bridge0 - # - #============================================================================ - - # Exit if anything goes wrong - set -e - - echo "vif-bridge $*" - - # Operation name. - OP=$1; shift - - # Pull variables in args into environment - for arg ; do export "${arg}" ; done - - # Required parameters. Fail if not set. - domain=${domain:?} - vif=${vif:?} - mac=${mac:?} - bridge=${bridge:?} - - # Optional parameters. Set defaults. - ip=${ip:-''} # default to null (do nothing) - - # Are we going up or down? - case $OP in - up) brcmd='add' ;; - down) brcmd='delete' ;; - *) - echo 'Invalid command: ' $OP - echo 'Valid commands are: up, down' - exit 1 - ;; - esac - - # Don't do anything if the bridge is "null". - if [ "${bridge}" = "null" ] ; then - exit - fi - - # Don't do anything if the bridge doesn't exist. - if ! ifconfig -l | grep "${bridge}" >/dev/null; then - exit - fi - - # Add/remove vif to/from bridge. - ifconfig x${vif} $OP - brconfig ${bridge} ${brcmd} x${vif} - -Now, running - - xm create -c /usr/pkg/etc/xen/nbsd - -should create a domain and load a NetBSD kernel in it. (Note: `-c` -causes xm to connect to the domain's console once created.) The kernel -will try to find its root file system on xbd0 (i.e., wd0e) which hasn't -been created yet. wd0e will be seen as a disk device in the new domain, -so it will be 'sub-partitioned'. We could attach a ccd to wd0e in -*domain0* and partition it, newfs and extract the NetBSD/i386 or amd64 -tarballs there, but there's an easier way: load the -`netbsd-INSTALL_XEN3_DOMU` kernel provided in the NetBSD binary sets. -Like other install kernels, it contains a ramdisk with sysinst, so you -can install NetBSD using sysinst on your new domain. +Then, start the domain as "xl create -c configname". -If you want to install NetBSD/Xen with a CDROM image, the following line -should be used in the `/usr/pkg/etc/xen/nbsd` file: +Alternatively, if you want to install NetBSD/Xen with a CDROM image, the following +line should be used in the config file. disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ] After booting the domain, the option to install via CDROM may be -selected. The CDROM device should be changed to `xbd1d`. +selected. The CDROM device should be changed to `xbd1d`. -Once done installing, `halt -p` the new domain (don't reboot or halt, it -would reload the INSTALL\_XEN3\_DOMU kernel even if you changed the -config file), switch the config file back to the XEN3\_DOMU kernel, and -start the new domain again. Now it should be able to use `root on xbd0a` -and you should have a second, functional NetBSD system on your xen -installation. +Once done installing, "halt -p" the new domain (don't reboot or halt, +it would reload the INSTALL_XEN3_DOMU kernel even if you changed the +config file), switch the config file back to the XEN3_DOMU kernel, +and start the new domain again. Now it should be able to use "root on +xbd0a" and you should have a, functional NetBSD domU. +TODO: check if this is still accurate. When the new domain is booting you'll see some warnings about *wscons* and the pseudo-terminals. These can be fixed by editing the files `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in @@ -471,14 +809,20 @@ Finally, all screens must be commented o It is also desirable to add - powerd=YES + powerd=YES 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. +It is not strictly necessary to have a kernel (as /netbsd) in the domU +filesystem. 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) -------------------------------------------- Creating unprivileged Linux domains isn't much different from @@ -490,30 +834,30 @@ the example below) disk = [ 'phy:/dev/wd0e,0x1,w' ] does matter to Linux. It wants a Linux device number here (e.g. 0x300 -for hda). Linux builds device numbers as: (major \<\< 8 + minor). So, -hda1 which has major 3 and minor 1 on a Linux system will have device -number 0x301. Alternatively, devices names can be used (hda, hdb, ...) -as xentools has a table to map these names to devices numbers. To export -a partition to a Linux guest we can use: +for hda). Linux builds device numbers as: (major \<\< 8 + minor). +So, hda1 which has major 3 and minor 1 on a Linux system will have +device number 0x301. Alternatively, devices names can be used (hda, +hdb, ...) as xentools has a table to map these