--- wikisrc/ports/xen/howto.mdwn 2014/12/26 20:28:45 1.50 +++ wikisrc/ports/xen/howto.mdwn 2014/12/31 00:33:48 1.69 @@ -2,17 +2,17 @@ Introduction ============ [![[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 -operating systems on a single physical machine. With Xen, 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. +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 @@ -49,6 +49,8 @@ specific PCI devices can be made availab 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 ------------- @@ -63,15 +65,6 @@ architecture. This HOWTO presumes famil 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 ========================== @@ -158,17 +151,36 @@ Build problems Ideally, all versions of Xen in pkgsrc would build on all versions of NetBSD on both i386 and amd64. However, that isn't the case. Besides aging code and aging compilers, qemu (included in xentools for HVM -support) is difficult to build. The following are known to fail: - - xenkernel3 netbsd-6 i386 - xentools42 netbsd-6 i386 - -The following are known to work: +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 ================ @@ -204,7 +216,9 @@ alternately with little problems, simply 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. +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 ---------------------- @@ -300,6 +314,13 @@ As with non-Xen systems, you should have kernel that works without Xen) and fallback versions of the non-Xen 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 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 @@ -309,6 +330,8 @@ boot.) Configuring Xen --------------- +Xen logs will be in /var/log/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. The @@ -332,27 +355,27 @@ installed 4.1 or 4.2): For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf: - xend=YES xencommons=YES + xend=YES -TODO: Explain why if xm is preferred on 4.1, rc.d/xendomains has xl. -Or fix the package. +(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 - xend=YES xencommons=YES + xend=YES For 4.2 with xl (preferred), add to rc.conf: - TODO: explain if there is a xend replacement 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 or -rebooted, run the following (or use xl) to inspect Xen's boot -messages, available resources, and running domains: +After you have configured the daemons and either started them (in the +order given) or rebooted, run the following (or use xl) to inspect +Xen's boot messages, available resources, and running domains: # xm dmesg [xen's boot info] @@ -403,10 +426,36 @@ 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. +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 --------------------- @@ -427,7 +476,7 @@ 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 anme, domU name and the domU's host +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 @@ -501,6 +550,8 @@ anyplace, reasonable places to store dom (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. @@ -593,7 +644,7 @@ dom0. This is often appropriate when ru 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 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. Sizing domains @@ -693,7 +744,7 @@ It is also desirable to add 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. @@ -748,78 +799,74 @@ See possibly outdated [Solaris domU instructions](/ports/xen/howto-solaris/). -Using PCI devices in guest domains ----------------------------------- +PCI passthrough: 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)`, +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 = [ '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: - - 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? +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". - # USB Hubs - uhub* at usb? - uhub* at uhub? port ? configuration ? interface ? + pci = [ '0000:00:06.0', '0000:00:0a.0' ] - # 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 +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 @@ -830,10 +877,50 @@ hardware. This section explains how to virtual private server where you do not control or have access to the dom0. -TODO: Perhaps reference panix, prmgr, amazon as interesting examples. +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 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. + +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. + +[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: Somewhere, discuss pvgrub and py-grub to load the domU kernel -from the domU filesystem. +TODO: add link to NetBSD amazon howto. Using npf --------- @@ -841,5 +928,22 @@ Using npf In standard kernels, npf is a module, and thus cannot be loadeed in a 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 + +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.