--- wikisrc/ports/xen/howto.mdwn 2014/12/24 00:04:47 1.15 +++ wikisrc/ports/xen/howto.mdwn 2014/12/24 15:17:25 1.29 @@ -27,14 +27,27 @@ code for Xen and need not be aware that Attempts to access hardware registers are trapped and emulated. This style is less efficient but can run unmodified guests. -At boot, the dom0 kernel is loaded as module with Xen as the kernel. +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 NetBSD as a domU in a VPS. +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. Prerequisites ------------- @@ -46,20 +59,26 @@ things must be done, guiding the reader 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. - -For more details on Xen, see [](http://www.xen.org/). +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/). + +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 ========================== -Most of the installation concepts and instructions are independent of -Xen version. This section gives advice on which version to choose. -Versions not in pkgsrc and older unsupported versions of NetBSD are -inentionally ignored. +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 --- @@ -70,7 +89,8 @@ but note that both packages must be inst matching versions. xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3. These no longer -receive security patches and should not be used. +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 @@ -81,30 +101,67 @@ of 2014-12. Ideally newer versions of Xen will be added to pkgsrc. +Note that NetBSD support is called XEN3. It works with 3.1 through +4.2 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. In 4.2 and later, "xl" is preferred. 4.4 is +the last version that has "xm". + 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. +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.) +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.) + Recommendation -------------- -Therefore, this HOWTO recommends running xenkernel42 (and xentools42) -and NetBSD 6 stable branch. +Therefore, this HOWTO recommends running xenkernel42 (and xentools42), +xl, the NetBSD 6 stable branch, and to use amd64 as the dom0. Either +the i386 or amd64 of NetBSD may be used as domUs. 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. Styles of dom0 operation ------------------------ @@ -127,165 +184,107 @@ 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. -Installation of NetBSD and Xen ------------------------------- - -Note that it doesn't make sense to talk about installing a dom0 OS -without also installing Xen itself. - -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 +Installation of NetBSD +---------------------- - 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. - +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. Both xen and NetBSD may be left compressed. (If +using i386, use releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.) + +In a dom0 kernel, kernfs is mandatory for xend to comunicate with the +kernel, so ensure that /kern is in fstab. + +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!) + +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. + +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. + +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 +--------------- + +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 +started because you still have to configure the dom0 tools. + +For 3.3 (and probably 3.1), add to rc.conf (but note that you should +have installed 4.2): + xend=YES + xenbackendd=YES + +For 4.1 and 4.2, add to rc.conf: + xend=YES + xencommons=YES + +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. Updating NetBSD in a dom0 ------------------------- @@ -298,13 +297,75 @@ 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. +To convert from grub to /boot, install an mbr bootblock with fdisk, +bootxx_ with installboot, /boot and /boot.cfg. This really should be +no different than completely reinstalling boot blocks on a non-Xen +system. + Updating Xen versions --------------------- -TODO: write +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. + -Creating unprivileged domains (domU) -==================================== +Unprivileged domains (domU) +=========================== + +This section describes general concepts about domUs. It does not +address specific domU operating systems or how to install them. + +Provided Resources for PV domains +--------------------------------- + +TODO: Explain that domUs get cpu, memory, disk and network. +Explain that randomness can be an issue. + +Virtual disks +------------- + +TODO: Explain how to set up files for vnd and that one should write all zeros to preallocate. +TODO: Explain in what NetBSD versions sparse vnd files do and don't work. + +Virtual Networking +------------------ + +TODO: explain xvif concept, and that it's general. + +There are two normal styles: bridging and NAT. + +With bridging, the domU perceives itself to be on the same network as +the dom0. For server virtualization, this is usually best. + +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. + +One can construct arbitrary other configurations, but there is no +script support. + +Config files +------------ + +TODO: give example config files. Use both lvm and vnd. + +TODO: explain the mess with 3 arguments for disks and how to cope (0x1). + +Starting domains +---------------- + +TODO: Explain "xm start" and "xl start". Explain rc.d/xendomains. + +TODO: Explain why 4.1 rc.d/xendomains has xl, when one should use xm +on 4.1. + +Creating specific unprivileged domains (domU) +============================================= Creating domUs is almost entirely independent of operating system. We first explain NetBSD, and then differences for Linux and Solaris. @@ -335,7 +396,7 @@ PKG\_SYSCONFDIR for its parameters. By d 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 +your system tools, like 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: @@ -445,14 +506,14 @@ like this: !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. +will be created on boot. See the 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: howto.mdwn,v 1.14 2014/12/23 23:43:27 gdt Exp $ + # $NetBSD: howto.mdwn,v 1.28 2014/12/24 14:35:23 gdt Exp $ # # /usr/pkg/etc/xen/vif-bridge # @@ -829,13 +890,16 @@ to use PCI devices in a domU. Here's a k 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](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.) -- An example of how to use NetBSD's native bootloader to load - NetBSD/Xen instead of Grub can be found in the i386/amd64 boot(8) - and boot.cfg(5) manpages. +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. + +TODO: Perhaps reference panix, prmgr, amazon as interesting examples. + +TODO: Somewhere, discuss pvgrub and py-grub to load the domU kernel +from the domU filesystem.