names to devices +numbers. To export a partition to a Linux guest we can use: - disk = [ 'phy:/dev/wd0e,0x300,w' ] - root = "/dev/hda1 ro" + disk = [ 'phy:/dev/wd0e,0x300,w' ] + root = "/dev/hda1 ro" and it will appear as /dev/hda on the Linux system, and be used as root partition. -To install the Linux system on the partition to be exported to the guest -domain, the following method can be used: install sysutils/e2fsprogs -from pkgsrc. Use mke2fs to format the partition that will be the root -partition of your Linux domain, and mount it. Then copy the files from a -working Linux system, make adjustments in `/etc` (fstab, network -config). It should also be possible to extract binary packages such as -.rpm or .deb directly to the mounted partition using the appropriate -tool, possibly running under NetBSD's Linux emulation. Once the -filesystem has been populated, umount it. If desirable, the filesystem -can be converted to ext3 using tune2fs -j. It should now be possible to -boot the Linux guest domain, using one of the vmlinuz-\*-xenU kernels -available in the Xen binary distribution. +To install the Linux system on the partition to be exported to the +guest domain, the following method can be used: install +sysutils/e2fsprogs from pkgsrc. Use mke2fs to format the partition +that will be the root partition of your Linux domain, and mount it. +Then copy the files from a working Linux system, make adjustments in +`/etc` (fstab, network config). It should also be possible to extract +binary packages such as .rpm or .deb directly to the mounted partition +using the appropriate tool, possibly running under NetBSD's Linux +emulation. Once the filesystem has been populated, umount it. If +desirable, the filesystem can be converted to ext3 using tune2fs -j. +It should now be possible to boot the Linux guest domain, using one of +the vmlinuz-\*-xenU kernels available in the Xen binary distribution. To get the linux console right, you need to add: @@ -522,224 +866,187 @@ To get the linux console right, you need to your configuration since not all linux distributions auto-attach a tty to the xen console. -Creating an unprivileged Solaris domain (DomU) +Creating an unprivileged Solaris domain (domU) ---------------------------------------------- -Download an Opensolaris [release](http://opensolaris.org/os/downloads/) -or [development snapshot](http://genunix.org/) DVD image. Attach the DVD -image to a MAN.VND.4 device. Copy the kernel and ramdisk filesystem -image to your dom0 filesystem. - - dom0# mkdir /root/solaris - dom0# vnconfig vnd0 osol-1002-124-x86.iso - dom0# mount /dev/vnd0a /mnt - - ## for a 64-bit guest - dom0# cp /mnt/boot/amd64/x86.microroot /root/solaris - dom0# cp /mnt/platform/i86xpv/kernel/amd64/unix /root/solaris - - ## for a 32-bit guest - dom0# cp /mnt/boot/x86.microroot /root/solaris - dom0# cp /mnt/platform/i86xpv/kernel/unix /root/solaris - - dom0# umount /mnt - - -Keep the MAN.VND.4 configured. For some reason the boot process stalls -unless the DVD image is attached to the guest as a "phy" device. Create -an initial configuration file with the following contents. Substitute -*/dev/wd0k* with an empty partition at least 8 GB large. - - memory = 640 - name = 'solaris' - disk = [ 'phy:/dev/wd0k,0,w' ] - disk += [ 'phy:/dev/vnd0d,6:cdrom,r' ] - vif = [ 'bridge=bridge0' ] - kernel = '/root/solaris/unix' - ramdisk = '/root/solaris/x86.microroot' - # for a 64-bit guest - extra = '/platform/i86xpv/kernel/amd64/unix - nowin -B install_media=cdrom' - # for a 32-bit guest - #extra = '/platform/i86xpv/kernel/unix - nowin -B install_media=cdrom' - - -Start the guest. - - dom0# xm create -c solaris.cfg - Started domain solaris - v3.3.2 chgset 'unavailable' - SunOS Release 5.11 Version snv_124 64-bit - Copyright 1983-2009 Sun Microsystems, Inc. All rights reserved. - Use is subject to license terms. - Hostname: opensolaris - Remounting root read/write - Probing for device nodes ... - WARNING: emlxs: ddi_modopen drv/fct failed: err 2 - Preparing live image for use - Done mounting Live image - - -Make sure the network is configured. Note that it can take a minute for -the xnf0 interface to appear. - - opensolaris console login: jack - Password: jack - Sun Microsystems Inc. SunOS 5.11 snv_124 November 2008 - jack@opensolaris:~$ pfexec sh - sh-3.2# ifconfig -a - sh-3.2# exit - - -Set a password for VNC and start the VNC server which provides the X11 -display where the installation program runs. - - jack@opensolaris:~$ vncpasswd - Password: solaris - Verify: solaris - jack@opensolaris:~$ cp .Xclients .vnc/xstartup - jack@opensolaris:~$ vncserver :1 - - -From a remote machine connect to the VNC server. Use `ifconfig xnf0` on -the guest to find the correct IP address to use. - - remote$ vncviewer 172.18.2.99:1 - - -It is also possible to launch the installation on a remote X11 display. - - jack@opensolaris:~$ export DISPLAY=172.18.1.1:0 - jack@opensolaris:~$ pfexec gui-install - - -After the GUI installation is complete you will be asked to reboot. -Before that you need to determine the ZFS ID for the new boot filesystem -and update the configuration file accordingly. Return to the guest -console. - - jack@opensolaris:~$ pfexec zdb -vvv rpool | grep bootfs - bootfs = 43 - ^C - jack@opensolaris:~$ - - -The final configuration file should look like this. Note in particular -the last line. - - memory = 640 - name = 'solaris' - disk = [ 'phy:/dev/wd0k,0,w' ] - vif = [ 'bridge=bridge0' ] - kernel = '/root/solaris/unix' - ramdisk = '/root/solaris/x86.microroot' - extra = '/platform/i86xpv/kernel/amd64/unix -B zfs-bootfs=rpool/43,bootpath="/xpvd/xdf@0:a"' - - -Restart the guest to verify it works correctly. - - dom0# xm destroy solaris - dom0# xm create -c solaris.cfg - Using config file "./solaris.cfg". - v3.3.2 chgset 'unavailable' - Started domain solaris - SunOS Release 5.11 Version snv_124 64-bit - Copyright 1983-2009 Sun Microsystems, Inc. All rights reserved. - Use is subject to license terms. - WARNING: emlxs: ddi_modopen drv/fct failed: err 2 - Hostname: osol - Configuring devices. - Loading smf(5) service descriptions: 160/160 - svccfg import warnings. See /var/svc/log/system-manifest-import:default.log . - Reading ZFS config: done. - Mounting ZFS filesystems: (6/6) - Creating new rsa public/private host key pair - Creating new dsa public/private host key pair - - osol console login: - - -Using PCI devices in guest domains -================================== - -The domain0 can give other domains access to selected PCI devices. This -can allow, for example, a non-privileged domain to have access to a -physical network interface or disk controller. However, 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, 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 domains (which means that -the primary VGA adapter can't be exported. A guest domain trying to -access the VGA registers will panic). - -This functionality is only available in NetBSD-5.1 (and later) domain0 -and domU. If the domain0 is NetBSD, it has to be running Xen 3.1, as -support has 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 the -`pciback` driver in domain0. Devices passed to the domain0 via the -pciback.hide boot parameter will attach to `pciback` instead of the -usual driver. The list of devices is specified as `(bus:dev.func)`, +See possibly outdated +[Solaris domU instructions](/ports/xen/howto-solaris/). + + +PCI passthrough: Using PCI devices in guest domains +--------------------------------------------------- + +The dom0 can give other domains access to selected PCI +devices. This can allow, for example, a non-privileged domain to have +access to a physical network interface or disk controller. However, +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, +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-dom0 +domains, which means that the primary VGA adapter can't be exported. +A guest domain trying to access the VGA registers will panic. + +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. + +For a PCI device to be exported to a domU, is has to be attached to +the "pciback" driver in dom0. Devices passed to the dom0 via the +pciback.hide boot parameter will attach to "pciback" instead of the +usual driver. The list of devices is specified as "(bus:dev.func)", where bus and dev are 2-digit hexadecimal numbers, and func a single-digit number: - pciback.hide=(00:0a.0)(00:06.0) + pciback.hide=(00:0a.0)(00:06.0) -pciback devices should show up in the domain0's boot messages, and the +pciback devices should show up in the dom0's boot messages, and the devices should be listed in the `/kern/xen/pci` directory. -PCI devices to be exported to a domU are listed in the `pci` array of -the domU's config file, with the format `'0000:bus:dev.func'` +PCI devices to be exported to a domU are listed in the "pci" array of +the domU's config file, with the format "0000:bus:dev.func". + + pci = [ '0000:00:06.0', '0000:00:0a.0' ] + +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 +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 +kernel to use PCI devices in a domU. Here's a kernel config example; +note that only the "xpci" lines are unusual. + + include "arch/i386/conf/XEN3_DOMU" + + # Add support for PCI busses to the XEN3_DOMU kernel + xpci* at xenbus ? + pci* at xpci ? + + # PCI USB controllers + uhci* at pci? dev ? function ? # Universal Host Controller (Intel) + + # USB bus support + usb* at uhci? + + # USB Hubs + uhub* at usb? + uhub* at uhub? port ? configuration ? interface ? + + # USB Mass Storage + umass* at uhub? port ? configuration ? interface ? + wd* at umass? + # SCSI controllers + ahc* at pci? dev ? function ? # Adaptec [23]94x, aic78x0 SCSI + + # SCSI bus support (for both ahc and umass) + scsibus* at scsi? + + # SCSI devices + sd* at scsibus? target ? lun ? # SCSI disk drives + cd* at scsibus? target ? lun ? # SCSI CD-ROM drives + + +NetBSD as a domU in a VPS +========================= + +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 +virtual private server where you do not control or have access to the +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 +configuration. The big issue is usually how one controls which kernel +is booted, because the kernel is nominally in the dom0 filesystem (to +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 +npf, run IPsec, or any other reason why someone would want to change +their kernel. + +One approach is to have an adminstrative interface to upload a kernel, +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 +------ + +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. + +[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. + +Amazon +------ + +See the [Amazon EC2 page](../amazon_ec2/). + +Using npf +--------- + +In standard kernels, npf is a module, and thus cannot be loaded in a +DOMU kernel. + +TODO: Explain how to compile npf into a custom kernel, answering (but +note that the problem was caused by not booting the right kernel) +[this email to +netbsd-users](http://mail-index.netbsd.org/netbsd-users/2014/12/26/msg015576.html). + +TODO items for improving NetBSD/xen +=================================== + +* Make the NetBSD dom0 kernel work with SMP. +* 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. +* 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. +* Solve somehow the issue with modules for GENERIC not being loadable + in a Xen dom0 or domU kernel. - pci = [ '0000:00:06.0', '0000:00:0a.0' ] +Random pointers +=============== -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 -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 kernel -to use PCI devices in a domU. Here's a kernel config example: - - include "arch/i386/conf/XEN3_DOMU" - #include "arch/i386/conf/XENU" # in NetBSD 3.0 - - # Add support for PCI busses to the XEN3_DOMU kernel - xpci* at xenbus ? - pci* at xpci ? - - # Now add PCI and related devices to be used by this domain - # USB Controller and Devices - - # PCI USB controllers - uhci* at pci? dev ? function ? # Universal Host Controller (Intel) - - # USB bus support - usb* at uhci? - - # USB Hubs - uhub* at usb? - uhub* at uhub? port ? configuration ? interface ? - - # USB Mass Storage - umass* at uhub? port ? configuration ? interface ? - wd* at umass? - # SCSI controllers - ahc* at pci? dev ? function ? # Adaptec [23]94x, aic78x0 SCSI - - # SCSI bus support (for both ahc and umass) - scsibus* at scsi? - - # SCSI devices - sd* at scsibus? target ? lun ? # SCSI disk drives - cd* at scsibus? target ? lun ? # SCSI CD-ROM drives - -Links and further information -============================= - -- The HowTo on - Installing into RAID-1 - gives some hints on using Xen (grub) with NetBSD's RAIDframe -- Harold Gutch wrote documentation on - setting up a Linux DomU with a NetBSD Dom0 -- An example of how to use NetBSD's native bootloader to load - NetBSD/Xen instead of Grub can be found in the i386/amd64 MAN.BOOT.8 - and MAN.BOOT.CFG.5 manpages. +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